Potential of exopolysaccharides producing endophytic fungus Aspergillus niger to mitigate NaCl stress in Brassica napus L seedlings

Title : Potential of exopolysaccharides producing endophytic fungus Aspergillus niger to mitigate NaCl stress in Brassica napus L seedlings

Abstract:

Brassica napus L. (Rapeseed) is a major source of edible oil in Pakistan and the rest of the world. The crop contributes about 21% of global edible oil production. Due to increase in salinity levels around the world and rising food demand, there is a dire need to find strategies to combat salinity induced losses. EPS producing endophytic fungi can improve plant fitness and stress tolerance, enhancing its potential of phytohormones and nutrients. The current study aimed to isolate EPS secreting, halotolerant endophytic fungi from salt affected areas of Mardan and industrial area of Swabi Pakistan and used them for NaCl stress alleviation in canola seedlings. Based on initial screening assays five fungal strains were selected for its ability to produce EPS (Control 174, 100mM 176, 200mM 177.46 and 500mM 226.66mg/g) and mitigate NaCl stress in the host seedlings. Amount of EPS released by the isolate increased with increasing salt concentration in the media. Experiment assessing endophytes salt stress mitigation in Brassica napus, seeds were sown in pots containing soil, fungal biomass and different NaCl concentrations (100, 150 and 200mM). The results showed they effectively colonized and improved growth, reduced ROS accumulation, and scavenged ROS more effectively than the control. Application of endophyte or its EPS increased chlorophyll accumulation, antioxidant enzymes and non-enzymatic antioxidants in the leaves of the host. The treatment also induced auxin, abscisic acid, jasmonic acid, and salicylic acid biosynthesis promoting seedling growth under salt stress. Our results revealed that fungal endophyte EPS effectively ameliorates salt stress in canola seedlings and showed application potential in agriculture. Therefore, such isolates may be of great importance for the developing of potential of bio-inoculant for the remediation of salt contaminant soils, while significantly enhancing the crop quality and quantity.

Keywords: Brassica napus, Exopolysaccharides (EPS), Phytohormones, Plant growth-promoting fungi (PGPF), Salt stress.

Biography:

Aneesa Nayab, a Ph.D. scholar in Botany department at Abdul Wali Khan University Mardan, Pakistan, under the supervision of Prof. Dr. Anwar Hussain. She completed her M.Phil in Botany (2018) with specialization in plant–microbe interactions. Her doctoral research examines the effect of exopolysaccharide producing endophytic fungi on canola (Brassica napus L.) growth under salt stress, exploring how these fungi enhance antioxidant enzyme activity and promote growth to mitigate salinity effects. This work supports sustainable strategies for improving crop productivity on salt-affected soils. She have also conducted research on plant physiology, ecology, and microbial interactions, and presented at the Second South Asian Symposium on Microbial Ecology (2023) in Kathmandu, Nepal.