Abstract:

【Objective】Soil salinization is one of the important abiotic stress factors that restricts crop production. Understanding the salt-tolerant mechanism of sorghum may provide a novel avenue to utilize saline soil for sorghum production. The objective of this study was to explore gene regulation mechanisms and metabolic pathways that related to salt tolerance of sorghum by transcriptome sequencing. 【Method】 The salt-tolerant genotype Bayeqi and salt-sensitive genotype PL212 were planted in plastic pots. At five-leaf stage (20 days after sowing), plants were treated with 180 mmol L ^-1 NaCl. Forty-eight hours after treatment, leaves treated by NaCl and unstressed control were sampled and were used for RNA extraction and transcriptome sequencing. Sequencing results were verified by qRT-PCR. 【Result】 Results showed that a total of 1 338 deferentially expressed genes, including 819 up-regulated and 519 down-regulated genes were detected. Cluster analysis revealed that in response to salt stress, five dependent oxygenase superfamily proteins, four cysteine-rich RLKs, three Glutathione S-transferase and three heavy metal transport/detoxification superfamily protein-related genes were significant up-regulated and/or down-regulated, and one K ⁺ ion transporter gene was also found to play an important role in salt-tolerance regulation. GO analysis found that 4 528 valid GO annotation entries were obtained from 15 418 genes, and salt-tolerant and salt-sensitive materials showed significant difference in biological processes, cellular components and molecular functions under salt stress treatment. The salt-tolerant materials exhibited obviously higher metabolic processes and cellular processes than salt-sensitive materials. Compared with salt-sensitive materials, multiple biological processes and localization processes were increased in salt-tolerant genotype, which might be the reasons of salt-tolerance. KEGG analysis showed that the salt-tolerant and salt-sensitive materials had more differential gene expression in phenylpropanoid biosynthesis, phenylalanine metabolism and flavonoid biosynthesis under control and salt stress conditions, which may be an important reason for the weak salt tolerance of sensitive materials. 【Conclusion】 The expression of salt-tolerant genes in sorghum is involved in many aspects of biological processes, cellular components and molecular functions. The gene expression in multiple processes and localization processes contributes to the salt tolerance, while excessive gene expression in phenylpropanoid biosynthesis, phenylalanine metabolism, and flavonoid biosynthesis likely contributes to the damage under salt stress.

Key words: sorghum, salt tolerance, transcriptome, differential gene expression, physiological regulation