Current Understanding of bHLH Transcription Factors in Plant Abiotic Stress Tolerance

Guo, Jianrong; Sun, Baixue; He, Huanrong; Zhang, Yifan; Tian, Huaying; Wang, Baoshan

doi:10.3390/ijms22094921

Cited by 107 publications

(65 citation statements)

References 86 publications

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“…The regulation of a large number of TFs belonging to 33 families is indicative of their significant roles in drought stress tolerance and rewatering. The bHLH TFs play important roles in drought stress in addition to their roles in reproduction (flower and fruit development) [ 83 ]. The downregulation of bHLH TFs in Z2, Z4, and Z6 as compared to Z8 indicates that drought stress affects the expression of these TFs in P. kingianum tubers.…”

Section: Discussionmentioning

confidence: 99%

Transcriptomic responses to drought stress in Polygonatum kingianum tuber

Qian

Cong

et al. 2021

BMC Plant Biol

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Background Polygonatum kingianum Coll. et Hemsl. is an important plant in Traditional Chinese Medicine. The extracts from its tubers are rich in polysaccharides and other metabolites such as saponins. It is a well-known concept that growing medicinal plants in semi-arid (or drought stress) increases their natural compounds concentrations. This study was conducted to explore the morpho-physiological responses of P. kingianum plants and transcriptomic signatures of P. kingianum tubers exposed to mild, moderate, and severe drought and rewatering. Results The stress effects on the morpho-physiological parameters were dependent on the intensity of the drought stress. The leaf area, relative water content, chlorophyll content, and shoot fresh weight decreased whereas electrolyte leakage increased with increase in drought stress intensity. A total of 53,081 unigenes were obtained; 59% of which were annotated. We observed that 1352 and 350 core genes were differentially expressed in drought and rewatering, respectively. Drought stress driven differentially expressed genes (DEGs) were enriched in phenylpropanoid biosynthesis, flavonoid biosynthesis, starch and sucrose metabolism, and stilbenoid diarylheptanoid and gingerol biosynthesis, and carotenoid biosynthesis pathways. Pathways such as plant-pathogen interaction and galactose metabolism were differentially regulated between severe drought and rewatering. Drought reduced the expression of lignin, gingerol, and flavonoid biosynthesis related genes and rewatering recovered the tubers from stress by increasing the expression of the genes. Increased expression of carotenoid biosynthesis pathway related genes under drought suggested their important role in stress endurance. An increase in starch and sucrose biosynthesis was evident from transcriptomic changes under drought stress. Rewatering recovered the drought affected tubers as evident from the contrasting expression profiles of genes related to these pathways. P. kingianum tuber experiences an increased biosynthesis of sucrose, starch, and carotenoid under drought stress. Drought decreases the flavonoids, phenylpropanoids, gingerol, and lignin biosynthesis. These changes can be reversed by rewatering the P. kingianum plants. Conclusions These results provide a transcriptome resource for P. kingianum and expands the knowledge on the effect of drought and rewatering on important pathways. This study also provides a large number of candidate genes that could be manipulated for drought stress tolerance and managing the polysaccharide and secondary metabolites’ contents in P. kingianum.

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Section: Discussionmentioning

confidence: 99%

Transcriptomic responses to drought stress in Polygonatum kingianum tuber

Qian

Cong

et al. 2021

BMC Plant Biol

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“…The stress tolerance of a plant depends on adversity genes, and the overexpression of these genes can improve the plant’s ability to adapt to a variety of environmental stresses [ 28 ]. Although several studies of the involvement of bHLH TFs in plant abiotic stress response have been performed, including studies on drought stress [ 29 – 32 ], salt stress [ 33 , 34 ], and chilling stress [ 35 , 36 ], further studies are still required, particularly in the peanut [ 37 , 38 ]. In-depth analysis and functional characterization of several of the family members can therefore provide an improved understanding of the members of the TF family in peanut involved in the response to stress.…”

Section: Discussionmentioning

confidence: 99%

The bHLH transcription factor AhbHLH112 improves the drought tolerance of peanut

Chunjuan¹,

Cheng²,

Sun³

et al. 2021

BMC Plant Biol

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Background Basic helix-loop-helix (bHLH) transcription factors (TFs) are one of the largest gene families in plants. They regulate gene expression through interactions with specific motifs in target genes. bHLH TFs are not only universally involved in plant growth but also play an important role in plant responses to abiotic stress. However, most members of this family have not been functionally characterized. Results Here, we characterized the function of a bHLH TF in the peanut, AhHLH112, in response to drought stress. AhHLH112 is localized in the nucleus and it was induced by drought stress. The overexpression of this gene improves the drought tolerance of transgenic plants both in seedling and adult stages. Compared to wild-type plants, the transgenic plants accumulated less reactive oxygen species (ROS), accompanied by increased activity and transcript levels of antioxidant enzymes (superoxide dismutase, peroxidase and catalase). In addition, the WT plants demonstrated higher MDA concentration levels and higher water loss rate than the transgenic plants under drought treatment. The Yeast one-hybrid result also demonstrates that AhbHLH112 directly and specifically binds to and activates the promoter of the peroxidase (POD) gene. Besides, overexpression of AhHLH112 improved ABA level under drought condition, and elevated the expression of genes associated with ABA biosynthesis and ABA responding, including AtNCED3 and AtRD29A. Conclusions Drawing on the results of our experiments, we propose that, by improving ROS-scavenging ability, at least in part through the regulation of POD -mediated H2O2 homeostasis, and possibly participates in ABA-dependent stress-responding pathway, AhbHLH112 acts as a positive factor in drought stress tolerance.

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“…Taken all above, we could conclude that SmbHLH1 was a repressor in anthocyanin biosynthesis. Moreover, the silencing of SmbHLH1 in fruit peel tissue to verify the fruit can accumulate more anthocyanins is worthy in the future, BHLH proteins are the second largest class of transcription factors in plants and can be divided into 26-32 subgroups (Carretero-Paulet et al, 2010;Pires and Dolan, 2010); they play important roles in stress tolerance, reproduction, and secondary metabolite biosynthesis (Sun et al, 2020b;Guo et al, 2021). It is worth noting that AtTT8, AtGL3, AtEGL1, and AtMYC1, which are positive regulator of anthocyanin biosynthesis, were placed into subgroup IIIf (Heim et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

The Basic Helix-Loop-Helix Transcription Factor SmbHLH1 Represses Anthocyanin Biosynthesis in Eggplant

et al. 2021

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Many basic helix-loop-helix transcription factors (TFs) have been reported to promote anthocyanin biosynthesis in numerous plant species, but little is known about bHLH TFs that inhibit anthocyanin accumulation. In this study, SmbHLH1 from Solanum melongena was identified as a negative regulator of anthocyanin biosynthesis. However, SmbHLH1 showed high identity with SmTT8, which acts as a SmMYB113-dependent positive regulator of anthocyanin-biosynthesis in plants. Overexpression of SmbHLH1 in eggplant caused a dramatic decrease in anthocyanin accumulation. Only the amino acid sequences at the N and C termini of SmbHLH1 differed from the SmTT8 sequence. Expression analysis revealed that the expression pattern of SmbHLH1 was opposite to that of anthocyanin accumulation. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that SmbHLH1 could not interact with SmMYB113. Dual-luciferase assay demonstrated that SmbHLH1 directly repressed the expression of SmDFR and SmANS. Our results demonstrate that the biological function of bHLHs in anthocyanin biosynthesis may have evolved and provide new insight into the molecular functions of orthologous genes from different plant species.

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Current Understanding of bHLH Transcription Factors in Plant Abiotic Stress Tolerance

Cited by 107 publications

References 86 publications

Transcriptomic responses to drought stress in Polygonatum kingianum tuber

Transcriptomic responses to drought stress in Polygonatum kingianum tuber

The bHLH transcription factor AhbHLH112 improves the drought tolerance of peanut

The Basic Helix-Loop-Helix Transcription Factor SmbHLH1 Represses Anthocyanin Biosynthesis in Eggplant

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