Rice pollen development is particularly affected by salinity at the young microspore phase, immediately after panicle initiation causing severe crop yield reduction. This work aims to understand how salinity affects rice pollen development. We are conducting proteomic analyses to identify proteins in male gametophytes (anthers) that may have an important role in salt tolerance during reproductive stage. To better understand the mechanisms underlying salt tolerance we compared responses (both physiological and molecular) between tolerant and sensitive rice genotypes. We are analyzing rice genotypes with different behavior towards salt tolerance at the seedling stage and reproductive stage. For proteomic analyses, salinity stress (EC=8 dS/m) was imposed at panicle initiation when the auricle distance was approximately 1cm, and maintained until panicle flowering. Rice anthers from panicles of both tolerant (BL22 and Zhen Chang 97) and sensitive (BL19) genotypes were collected just prior to anthesis, thus corresponding to mature pollen (trinucleate). Interestingly, a genotype scored as salt sensitive during the seedling stage, exhibited a typical stress escape mechanism at the reproductive stage, by anticipating flowering in comparison to plants grown in control conditions.
Additionally, we are using anther culture (AC) as an effective breeding strategy to improve rice salt tolerance. In this context, we are developing rice di-haploids from a cross between a salt-tolerant and salt sensitive line, thus establishing the ground for the development of salt tolerant lines by AC.