The effect of drought stress on morphological and physiological traits and the relative expression of important antioxidant genes in Canola

This study was conducted for investigating the effect of drought different levels on morphological and physiological traits of Canola and investigating relative expression of antioxidant genes to identify the antioxidant response of tolerant genotype at drought different levels. The factorial experiment based on unbalanced completely random design was conducted at the end of the 5-leaf stage of Canola in 3 replications in the greenhouse of Agricultural Sciences Faculty of Gilan University on the year 2022. The effect of different drought levels, including non-stress (100%), low (75%), medium (50%), severe (25%) and very severe stress (20%FC) on morphological and physiological traits in SLM046 and Licord Canola genotypes, as well as the relative expression of important antioxidant genes of Ferredoxin-NADP+oxidoreductase (FNR) and NADPH-thioredoxin reductase (NTR) in the tolerant genotype were investigated using Real-time PCR based on Livak method. The interaction effect of stress on genotype for root length, shoot and root dry weight, allometric coefficient, root water weight, chlorophyll a and b, total chlorophyll, carotenoid and anthocyanin was significant at 1% probability level. The allometric coefficient at 20%FC, and root dry weight at all levels were higher in SLM046 than Licord under drought stress. Drought stress caused a decrease in RWC at 75% FC in both genotypes. Also, the drough treatment at the level of 20% FC caused a decrease in the leaf area and the treatment of all stress levels caused a decrease in the amount of anthocyanin in both genotypes. The stress treatment at 20%FC increased the amount of chlorophyll b and total chlorophyll in SLM046 genotype. The treatment at all stress levels decreased the chlorophyll a and b, total chlorophyll and carotenoid in Licord genotype. The results showed that the expression of FNR and NTR genes increased in SLM046 genotype at higher stress levels. It seems that the SLM046 is tolerant under severe and very severe drought. The increase in FNR expression, which leads to the production of NADPH, is regulated by the NTR expression, and by regulating the expression of genes involved in oxidative stress, it can cause drought tolerance and plant survival in tolerant genotype.