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					 American Journal of Plant Sciences, 2013, 4, 1821-1833  http://dx.doi.org/10.4236/ajps.2013.49224 Published Online September 2013 (http://www.scirp.org/journal/ajps)  Phenotypic and Molecular Characterization of Wheat Leaf  Rust Resistance Gene Lr34 in Iranian Wheat Cultivars and  Advanced Lines  Seyed Taha Dadrezaei1,2*, Kumarse Nazari3, Farzad Afshari2, Ebrahim Mohammadi Goltapeh1    1College of Agriculture, TarbiatModares University, Tehran, Iran; 2Seed and Plant Improvement Institute (SPII), Karaj, Iran; 3Inter- national Center for Agricultural Research in the Dry Areas (ICARDA), Aleppo, Syria.  Email: *tahareza2000@yahoo.com    Received April 20th, 2013; revised May 20th, 2013; accepted June 15th, 2013    Copyright © 2013 Seyed Taha Dadrezaei et al. This is an open access article distributed under the Creative Commons Attribution  License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.  ABSTRACT  Lr34 is a vital gene in developing resistance to leaf rust, stripe rust, and powdery mildew of wheat. Providing simulta-  neous resistance to various pathogens has made this gene valuable in breeding for wheat resistance to many diseases.  The present study investigates the csLV34 marker’s capability in diagnosing this locus in130 wheat commercial cultivars  and advanced wheat lines from Iran, and assesses the impact of this gene on disease severity in field conditions. To as-  sess the reactions of cultivars and lines which contained Lr34 under epidemic conditions of leaf rust, these cultivars were  cultivated during the 2009 and 2010 cropping season. Of the 130 studied cultivars, 43 contained Lr34. Cultivars that  were selected and studied in stress conditions had the most frequent presence of Lr34. It can be concluded that this gene  plays a vital role in increasing the tolerance of cultivars under stress conditions. Lr34 seems to cause active transition of  materials out of the cell. In addition to being resistant to several important diseases of wheat, Lr34 can increase tolerance  to stresses such as salinity. Considering the calculated value for AUDPC (3% - 440%/d) in cultivars containing Lr34, it  seems that some cultivars contained additional resistance genes. The rate of infection in all cultivars, when presence of  Lr34 was detected through the molecular marker, was lower than in other cultivars. Field results confirmed the results of  the analysis using the csLV34b molecular marker.    Keywords: Lr34 Gene; AUDPC; Salinity Stress; Leaf Rust; Puccinia triticina  1. Introduction  Leaf rust caused by Puccinia triticina (Pt) is the most  common and widely distributed of the three wheat rusts.  Although losses from leaf rust are usually less damaging  than those from stem rust and stripe rust, because of its  regular and widespread occurrence, the global leaf rust  damages are greater than the other two rust [1,2]. Wheat  leaf rust is present in all wheat growing areas in Iran. In  general, leaf rust is the second most important disease of  wheat in Iran but in southern areas leaf rust is the most  important disease of wheat [3]. The Pt population in Iran  is extremely dynamic and a large number of races were  found in a recent study of pathogenic variability of Pt  population in Iran [4]. Improving the resistance of wheat  cultivars to this disease is a preventive strategy with the  greatest effect on reducing its damage. Rust resistance  genes in wheat can be categorized into two groups: seed-  ling resistance genes and adult plant resistance (APR)  genes. Seedling resistance genes appear in both the seed-  ling and adult plant stages and can be recognized; as a  result, they show resistance in all phenotypic stages.  Seedling resistance genes often lead to a hyper sensitive  reaction (cell death-HR) or to lignifications of the cell  membrane [5]. Adult plant gene resistance acts non-spe-  cifically on race pathogens in the adult plant stage, and  cultivars containing these genes are susceptible at seed-  ling stage and have various levels of comparative resis-  tance to disease at the adult plant stage [6]. This type of  resistance is called race non-specific gene resistance since  there is no relationship between host genes and pathogen  genes. Additionally, it provides resistance to all pathogen  isolates. Compared with susceptible plants, Lr34 resistance  has a longer period of infection with fewer and smaller  uredinial pustules at two weeks after infection [6,7].  *Corresponding author.  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1822  More than 70 leaf rust resistance genes have been iden-  tified, most of which are involved in race-specific cate-  gory and follow the boom and bust cycle due to the high  pathogenic variability of Pt population. Among the race  non-specific genes, the Lr34/Yr18 complex [7], Lr46 [8]  and Lr67 [9] are the most commonly used genes in global  wheat. The Lr34 gene was initially introduced as an APR  gene in cultivar “Frontana” [10], this gene encoding ATP  Binding Cassette (ABC) transporter[7], with the locus of  the gene on the short arm of wheat chromosome 7D [11].  With few exceptions, the race specific genes are asso-  ciated with a very short durability. There is increasing  interests in identification and development of race-non-  specific slow rusting genes which have been shown to be  more durable than race-specific genes [12,13]. So far leaf  rust pathogens have not been reported as virulent on Lr34  [7,14]. Lr34 is genetically linked with the stripe rust  adult-plant resistance gene Yr18, morphological marker  leaf tip necrosis (Ltn1) [15], and an adult-plant powdery  mildew resistance gene (Pm38) [16,17]. Tolerance to  Barley yellow dwarf virus (Bdv1) in Lr34 carrying culti-  vars is also reported [18]. The incorporation of leaf rust  resistance gene Lr34 into “Thatcher” background is  known to enhance stem rust resistance [10,11]. These si-  multaneous resistances to several pathogens have made  the Lr34/Yr18 locus one of the most valuable gene regions  for disease resistance breeding in wheat. Leaf tip necrosis  (Ltn1) has been used as a phenotypic marker for field  selection of slow-rusting resistance conferred by Lr34/  Yr18 [15] by national and international breeding programs,  but because of variable expression of Ltn1 under differ-  ent environmental conditions and in different genetic  background [18], the leaf tip necrosis could not be used  as a reliable and diagnostic marker.  Development and application of molecular markers for  Lr34/Yr18 have been an important objective in marker-as-  sisted selection in breeding for durable leaf rust resis-  tance. Application of previously developed markers, such  as gwm295 and gwm1220 [19,20], has shown their lim-  ited use in breeding application due to their low diagnos-  tic capability in precise detection of Lr34 in different ge-  netic backgrounds. During the last few years significant  progress has been made in the development of more  closely linked markers for Lr34/Yr18 complex trait such as  SWM10 and csL V 34 [21]. More recently, Kolmer et al.  (2008) [18] confirmed robustness of a tightly linked  csLV34 marker with Lr34/Yr18 across a wide range of  global wheat germplasm and its utility in wheat breeding.  In present study seedling and adult-plant assessment of  resistance to leaf rust coupled with application of the  tightly linked marker csLV34 with Lr34/Yr18 were used in  the characterization of adult-plant resistance of some of  the Iranian bread and durum wheat genotypes to leaf rust.  2. Materials and Methods  2.1. Plant Materials  There were 130 commercial wheat cultivars and ad-  vanced lines of hexaploid and tetraploid wheat from Iran  (Table 1). Seeds of test genotypes were obtained from  department of cereal research at Seed and Plant Improve-  ment Institute Research (SPII), Karaj, Iran. A set of That-  cher near isogenic lines (TcNILs) were used both at seed-  ling and adult-plant assessments. Seeds of TcNILs were  kindly provided by International Maize and Wheat Im-  provement Center (CIMMYT). The universal leaf rust  susceptible cultivar “Thatcher” and a local susceptible  cultivar “Bolani” were used in seedling and adult plant  tests.  2.2. Seedling Test  Assessment of seedling resistance was carried out at ce-  real rust pathology laboratory at SPII. The 130 test ge-  notypes and leaf rust Thatcher near isogenic lines were  used in seedling assessment against a local Pt isolate.  Eight to 10 seeds of each genotype were planted in a 9  cm diameter pot filled with potting mix at two replica-  tions. The seedlings were grown in a rust-free green-  house at 20˚C and 16 hours light. At two leaf stage, seed-  lings were inoculated with the local leaf rust isolate col-  lected from the field trial site at Khuzestan Agricultural  Research Station, in south of Iran. This isolate used in  seedling tests and field inoculations. Urediniospores stored  at −80˚C were first heat shocked at 42˚C for 5 minutes  and then mixed with Talcum powder (1:4). Seedlings  were inoculated with the talc-spore mixture using a small  duster. Inoculated plants were placed overnight in a hu-  mid chamber at 17˚C ± 2˚C and dark condition. After the  incubation period, plants were placed in a greenhouse  with 20˚C ± 2˚C and 16 hrs supplementary light. Seed-  ling infection types were recorded 12 days post-inocu-  lation using; (fleck) and 0 to 4 scale [22]. Infection types;  and 0 to 3 were considered resistant reactions, while in-  fection types higher than 3 were considered as suscepti-  ble.  2.3. Field Experiments  In order to evaluate adult-plant resistance of test geno-  types and TcNILs, a field trial was carried out under mist  irrigation system at Khuzestan Agricultural Research  Center in 2009. Each genotype was planted as two 1-m  row plot and 30 cm space. To facilitate inoculum build-  up and uniform dissemination of infection, the suscepti-  ble cultivar Bolani was planted perpendicular to the rows  of entries. Bolani was also planted at each 10 plot inter-  vals. Disease epidemic was created by artificial inocula-   Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  Copyright © 2013 SciRes.                                                                                 AJPS  1823 ger UV (Gel DocTM XR Bio rad Universal Hood II) was  used for visualization and documentation of banding pat-  terns.  tion of the local leaf rust isolate collected from the same  site in 2008. Preserved urediniospores were first multi-  plied on susceptible cultivar Bolani under greenhouse  conditions following the above described procedure. Fre-  shly collected urediniospores were mixed with talcum  powder and inoculation was carried over entries after  misting irrigation at late afternoons by atomizer back-  pack duster. First inoculation was started at 20 January  2010 when plants were at tillering stage and it was re-  peated four times at fortnight intervals. Disease severities  (0% - 100%) were recorded according to the Modified  Cobb’s scale [23] and the adult-plant reactions were re-  corded for the major infection types R (resistant), MR  (moderately resistant), MS (moderately susceptible) and  S (susceptible) according to Roelfs et al. (1992) [24].  Field scoring started from early onset of uniform infec-  tions in Bloani with 10 days intervals. Data on the dis-  ease severities and infection types were used in calcula-  tion of coefficient of infection (CI) for each individual  score [24].The area under the disease progress curve  (AUDPC) [25] was then calculated as follows using the  CIs for three disease scores:  3. Results  3.1. Molecular Marker Screening  The presence of a 150-bp band is diagnostic of the Lr34  gene, indicating the presence of Lr34 in cultivars and lines  carrying the gene. This band belongs to the csLV34b al-  lele, which is associated with Lr34. Another longer band  (229-bp) is produced and belongs to the csLV34a allele,  which is associated with the absence of Lr34; i.e. when  the cultivar does not contain Lr34, and then the longer  band is produced. However, in cultivars that are het-  erozygous both alleles are present and so both bands are  generated simultaneously.  Of the130 investigated genotypes, 87 lacked Lr34;  shown by the presence of the 229-bpband of allele  csLV34a. There were 43 genotypes with Lr34, shown by  the presence of the 150-bp band. These 43genotypes  were divided into two groups: 26 homozygous cultivars  with the 150-bp band and17 genotypes with both the  229- and 150-bp bands. Of the 17 hetero zygous geno-  types, 15 had unique phenotype markers. In these 15 ge-  notypes, there produced PCR product possessed a three-  band pattern consisting csLV34 a and  csLV34b alleles,  both of which were accompanied by an additional band  with a higher molecular weight (280 bp). In the study of  global wheat cultivars Kolmer et al. (2008) observed the  three-band pattern in heterozygous cultivars; however,  most heterozygous cultivars had a two-band pattern and  cultivars with a three-band pattern were less frequent.  Moreover, the positive control sample in the present study  was the 150-bp band; and “Thatcher”, susceptible “Bo-  lani”, and all susceptible cultivars only produced the 229-  bp band and the negative control sample (water) had no  bands (Figure 1).   i1 N ii1 i1 i i1 yy AUDPCt t 2           with:  i—index for scoring date;  yi—Coefficient of leaf rust infection at scoring date i;  ti—scoring date i expressed in days after scoring date 1;  n—total number of scoring dates in the trial.  2.4. DNA Extraction and PCR Analysis  For extraction of genomic DNA, 100 mg of harvested  leaves from 14 days old seedlings of each tested geno-  type was ground to fine powder on liquid nitrogen. The  fine powder was immediately transferred into a 2 ml  tubes and the small scale DNA extraction protocol was  followed as described in CIMMYT applied molecular  protocol [26]. PCR reaction was performed in 20 μl for  the CsLV34 marker following published protocol [18,21]  in a PTC 100 Thermocycler (MJ Research, Waltham,  MA). The PCR product was separated on 1.5% agarose  gel containing TBE 0.5× buffer. Digital molecular ima-  There was a high frequency of csLV34 allele (150 bp),  which is associated with Lr34 in the assessed Iranian lines  and cultivars. Of the 130 studied genotypes, 43 contained  the diagnostic Lr34 allele, representing a frequency of  33% (Table 1) as follows:      csLV34b (229 bp)  csL 34b (150 bp)  1     2     3  4    5  6     7    8    Figure 1. Polymerase chain reaction amplification products from wheat cultivars using csLV34 marker. 1. Thatcher +Lr34  (Lr34); 2. Falat (Lr34); 3. Ghods (Lr34); 4. Star (heterozygote); 5. Bam (Lr34); 6. Dez (Lr34); 7. Aflak (Lr34); 8.  Cham ran  (Lr34).  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1824  Table 1. Verification of Lr34 by applied molecular marker csLV34 and comparison of leaf rust infection in Iranian commer- cial wheat cultivars and advanced lines in adult and seeding plant.  Entry   No Wheat variety Pedigree  Final field  score  Seedling  infection type AUDPC csLV34 1 Chamran Attila,(CM85836-50Y-OM-OY-3M-OY) Bread  Wheat 10MS 2 44 a  2 Falat Kvz/Buho"s"//Kal/Bb= Seri82 Bread  Wheat 5MS 0 22 a  3 Maron Avd*Pchu((28mt54A*N10-Brv21-  1c/Kt54B)Nar59,1093))7c  Bread  Wheat 30MS 2 290 a  4 Navid (Kirkpinar 79) 63-112/66-2*7C Bread  Wheat 40MS 3 340 a  5 Hirmand Byt/4/Jar//Cfn//Sr70/3/Jup"s" Bread  Wheat 5MS ; 23 b  6 Alvand 1-27-6275/CF1770 Bread  Wheat 60MS 3 580 a  7 Alamoot KVZ/Ti71/3/Maya"s"//Bb/Inia/  4/Kj2/5/Anza/3/Pi/Ndr//Hys  Bread  Wheat 30MS N , 1 220 a  8 Mahdavi Ti/Pch/5/Mt48/3/Wt*//Nar59/  Tota63/4/Mus  Bread  Wheat 50MS 2 560 a  9 Zarin PK15841 Bread  Wheat 5MS ; , 1 23 a  10 Darab 2 Maya"s"/Nac Bread  Wheat 10MS ; , 1 44 b  Check Susceptible  control Bolany Bread  Wheat 80S  1120 a  11 Chanab Chanab Bread  Wheat 40MS 3 414 a  12 Tajan Bow"s"/Nkt"s"(CM67428-GM-LR-  5M-3R-LB-Y)  Bread  Wheat 20MS N , 1 90 b  13 Atrak Bow"s"/Nkt"s"(CM67428-GM-LR-  5M-3R-LB-Y)  Bread  Wheat 30MS 0 282 b  14 Nicknejad F13471/Crow"s" Bread  Wheat 30MS 3- 129 b  15 Kavir Stm/3/Kal//V534/Jit716 Bread  Wheat 30MS 2 , 1 202 a  16 Shirodi Attila,(CM85836-4Y-OM-OY-  8M-OY-opz)  Bread  Wheat R 0 4 a  17 Marvdasht HD2172/Bloudan//Azadi Bread  Wheat 5MS 0 24 a  18 Pishtaz Alvand//Aldan/Ias58 Bread  Wheat 20MS 2 242 a  19 Shiraz Gv/D630//Ald"s"/3/Azd Bread  Wheat 50S 3 510 a  20 Dez Kauz*2/Opta//Kauz Bread  Wheat 10MR 0 41 b  Check Susceptible   control Bolany Bread  Wheat 90S  1410 a  21 Hamon Falat/Roshan Bread  Wheat 80S 3+ 660 a  22 Toos "Spn/Mcd//Cama/3/Nzr" Bread  Wheat 50S 3 572 a  23 Shahriar KVZ/Ti71/3/Maya"s"//Bb/Inia/4/  Kj2/5/Anza/3/Pi/Ndr//Hys  Bread  Wheat 50MS 2 250 a  24 Ghods Rsh/5/Wt/4/Nor10/K54*2//Fn/3/Ptr/  6/Omid//Kal/Bb  Bread  Wheat 60S 2 630 a  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines 1825 Continued  25 Sistan Bank"s"/Vee"s" Bread   Wheat 30MS 3 202 b  26 Bam Vee"s"/Nac//1-66-22 Bread   Wheat 30MS 2 202 b  27 Neishabour 1-63-31/3/12300/Tob//cno/sx Bread   Wheat 30MS 3- 200 b  28 Bahar Bloyka Bread   Wheat 10MS ; , 1 42 a  29 Moghan 1 (LR-N10B)*An3E Bread   Wheat 30MS 3 282 b  30 Moghan 2 chotiLerma Bread   Wheat 30MS 2 , 1 200 b  Check Susceptible   control Bolany Bread   Wheat 70S  1010 a  31 Moghan 3 Luan/3/V763.23/V879.C8//Pvn/4/  Picus/5/Opata  Bread   Wheat 20MS ; 120 a  32 Darya SHAU/Chil Bread   Wheat 20MS 1 , 2 400 a  33 Yavarous Yavaros79 Durum  wheat 5MR 1 10 MIS  34 Zagros CN,79/7/2*Seri82 Bread   Wheat R 1++ 3 b  35 Arta Arta Bread   Wheat 20MS ; 161 a  36 Sepahan Azd/5/L2453/1347/4/Kal//Bb/Kal/3/  Au//Y50E/Kal*3  Bread   Wheat 20MS N , 1 160 b  37 Star Star"s" Bread   Wheat 20MS 2+ 120 b  38 Dena Tarro3 Durum  wheat R ; 3 MIS  39 Pishgham Bkt/90-Zhong87 Bread   Wheat 70MS 3 530 a  40 Sabalan 908*FnA12)*1-32-4382 Bread   Wheat 50MS 3 620 a  Check Susceptible   control Bolany Bread   Wheat 90S   1310 a  41 Sivand Kaus"s"/Azd Bread   Wheat 10MR 2 40 a  42 Omid Omid Bread   Wheat 50MS 3 540 a  43 Shapasand Shapasand Bread   Wheat 90S 3 1130 a  44 Karaj 1 (200H*Vfn)Rsh Bread   Wheat 80S 3 1040 a  45 Karaj 2 (Fa*Th-Mt)Omid Bread   Wheat 70S 3 990 a  46 Karaj 3 (Drc*Mxp/Son64*Tzpp-Y54)Nai60 Bread   Wheat 60MS 3 580 a  47 Rasool Veery"s"=Kvz/Buho "s"//Kal/BB Bread   Wheat 40MS ; 440 b  48 Tabasea Tabasea Bread   Wheat 80S 3 1040 a  49 Adl Adl Bread   Wheat 50S 3 710 a  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1826  Continued  50 Inia Inia Bread  Wheat 40MS 1 402 b  Check Susceptible   control Bolany Bread  Wheat 100S  1280a  51 Golestan Alondra”s” Bread  Wheat 20MS 2 161 a  52 Alborz Fn-Md*K117a/Cofn2(Son64-k1.Rend/  Cno”s”LR642-SON64)CM-2182  Bread  Wheat R N , 1 81 a  53 Kaveh Fta-P1 Bread  Wheat 50S 3 590 a  54 SorkhTokhm SorkhTokhm Bread  Wheat 80S 3 1160a  55 Azar 2 Azar 2 Bread  Wheat 40MS 2 482 a  56 Morvaread ilan/shaw7 Bread  Wheat R ; 3 a  57 Gaspard Gaspard Bread  Wheat 10MS 1+ 46 a  58 Gascogen Gascogen Bread  Wheat 20MS 2+ 122 a  59 Sayvan Sayvan Bread  Wheat 40MS 2 490 a  60 MV-17 MV-17 Bread  Wheat R ; 3 b  Check Susceptible   control Bolany Bread  Wheat 70S  1150a  61 Karkheh Shwa/Mald//Aaz Durum  wheat R 1 3 MIS 62 Arya Stork Durum  wheat 20MS 2 160 MIS 63 N-88-3 MERUA//TURACO/CHIL/3/TAJAN Bread  Wheat 30MS 2 160 a  64 N-86-4 MILAN CM75118//KA CM 75118/  K1/3/TAJAN (DH)  Bread  Wheat 20MR ; 80 a  65 N-86-6  VORONA/CNO79//KAUZ/3/MILAN Bread  Wheat R 0  3 a  66 N-86-11 CMH82A.1294/2*KAUZ//MUNIA/  CHTO/3/MILAN  Bread  Wheat R 0 3 a  67 N-87-4 BAV92/PRINIA//TAM200/PRL Bread  Wheat R 0 3 a  68 N-87-6 JIMAI36/3/3/OASIS/SKAUZ//  4*BCN/4/89ZHONG2  Bread  Wheat 10MR 0 40 a  69 N-87-9 SUNSU/PBW343 Bread  Wheat R 0 3 a  70 N-87-13  PF74354//LD/ALD/4/2*BR12*2/3/  JUP//PAR214*6/FB6631/5/  SW89-5124*2/FASAN/6/TILH  Bread  Wheat R 0 3 a  Check Susceptible   control Bolany Bread  Wheat 80S  1060a  71 N-87-16  NANJING2149/KAUZ/4/JUP/ALD”S”//  KIT”S”/3/VEE”S”/5/SHA 7//  HAHN”S”*2/PRL”S”  Bread  Wheat 30MS 3 160 a  72 C-87-14 SHA 7//HAHN”S”*2/PRL “S”/3/ATRAK Bread  Wheat 10MR 0 62 a  73 C-83-7 Alvand//Ns732/Her Bread  Wheat 40MS 2 402 a  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines 1827 Continued  74 C-83-8 130L1.11//F35.70/Mo73/4/Ymh/Tob  //Mcd/3/Lira  Bread  Wheat 10MS 2 122 b 75 C-84-8 Mihan = BKT/90Zhong87 Bread  Wheat 50MS 0 560 a 76 C-85-6 Mv17/Zrn Bread  Wheat 30MS 0 122 b 77 C-85-3 Ghk"S"/Bow"S"//90Zong87/3/Shiroodi Bread  Wheat 30MS 0 202 a 78 C-86-3 Bloudan/3/Bb/7C*2//Y50E/3*Kal/4/Mv17 Bread  Wheat 40MS 2 420 a 79 C-86-5 Yan7578.128//Chil/2*Star Bread  Wheat 40MS 3 340 b 80 C-86-6 Yan7578.128//Chil/2*Star Bread  Wheat 40MS 3 242 a Check Susceptible   control Bolany Bread  Wheat 80S  1020 a 81 M-85-6 Seri 82//Shuha"S"/4/Rbs/Anza/3/Kvz/  Hys//Ymg/Tob  Bread  Wheat 10MS 2++ 122 b 82 M-85-7 Seri82//Shuha"S"/4/Rbs/Anza/3/Kvz/  Hys//Ymg/Tob  Bread  Wheat R 3 4 b 83 M-85-15 Mv22-77//Stephon/3/Mon"s"/Lmu"s"//  Falke/4/Zarin  Bread  Wheat 50S 3 690 a 84 M-85-16 PASTOR/3/VORONA/CNO79//KAUZ Bread  Wheat R ; 4 a 85 M-85-16 PASTOR/3/VORONA/CNO79//KAUZ Bread  Wheat R ; 3 a 86 M-86-3 Gaspard/3/Jup/Bjy//Kauz/4/Kayson/Glenson Bread  Wheat 5MR 0 19 a 87 M-86-5 Alvd//Aldan/Ias*2/3/Gaspard Bread  Wheat 40MS 2+ 241 a 88 M-86-7 Alvd//Aldan/Ias/3/Druchamps/4/kauz/Stm Bread  Wheat 30MS 1 201 a 89 M-86-9 Owl 85256-*3OH-*O-*EOH/Mv17/  3/Alvd//Aldan/Ias  Bread  Wheat 40MS 3 401 a 90 M-87-18 BABAX/LR42//BABAX Bread  Wheat R ;  3 a Check Susceptible   control Bolany Bread  Wheat 60S  960 a 91 Aflak S-80-18 Bread  Wheat 5MR 3 12 b 92 S-83-3 Attila 50Y//Attila/Bcn Bread  Wheat R 0 3 a 93 S-83-4 F60314.76/MRL//CNO79/3/KA/NAC/  4/STAR  Bread  Wheat R 0 3 b 94 S-84-14 PASTOR/3/KAUZ*2/OPATA//KAUZ Bread  Wheat 10MS ; 48 b 95 S-85-19 INQALAB91*2/KUKUN Bread  Wheat R ; 3 a 96 S-87-2 VEE/PJN//2*KAUZ/3/PASTOR Bread  Wheat 5MR 0 12 a 97 S-87-8 KAUZ*2/BOW//KAUZ/3/BABAX Bread  Wheat 10MR 3 22 a 98 S-87-12 PASTOR/3/VORONA/CNO79//KAUZ Bread  Wheat 5MR ; 12 a Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1828  Continued  99 S-87-18 CBRD-3/STORK X DICOCCOIDES Bread   Wheat 5MR ; 12 a  100 S-87-20 OASIS/SKAUZ//4*BCN/3/2*PASTOR Bread   Wheat 30MS ; 122 b  Check Susceptible   control Bolany Bread   Wheat 70S  1070 a  101 S-87-21 520- BABAX/LR42//BABAX*2/  3/VIVITSI  Bread   Wheat R 0 3 a  102 DM-79-2 PORTO-7 Durum  wheat 5MR 0 16 MIS  103 DM-81-6 PLATA-1/SNM//PLATA-9 Durum  wheat R ; 3 MIS  104 DM-82-6 SOOTY-9/RASCON-37 Durum  wheat R ; 3 MIS  105 DM-83-10 AUK/GUIL//GREEN Durum  wheat R ; 3 MIS  106 DM-84-3 RASCON-37/BEJAH-7 Durum  wheat R ; 4 MIS  107 DM-85-10 RASCON-37/BEJAH-7 Durum  wheat 5MR ; 12 MIS  108 WS-85-10 PRL/2*PASTOR Bread   Wheat 10MR 3 22 a  109 WS-85-15 PBW343*2/KONK Bread   Wheat R 0 3 b  110 WS-86-5 Shi#4414/Crow"S"//Azd Bread   Wheat R 0 3 a  Check Susceptible   control Bolany Bread   Wheat 80S  1080 a  111 WS-86-8 SW89.5181/KAUZ Bread   Wheat R 0 25 b  112 WS-86-11 MUNIA/3/RUFF/FGO//YAV79/4/  PASTOR  Bread   Wheat 20MS ; 83 a  113 WS-86-12 PJN/BOW//OPATA*2/3/CROC_1/  AE.SQUARROSA (224)//OPATA  Bread   Wheat 10MS 0 42 b  114 WS-86-13 VORONA/CNO79//KAUZ/3/MILAN Bread   Wheat 5MS 0 22 a  115 WS-86-14 KAUZ/PASTOR Bread   Wheat 20MS 0 82 b  116 MS-85-15 Ombu/Alamo//Mahooti/3/1-66-22 Bread   Wheat 30MS 0 124 b  117 MS-85-12 Ombu/Alamo//Alvd/3/Kauz/Stm Bread   Wheat 30MS 1 160 b  118 MS-84-13 GF-gy54/Attila Bread   Wheat 40MS 3 242 b  119 MS-85-17 Sakha 8/Darab#2//1-66-22 Bread   Wheat 30MS 3 204 b  120 MS-84-16 Gkzombor/Zrn Bread   Wheat 30MR 3 300 a  Check Susceptible   control Bolany Bread   Wheat 80S  1300 a  121 SS-85-6 1-66-22/3/GUP/BGY//kauz Bread   Wheat 30MS 3 202 b  122 SS-85-10 OMBU/ALAMO//ALVD/3/1-66-22 Bread   Wheat 30MS 3 202 b  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  Copyright © 2013 SciRes.                                                                                 AJPS  1829 Continued    123 SS-85-11 OMBU/ALAMO//MAHOOTI/3/1-66-22 Bread   Wheat 30MS ; 202 b  124 SS-85-14 SAKHA 8/DARAB#2//1-66-22 Bread   Wheat 30MS ; 282 b  125 SS-85-20 OMBU/ALAMO//KAV/3/PASOR/  SORKHTOKHM..  Bread   Wheat 30MS 0 202 b  126 DW-79-5 LAGOST-2 Durum  wheat 20MS ; 89 b  127 DW-81-18 SORA/2*PLATA12 Durum  wheat 20MS ; 85 b  128 DW-84-5 GREEN_14//YAV_10/AUK Durum  wheat R ; 6 MIS  129 Bezostaya Bezostaya Bread   Wheat  3  b  130 Veerynak Veerynak Bread   Wheat  2  a  Check Susceptible   control Bolany Bread   Wheat 100S 3+ 1280 a  Check Positive   control Thatcher (Lr34) Bread   Wheat 30MS 3- 300 b    Among commercial Iranian cultivars, 18 of 64 culti-  vars contained csLV34b, indicating presence of Lr34; only  “Hirmand” and “Bam” which were the result of national  crossing program, which had origin in international germ-  plasm.  None of the nine advanced lines bread wheat for the  warm and humid climate of northern Iran carried Lr34, i.e.  they contained csLV34a. Among the nine advanced lines  bread wheat for cold climates, three had Lr34; among the  11 advanced lines bread wheat for the warm climate of  the south, five carried Lr34.  From nine lines bread wheat for mild climates, two  had the 150-bp band indicating the presence of Lr34.  However, cultivars studied in environmental stress con-  ditions and selected to assess their tolerance of these  conditions were totally different as follows. Among the  eight chosen advanced lines bread wheat for humid stress  conditions, four had Lr34 (50%). Of the five selected ad-  vanced lines bread wheat for saline conditions located in  mild climate areas, four contained Lr34; among five ad-  vanced lines bread wheat for saline conditions in the  warm climate of the south, all five carried Lr34, i.e. 90%  of advanced cultivars bread wheat to tolerate salinity  contained Lr34. It seems that cultivars carrying Lr34 could  better tolerate stress conditions, and most cultivars pre-  viously introduced for areas with salinity stress in mild  climates such as “Hirmand”, “Sistan”, “Neishabour”,  “Nicknejad”, “Tajan”, and “Darab2” contained Lr34.  “Inia” is a cultivar resistant to salinity in experiments and  also contained Lr34. “Star” is a late maturity cultivar, and  is presently widely cultivated in Khuzestan Province. In  evaluation of salinity resistance of wheat cultivars in  laboratory and field conditions, the percentage of germi-  nation and seedling establishment of “Star” under saline  conditions was good relative superiority. “Bam” was re-  cently introduced for mild climate areas with soil and  water salinity stress, and contains Lr34 [27]. Cultivars that  were not resistant to environmental stress such as salinity  lacked Lr34, e.g. lines bread wheat for the northern cli-  mate or cultivars “Darya”, “Golestan”, “Alborz”, “Kaveh”,  and “Bahar” (Table 1).  In the present research, 13 genotypes of durum wheat  were also investigated, four cultivars and seven lines of  which did not produce any bands to confirm the presence  or absence of Lr34. A separate experiment for these cul-  tivars was repeatedly conducted with positive and nega-  tive controls and a similar result was obtained. Absence  of a reproduced band or piece in durum wheat was likely  due to the lack of the D genome since Lr34 is located on  the small arm of chromosome 7 of genome D and prim-  ers should be placed on this part to be reproduced. Be-  cause of the absence of this genome in tetraploid culti-  vars (e.g. durum wheat), this piece was not reproduced in  these cultivars.  3.2. Phenotypic Characterization  About 44 cultivars gave R or MR reactions in field as-  sessment, among which only eight carried Lr34. Most  cultivars (35 genotypes) contained Lr34 or were MS. The  estimated AUDPC for cultivars carrying Lr34 was within  3% - 440%/day, indicating that some cultivars may carry  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1830  some other resistance genes as well as Lr34. This was  confirmed by further studies conducted with other mark-  ers of race-specific genes on the same cultivars (unpub-  lished data). In wheat cultivars with a combination of  resistance genes genetic infection type with the highest  resistance conceals the impact of the type with lower in-  fection; therefore, these cultivars that contain race-spe-  cific resistance genes in addition to Lr34, an infection  type of R or MR is seen instead of MS resistance type  and the presence of Lr34 is masked by other main genes.  Accordingly, methods such as molecular methods which  can easily identify this gene are important. The pheno-  typic method used currently relies on Ltn1 and makes it  very difficult to recognize Lr34 from the visual phenotype  of leaves since Ltn1 does not express equally in different  environments. This method requires a lot of experience  and the results are not always correct.  AUDPC for the examined cultivars in the present  study was within 3% - 1410%/day. AUDPC of control  susceptible “Bolani”, which was repeated 13 times among  the field-grown cultivars (was planted at the end of the  experiment and after each plot of 10 cultivars as suscep-  tible control), was calculated to be 960% - 1410%/d, this  difference in AUDPC is the result of environment.  AUDPC of other cultivars, except for that of the sus-  ceptible control (Check), was 3% - 1160%/day. The lower  AUDPC belonged to cultivars that were resistant due to  their effective race-specific resistance genes and were  discussed previously. The results showed that AUDPC of  500% - 800%/day indicated a susceptible cultivar and  AUDPC > 800 indicated a too susceptible one.  In this experiment AUDPC < 500 was regarded as ac-  ceptable resistance because about two months after an epi-  demic of the disease and at the time of maximum flag  leaf efficiency in photosynthesis and grain filling, the  maximum infection remained at 40 MS. The highest  AUDPC for genotypes containing Lr34 was for “Rasool”,  “Inia”, and line C-86-5 with values 440%, 402%, and  340%/day, respectively. Most lines and cultivars con-  taining this gene had AUDPC of about 200%/day and  “Thatcher” had 300%/day. Accordingly, AUDPC of 250  - 500 was considered as semi-susceptible or relatively re-  sistant; AUDPC of 150 - 250 was considered semi-re-  sistant, and AUDPC < 150 was considered resistant.    The flag leaf plays a crucial role in grain filling. The  surface of this leaf in susceptible cultivars can be rapidly  covered with leaf rust pustules at the time of grain filling.  As a result, the entire surface can be infected and so  harms its function. However, cultivars containing Lr34  are resistant to rapid development of the pathogen and  delay it. The flag leaf of such cultivars is more capable of  grain filling and incurs less damage.  In epidemics, leaf rusts do much damage to flag leaves;  therefore, assessing resistance to leaf and yellow rust at  the adult plant stage is very important in improvement  programs. Most assessment of resistance to leaf rust is  done on the flag leaf because severity of the disease on  leaves reflects the primary growth of the pathogen and  damage to the plant [24].  An obvious advantage of presence of Lr34/Yr18 in cul-  tivars is the absence of high intensities of infection at the  end of the wheat growing season. However, cultivars that  do not contain this gene can be highly infected by leaf  rust during the whole growing season. Cultivars with  race-specific genes, which are widely used in cultivars,  are expected not to show long-term resistance for patho-  types that are virulent on the Lr9 resistance gene. These  were previously discussed by Kolmer [28]. However, if  resistance of a race-specific gene is broken, Lr34 prevents  rapid epidemics of the disease and major damage. In all  cultivars in which the presence of Lr34 was shown by  molecular marker, infection rate was less than in culti-  vars not containing this gene (Table 1). Field results con-  firmed the analysis results concerning the csLV34b mar-  ker (Table 1).  Lr34 is believed to be dominant. The results clearly  showed gradual rust resistance in heterozygous cultivars  and with no difference for cultivars homozygous for this  gene.  Cultivars not containing Lr34 included 87 genotypes,  divided into four groups according to resistance and sus-  ceptibility in field and greenhouse as follows.  The first group of seven genotypes was susceptible in  the seedling stage and resistant in the adult plant stage:  N-87-16, C-86-6, M-86-9, S-87-8, WS-85-10, and MS-  84-16. These genotypes are crucial since they carry a  gene or genes of adult plant stage resistance other than  Lr34. Markers are needed to verify and identify the pres-  ence of these genes.  The second group included 57 genotypes resistant in  both adult plant and seedling stages. This group con-  tained race-specific resistance genes to the utilized genes.  These genotypes may contain non-specific race resis-  tance genes other than Lr34 that are masked by the effect  of specific resistance genes.  The third group included 17 cultivars which were sus-  ceptible in both seedling and adult plant stages. This  group lacked adult plant stage genes and effective spe-  cific race genes to the applied isolate.  In the fourth group, five cultivars were resistant or  immune in the seedling stage but susceptible in the adult  plant stage. This showed that these cultivars lacked adult  plant stage resistance genes; however, they were influ-  enced by pathogen races other than those present in the  seedling stage in the field. At the time of collecting  spores and testing them in greenhouse condition, this  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines 1831 race did not exist or was just part of the field’s patho-  genic population. The population or race which could in-  fect these cultivars was not present in the population ga-  thered and used in the greenhouse, or alternatively their  frequency was low. Thus, they did not have the opportu-  nity to appear under greenhouse conditions but could  have greater effect in the field due to the longer time  available.  Cultivars carrying Lr34 were categorized into three  groups, based on their reaction to leaf rust in field and  greenhouse. Cultivars in the first group included 33 ge-  notypes that were resistant in both seedling stage and  adult plant stages, indicating that they contained effective  race-specific genes other than Lr34.  The second category included two groups. The first  group contains delight cultivars susceptible in the seed-  ling stage and semi-resistant (MR) or semi-susceptible  (MS) in the adult plant stage. This is characteristic of  Lr34 and these cultivars apparently carried only Lr34. The  second group was “Aflak” and the line M-85-7. They  were totally susceptible in the seedling stage and com-  pletely resistant in the adult plant stage. It seems that  these cultivars lack the effective race-specific resistance  gene to the utilized isolate. However, their high resis-  tance in field conditions indicated that they contained a  gene or genes of adult plant stage resistance other than  Lr34. This makes them unique and they require further  investigation.  4. Discussion  In the present study, in cultivars of Iranian origin Lr34  was only present in cultivars and lines linked with the  very old 22-66-1 lines of ill-defined pedigree. Almost all  other Iranian cultivars containing this gene originated  from international germplasm, especially from CYMMIT.  Lr34was also present in cultivars of international germ- plasm. Introducing cultivars of CYMMIT origin into Iran  has increased the frequency of Lr34in Iranian cultivars.  Lr34 has received much attention in recent years, since  this gene is present in high frequency in CIMMYT bread  wheat germplasm and derived cultivars with CIMMYT  origin [29].  Examination of 123 local cultivars (landraces) of Iran  by Kolmer et al. [18] showed that only three cultivars  (2.4%) had Lr34. Also, in other parts of the world, the  csLV34b allele did not exist in most local cultivars and  had a low frequency, compared with the general fre-  quency in improved wheat cultivars. The incongruity of  csLV34b occurring among improved and local cultivars  may be directly or indirectly caused by improvement  trials to combine Lr34/Yr18 into new cultivars. Among  international cultivars, those from CYMMIT showed high  frequency (30%) of csLV34b.   The mentioned result was verified by assessing the in-  fection, analysis of molecular markers, and data gathered  through pedigree for presence of Lr34. Of 130 cultivars,  which had Lr34 according to pedigree, specific bands  were produced in only 43. Due to the high sensitivity of  this marker in detecting the Lr34 gene allele, having pure  seeds from the desired cultivars, and not mixing with  other cultivars are critical to providing reliable results.  Studies have shown that due to probable mistakes in data  in pedigrees, it is crucial to apply specific molecular mar-  kers to confirm the presence of resistant genes against  leaf rust in wheat cultivars. Many researchers have con-  cluded that molecular markers are better for this predic-  tion than pedigree data [30,31].  In the present study, cultivars selected and investigated  in stress conditions had the highest percentage presence  of Lr34 and it seems that this gene was effective in in-  creasing the tolerance of cultivars in environmental stress  conditions. All chosen lines and cultivars of the warm  and humid climate in the north of Iran lacked Lr34, and  these cultivars were selected in environmental conditions  without stresses such as drought, heat, cold, and salinity.  The warm and dry climate of the south of Iran, followed  by lines bread wheat lines for cold climates, had the  highest frequency of Lr34.  Lr34 belongs to the super family of ABC transporters  that produce proteins connected to the plasma membrane,  which plays an important role in transferring materials in  and out of the membrane. ABC transporters can transport  a wide range of materials that can be cytotoxic, including  ions, so that they transport macromolecules against the  diffusion gradient on both sides of the cell membrane  [32,33]. Drug transporters were primarily recognized in  cancer cells which were resistant to drugs. These trans-  porters carry the consumed drugs out of cancer cells and  make the cells resistant to drugs. This mechanism was  also discovered in drug-resistant fungi such that, in the  resistant mutant fungi, gene expression or drug trans-  porter genes and accordingly related proteins greatly in-  creased. Consequently, by discharging more and lower-  ing fungicide concentrations below the fatality threshold  in fungal cells this causes resistance to fungicides. In ad-  dition to fungicide disposal, drug transporters can pass  mycotoxin discharge of other fungi, natural antimicrobial  compounds of other organisms, and plant defense com-  pounds out of the cell and cause resistance in fungi [34].    It seems that ABC transporters are one effective factor  in resistance to salinity in plants. This system is probably  active in cultivars resistant to salinity that contain ABC  transporters, and extra salt ions are actively pumped out  of the cells. As a result, transporters enable salinity tol-  erance in various cultivars or help the process of identi-  Copyright © 2013 SciRes.                                                                                 AJPS  Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene Lr34  in Iranian Wheat Cultivars and Advanced Lines  1832  fying salinity ions and prevent them entering the cytosol.  Accordingly, these cultivars are probably resistant to sa-  linity. This hypothesis was also strengthened by assess-  ing durum cultivars, which lack the D genome and are  more susceptible to salinity than wheat cultivars. There-  fore, Lr34—in addition to providing resistance to leaf rust,  yellow rust, powdery mildew, and barley yellow dwarf  virus in wheat—plays an important role in improving  tolerance to environmental stresses such as salinity. Per-  haps one mechanism of Lr34 in providing relative resis-  tance to leaf rust agent pathogen is removing toxins, me-  tabolites, or other harmful substances discharged by pa-  thogens into host cells. As an example, virulent factors,  which are discharged by haustoria of pathogens and are  vital for aiding pathogen growth in the host cell, are  pumped out of the cell by these transporters. This makes  the pathogen grow slowly compared to hosts which lack  this gene. 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