Differential Gene Expression Between Roots of Drought-Tolerant and -Sensitive Sugar Cane Cultivars

Drought is an abiotic stresses that limits the productivity and geographical distribution of sugar cane. The identification of new plant genotypes that can be more tolerant to water stress is essential for worldwide agriculture and economy. In addition, may help the understanding of basic mechanisms in the evolutionary adaptation to this type of stress. We conducted a comparative analysis of gene expression profiles between root tissues from a drought tolerant sugar cane cultivar (RB867515) and a drought susceptible cultivar (SP86-155) using cDNA-AFLP. The effects of water stress were evaluated at four sampling time points (1, 3, 5, and 10 days after water restriction) using the cDNA-AFLP technique and these results were validated using qRT-PCR. A total of 173 fragments were identified as differentially expressed (DEF) in response to water stress in the tolerant cultivar, with sizes ranging from 80 to 1000 bp. Seventy out of these DEFs were re-amplified, cloned, sequenced, and analyzed through comparisons with NCBI and SUCEST public databases. The similarity analyses revealed that many DEFs are involved in stress response (chaperones, glutathione peroxidase 4, ABA synthesis, aspartic proteases, protease inhibitor protein and trehalose-phosphate synthase), some are involved in communication pathways and signal transduction (Myb; bHLH), and some are unknown genes. Four genes were analyzed and validated by real time quantitative PCR and showed consistency with the cDNA-AFLP analyses. Our results can contribute to the development of cultivars of sugar cane that are more tolerant to water stress.