Identification of two new drought specific candidate genes in sugarcane (Saccharum spp.)

Effective identification and understanding of genes contribute to improve plant drought resistance. A study was conducted toidentify drought responsive candidate genes in sugarcane. Two genes viz., SOD (Superoxide dismutase) and IGS (Indole 3-glycerol phosphate synthase) were used as gene specific markers. Specific primers were designed based on the sequences inGenbank databases. Mapping population developed by crossing a drought tolerant parent (Co 740) and a drought susceptibleparent (Co 775) were phenotyped using physiological and sugar yield contributing parameters and were characterized into groupsof varying levels of resistance and susceptibility. Parental polymorphism for SOD and IGS specific primers was established usinggenomic DNA from field grown drought tolerant and susceptible parents, as the presence in Co 740 (resistant) and absence in Co775 (susceptible) respectively. Resistant and susceptible parents and six each resistant and susceptible progeny were subjected todrought imposition and RNA were isolated and RT - PCR analysis performed using these gene specific primers. A specific bandof 618 bp was identified in drought tolerant parent and progeny, absent in drought susceptible parent and progeny genotypedusing SOD gene. A specific band of 340 bp was identified in drought tolerant parent and progeny while it was absent in droughtsusceptible parent and progeny genotyped using IGS gene. These two fragments of interests were cloned in PTz57R/T vector andsequenced. SOD618 sequence was BLAST searched that showed 98 % homology with the drought inducible protein in Saccharumhybrid and IGS340 showed 80 % homology with the hypothetical protein expressed in rice genome. These new genes hold promiseimproving drought resistance of sugarcane through their use as candidate genes in marker assisted selection and in genetictransformation.