The transcription factor OsbHLH035 mediates seed germination and enables seedling recovery from salt stress through ABA-dependent and ABA-independent pathways, respectively

Abstract

BackgroundMany transcription factors (TFs), such as those in the basic helix-loop-helix (bHLH) family, are important for regulating plant growth and plant responses to abiotic stress. The expression of OsbHLH035 is induced by drought and salinity. However, its functional role in rice growth, development, and the salt response is still unknown.ResultsThe bHLH TF OsbHLH035 is a salt-induced gene that is primarily expressed in germinating seeds and seedlings. Stable expression of GFP-fused OsbHLH035 in rice transgenic plants revealed that this protein is predominantly localized to the nucleus. Osbhlh035 mutants show delayed seed germination, particularly under salt-stress conditions. In parallel, abscisic acid (ABA) contents are over-accumulated, and the expression of the ABA biosynthetic genes OsABA2 and OsAAO3 is upregulated; furthermore, compared with that in wild-type (WT) seedlings, the salt-induced expression of OsABA8ox1, an ABA catabolic gene, in germinating Osbhlh035 mutant seeds is downregulated. Moreover, Osbhlh035 mutant seedlings are unable to recover from salt-stress treatment. Consistently, sodium is over-accumulated in aerial tissues but slightly reduced in terrestrial tissues from Osbhlh035 seedlings after salt treatment. Additionally, the expression of the sodium transporters OsHKT1;3 and 1;5 is reduced in Osbhlh035 aerial and terrestrial tissues, respectively. Furthermore, genetic complementation can restore both the delayed seed germination and the impaired recovery of salt-treated Osbhlh035 seedlings to normal growth.ConclusionOsbHLH035 mediates seed germination and seedling recovery after salt stress relief through the ABA-dependent and ABA-independent activation of OsHKT pathways, respectively.Electronic supplementary materialThe online version of this article (10.1186/s12284-018-0244-z) contains supplementary material, which is available to authorized users.

Characterization of Drought-Responsive Transcriptome During Seed Germination in Adzuki Bean (Vigna angularis L.) by PacBio SMRT and Illumina Sequencing

“…TFs are critical regulatory factors for developmental processes and stress responses in plant. TFs bHLH, MYB, NAC participated in regulating seed germination in rice, wheat, and Arabidopsis, respectively (Chen et al, 2018;Zhao et al, 2018;Guan et al, 2019). Four DEGs encoding ubiquitin proteasome system proteins (GeneID: 108332901, 108337045, 108319922, 108329730), and five TFs (GeneID: 108331170, NC_030637.1.548, 108331246, 108338278, 108346333) were identified, indicating they might regulate seed germination in response to drought stress in adzuki bean.…”

QTL analysis for rice salinity tolerance and fine mapping of a candidate locus qSL7 for shoot length under salt stress

“…Among 40 predicted genes in this region, only one gene LOC_Os07g43530 DNA-binding domain containing protein belongs to basic helix-loop-helix (bHLH) family has been reported previously as a transcription factor that plays a positive role in salt stress tolerance by binds to the promoter of a potassium ion transporter gene to regulate potassium homeostasis during salt stress (Wu et al 2015). A number of transcription factor of the bHLH gene family are important for regulating plant growth and plant responses to salt stress, such as OsbHLH094, OsbHLH062, and OsbHLH035 already reported to take part in salt tolerance by DNA-binding in the promoter region of some ion transporter genes (Blumwald 2000;Chen et al 2018;Toda et al Fig. 5 Fine mapping of qSL7 on chromosome 7.…”

Identification and Validation a Major QTL from “Sea Rice 86” Seedlings Conferred Salt Tolerance

“…Coincidentally, SKC1 was also located in qST1.1, and SR86 had the same amino acid sequence as Nona Bokra ( Figure S4). The balance of cations, such as Na + , K + , and Ca 2+ , and their transport ability played key roles in the salt tolerance response of rice [31,34,35]. Whether the ions transport affects salt tolerance in SR86 remains to be further explored.…”