EgSPEECHLESS Responses to Salt Stress by Regulating Stomatal Development in Oil Palm

Abstract

Oil palm is the most productive oil producing plant. Salt stress leads to growth damage and a decrease in yield of oil palm. However, the physiological responses of oil palm to salt stress and their underlying mechanisms are not clear. RNA-Seq was conducted on control and leaf samples from young palms challenged under three levels of salts (100, 250, and 500 mM NaCl) for 14 days. All three levels of salt stress activated EgSPCH expression and increased stomatal density of oil palm. Around 41% of differential expressed genes (DEGs) were putative EgSPCH binding target and were involved in multiple bioprocesses related to salt response. Overexpression of EgSPCH in Arabidopsis increased the stomatal production and lowered the salt tolerance. These data indicate that, in oil palm, salt activates EgSPCH to generate more stomata in response to salt stress, which differs from herbaceous plants. Our results might mirror the difference of salt-induced stomatal development between ligneous and herbaceous crops.

Transcriptome analysis reveals the key pathways and candidate genes involved in salt stress responses in Cymbidium ensifolium leaves

“…The known functions of these genes and their expression trends in T48 and T96 suggest that C. ensifolium undergoes changes in stomata development [ 27 ] and guard cell related functions under salt stress [ 28 , 29 ]. Moreover, genes/TFs related to stomata closure, e.g., SPEECHLESS, were downregulated in T48 compared to CK and in T96 compared to T48 [ 30 , 31 ]. In addition, one of the five MYB61 transcripts showed higher expression in T48 compared to CK.…”

“…In particular, the small subunit ribosomal proteins (S9e, S20e, S24e, S27e, S5e, S10e, S16e) large subunit ribosomal protein l7e, cellulose synthase A (CESA), catalase (CAT), V-type H + -transporting ATPase (V-ATPase), endoglucanases, beta-mannan synthase, expansins, auxin-binding proteins, POD, pectinesterases were upregulated in T48 compared to CK (Supplementary Table 2). Overall, the differential expression of stomata-related genes suggests that salt-stress may lead to reduced stomatal density [ 31 ] and increased stomata closure [ 30 ]. Furthermore, extensive rearrangements and remodeling may occur in the cell-wall [ 32 ].…”

“…These TFs/TRs belonged to 77 families. The most differentially expressed TFs in CKvsT48 were bHLH (45), followed by MYB (43), NAC (38), MYB-related (35), and C3H (30). Highly upregulated TFs in T48 compared to CK were B3-ARF, SET, bHLH, CSD, and GARP-G2-like.…”

Structural and functional analysis of stress-inducible genes and their promoters selected from young oil palm (Elaeis guineensis) under salt stress

“…The molecular mechanisms of salt resistance were the object of extensive studies in Arabidopsis and agronomic plant species such as rice [ 4 , 5 , 6 ]. Salt stress directly alters biological and chemical compounds in plant cells, which activates the cellular response in glycophytic plants [ 7 – 9 ]. Furthermore, salt stress leads to ionic, secondary, osmotic, and oxidative stresses, triggering multiple complex signaling pathways [ 7 ].…”

“…Salt stress directly alters biological and chemical compounds in plant cells, which activates the cellular response in glycophytic plants [ 7 – 9 ]. Furthermore, salt stress leads to ionic, secondary, osmotic, and oxidative stresses, triggering multiple complex signaling pathways [ 7 ].…”