Regulatory network of lncRNAs and mRNAs explains why salinity promotes photosynthesis and plant growth in the halophyte Suaeda salsa

Abstract

Suaeda salsa L. exhibits strong salt tolerance, with 200 mM NaCl being the optimum salt concentration for its growth. However, the specific molecular regulatory network remains unclear. This study used high-throughput sequencing technology to identify the expression abundance of lncRNAs after 24 h of 200 mM NaCl treatment (S24). A total of 16533 novel_lncRNAs were obtained, mainly divided into 10764 lincRNAs (65.11 %), 4936 antisense (29.85 %), and 833 sense overlap (5.04 %). Comparing lncRNAs at S24 and CK revealed 231 up-regulated and 257 down-regulated lncRNAs detected. The differential target genes corresponding to lncRNAs were mainly enriched in carbon metabolism, glycolysis/gluconeogenesis, carbon fixation in photosynthetic organisms and glyoxylate and dicarboxylate metabolism. Comparing the mRNAs at S24 and CK, the up-and down-regulated genes were 998 and 776, respectively, which corresponded to those for lncRNAs. Further investigation revealed that a particular lncRNA, TCONS_00024624 (lnc24), interacts with three genes that collectively regulate ribulose bisphosphate carboxylase (Rubisco). The expression of target genes of lncRNAs and activity of Rubisco and GAPDH in the leaves of S. salsa were upregulated and increased at S24 compared with CK. In conclusion, the results suggest that lncRNAs play important roles in enhancing the photosynthetic capacity of S. salsa and promoting its growth at 200 mM NaCl. This provides new references for studying salt tolerance mechanisms in S. salsa.