Comparative Analysis of Drought-Responsive Transcriptome in Different Genotype Saccharum spontaneum L.

Abstract

Saccharum spontaneum L. is one of the most drought-resistant plants among sugarcane breeding materials. To elucidate the internal molecular mechanisms that occur under drought stress conditions in drought-resistant clone 13-13 and drought-sensitive clone 84-261 of S. spontaneum, functional genes closely associated with drought resistance were identified to improve the study and utilization of stress resistance genes in S. spontaneum. High-throughput transcriptome sequencing analyses were performed on the 13-13 and 84-261 clones of this species as well as on control leaves of these materials after 7 days of drought stress. The genes in these two samples that displayed very significant differential expression mainly participated in metabolic activities associated with abiotic stress or adversity, including plant hormone signal transduction, glycolysis/gluconeogenesis, starch and sucrose metabolism, photosynthesis, and oxidative phosphorylation. This study identified some key DEGs for drought resistance, such as DEGs involved in the osmotic regulator, ROS removal system, toxin-degrading enzymes, secondary metabolism, signaling, transcription factors, and biotic and abiotic stresses. We speculated that these genes may have played an important role to resist drought in S. spontaneum. This study identified changes in gene expression and obtained functional information on DEGs in two drought-stressed samples and control. The results showed that the 13-13 had more DEGs than the 84-261. In addition, 13-13 had more down-regulated genes than up-regulated genes, whereas 84-261 had more up-regulated genes than down-regulated genes. These results confirm that drought-resistant S. spontaneum uses the constitutive expression of certain genes to respond to drought stress, whereas drought-sensitive S. spontaneum expresses drought-resistant genes only during drought stress. Thus, the S. spontaneum clone 13-13 exhibited stronger drought resistance than clone 84-261. The results of this study indicate that the response of S. spontaneum to drought stress involves the coordinated regulation of multiple genes and multiple biological metabolic processes and suggest that changes in gene expression might be the major regulatory method through which this species copes with drought stress.