Abstract
As a new plant biostimulant, poly-γ-glutamic acid (γ-PGA) may be an effective anti-drought agent that can efficiently alleviate the damage to plants under drought stress. In this study, the effects of γ-PGA on the physiological responses of oilseed rape (Brassica napus L.) seedlings under drought stress were investigated using hydroponics. Growth and development of the rape seedlings were significantly inhibited in a polyethylene glycol-simulated drought environment. However, 12 d after application of γ-PGA under drought stress, the fresh weight, chlorophyll content, and relative water content of rape seedlings all markedly increased. Moreover, proline content and antioxidant enzyme activity were all markedly enhanced, and the malondialdehyde content was significantly reduced in rape seedlings treated with γ-PGA. Furthermore, the content of the important anti-drought response hormone, abscisic acid (ABA), as well as the expression levels of the ABA metabolism regulation genes BnNCED3, BnZEP, and BnAAO4, significantly increased. These results indicate that γ-PGA may induce elements of a tolerance system to drought stress by promoting ABA accumulation in B. Napus.
Highlights
As a new plant biostimulant, poly-γ-glutamic acid (γ-PGA) may be an effective anti-drought agent that can efficiently alleviate the damage to plants under drought stress
NCED enzymescleave the cis-isomers of violaxanthin and neoxanthin to form xanthoxin, which is the precursor of abscisic acid (ABA), xanthoxin will be oxidized to ABA by AAO17
After 12 d of treatment, the proline content of rape seedlings in the PGA + polyethylene glycol (PEG) group reached 3815.5 μg/g dry weight (DW), which was 79.9% higher than that in the PEG group. These results show that γ-PGA enhanced the synthesis of proline in rape seedlings, and this enhancement was more pronounced under drought stress
Summary
As a new plant biostimulant, poly-γ-glutamic acid (γ-PGA) may be an effective anti-drought agent that can efficiently alleviate the damage to plants under drought stress. The effects of γ-PGA on the physiological responses of oilseed rape (Brassica napus L.) seedlings under drought stress were investigated using hydroponics. The content of the important anti-drought response hormone, abscisic acid (ABA), as well as the expression levels of the ABA metabolism regulation genes BnNCED3, BnZEP, and BnAAO4, significantly increased. These results indicate that γ-PGA may induce elements of a tolerance system to drought stress by promoting ABA accumulation in B. Plants use several strategies to reduce damage caused by dry environments, including the accumulation of proline which has been shown to effectively alleviate drought-induced osmotic stress[8].
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