Plant species adapt to various environmental stresses like heat, drought by incorporating sequence changes and alterations in their physiological processes and pathways. Understanding the nature of adaptation will help in engineering better future plants for wider adaptability. During photosynthesis process, Rubisco activase (Rca) activates Rubisco enzyme by removing the inhibitory molecules and sugar phosphates from the CO2 and the metal binding sites. The inability of Rca to keep pace with faster Rubisco deactivation during heat stress constraints photosynthesis in many important crop species including wheat. Rubisco activation and CO2fixation rate of wheat start to decline even at 30°C and complete photosynthesis inhibition occurs at temperatures above 38°C. The ‘thermal stability’ and ‘temperature optimum’ of Rca is low in wheat and Arabidopsis as compared to maize, sorghum and rice. It is unclear, whether this heat stability is attributed to ‘gene expression level’ or ‘protein stability’. Previously, we reported that Rca gene family is tandemly duplicated in throughout majority of plant species. Duplicated copies are differentially regulated for transcript abundance during heat stress. Further expression analysis of tandemly duplicated gene copies in hexaploid wheat revealed genotypic differences for gene expression. Secondly, different insertions and mutations in the promoter and coding sequences in one of the Rca genes appeared to be responsible for its heat induced expression pattern and thermal stability in heat tolerant cereal crops. Insertion of transposable elements was common in the promoter or intergenic sequences and many of these transposons contained Heat Responsive Elements. Thus, for studying the sequence changes, allelic diversity study will be conducted on wide variety of germplasm to further understand the role of promoter and genic changes in providing heat stress tolerance. Thus, understanding the role of Rca in thermal tolerance will help us in improving and engineering better wheat cultivars.

Subtheme: b. Structural and Functional Genomics of Wheat and Wheat Relatives

Presentation Preference: Poster

Student: Yes