Molecular Characterization of Terminal Heat Tolerance in Hexaploid Wheat Cultivars (Triticum Aestivum L.)

Abstract

Wheal IS one of the most mportant food crops 1n the world on terms of area harvested. production and nutrition. It IS the second largest crop of lndoa consumed after nee The demand for wheat IS expected to grow faster than for any other maJor crop Global warm1ng IS I he current ossue as well as ma,or problem of all over the world. The scoentlfoc commumty near consensus on the eXIStence of global warm1ng al t1 makes the atmosphere warmer results on the ftuctua!Jon m the yoeld and quahty of crops Wheat crop 1n lndoa faces heat stress on Its lrfe cycle either due to global warmong or by delayed SOWing due to late harvesting of sugarcane and nee. A rapidly grOWing and more affluent world population is 1ncreas1ng the demand for food commodities Sustainable growth and diversifocant of food production w~h specific attenbon lo productivity of small scale producers is needed w1lhin a context of aboollc stresses part1culal1y heat stress which affect the wheat crop productiOn adversely and a majOr challenge for secunng food security 1n lndl8 One hundred fifty one wheal genotypes were assessed thermal stress corldotJons usmg Mor)lho1lhys101ogocal. biOChemocal and molecular toots A set of 151 wheal genotypes were used under normal sown 111 1mgated condrtJon and other two sets was 1n late SOWing corld~oons Resu~ revealed that post ftowenng thermal stress reduce the gram yoeld and yoeld components 1n all genotypes the highest yoeld toss was caused by the number of gram per sp1ke and test weight (1000 grain) reduction under heat stress conditions. The genotype K-7903. PBW-373, Raj-3765, V-6, Lok-1 and C-306 showed minimum dechne and K-9107, K9006. K-307. PBW 343 showed sharp decline for morphological and physoologlcal as well as yield character 1n stress at anthe11s However low to hogh reductiOns were ob&efVed 1n stress conditions as compared to controlled condtiiOOS. Tempeature greatly Influences geiTlllnauon of seeds The maxiiTium seed gerrrunat1011 occ;urred al 2f!C and these temperalure regmes were Identified as optimum for wheat seed germonatl()(l In th1s study 50 SSR pnmers could be used to dost1ngu1sh genellc varl8tl0n among 30 wheal genotypes Among 50 p rimers only 14 pnmer showed highest polymorphism (100%) and 17 pnmer are monomorphic in nature Max1mum similarity value ol 0 95 was recorded between AKW 1071 and K9107 wh1le C-306. Raj-3765 and UP-2425 were found to be genetocally most doverse with s1mllanty value 0 79 To understand the expressiOn of gene encod•rog tbcS. tbcl and TaHsp 101 was examonecl by usmg RT -PCR After heat stress treatment tolerant genotype C-306. Ra,.3765 and Lok·1 showed a reductl()(l 1n the expression level of tbcl wh•te no reductiOn 1n PBW 343 and K 9006 was observed SIQnlfiC8nt reductiOn 1n the expressiOn of the unclear encoded 1n the expressoon of the nuclear encoded rbcS gene was observed 1n PBW 343 and K-9006 •n stress condtll()(l In heat tolerant genotype expression tevel of TaHsp 101 showed up regufall()(l et h19h temperature condrtl()(l while In susceptible genotypes showed reductoon at high temperature tt can be concluded that terminal heat stress had substantial effects on germmahon and seedhng growth stage Morph()ollhy&lologocat, Biochemical. Physootogocal and molecular analysiS reveled that adequate genetoc difference lor terrmr~&l heat $1ress existed •n wheal genotypes tested w~ cu~1vars C-306. Raj-3765 end K7903 may prove a promising parent mater~&l lor heat tolerantoJ