Salicylic acid (SA), yeast elicitor (YEL), and chitosan (CHT) induced stomatal closure in Arabidopsis wild-type and aba2-2 plants, induced stomatal closure in fluridon-treated wild-type plants, and induced stomatal closure in aos mutants. These results suggest that neither endogenous abscisic acid nor endogenous jasmonic acid is involved in SA-, YEL-, or CHT-induced stomatal closure.
An elicitor chitosan (CHT) induces stomatal closure but the mechanism remains to be clarified. A phytohormone salicylic acid (SA) is crucial for elicitor-induced defense signaling in plants. Here we investigated whether endogenous SA is required for CHT signaling in guard cells. In the SA-deficient nahG mutant, treatment of CHT did not induce either apoplastic reactive oxygen species (ROS) production or stomatal closure but co-treatment of CHT and SA induced both apoplastic ROS production and stomatal closure, indicating the involvement of endogenous SA in CHT-induced apoplastic ROS production and CHT-induced stomatal closure. Furthermore, CHT induced transient cytosolic free calcium concentration increments in the nahG mutant in the presence of exogenous SA but not in the absence of exogenous SA. These results provide evidence that endogenous SA is a crucial element in CHT-induced stomatal closure.
The experiment was conducted to study the effect of salicylic acid (SA) as foliar spray on yield and yield contributing characters of BRRI Hybrid dhan3.The experiment was laid out in a randomized complete block design (RCBD) with three replications and six treatment combinations as, T1: 0 µM SA, T2: 200 µM SA, T3: 400 µM SA, T4: 600 µM SA, T5: 800 µM SA and T6: 1000 µM SA. The results revealed that biomass production, dry matter production and yield and yield contributing characters were significantly increased due to the foliar application of SA. At the maximum tillering (MT) stage, the highest biomass production (15.0 t/ha) and dry matter production was observed in T3 treatment. Treatments T4, T5 and T6 showed significant variation on the effective tillers/hill. The maximum effective tillers/hill were found in the treatment T6. The percentages of spikelet sterility were decreased with increasing the level of SA and the percentage of filled grains/panicle were increased with increasing level of SA. The insect infestation was reduced with increasing level of SA to up to 1000 µM. The maximum grain yield (9.21 t/ha) and straw yield (9.22 t/ha) was found in the treatment T6 which was identical to T5. On the other hand, in all cases the lowest results were found in the control treatment. The result showed that grain yield of rice increased with increasing level of SA to up to 1000 µM (T6 treatment). Our results suggest that foliar spray of SA might be applied to increase the yield of hybrid rice in Bangladesh.
To cite this article:
Chitosan (CHT) induces stomatal closure and thus plays a crucial role in plants to adapt to the adverse environments. Our previous results of a SA-deficient mutant nahG suggest that endogenous salicylic acid (SA) is involved in the CHT signaling in guard cells. Here in order to make the involvement definite, we examined stomatal responses to CHT of another SA-deficient mutant, sid2, and an SA receptor mutant, npr1-3. The sid2 mutation impaired CHT-induced stomatal closure and reactive oxygen species production and both impairments were complemented with exogenous SA application. Moreover, the CHT-induced stomatal closure is disrupted in the npr1-3 mutant. These results suggest that endogenous SA is involved in the CHT-induced stomatal closure via the SA receptor, NPR1.
Abbreviations
SA: salicylic acid; ABA: abscisic acid; ROS: reactive oxygen species; NPR1: nonexpresser of pathogenesis-related genes1; CHT: chitosan; DAB: 3,3′-diaminobenzidine
Gamma irradiation increased catalase activities at 0.1 kGy and decreased them at 10 kGy in Arabidopsis wild type and catalase-deficient mutants, cat3-1 and cat1 cat3. Irradiation induced DNA damage, H2O2 accumulation, and lipid peroxidation in both mutants as well as the wild type. Thus catalases might not be key enzymes protecting gamma irradiation-induced damage.
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