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Chromosome location of bHLH genes in B. rapa (a) and B. oleracea (b). The symbols + and − indicate the gene located in sense or antisense strands, respectively. The genes in red are the newly identified bHLH genes in B. rapa
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Abstract Background The basic helix–loop–helix (bHLH) is the second largest gene family in the plant, some members play important roles in pistil development and response to drought, waterlogging, cold stress and salt stress. The bHLH gene family has been identified in many species, except for Brassica oleracea and B. napus thus far. This study aim...
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... bHLH genes were named based on their gene ID (Table S1, S2, S3 and S4). We constructed an unrooted cladogram with domain sequences of all bHLH genes of B. oleracea, B. rapa, B. napus and A. thaliana ( Figure S1), and branches of the bHLH genes in A. thaliana and B. rapa were labeled in red and green, respectively. We also constructed NJ phylogenetic trees by using the domain sequences of bHLH genes from B. oleracea, B. rapa, and B. napus, respectively ( Figure S2, Figure S3, Figure S4, Figure S5). ...
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... used three methods to determine the subfamily of bHLH genes in B. oleracea and B napus. The first one, according to the subfamiles of bHLH genes in A. thaliana and B. rapa, the subfamilies of newly identified bHLH genes in B. oleracea, B. rapa and B. napus were classified ( Figure S1). The second one, we classified the newly identified bHLH genes by the distance between the branches of their phylogenetic trees ( Figures S2, Fig- ure S3, Figure S4. Figure S5). ...
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... determine whether the number of exons and introns in different subfamilies is conserved, we analyze the intron-exon location of all bHLH members from three Brassica crops and integrated the results according to the NJ phylogenetic trees, as shown in Figure S10, Figure S11 and Figure S12. In B. oleracea, most members in some subfamilies had the similar gene structure. ...
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... determine whether the number of exons and introns in different subfamilies is conserved, we analyze the intron-exon location of all bHLH members from three Brassica crops and integrated the results according to the NJ phylogenetic trees, as shown in Figure S10, Figure S11 and Figure S12. In B. oleracea, most members in some subfamilies had the similar gene structure. ...
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... determine whether the number of exons and introns in different subfamilies is conserved, we analyze the intron-exon location of all bHLH members from three Brassica crops and integrated the results according to the NJ phylogenetic trees, as shown in Figure S10, Figure S11 and Figure S12. In B. oleracea, most members in some subfamilies had the similar gene structure. ...
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... B. rapa, 247 bHLH genes were distributed on 10 chromosomes (i.e., A01-A10) (Fig. 1a). For the 21 newly identified genes, BrabHLH237, BrabHLH242, and BrabHLH251 were distributed on A01 chromosomes; BrabHLH234 and BrabHLH248 were distributed on A02; and BrabHLH231 and BrabHLH243 were distributed on A03 and A06. Two genes were located on A04 and A10, three genes were distributed on A05 and A07, and four members were ...
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... distributed on A01 chromosomes; BrabHLH234 and BrabHLH248 were distributed on A02; and BrabHLH231 and BrabHLH243 were distributed on A03 and A06. Two genes were located on A04 and A10, three genes were distributed on A05 and A07, and four members were mapped on A09. A total of 222 BolbHLH genes were distributed in 9 chromosomes (i.e., C01-C09) (Fig. 1b). The location of all BolbHLH genes on the chromosome can be found in Table S1. The number of bHLH genes distributed on C06 was the least, with only 16 genes, while 35 genes were distributed on C04. A total of 33 genes were distributed on the C03 chromosome, 28 genes on C08, 25 genes on C01 and C07, 21 genes on C02 and C09, and 18 genes ...
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... this study, we predicted the signal peptides of 268, 251 and 440 bHLH proteins in B. oleracea, B. rapa, and B. napu, respectively. Only one and two members had signal peptides in B. oleracea and B. rapa, which were BolbHLH128 (Bol021805), BrabHLH084 (Bra014653), and BrabHLH168 (Bra029354, Figure S13). According to the C, S, and Y values, the site near serine may be a potential signal peptide shear site. ...
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... genes have randomly been chosen to conduct gene expression analysis after ABA and JA treatments. The leaves sampled at 0 h after treatments were used as the control and the relative expression of others samples were calculated (Table S10). All the relative expression results underwent logarithmic transformation and visualized with a heat map (Fig. 10). For ABA treatment, the expression levels of 24 genes decreased after treatment, including 13 BrabHLH genes, 4 BnabHLH genes and 7 BolbHLH genes. The expression levels of 16 genes were increased in, not in B. rapa, 10 in B. napus and 6 in B. olerace. The expression levels increased first and then decreased of 4 BrabHLH genes, 2 BnabHLH ...
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... selection [34,35]. Theoretically, after WGD and WGT events, the genome size of B. oleracea should be threefold larger than that of A. thaliana. However, the size was much smaller than the theoretical value. The retention rate of AtbHLH orthologous genes was 57% in B. oleracea, which was close to its retention rate (56%) in B. rapa, while the Fig. 10 Expression analysis of 20 BolbHLH, 20 BrabHLH and 20 BnabHLH genes under ABA and JA treatments actual retention rates in B. rapa and B. oleracea were 51.6 and 55.1%. The retention rate of BolbHLH was close to that of the core and random genes and slightly higher than that of the other gene families, such as the PMEI (52%) [35] and SDG ...
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Citations
... Ks and Ka values were utilized to evaluate the date of divergence within the BoBPC gene family, and Ka/Ks ratios were employed to calculate the rates of molecular evolution for every pair of paralogous genes. Assuming λ to be 6.96 × 10−9, the divergence time (T) was computed using the method T=Ks/2 [25]. To create graphical representations for the synteny study, TBtools' Multiple Synteny Plot function was used. ...
Originating in the Mediterranean, B. oleracea is grown all over the world and is highly valued for its nutritional value and variety in cooking. Its susceptibility to pests, diseases, and environmental stressors, however, poses significant challenges to sustaining consistent crop quality and productivity. The BASIC PENTACYSTEINE gene significantly impacts plant growth and responses to abiotic stresses. Nevertheless, little is known about its precise role and the underlying biological processes in B. oleracea. Eleven BPC genes in B. oleracea were identified by a thorough genome-wide investigation and categorized into three categories according to their structural traits and gene motifs. There were eight different chromosomes on which these BoBPCs were located. Comparative synteny analysis was used to reveal the evolutionary traits of potatoes, Arabidopsis, and B. oleracea. The BoBPC family genes in B. oleracea were found to have specific cis-elements linked to growth, stress responses, and hormone regulation when their promoter regions were studied. Cuticular wax synthesis expression revealed that all BoBZR1 genes, from wild to mutant, expressed at varied amounts in distinct types. Moreover, distinctive BoBPC gene expression patterns were found in the seven distinct tissues that were studied. Our thorough analysis shows that the BoBPC family is widely involved in B. oleracea developmental processes. The present findings provide an established theoretical basis for further exploration into the composition and roles of BoBPC in B. oleracea.
... SSRs developed by the MADS box genes can represent a useful tool to detect polymorphisms inducing a hypertrophic curd induction (Treccarichi et al. 2021(Treccarichi et al. , 2023 Basic helix-loop-helix genes represent the second largest plants' family genes, which are involved in pistil development and in the abiotic and biotic stresses response and belong to a family of transcriptional regulators present in three eukaryotic kingdoms (Heim et al. 2003;Skinner et al. 2010). The study of Miao et al. (2020) allowed for the identification of 268 bHLH genes in B. oleracea, 440 genes in B. napus, and 251 genes in B. rapa, including 21 new bHLH members and the gene structures, Phylogeny threes and the conservative motif analysis were carried out showing similar expression patterns between B. rapa and B. napus in roots and contrasting ones in stems, leaves and in reproductive organs (Miao et al. 2020). Genome wide analysis of the bHLH transcription factor was studied for Chinese-cabbage showing the interaction network associated to the ArabidopsisbHLH genes and in cabbage, which revealed several chilling response patterns (Song et al. 2019;Shan et al. 2019). ...
... SSRs developed by the MADS box genes can represent a useful tool to detect polymorphisms inducing a hypertrophic curd induction (Treccarichi et al. 2021(Treccarichi et al. , 2023 Basic helix-loop-helix genes represent the second largest plants' family genes, which are involved in pistil development and in the abiotic and biotic stresses response and belong to a family of transcriptional regulators present in three eukaryotic kingdoms (Heim et al. 2003;Skinner et al. 2010). The study of Miao et al. (2020) allowed for the identification of 268 bHLH genes in B. oleracea, 440 genes in B. napus, and 251 genes in B. rapa, including 21 new bHLH members and the gene structures, Phylogeny threes and the conservative motif analysis were carried out showing similar expression patterns between B. rapa and B. napus in roots and contrasting ones in stems, leaves and in reproductive organs (Miao et al. 2020). Genome wide analysis of the bHLH transcription factor was studied for Chinese-cabbage showing the interaction network associated to the ArabidopsisbHLH genes and in cabbage, which revealed several chilling response patterns (Song et al. 2019;Shan et al. 2019). ...
... S5, S14, S15, and S45 appear to be the most recessive S-alleles in the stigma, while S23, S29, S35, S36, and S39 appear to be the most dominant. The importance of dominance between S-alleles in the breeding system of Brussels sprouts is discussed, and an explanation for the high frequency of S2 based on its unusual dominance behavior is proposed (Ockendon 1975 Ockendon 1982;Brace et al. 1994;Kusaba et al. 1999;Kimura et al. 2002;Sato et al. 2003;Shan et al. 2019;Miao et al. 2020 ...
... With the development of sequencing skills and bioinformatics, the genome sequences of Brassica plants, B. napus, B. rapa, and B. oleracea, have been completed at recent years (Lagercrantz 1998;Morant et al. 2002;Blanc et al. 2003;Wang et al. 2011;Cheng et al. 2014;Nguyen et al. 2020). Several family genes have been identified in Brassica species based on the genome databases (Liang et al. 2019;Wei et al. 2019;Zhao et al. 2019;Miao et al. 2020). We conducted the comparative analysis of PHO1 family genes in three Brassica species and analyzed their expression patterns under low Pi stress. ...
The members of PHOSPHATE 1 (PHO1) family play important roles in plant phosphate (Pi) transport and adaptation to Pi deficiency. The functions of PHO1 family proteins have been reported in several plant species, with the exception of Brassica species. Here, we identified 23, 23, and 44 putative PHO1 family genes in Brassica rapa, Brassica oleracea, and Brassica napus by whole genome analysis, respectively. The phylogenetic analysis divided PHO1 family proteins into eight groups, which represented the orthologous relationships among PHO1 members. The gene structure and the conserved motif analysis indicated that the most PHO1 family genes had similar gene structures and the PHO1 proteins shared mutual conserved motifs. The chromosome distribution analysis showed that the majority of BnPHO1 family genes distributed analogously at chromosomes with BrPHO1 and BoPHO1 family genes. The data showed that PHO1 family genes were highly conserved during evolution from diploid to tetraploid. Furthermore, the expression analysis showed that PHO1 family genes had different expression patterns in plant tissues, suggesting the diversity of gene functions in Brassica species. Meanwhile, the expression analysis also revealed that some PHO1 family genes were significantly responsive to Pi deficiency, suggesting that PHO1 family genes play critical roles in Pi uptake and homeostasis under low Pi stress. Altogether, the characteristics of PHO1 family genes provide a reliable groundwork for further dissecting their functions in Brassica species.
... The bHLH gene family gets its name from the bHLH domain it contains. This domain is comprised of 50-60 amino acids which can be divided into basic amino acids at the Nterminus (10-15 amino acids) and the Helix-Loop-Helix (HLH) at the C-terminus (about 40 amino acids) (Li et al. 2006;Miao et al. 2020;Zhang et al. 2020). Furthermore, this region contains six basic residues and a highly conserved HER motif (His 5-Glu 9-Arg 13), both of which are believed to bind certain DNA sequences (Kavas et al. 2016;Kurt & Filiz 2018;Sun et al. 2020). ...
The basic Helix-Loop-Helix (bHLH) superfamily is the most widespread family of transcription factors in eukaryotic organisms, which can activate the expression of genes by interacting with specific promoters in the genes. The bHLH transcription factors direct the development and metabolic process of plants, including flowering initiation and secondary metabolite production, by attaching to specific sites on their promoters. These transcription factors are essential for encouraging plant tolerance or the adjustment to harsh environmental conditions. The involvement of bHLH genes in anthocyanin formation in fleshy fruit-bearing plants, as well as the role of these genes in response to stimuli including drought, salt, and cold stress, are discussed in this article. New concepts and goals for the production of stress-tolerant fruit species are suggested. Furthermore, solid evidence for the critical role of bHLH genes in the growth and development, as well as anthocyanin biosynthesis in fleshy fruit plants, are also presented in this article. This review identifies several future research directions that can shed light on the roles of bHLH genes in fruit-bearing plants and will assist the use of these genes in efforts to breed fruit crop varieties that are more resistant to stress. Generally, there has been little research carried out on the role of bHLHs transcription factor family genes in fleshy fruit-bearing plant species and more in-depth studies are required to fully understand the diverse role of bHLH genes in these species.
... Additionally, the whole genome triplication (WGT) also exists in the R. sativus genome as is the case for the B. rapa and B. oleracea genomes [12]. BHLH genes have been confirmed in B. rapa and B. oleracea, with 251 B. rapa bHLHs and 268 B. oleracea bHLHs, respectively [13]. To understand the synteny relationships between RsbHLH genes and Bra/BolbHLH genes, the syntenic orthologous gene pairs were identified between RsbHLHs and Bra/BolbHLHs. ...
Background
Green-fleshed radish (Raphanus sativus L.) is an economically important root vegetable of the Brassicaceae family, and chlorophyll accumulates in its root tissues. It was reported that the basic helix-loop-helix (bHLH) transcription factors play vital roles in the process of chlorophyll metabolism. Nevertheless, a comprehensive study on the bHLH gene family has not been performed in Raphanus sativus L.
Results
In this study, a total of 213 Raphanus sativus L. bHLH (RsbHLH) genes were screened in the radish genome, which were grouped into 22 subfamilies. 204 RsbHLH genes were unevenly distributed on nine chromosomes, and nine RsbHLH genes were located on the scaffolds. Gene structure analysis showed that 25 RsbHLH genes were intron-less. Collineation analysis revealed the syntenic orthologous bHLH gene pairs between radish and Arabidopsis thaliana/Brassica rapa/Brassica oleracea. 162 RsbHLH genes were duplicated and retained from the whole genome duplication event, indicating that the whole genome duplication contributed to the expansion of the RsbHLH gene family. RNA-seq results revealed that RsbHLH genes had a variety of expression patterns at five development stages of green-fleshed radish and white-fleshed radish. In addition, the weighted gene co-expression network analysis confirmed four RsbHLH genes closely related to chlorophyll content.
Conclusions
A total of 213 RsbHLH genes were identified, and we systematically analyzed their gene structure, evolutionary and collineation relationships, conserved motifs, gene duplication, cis-regulatory elements and expression patterns. Finally, four bHLH genes closely involved in chlorophyll content were identified, which may be associated with the photosynthesis of the green-fleshed radish. The current study would provide valuable information for further functional exploration of RsbHLH genes, and facilitate clarifying the molecular mechanism underlying photosynthesis process in green-fleshed radish.
... The other side, many bHLH genes have been shown to respond to various forms of stress such as drought, salt, and cold stresses [52,57,63]. Other TFs (e.g., NAC, MYB, and WRKY) have been investigated for their capacities to improve tolerance and resistance in many plants [64][65][66][67][68], while participating in abiotic and biotic stress responses [18,69,70]. ...
Opisthopappus is a major wild source of Asteraceae with resistance to cold and drought. Two species of this genus ( Opisthopappus taihangensis and O. longilobus ) have been employed as model systems to address the evolutionary history of perennial herb biomes in the Taihang Mountains of China. However, further studies on the adaptive divergence processes of these two species are currently impeded by the lack of genomic resources. To elucidate the molecular mechanisms involved, a comparative analysis of these two species was conducted. Among the identified transcription factors, the bHLH members were most prevalent, which exhibited significantly different expression levels in the terpenoid metabolic pathway. O. longilobus showed higher level of expression than did O. taihangensis in terms of terpenes biosynthesis and metabolism, particularly monoterpenoids and diterpenoids. Analyses of the positive selection genes (PSGs) identified from O. taihangensis and O. longilobus revealed that 1203 genes were related to adaptative divergence, which were under rapid evolution and/or have signs of positive selection. Differential expressions of PSG occurred primarily in the mitochondrial electron transport, starch degradation, secondary metabolism, as well as nucleotide synthesis and S-metabolism pathway processes. Several PSGs were obviously differentially expressed in terpenes biosynthesis that might result in the fragrances divergence between O. longilobus and O. taihangensis , which would provide insights into adaptation of the two species to different environments that characterized by sub-humid warm temperate and temperate continental monsoon climates. The comparative analysis for these two species in Opisthopappus not only revealed how the divergence occurred from molecular perspective, but also provided novel insights into how differential adaptations occurred in Taihang Mountains.
... The error bar is standard deviation (n = 3; P < 0.05; Student's t test) ◂ Content courtesy of Springer Nature, terms of use apply. Rights reserved. of homologous genes in different species are similar, but there are differences to some extent (Lohani et al. 2019;He et al. 2020;Miao et al. 2020). For example, some genes with high expression in B. napus roots, stem and leaves had low expression in B. rapa and B. oleracea, while some gene with low expression in B. napus flowers and siliques were highly expressed in B. rapa and B. oleracea (Miao et al. 2020). ...
... Rights reserved. of homologous genes in different species are similar, but there are differences to some extent (Lohani et al. 2019;He et al. 2020;Miao et al. 2020). For example, some genes with high expression in B. napus roots, stem and leaves had low expression in B. rapa and B. oleracea, while some gene with low expression in B. napus flowers and siliques were highly expressed in B. rapa and B. oleracea (Miao et al. 2020). ...
Main conclusion
A total of 278 BnWRKYs were identified and analyzed. Ectopic expression of BnWRKY149 and BnWRKY217 suggests that they function in the ABA signaling pathway.
Abstract
WRKY transcription factors play an important role in plant development, however, their function in Brassica napus L. abiotic stress response is still unclear. In this study, a total of 278 BnWRKY transcription factors were identified from the B. napus genome data, and they were subsequently distributed in three main groups. The protein motifs and classification of BnWRKY transcription factors were analyzed, and the locations of their corresponding encoding genes were mapped on the chromosomes of B. napus. Transcriptome analysis of rapeseed seedlings exposed to drought, salt, heat, cold and abscisic acid treatment revealed that 99 BnWRKYs responded to at least one of these stresses. The expression profiles of 12 BnWRKYs were examined with qPCR and the result coincided with RNA-seq analysis. Two genes of interest, BnWRKY149 and BnWRKY217 (homologs of AtWRKY40), were overexpressed in Arabidopsis, and the corresponding proteins were located to the nucleus. Transgene plants of BnWRKY149 and BnWRKY217 were less sensitive to ABA than Arabidopsis Col-0 plants, suggesting they might play important roles in the responses of rapeseed to abiotic stress.
... The bHLH gene family was comparatively analyzed in several Brassicaceae species, B. oleracea, B. rapa, and B. napus [32]. In Arabidopsis, AtHFR1, an atypical member of the bHLH family that lacks the DNA-binding capacity, was showed to negatively regulate the SAS via interacting PIF4/5 and thereby prohibiting the functions of these transcription factors [33]. ...
Background
Plants grown under shade are exposed to low red/far-red ratio, thereby triggering an array of altered phenotypes called shade avoidance syndrome (SAS). Shade negatively influences plant growth, leading to a reduction in agricultural productivity. Understanding of SAS is crucial for sustainable agricultural practices, especially for high-density indoor farming. Brassicaceae vegetables are widely consumed around the world and are commonly cultivated in indoor farms. However, our understanding of SAS in Brassicaceae vegetables and their genome-wide transcriptional regulatory networks are still largely unexplored.
Results
Shade induced common signs of SAS, including hypocotyl elongation and reduced carotenoids/anthocyanins biosynthesis, in two different Brassicaceae species: Brassica rapa (Choy Sum and Pak Choy) and Brassica oleracea (Kai Lan). Phenotype-assisted transcriptome analysis identified a set of genes induced by shade in these species, many of which were related to auxin biosynthesis and signaling [e.g. YUCCA8 ( YUC8 ), YUC9 , and INDOLE-3-ACETIC ACID INDUCIBLE ( IAAs )] and other phytohormones signaling pathways including brassinosteroids and ethylene. The genes functioning in plant defense (e.g. MYB29 and JASMONATE-ZIM-DOMAIN PROTEIN 9 ) as well as in biosynthesis of anthocyanins and glucosinolates were repressed upon shade. Besides, each species also exhibited distinct SAS phenotypes. Shade strongly reduced primary roots and elongated petioles of B. oleracea, Kai Lan. However, these SAS phenotypes were not clearly recognized in B. rapa , Choy Sum and Pak Choy. Some auxin signaling genes (e.g. AUXIN RESPONSE FACTOR 19 , IAA10 , and IAA20 ) were specifically induced in B. oleracea , while homologs in B. rapa were not up-regulated under shade. Contrastingly, shade-exposed B. rapa vegetables triggered the ethylene signaling pathway earlier than B. oleracea , Kai Lan. Interestingly, shade induced the transcript levels of LONG HYPOCOTYL IN FAR-RED 1 ( HFR1 ) homolog in only Pak Choy as B. rapa . As HFR1 is a key negative regulator of SAS in Arabidopsis, our finding suggests that Pak Choy HFR1 homolog may also function in conferring higher shade tolerance in this variety.
Conclusions
Our study shows that two Brassicaceae species not only share a conserved SAS mechanism but also exhibit distinct responses to shade, which will provide comprehensive information to develop new shade-tolerant cultivars that are suitable for high-density indoor farms.
... 162 bHLH A. thaliana and 167 rice bHLH genes were also grouped into 25 subfamilies in A. thaliana ). Besides, different other studies on this bHLH family have been reported in plant species before phylogenetic tree comparison, as described by Miao et al. (2020). In legumes, studies have been showing that transcriptomic techniques are the most positive ways to elucidate abiotic stresses (Babar et al. 2014). ...
The basic helix loop helix (bHLH) transcription factor comprises one of the largest plant-specific transcriptional regulators in plant growth and development that response to biotic and abiotic stresses. Many members of bHLH play essential roles in the growth of root hair and response to drought, salt, and cold stresses. The family of bHLH genes has been found in many species; nevertheless, the barrel medic and alfalfa species still have a minute gap of bHLH new members thus far. This research aims to identify members of the bHLH family in barrel medic and alfalfa and elucidate their expression pattern level, network analysis, predictive 3D modeling and phylogenetic relationships. Here, we identified and characterized the bHLH gene family in both barrel medic and alfalfa plants and their genes expression response to drought, salinity, and cold stresses. A total of 159 MtbHLH and 133 MsbHLH genes were identified and characterized, divided into 18 subgroups and 17 subgroups, respectively. As a ubiquitous and popular method, neighbor-joining clustering was used. Based on the phylogenetic analyses, the VIII and IX subfamily and X subfamily were selected as the stress-related subfamily in these two species. The 154 MtbHLH genes were progressively distributed on the 8 chromosomes and 23 tandem duplicated genes, and 44 duplicated genes segments were detected in MtbHLH family. The analyses of gene ontology discovered the bHLH predominantly functions in protein and DNA binding in these two species. The results of Ka/Ks were < 1, which showed that the most orthologous of the bHLH gene values was found between A. thaliana and M. truncatula species. Remarkably, 7 MtbHLH and 10 MsbHLH genes were selected and validated with qRT-PCR after the treatment’s samples sampled under stressed abiotic conditions. The similar expression patterns between M. truncatula and M. sativa L have demonstrated identical expression patterns level in the root, and contrasting patterns in the stems and leaves were diverse. It was highlighted that the gene expression analyses of 17 bHLH genes were up-regulated to stresses, respectively, apart from some genes that were timely trended down-regulated to control (0 h). This study provided a concise understanding of the tissue specific of bHLH gene functions in genome-wide levels under drought, salt, and cold stresses. Our analyses provide the first insights onto the M. truncatula and M. sativa L evolution that contributes to molecular breeding for improving plant yield and stress tolerance.
... bHLHs are involved in regulating the synthesis of flavonoids (Ludwig et al., 1989), which play important roles in the ROS homeostasis under these stresses. As an illustration of the size of the bHLHs family in various plant species, 164 bHLH TFs have been found in Arabidopsis (Arabidopsis thaliana L.), while there are 180 in rice (Oryza sativa L.), 190 in tobacco (Nicotiana tabacum L.), 191 in grapes (Vitis vinifera L.), 102 in walnut (Juglans regia L.), 85 in Ginkgo biloba, 268 in Brassica oleracea, 440 in Brassica napus, and 251 Brassica rapa (Xiong et al., 2005;Jaillon et al., 2007;Rushton et al., 2008;Carretero-Paulet et al., 2010;Miao et al., 2020;Zhou et al., 2020;Zhao et al., 2021). ...
Basic helix-loop-helix proteins (bHLHs) comprise one of the largest families of transcription factors in plants. They have been shown to be involved in responses to various abiotic stresses, such as drought, salinity, chilling, heavy metal toxicity, iron deficiency, and osmotic damages. By specifically binding to cis-elements in the promoter region of stress related genes, bHLHs can regulate their transcriptional expression, thereby regulating the plant’s adaptive responses. This review focuses on the structural characteristics of bHLHs, the regulatory mechanism of how bHLHs are involved transcriptional activation, and the mechanism of how bHLHs regulate the transcription of target genes under various stresses. Finally, as increasing research demonstrates that flavonoids are usually induced under fluctuating environments, the latest research progress and future research prospects are described on the mechanisms of how flavonoid biosynthesis is regulated by bHLHs in the regulation of the plant’s responses to abiotic stresses.
