IDENTIFICATION OF SSR MARKERS FOR DROUGHT STRESS INDUCED BY MANNITOL IN THREE DIFFERENT GRAMINEAE PLANT GENERA

Abstract

The negative effects of drought stress induced by mannitol on three different plant genera of gramineae were studied. Identification of SSR markers for drought tolerance in gramineae was an important goal for this study. Four cultivars from three different plant genera of gramineae (rice, wheat and barley), two tolerant and two sensitive from each genus were treated with three different mannitol concentrations (125, 250 and 500 mM) in addition to control and incubated for three weeks in room temperature. Data were collected for three drought related important seedling traits (root length, shoot length and germination%). Significant differences for genotypes were revealed by analysis of variance for root length and shoot length in rice and barley cultivars. While in rice, wheat and barley, significant differences were observed in mannitol treatments. On the other hand, significant differences for shoot length only in rice cultivars were recorded for the interaction between genotypes and treatments. Data showed that mean performances of the studied traits decreased linearly in the three plant genera with increasing mannitol concentrations. The highest values of root length, shoot length and germination% were recorded for the control treatments in rice and barley, while the lowest values for these traits were identified in the highest concentration of mannitol treatment (500 mM) in rice and wheat. Based on the molecular analysis using 13 SSR primers associated with drought tolerance in rice, evaluation of genetic diversity of 12 studied cultivars produced clear and polymorphic banding patterns. In general, 73 polymorphic alleles with an average of 5.62 alleles per primer and sizes varied from 113 to 692 bp were amplified among the 12 studied cultivars. Polymorphic information content (PIC) values ranged from 0.22 to 0.47 with an average of 0.33 per primer. Only RM55 primer succeeded in showing distinct differences between tolerant and sensitive cultivars in all the three genera; rice, wheat and barley. Using cluster analysis, the 12 studied genotypes were divided into two main clusters which relatively corresponding with drought response. This study represents a significant addition that can play important role in the discovery of new common drought SSR markers available for diversity analysis among the three different plant genera.