Improved reproductive growth of euhalophyte Suaeda salsa under salinity is correlated with altered phytohormone biosynthesis and signal transduction

Abstract

Phytohormones are essential for plant reproductive growth. Salinity limits crop reproductive growth and yield, but improves reproductive growth of euhalophytes. However, little is known about the mechanisms underlying salinity's effects on plant reproductive growth. To elucidate the role of plant hormones in flower development of the euhalophyte Suaeda salsa under saline conditions, we analysed endogenous gibberellic acid (GA3,4), indoleacetic acid (IAA), zeatin riboside (ZR), abscisic acid (ABA), and brassinosteroids (BRs) during flowering in control (0 mM) and NaCl-treated (200 mM) plants. At the end of vegetative growth, endogenous GA3, GA4, ABA and BR contents in stems of NaCl-treated plants were significantly higher than those in controls. During flowering, GA3, GA4, IAA and ZR contents showed the most significant enhancement in flower organs of plants treated with NaCl when compared with controls. Additionally, genes related to ZR, IAA, GA, BR and ABA biosynthesis and plant hormone signal transduction, such as those encoding CYP735A, CYP85A, GID1, NCED, PIF4, AHP, TCH4, SnRK2 and ABF, were upregulated in S. salsa flowers from NaCl-treated plants. These results suggest that coordinated upregulation of genes involved in phytohormone biosynthesis and signal transduction contributes to the enhanced reproductive growth of S. salsa under salinity.