Roles of Gibberellins and Abscisic Acid in Regulating Germination of Suaeda salsa Dimorphic Seeds Under Salt Stress

Abstract

Seed heteromorphism observed in many halophytes is an adaptive phenomenon toward high salinity. However, the relationship between heteromorphic seed germination and germination-related hormones under salt stress remains elusive. To gain an insight into this relationship, the roles of gibberellins (GAs) and abscisic acid (ABA) in regulating germination of Suaeda salsa dimorphic brown and black seeds under salinity were elucidated by studying the kinetics of the two hormones during germination of the two seed types with or without salinity treatment. Morphological analysis suggested that brown and black are in different development stage. The content of ABA was higher in dry brown than in black seeds, which gradually decreased after imbibition in water and salt solutions. Salt stress induced ABA accumulation in both germinating seed types, with higher induction effect on black than brown seeds. Black seeds showed lower germination percentage than brown seeds under both water and salt stress, which might be attributed to their higher ABA sensitivity rather than the difference in ABA content between black and brown seeds. Bioactive GA4 and its biosynthetic precursors showed higher levels in brown than in black seeds, whereas deactivated GAs showed higher content in black than brown seeds in dry or in germinating water or salt solutions. High salinity inhibited seed germination through decreasing the levels of GA4 in both seeds, and the inhibited effect of salt stress on GA4 level of black seeds was more profound than that of brown seeds. Taken together higher GA4 content, and lower ABA sensitivity contributed to the higher germination percentage of brown seeds than black seeds in water and salinity; increased ABA content and sensitivity, and decreased GA4 content by salinity were more profound in black than brown seeds, which contributed to lower germination of black seeds than brown seeds in salinity. The differential regulation of ABA and GA homeostases by salt stress in dimorphic seeds might provide a strategy for S. salsa plants to survive adverse environmental conditions.

Photosynthetic Regulation Under Salt Stress and Salt-Tolerance Mechanism of Sweet Sorghum

“…Hormones play essential roles in the germination, growth, and development of plants (Chen et al, 2013a;Li et al, 2015). Hormones and their signaling pathways are integrated to allow the triggering of appropriate cellular and physiological responses to adapt to stress circumstances (Ryu and Cho, 2015).…”

High salinity impacts germination of the halophyte Cakile maritima but primes seeds for rapid germination upon stress release

“…More generally, this is consistent with other reports highlighting the salt-sensitivity of annual halophytes at the early developmental stages of their ontogeny. For instance, the delayed germination onset was documented for halophytes like Suaeda salsa (Li et al 2015), Plantago coronopus (Bueno et al 2017) and Eutrema salsugineum (Kazachkova et al 2016). In rice, the prolongation of phase II (imbibition) in response to high salinity accounted for the slower germination rate (Xu et al 2017).…”

Analysis of widely targeted metabolites of the euhalophyte Suaeda salsa under saline conditions provides new insights into salt tolerance and nutritional value in halophytic species

“…S. salsa is an euhalophyte with high salt tolerance during germination [23][24][25][26], vegetative growth [27] and reproductive stages [28][29][30][31]. The species is considered to have potential as a vegetable and oilseed crop [32,33], and it is rich in protein, crude fiber, carotenoids and amino acids [34].…”