Physiological and proteomic analysis of two contrasting Sorghum bicolor genotypes in response to drought stress

摘要

Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In this study, two sorghum(Sorghum bicolor L.) genotypes with contrasting sensitivity to drought were subjected drought stress by withholding water for 7days at seedling stage; physiological and protein analyses were made. Reduction percentage was recorded on leaf water content,chlorophyll a and b and total chlorophyll. Shoot and root lengths reductions were observed in the drought-sensitive Cultivar (Tabat)while the drought-tolerant line (EL9) showed an increase in shoot and root lengths under drought conditions. Drought tolerantsorghum line EL9 accumulated higher proline (26% increase) when compared to the sensitive cultivar Tabat (5% increase). Massspectrometry analysis coupled with nanoflow UPLC was used to compare daily-watered with drought stressed (7 days) seedlings. Atotal of 36 protein spots were detected, of which 23 were recorded for one or both accessions under drought stress conditionsonly. These proteins were identified using MASCOT database search in accordance with sequence similarity with previouslycharacterized proteins from the Uniprot database. The identified proteins were assigned to different functional categories asfollows: Response to stress (35%); metabolic processes (26%); photosynthetic (13%); fatty acid biosynthesis (4%) and cell wallbiogenesis/degradation (4%). Seven of the identified proteins under stress condition were unique to El9, in contrast to 4 proteinswere unique to Tabat. This study showed a differential protein expression pattern of two sorghum accessions under drought stress,which will be valuable for studying the molecular mechanisms underlying drought tolerance in the future. Also, these proteinscould be potential candidates for development of markers to be used in markers assisted selection.