Gene expression profiling of heat tolerance genes in pearl millet (Pennisetum glaucum (L).R.Br)
Creators: name: Sankar, Mukesh
Publisher: name: figshare
Year: 2021
Subjects: subject: 100199 Agricultural Biotechnology not elsewhere classified
subject: FOS: Agricultural biotechnology

description: Pearl millet [Pennisetum glaucum (L.) R. Br.] is one of the staple food as well fodder crop for millions of resource poor peoples of semi-arid and arid tropics. It is widely cultivated as food crop in India, Africa and Latin America and as fodder in USA, Australia and Brazil. In India it is the fourth important cereal grain crop, covers an area more than 9.3 m. ha with production of 9.5 m. tonnes and productivity of 1044 kg/ha. Nearly 95 percent of the acreage under pearl millet is occupied in the states of Rajasthan, Maharashtra, Gujarat, Uttar Pradesh and Haryana. Pearl millet is very hardy and well adapted to harsh environments like drought, high temperature, salinity, poor soils with low nutrient status etc in which other cereals fails. In recent years, it has been getting increased recognition as a substitute for major cereal crops due to its suitability to changing climatic conditions and also to fill the gap between the food security and increasing world population. The problem of high temperature stress is one of the main reasons for low productivity in pearl millet under semi arid and arid environment. High temperature particularly during seedling stage of pearl millet, affects the germination and further crop stand. Acquisition of thermotolerance is largely controlled through molecular mechanisms based on the activation and regulation of specific stress-related genes. There exist genetic variation present among pearl millet genotypes in seedling survival and thermotolerance. A number of cultivars and breeding lines have been generated containing different genes responsible for thermotolerance in Pearl millet in India. The present study aims at evaluating the genetic diversity among these lines for thermotolerance based on morphological data and the transcript expression profile under high temperature stress. Assessment of thermotolerance in various genotypes using physiological parameter membrane stability index, suggest there exist variability among genotypes for 113 thermotolerance, showing good heritability and can be used as a screening method for the breeding superior cultivars having good agronomic characters along with high temperature resistance ensuring food security under threats of global warming. Analysis of variance indicated the presence of significant difference for various traits and genotypes. The analysis of diversity based on D2 statistics grouped the genotypes into three distinct clusters. The relative contribution of each character towards divergence clearly indicated that leaf blade length, leaf sheath length, leaf blade width, membrane stability index and number of nodes per plant contributed maximum to the diversity among the material under study. Present investigation on transcript expression profile of heat tolerance genes suggests that heat stress induces various thermotolerant genes like heat shock factors and heat shock protein genes in pearl millet genotypes. Transcript accumulation was achieved by increased activity towards the expression of genes encoding transcripts involved in thermotolerance in response to thermal stress. The study indicated that there is differential response of different genotypes to heat stress in the form of accumulation of heat shock responsive gene transcript. Genotypes such as 841 B,TT 1,WGI 126 showed positive response to thermal stress for transcript accumulation for both Pg cp 70 and Pg HSF and also had better growth under heat stress, where as PPMI 69 showed least responsiveness to transcript accumulation supporting the membrane stability index data for scoring thermotolerance. Therefore differential accumulation of heat shock responsive gene transcript can be a useful trait to select heat tolerant pearl millet genotype even at seedling stage and can be further used for development of high temperature stress resistant genotypes. The present study on isolation and cloning of heat tolerance genes like Pg HSF 16.97 proved to be useful in understanding the basics of protein gene interactions such as various motifs which play a major role in thermotolerance and also helps in development of heat tolerant genotypes through transgenic approach using pearl millet heat tolerant genes in heat susceptible crops such as wheat, rice etc.