Differential response of wild and cultivated wheats to water deficits during grain development: changes in soluble carbohydrates and invertases.

Wheat, staple food crop of the world, is sensitive to drought, especially during the grain-filling period. Water soluble carbohydrates (WSCs), stem reserve mobilization and higher invertase activity in the developing grains are important biochemical traits for breeding wheat to enhance tolerance to terminal drought. These traits were studied for three accessions of Triticum dicoccoides(a tetraploid wheat progenitor species) - acc 7054 (EC 171812), acc 7079 (EC 171837) and acc 14004 (G-194-3 M-6 M) selected previously on the basis of grain filling characteristics. Check wheat cultivars- PBW-343 (a popular bread wheat cultivar for irrigated environments) and C-306 (widely adapted variety for rain-fed agriculture) were also included in this set. Analysis of variance revealed significant genotypic differences for the content of water soluble carbohydrates, activity of acid invertase and alkaline invertase. Acc 7079 was found to be a very efficient mobilizer of water soluble carbohydrates (236.43 mg g(-1) peduncle DW) when averaged over irrigated and rain-fed conditions. Acid invertase activity revealed marked genotypic differences between wild and cultivated wheats. Alkaline invertase activity was highest in Acc 7079 when pooled across both the environments. On the whole, acc 7079 qualifies as a suitable donor for enhancing tolerance of bread wheat to terminal drought. The association of physio-biochemical differences observed with grain filling attributes on one hand and molecular markers on the other could be of use in improving wheat for water stress conditions.