Physiological, biochemical and proteomic responses of rice ( Oryza sativa L.)varieties Godaheenati and Pokkali for drought stress at the seedling stage

Abiotic stresses are key limiting factors that restrict rice production. Among them, drought is one of the major factors that induce several physiological, biochemical and molecular responses in plants. Screening of rice varieties against drought stress is a prerequisite to produce stress tolerant rice varieties. Two rice varieties, i.e. Godaheenati (4049) and Pokkali were screened for drought stress responses based on biochemical attributes at the seedling stage. Relative water content, the total protein content of leaves of two-week-old rice seedlings and photosynthetic pigment levels were measured over a fiveday drought period. The varieties tested responded with different relative water content, protein concentrations and pigment levels, potentially due to their genetic differences. Godaheenati showed an increase of the relative water content on the fourth day under drought stress, indicative of its cell recovering capability, and thus may be drought tolerant than Pokkali . Dehydration stress resulted in the fluctuation of all three photosynthetic pigments in both varieties. On the fourth day, Godaheenati showed a significant increase of photosynthetic pigments than Pokkali , and this could be a result of recovery of plant cells due to the increase of water content. The total protein content extracted from leaves of twoweek- old rice seedlings of Godaheenati exposed to drought conditions was subjected to twodimensional gel electrophoresis.The results showed alterations in the total proteome of rice leaves, and an up regulation of genes responsible for drought stress tolerance in rice. Further screening is recommended for Godaheenati as a drought tolerant rice variety to be used in rice breeding programs.