Molecular Characterization Using Ssr Markers and Effects Of Heat Stress on Rice (Oryza Sativa L.) Genotypes

Abstract

Rice ( Oryza sativa L.) is the most important staple food of developing nations and food security of many countries depends largely on its productivity. Due to the effects of climate change productivity of rice is highly threatened. Even though, the rice scientific community has escalated etlorts in developing rice varieties that will be capable of withstanding adverse conditions of high temperature stress that may be created by climate change effects in all growth stages. Unfortunately, less attention has been specifically given to Basmati rice; which is premium, • preferred._ commanding high price and good foreign exchange. This present investigation is focuses at identifying a basmati variety that is relatively showing heat tolerant trait and to attempt understanding the molecular basis of the trait. This thesis met this twin research aim by establishing diversity relationship within 18 rice genotypes using SSR markers, screening the genotypes on effect of heat stress (34 oc, 3 soc & ambient - control) at anthesis, selecting four varieties for further evaluation of heat stress (30oC & 45°C) at seedling stage by estimating the effect on Membrane Stability Index and Proline content after 18hrs of stress, furthennore .. expression analysis of six heat - inducible genes were evaluated at intervals of Ohrs and 12hrs. This research produced a number of key findings: genetic diversity differentiated 18 genotypes into 5 groups. separating traditional Basmati varieties from cross-bred and non-aromatic varieties: heat stress screening at anthesis stage, showed significant effect in all morphological characteristics viz. plant height. number of tillers, panicle length, number of panicles and spikelet fertility and reveals responses of different varieties. Furthermore, selected varieties at seedling stage under heat stress showed significant difference in Membrane Stability Index and proline content. with B - 370 variety. analysis of all the selected varieties performang better than others. In addataon, gene expressaon displayed B- 370 as tolerant Basmati variety to heat stress at seedling stage. Based on the findings · · · · · h B 370 · more tolerant to heat stress at seedling of thas anvestlgatton, we therefore conclude t at - as · · d rt · n this variety as breeder s material for stage. However .. further assessment IS requ1re to asce aa I B t. ar'eni~at -aff stages of grov.rth.