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<p>Drought stress significantly reduces the growth and yield of Indian mustard (<i>Brassica juncea</i>), an economically important oilseed crop widely cultivated for its oil and protein rich seeds. About one-sixth of India's land is drought-prone, especially in western regions, and by 2050, drought-related crop losses could exceed 50% for key crops. About 37% of rapeseed-mustard in India is rainfed and highly vulnerable to drought, causing major yield losses in eastern and western India. Globally, drought contributes to an average annual crop yield loss of around 17%, with losses reaching as high as 70% under severe conditions. The aim of the study was to evaluate the effectiveness of a plant growth-promoting rhizobacteria (PGPR) consortium comprising <i>Enterobacter hormaechei</i>, <i>Pantoea dispersa</i>, and <i>Acinetobacter</i> sp. to mitigate drought stress in four genotypes of <i>B. juncea</i> (RH-725, RH-761, RH-749, and RH-30). Under drought conditions, all genotypes showed a decline in growth, with RH-749 being identified as the most drought sensitive, followed by RH-30, while RH-725 and RH-761 demonstrated greater drought tolerance. PGPR application improved growth parameters, including shoot length (up to 15.73%) and root length (up to 29.14%) under drought stress. PGPR-treated plants also retained more water, with relative water content increasing by up to 20.86%, and showed reduced membrane damage, as indicated by decreased electrolyte leakage (up to 10.26%). Additionally, PGPR enhanced chlorophyll content (up to 18.24%) and improved gas exchange. Biochemical analyses revealed elevated levels of proline (up to 14.26%) and total sugars (up to 13.24%), coupled with lower concentrations of malondialdehyde (MDA) (up to 22.87%) and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) (up to 25.11%), reflecting reduced oxidative stress. Enhanced activities of antioxidant enzymes such as superoxide dismutase (up to 15.79%), catalase (up to 27.59%), peroxidase (up to 18.11%), and ascorbate peroxidase (up to 28.09%) were also observed, contributing to the genotypes’ improved drought tolerance. Furthermore, PGPR treatment positively affected yield components, increasing siliquae per plant (up to 13.10%), seeds per siliqua (up to 13.70%), seed size (up to 17.02%), 1000-seed weight (up to 8.59%), and oil content (up to 11.97%) under drought stress. These findings highlight the effectiveness of PGPR in enhancing drought tolerance and improving productivity in <i>B. juncea</i>, providing a sustainable approach to farming in drought-prone regions.</p>

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PGPR-Mediated Drought Tolerance in Brassica juncea by Modulating Morpho-Physiological, Biochemical, and Antioxidant Responses

  • 期刊论文

  • 发表日期：

    2025年10月6日

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  • Asha Rani Sheoran,
  • Nita Lakra,
  • Baljeet Singh Saharan,
  • Annu Luhach

摘要

Drought stress significantly reduces the growth and yield of Indian mustard (Brassica juncea), an economically important oilseed crop widely cultivated for its oil and protein rich seeds. About one-sixth of India's land is drought-prone, especially in western regions, and by 2050, drought-related crop losses could exceed 50% for key crops. About 37% of rapeseed-mustard in India is rainfed and highly vulnerable to drought, causing major yield losses in eastern and western India. Globally, drought contributes to an average annual crop yield loss of around 17%, with losses reaching as high as 70% under severe conditions. The aim of the study was to evaluate the effectiveness of a plant growth-promoting rhizobacteria (PGPR) consortium comprising Enterobacter hormaechei, Pantoea dispersa, and Acinetobacter sp. to mitigate drought stress in four genotypes of B. juncea (RH-725, RH-761, RH-749, and RH-30). Under drought conditions, all genotypes showed a decline in growth, with RH-749 being identified as the most drought sensitive, followed by RH-30, while RH-725 and RH-761 demonstrated greater drought tolerance. PGPR application improved growth parameters, including shoot length (up to 15.73%) and root length (up to 29.14%) under drought stress. PGPR-treated plants also retained more water, with relative water content increasing by up to 20.86%, and showed reduced membrane damage, as indicated by decreased electrolyte leakage (up to 10.26%). Additionally, PGPR enhanced chlorophyll content (up to 18.24%) and improved gas exchange. Biochemical analyses revealed elevated levels of proline (up to 14.26%) and total sugars (up to 13.24%), coupled with lower concentrations of malondialdehyde (MDA) (up to 22.87%) and hydrogen peroxide (H2O2) (up to 25.11%), reflecting reduced oxidative stress. Enhanced activities of antioxidant enzymes such as superoxide dismutase (up to 15.79%), catalase (up to 27.59%), peroxidase (up to 18.11%), and ascorbate peroxidase (up to 28.09%) were also observed, contributing to the genotypes’ improved drought tolerance. Furthermore, PGPR treatment positively affected yield components, increasing siliquae per plant (up to 13.10%), seeds per siliqua (up to 13.70%), seed size (up to 17.02%), 1000-seed weight (up to 8.59%), and oil content (up to 11.97%) under drought stress. These findings highlight the effectiveness of PGPR in enhancing drought tolerance and improving productivity in B. juncea, providing a sustainable approach to farming in drought-prone regions.