UMA SHAANKER, R.MANASA, K. M.2020-10-052020-10-052019-05-31Th-12267https://krishikosh.egranth.ac.in/handle/1/5810152385Soil salinity is a major threat to agriculture, affecting the crop growth at all the growth phases and decreasing the production and productivity of crops. Attempts to obtain better plant phenotype through conventional and gene pyramiding approaches are laborious and less fruitful at the field level. An alternative and emerging strategy is the plant-biotic approach, where microorganisms such as endophytic fungi are being explored to make plants resilient to salt stress. Endophytes are symptomless, ubiquitously present in all plants. The aim of this study was to isolate endophytic fungi from salt adapted plants, and a) evaluate their tolerance to salinity stress and b) explore, if such endophytes are also able to impart tolerance to salt sensitive paddy genotype, IR-64. A total of 270 endophytic fungi isolated from nine halophytes plant species were assigned to 50 operational taxonomic units (OTUs) which were further identified using ITS primers. Twenty-seven fungal isolates from 13 genera were recovered, with Fusarium as the dominant. Of the various fungi, two, namely, Fusarium incarnatum and F. chlamydosporum were found to be highly tolerant to salinity stress. Cross-infection of these halotolerant fungi to sensitive paddy genotype, IR-64 showed increased plant growth at 200 mM NaCl. Plants enriched with endophyte showed significant increase in various parameters such as assimilation rate, chlorophyll content, membrane integrity, pollen viability, shoot and root dry weight along with decreased Na+:K+ ratio at 6 dSm-1 and 8 dSm-1. There was a nearly 50 % increase in productive tillers, spikelet fertility and grain yield in plants enriched with halotolerant endophyte at 8 dS m-1. There was also a trans-generational effect of endophyte enrichment. Overall the study provides a proof of concept that endophytes from plants adapted to extreme habitats could be effectively used to modulate plant responses to abiotic stresses such as salinity.EnglishThesis