An alternative to the use of chemical fungicides is to enhance the defensive response of plants by appropriate stimulation, a phenomenon known as induction of resistance. The aim of this study was to determine the changes of endogen levels of salicylic acid (SA) and jasmonic acid (JA) in potato plants as response to foliar application of biotic and abiotic inductors. Treatments T1 = Best Ultra F ( Bacillus spp. 108 cfu/mL and Pseudomonas fluorescens 108 cfu/mL) 0.5%, T2 = FullKover HF (microbial jasmonic acid 1500 ppm) 0.2%, T3 = T1 0.5% + T2 0.1%, T4 = Milor <sup>®</sup> (Chlorothalonil + Metalaxyl) 0.5% and T5 = control (water) were applied in potato plants. The application of biotic and abiotic inductors improved the SA and JA production in potato plants. The production of salicylic acid in potato plants was observed by application of Bacillus spp. and Pseudomonas fluorescens (T1) and fungicide Milor <sup>®</sup> (T4). The application of T1 Best Ultra F, T2 FullKover HF (microbial JA), T3 (T1 + T2) and T4 Milor <sup>®</sup> improved the JA production in potato plants.
Excessive use of pesticides to control plant diseases is an important problem in the agricultural fields, so it is a priority study for biological control, because the current production systems demand the crop protection by innovative and environmentally methods compatible with sustainable agriculture as an alternative to chemical application [
Currently there are two ways to induce resistance, the acquired systemic resistance (ASR) and induced systemic resistance (ISR), which can be differentiated by the nature and regulatory paths of the inductor (also called elicitor) [
It has been reported that ISR (another type of resistance) is effective against viral, bacterial and fungal diseases, is dependent of JA signaling and occurs when the plant roots are colonized by some nonpathogenic rhizobacteria or herbivores insect damage [
The aim of this study was to determinate the changes of endogen levels of SA and JA in potato plants as a response to foliar application of biotic and abiotic inductors.
Potato minituber var alpha were seeded in plastic packages containing a mixture of peat-most and forest land (1:1), the cultures were kept under greenhouse conditions at the Universidad Autónoma Agraria Antonio Narro, Saltillo, Coahuila, México. When the plants reached 30 days old the treatments application was carried out.
The biological treatments evaluated were provided by the company Green Corp Biorganiks of México and consisted of: T1 = Best Ultra F (Bacillus spp. 108 cfu/mL and Pseudomonas fluorescens 108 cfu/mL) concentration 0.5%, T2 = FullKover HF (aqueous solution of microbial origin jasmonic acid 1500 ppm) 0.2% and T3 = mix T1 Best Ultra F 0.5% + T2 FullKover HF 0.1%; T4 = Milor® (Chlorothalonil + Metalaxyl) 0.5% and T5 = absolute control (water). Application was made by spraying on the foliage using a hand sprayer. Samples were collected at 0, 1, 3, 6, 12, 24 and 48 h after treatment application, time 0 was collected before application. The samples were lyophilized, macerated and stored at −20˚C until use.
To extract SA, 50 mg of macerated tissue were placed in Eppendorf tubes and 1 mL of extraction solution was added (10% methanol: 1% acetic acid: 89% distilled water), tubes were stirred by vortex during 15 sec and then sonic vibration was used. Tubes were centrifuged at 13,000 rpm by 10 min, the supernatant was recovered, filtered through 0.45 µm nylon membrane and placed in a new tube. Quantification of SA was performed using an Agilent 1120 LC chromatography system with UV detector, separation was performed on a Agilent 4.6 × 150 mm C18 5 um column at 30˚C. Mobile phases were 50% phase A (94.9% water: 5% acetonitrile: 0.1% formic acid) and 50% phase B (5% water: 94.9% acetonitrile: 0.1 % formic acid) [
To extract JA, 100 mg of macerated tissue were placed in Eppendorf tubes and 450 µL of extraction solution were added (95% methanol: 5% ethyl acetate), tubes were stirred by vortex during 15 sec and then sonic vibration was used. Tubes were centrifuged at 13,000 rpm by 10 min, the supernatant was recovered, filtered through 0.45 µm nylon membrane and placed in glass vial. Solvent was evaporated in an oven at 50˚C and the residue was resuspended in 1 mL of mobile phase (60% methanol: 40% water: 1% acetic acid) [
The experiment was carried out only one time in a randomized experimental design, with three replicates per treatment in each time. Data were analyzed using ANOVA and with Tukey test, 0.5 significance.
The results shown significant differences between treatments in each sampling time analyzed separately by ANOVA. SA concentration in potato plants it was between 3.68 and 114.02 μg/g dry weight (DW) during the experiment. In the first hour T4 (Milor®) was statistically different from the control with 112.05 µg/g DW (492% more than control), however, this value decreased from 3 h to reach statistically similar levels to the control. T1 (Best Ultra F) increased significantly the SA concentration at 3 h reaching 114.02 µg/g・DW (469% more than control), the results are shown in the
T4 (Milor®) is a mixture of fungicides, Metalaxyl with systemic action and Chlorothalonil with contact action, it is widely used to control diseases caused by oomycetes. In this study it was demonstrated the protectant effect and the potential as defense mechanism activator of Milor® by SA accumulation. It is known that ASR activation is given by abiotic elicitors, such as chemicals products that interact with signaling pathways associated with plants resistance stimulating their defenses, also have a direct negative effect on the pathogen. For example, the fungicide Probenazole induces ASR in Arabidopsis by signaling and accumulation of SA [
As for T1 (Best Ultra F) containing spores of Bacillus spp. and P. fluorescens, a significant increase was observed in the production of SA 3 h after application, which coincides with the results reported by Segarra et al. [
particularly SA, are involved in the resistance induction in plants [
T2 (FullKover HF) containing JA of microbial origin did not induce significant increase of SA compared to control, this can be explained by the fact that JA is the ISR messenger. When ISR is activated, it is characterized by an accumulation of JA, therefore, exogenous application of JA in plants should increase the JA concentration, but not SA concentration, as was observed in this study.
On the other hand, T3 formulated with Bacillus spp., P. fluorescens and JA (T1 + T2) induced a time delay for the JA production, this could be attributed to a possible antagonistic interaction of these compounds. It is known that both, SA and JA have a cross signaling, both pathways are mutually antagonistic (Kunkel and Brooks [
No JA levels were detected in the control, only in treated plants. The maximum concentrations were obtained at 1 h (1572.18 µg/g DW) and 3 h (569.28 µg/g DW) with T4 (Milor®). All treatments, except the control had similar JA levels at 6 h, T1 (Best Ultra F) reached 550.02, T2 (FullKover HF) 833.32, T3 (T1 + T2) 562.48 and T4 (Milor®) 529.62 µg/g DW. T4 (Milor®) was the only that kept the JA production at 12, 24 and 48 h (
JA is the ISR messenger, in plants the level of this hormone depends on the tissue, cell type, development stage and response to different environmental stimuli [
T4 Milor® induced in the plant JA production at all times (
signals by the production of SA and JA, can be explained by a possible crosstalk that is still not entirely clear and that generates a synergistic interaction between these hormones, this synergism depends on the combination and concentrations used [
Although the experiment was performed once, the results show the potential use of Bacillus spp., P. fluorescens and JA of microbial origin from formulated products to induce resistance in plants as a strategy in the management of diseases and reducing levels of environmental pollution caused by the use of conventional pesticides.
The application of biotic and abiotic inductors improved the SA and JA production in potato plants. The application of T1 Best Ultra F (Bacillus spp. and Pseudomonas fluorescens) and T4 Milor® improved the SA production in potato plants. The application of T1 Best Ultra F, T2 FullKover HF (microbial JA), T3 (T1 + T2) and T4 Milor® improved the JA production in potato plants.
E. González-Gallegos wants to thank CONACYT for the scholarship assigned to this postgraduate study in the program of Agricultural Parasitology, UAAAN. Authors thank the commercial products provided by the company Green Corp Biorganiks of México.
EsmeraldaGonzález-Gallegos,ElanLaredo-Alcalá,JuanAscacio-Valdés,Diana Jassode Rodríguez,Francisco DanielHernández-Castillo, (2015) Changes in the Production of Salicylic and Jasmonic Acid in Potato Plants (<i>Solanum tuberosum</i>) as Response to Foliar Application of Biotic and Abiotic Inductors. American Journal of Plant Sciences,06,1785-1791. doi: 10.4236/ajps.2015.611179