Trihelix Transcription Factor Research Articles

CRISPR/Cas9 edited SlGT30 improved both drought resistance and fruit yield through endoreduplication.

There is often a trade-off effect between different agronomic traits due to gene pleiotropy, leading to a negative correlation between yield and resistance. Consequently, using gene-editing techniques to develop superior traits becomes challenging. Genetic resources that defy this constraint are scarce but hold great potential as targets for improvement through the utilisation of CRISPR. Transcription factors are critical in modulating numerous gene expressions across diverse biological processes. Here, we found that the trihelix transcription factor SlGT30 plays a role in drought resistance and tomato fruit development. We edited the SlGT30 gene with CRISPR/Cas9 technology and found that the knockout lines showed decreased stomata density in the leaves and large fruits. Subsequent examination revealed that cell ploidy was impacted in the leaves and fruits of SlGT30 knockout lines. SlGT30 knockout affected cell size through the endoreduplication pathway, manifested in decreased stomata density and reduced water loss. Consequently, this resulted in an enhancement of drought resistance. For the fruit, both cell size and cell number increased in the fruit pericarp of knockout lines, improving the fruit size and weight accordingly. Therefore, SlGT30 represents a promising candidate gene for gene editing in breeding practice.

E3 Ubiquitin Ligase PUB23 in Kiwifruit Interacts with Trihelix Transcription Factor GT1 and Negatively Regulates Immune Responses against Pseudomonas syringae pv. actinidiae.

Kiwifruit bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) is the most serious disease threatening kiwifruit production. Our previous study found genes encoding the U-box containing proteins were significantly regulated by Psa infection. Here, we report a U-box type E3 ubiquitin ligase PUB23 in kiwifruit which acts as a negative regulator of immune responses against Psa. PUB23 was found to physically interact with GT1, a trihelix transcription factor, in vitro and in vivo. The expression of GT1 was up-regulated in PUB23-silenced plants, indicating that interacting with PUB23 may directly or indirectly suppress GT1 expression. The silencing of PUB23 led to enhanced immune responses of PAMP-triggered immunity (PTI), including a higher expression level of defense marker genes PR1 and RIN4, and increased accumulation of hydrogen peroxide and superoxide anion. Our results reveal a negative role PUB23 plays in kiwifruit immune responses against Psa and may regulate gene expression by interacting with GT1.

The trihelix transcription factor MdSIP1-2 interacts with MdNIR1 promoter to regulate nitrate utilization in apple

Nitrate is not only the main nitrogen (N) source for plant growth and development, but also an important signaling molecule for plants to cope with the changing environment. To adapt to N fluctuations in the environment, plants have established sophisticated regulatory networks. Although some nitrate signaling regulatory genes have been determined, whether the trihelix transcription factors (TFs) regulate N metabolism remains unclear. Here, an apple trihelix TF-encoding gene 6B-INTERACTING PROTEIN1–2 (SIP1–2) was identified, which is inducible upon nitrate treatment. Under N deficiency condition, the MdSIP1–2-OE transgenic apple calli and Arabidopsis repressed the expression of genes involved in N transport and metabolism, and repressed the activity of both nitrate reductase and nitrite reductase, leading to decreased N content and biomass. These results indicated that MdSIP1–2 inhibited the utilization of nitrate, and MdSIP1–2 may play a negative regulatory role in nitrate signal transduction in plant. In vivo and in vitro experiments showed that MdSIP1–2 directly bound to the GT1 motif of the MdNIR1 promoter to repress its transcription. Taken together, these results revealed that the trihelix TF family gene MdSIP1–2 plays a crucial role in regulating nitrate transport and metabolism, and providing new insights for plants to adapt to N fluctuation in environment.

Comprehensive Genomic Analysis of Trihelix Family in Tea Plant (Camellia sinensis) and Their Putative Roles in Osmotic Stress.

In plants, Trihelix transcription factors are responsible for regulating growth, development, and reaction to various abiotic stresses. However, their functions in tea plants are not yet fully understood. This study identified a total of 40 complete Trihelix genes in the tea plant genome, which are classified into five clades: GT-1 (5 genes), GT-2 (8 genes), GTγ (2 genes), SH4 (7 genes), and SIP1 (18 genes). The same subfamily exhibits similar gene structures and functional domains. Chromosomal mapping analysis revealed that chromosome 2 has the most significant number of trihelix family members. Promoter analysis identified cis-acting elements in C. sinensis trihelix (CsTH), indicating their potential to respond to various phytohormones and stresses. The expression analysis of eight representative CsTH genes from four subfamilies showed that all CsTHs were expressed in more tissues, and three CsTHs were significantly induced under ABA, NaCl, and drought stress. This suggests that CsTHs plays an essential role in tea plant growth, development, and response to osmotic stress. Furthermore, yeast strains have preliminarily proven that CsTH28, CsTH36, and CsTH39 can confer salt and drought tolerance. Our study provides insights into the phylogenetic relationships and functions of the trihelix transcription factors in tea plants. It also presents new candidate genes for stress-tolerance breeding.

Genome-wide identification of trihelix transcription factor family genes in pear (Pyrus bretschneideri) and functional characterization of PbrGT15 in black spot resistance

Pear (Pyrus bretschneideri), a valuable widely cultivated fruit, faces significant economic losses due to black spot disease caused by Alternaria alternate (Fr.) Keissl. Trihelix transcription factors (TFs) are crucial in regulating plant defense and autoimmunity. This study aimed to analyze the trihelix transcription factor (GT) genes within pear through genome-wide identification, phylogenetic, gene structure, synteny, and cis-acting elements analyses. Among the 31 trihelix genes, 28 were on 12 known chromosomes, while the remaining 3 were located on unknown chromosomes. These genes were categorized into five clades: SIP1, GTγ, GT1, GT2 and SH4, containing 7, 2, 9, 11 and 2 genes, respectively. Synteny analysis indicated eight duplicated gene pairs. Based on the expression pattern of PbGT genes in seven tissues from the database, the PbGT genes of the GT2 clade were selected for further investigation. The quantitative reverse transcriptase–polymerase chain reaction confirmed that PbrGT5, PbrGT6, PbrGT15 and PbrGT16 correlated with black spot disease resistance. Notably, the salicylic acid (SA) treatment significantly upregulated the expression levels of PbrGT10, PbrGT13, PbrGT15 and PbrGT23. Among these, PbrGT15 showed the highest induction to both SA and black spot infection. Subcellular localization demonstrated that PbrGT15 functions as a nuclear protein. Virus-induced gene silencing of PbrGT15 increased pear plants' susceptibility to black spot disease, indicating its pivotal role in enhancing resistance. These results indicated that PbrGT15 positively regulated black spot disease resistance in pears.

Genome-Wide Identification of the Trihelix Transcription Factor Family and Functional Analysis of the Drought Stress-Responsive Genes in Melilotus albus.

The trihelix gene family is a plant-specific family of transcription factors that play an important role in many metabolic pathways, including plant growth and development and stress responses. Drought stress is a major factor limiting the distribution and yield of Melilotus albus. However, the distribution of this gene family in M. albus and its biological functions in response to drought stress have not been reported. To investigate the responses of functional genes to drought stress in M. albus, in this study, a total of 34 MaGTs were identified and characterized, of which 32 MaGT proteins were predicted to be nuclear-localized. Based on conserved motif and phylogenetic analyses, the MaGTs could be divided into five subgroups (GT-1, GT-2, SH4, GT-γ, SIP1). Seven potential candidate genes for drought tolerance were screened and identified via qRT-PCR based on a transcriptome data analysis of drought stress in M. albus. The results indicated that MaGT17 was not only significantly upregulated in the roots after 24 h of drought stress, but also showed a significant induction in the shoots. This finding further confirms that MaGT17 is capable of responding to drought stress in M. albus. Taken together, these results will offer essential insights for understanding the underlying molecular mechanisms of the trihelix proteins and useful data for further research on the growth, development and stress responses of trihelix proteins in M. albus.

Retraction: Soybean Trihelix Transcription Factors GmGT-2A and GmGT-2B Improve Plant Tolerance to Abiotic Stresses in Transgenic Arabidopsis.

Retraction: Soybean Trihelix Transcription Factors GmGT-2A and GmGT-2B Improve Plant Tolerance to Abiotic Stresses in Transgenic Arabidopsis.

Down-regulation of SlGT-26 gene confers dwarf plants and enhances drought and salt stress resistance in tomato

Plant architecture, an important agronomic trait closely associated with yield, is governed by a highly intricate molecular network. Despite extensive research, many mysteries surrounding this regulation remain unresolved. Trihelix transcription factor family plays a crucial role in the development of plant morphology and abiotic stresses. Here, we identified a novel trihelix transcription factor named SlGT-26, and its down-regulation led to significant alterations in plant architecture, including dwarfing, reduced internode length, smaller leaves, and shorter petioles. The dwarf phenotype of SlGT-26 silenced transgenic plants could be recovered after spraying exogenous GA3, and the GA3 content were decreased in the RNAi plants. Additionally, the expression levels of gibberellin-related genes were affected in the RNAi lines. These results indicate that the dwarf of SlGT-26-RNAi plants may be a kind of GA3-sensitive dwarf. SlGT-26 was response to drought and salt stress treatments. SlGT-26-RNAi transgenic plants demonstrated significantly enhanced drought resistance and salt tolerance in comparison to their wild-type tomato counterparts. SlGT-26-RNAi transgenic plants grew better, had higher relative water content and lower MDA and H2O2 contents. The expression of multiple stress-related genes was also up-regulated. In summary, we have discovered a novel gene, SlGT-26, which plays a crucial role in regulating plant architecture and in respond to drought and salt stress.

The root-knot nematode effector Mi2G02 hijacks a host plant trihelix transcription factor to promote nematode parasitism

Root-knot nematodes (RKNs) cause huge agricultural losses every year. They secrete a repertoire of effectors to facilitate parasitism through the induction of plant-derived giant feeding cells, which serve as their sole source of nutrients. However, the mode of action of these effectors and their targeted host proteins remain largely unknown. In this study, we investigated the role of the effector Mi2G02 in Meloidogyne incognita parasitism. Host-derived Mi2G02 RNA interference in Arabidopsis thaliana affected giant cell development, whereas ectopic expression of Mi2G02 promoted root growth and increased plant susceptibility to M. incognita. We used various combinations of approaches to study the specific interactions between Mi2G02 and A. thaliana GT-3a, a trihelix transcription factor. GT-3a knockout in A. thaliana affected feeding-site development, resulting in production of fewer egg masses, whereas GT-3a overexpression in A. thaliana increased susceptibility to M. incognita and also root growth. Moreover, we demonstrated that Mi2G02 plays a role in maintaining GT-3a protein stabilization by inhibiting the 26S proteasome-dependent pathway, leading to suppression of TOZ and RAD23C expression and thus promoting nematode parasitism. This work enhances our understanding of how a pathogen effector manipulates the role and regulation of a transcription factor by interfering with a proteolysis pathway to reprogram gene expression for development of nematode feeding cells.

Genome-wide identification and expression analysis of the trihelix transcription factor family in sesame (Sesamum indicum L.) under abiotic stress.

The plant trihelix gene family is among the earliest discovered transcription factor families, and it is vital in modulating light, plant growth, and stress responses. The identification and characterization of trihelix family members in the sesame genome were analyzed by bioinformatics methods, and the expression patterns of sesame trihelix genes were assessed by quantitative real-time PCR. There were 34 trihelix genes discovered in the genome of sesame, which were irregularly distributed among 10 linkage groups. Also, the genome contained 5 duplicate gene pairs. The 34 trihelix genes were divided into six sub-families through a phylogenetic study. A tissue-specific expression revealed that SiTH genes exhibited spatial expression patterns distinct from other trihelix genes in the same subfamily. The cis-element showed that the SiTHs gene promoter contained various elements associated with responses to hormones and multiple abiotic stresses. Additionally, the expression patterns of 8 SiTH genes in leaves under abiotic stresses demonstrated that all selected genes were significantly upregulated or downregulated at least once in the stress period. Furthermore, the SiTH4 gene was significantly induced in response to drought and salt stress, showing that SiTH genes may be engaged in the stress response mechanisms of sesame. These findings establish a foundation for further investigation of the trihelix gene-mediated response to abiotic stress in sesame.

Genome-wide characterization, evolutionary analysis, and expression pattern analysis of the trihelix transcription factor family and gene expression analysis under MeJA treatment in Panax ginseng

Panax ginseng is a well-known medicinal plant with several pharmacological uses in China. The trihelix family transcription factors, also known as GT factors, can be involved in the regulation of growth and developmental processes in plants. There have been no in-depth reports or systematic studies about the trihelix transcription factor in ginseng. In this study, the structure, chromosomal localization, gene duplication, phylogeny, functional differentiation, expression patterns and coexpression interactions of trihelix transcripts were analysed using bioinformatics methods based on the ginseng transcriptome database. Thirty-two trihelix transcription factor genes were identified in ginseng, and these genes were alternatively spliced to obtain 218 transcripts. These transcripts were unevenly distributed on different chromosomes of ginseng, and phylogenetic analysis classified the PgGT transcripts into five subgroups. Gene Ontology (GO) analysis classified PgGT transcripts into eight functional subclasses, indicating that they are functionally diverse. The expression pattern analysis of 218 PgGT transcripts revealed that their expression was tissue-specific and spatiotemporally-specific in 14 different tissues of 4-year-old ginseng, 4 different ages of ginseng roots, and 42 farmers’ cultivars of 4-year-old ginseng roots. Despite the differences in the expression patterns of these transcripts, coexpression network analysis revealed that these transcripts could be expressed synergistically in ginseng. In addition, two randomly selected PgGT transcripts in each of the five different subfamilies were subjected to methyl jasmonate treatment at different times, and PgGT was able to respond to the regulation of methy1 jasmonate. These results provide a theoretical basis and gene resources for an in-depth study of the function of trihelix genes in other plants.

Large-scale analysis of trihelix transcription factors reveals their expansion and evolutionary footprint in plants.

The trihelix transcription factor (TTF) gene family is an important class of transcription factors that play key roles in regulating developmental processes and responding to various stresses. To date, no comprehensive analysis of the TTF gene family in large-scale species has been performed. A cross-genome exploration of its origin, copy number variation, and expression pattern in plants is also unavailable. Here, we identified and characterized the TTF gene family in 110 species representing typical plant phylogenetic taxa. Interestingly, we found that the number of TTF genes was significantly expanded in Chara braunii compared to other species. Based on the available plant genomic datasets, our comparative analysis suggested that the TTF gene family likely originated from the GT-1-1 group and then expanded to form other groups through duplication or deletion of some domains. We found evidence that whole-genome duplication/triplication contributed most to the expansion of the TTF gene family in dicots, monocots and basal angiosperms. In contrast, dispersed and proximal duplications contributed to the expansion of the TTF gene family in algae and bryophyta. The expression patterns of TTF genes and their upstream and downstream genes in different treatments showed a functional divergence of TTF-related genes. Furthermore, we constructed the interaction network between TTF genes and the corresponding upstream and downstream genes, providing a blueprint for their regulatory pathways. This study provided a cross-genome comparative analysis of TTF genes in 110 species, which contributed to understanding their copy number expansion and evolutionary footprint in plants.

Trihelix transcription factor SlGT31 regulates fruit ripening mediated by ethylene in tomato.

Trihelix proteins are plant-specific transcription factors that play crucial roles in plant development and stress responses. However, the involvement of trihelix proteins in fruit ripening and transcriptional regulatory mechanisms remains largely unclear. In this study, we cloned a trihelix gene SlGT31, whose relative expression was significantly induced by the application of exogenous ethylene but repressed by 1-methylcyclopropene (1-MCP). Suppression of SlGT31 resulted in delayed fruit ripening, decreased accumulation of total carotenoids and ethylene content, and inhibition of relative expression of genes related to ethylene and fruit ripening. Conversely, the opposite results were observed in SlGT31-overexpression lines. Yeast one-hybrid and dual-luciferase assays suggested that SlGT31 could bind to the promoters of two key ethylene biosynthesis genes ACO1 and ACS4. These results indicate that SlGT31 may act as a positive modulator during fruit ripening.

Genetic diversity and genome-wide association study of 13 agronomic traits in 977 Beta vulgaris L. germplasms

BackgroundSugar beet (Beta vulgaris L.) is an economically essential sugar crop worldwide. Its agronomic traits are highly diverse and phenotypically plastic, influencing taproot yield and quality. The National Beet Medium-term Gene Bank in China maintains more than 1700 beet germplasms with diverse countries of origin. However, it lacks detailed genetic background associated with morphological variability and diversity.ResultsHere, a comprehensive genome-wide association study (GWAS) of 13 agronomic traits was conducted in a panel of 977 sugar beet accessions. Almost all phenotypic traits exhibited wide genetic diversity and high coefficient of variation (CV). A total of 170,750 high-quality single-nucleotide polymorphisms (SNPs) were obtained using the genotyping-by-sequencing (GBS). Neighbour-joining phylogenetic analysis, principal component analysis, population structure and kinship showed no obvious relationships among these genotypes based on subgroups or regional sources. GWAS was carried out using a mixed linear model, and 159 significant associations were detected for these traits. Within the 25 kb linkage disequilibrium decay of the associated markers, NRT1/PTR FAMILY 6.3 (BVRB_5g097760); nudix hydrolase 15 (BVRB_8g182070) and TRANSPORT INHIBITOR RESPONSE 1 (BVRB_8g181550); transcription factor MYB77 (BVRB_2g023500); and ethylene-responsive transcription factor ERF014 (BVRB_1g000090) were predicted to be strongly associated with the taproot traits of root groove depth (RGD); root shape (RS); crown size (CS); and flesh colour (FC), respectively. For the aboveground traits, UDP-glycosyltransferase 79B6 (BVRB_9g223780) and NAC domain-containing protein 7 (BVRB_5g097990); F-box protein At1g10780 (BVRB_6g140760); phosphate transporter PHO1 (BVRB_3g048660); F-box protein CPR1 (BVRB_8g181140); and transcription factor MYB77 (BVRB_2g023500) and alcohol acyltransferase 9 (BVRB_2g023460) might be associated with the hypocotyl colour (HC); plant type (PT); petiole length (PL); cotyledon size (C); and fascicled leaf type (FLT) of sugar beet, respectively. AP-2 complex subunit mu (BVRB_5g106130), trihelix transcription factor ASIL2 (BVRB_2g041790) and late embryogenesis abundant protein 18 (BVRB_5g106150) might be involved in pollen quantity (PQ) variation. The candidate genes extensively participated in hormone response, nitrogen and phosphorus transportation, secondary metabolism, fertilization and embryo maturation.ConclusionsThe genetic basis of agronomical traits is complicated in heterozygous diploid sugar beet. The putative valuable genes found in this study will help further elucidate the molecular mechanism of each phenotypic trait for beet breeding.

Genome-wide identification of trihelix transcription factors in the apple genome in silico.

Trihelix transcription factors are involved in the growth and development of plants, as well as various stress responses. In the study presented, we identified 37 trihelix family genes in the apple genome (MdTH). The trihelix genes were located on 13 chromosomes. Phylogenetic analysis of these MdTH and the trihelix genes of other species divided them into six subfamilies: GT-1, GT-2, SH4, SIP1, GTγ, and GTδ. The genes of different groups significantly diverged in their gene structure and conserved functional domains. Cis-element analysis showed that promoter sequences of MdTH genes contained light response elements, phytohormone response elements, and stress-related cis-elements. The expression pattern analysis results demonstrated that MdTH were regulated by drought, salinity, as well as high and low temperatures. MdTH4 and MdTH24 were highly regulated by soil salinity, MdTH4-by drought. MdTH30 showed high expression under low temperature; MdTH8, MdTH20, and MdTH36-under high temperature.

Transcriptomic Profiling Highlights the ABA Response Role of BnSIP1-1 in Brassica napus.

BnSIP1-1 is the first identified SIP1 (6b Interacting Protein1) subfamily gene of the trihelix transcription factor family from Brassica napus (B. napus). We previously used a reverse genetic method to reveal its abiotic stress response function in endowing plants resistance to drought and salinity, as well as ABA (Abscisic acid). However, the molecular mechanisms of BnSIP1-1 are unclear. In this study, the global transcriptome files of BnSIP1-1-overexpressing transgenic and wildtype B. napus seedlings under ABA treatment were constructed using RNA-seq. A total of 1823 and 5512 DEGs (Differentially Expressed Genes) were identified in OE vs. WT and OE_ABA vs. WT_ABA comparison groups, which included 751 and 2567 up-regulated DEGs, and 1072 and 2945 down-regulated DEGs, separately. The impact of overexpressed BnSIP1-1 on plants was amplified by ABA, indicating BnSIP1-1 was an ABA-conditioned responsive gene. More interestingly, we found the reasons for BnSIP1-1 increasing plants' insensitivity to ABA were not by regulating ABA synthesis and catabolism, but by manipulating ABA transportation, ABA signal perception and transduction, inositol phosphate metabolism, as well as endomembrane trafficking, indirectly suggesting this gene may play roles upstream of the core ABA response pathway. Our results provided new insights into improving the knowledge about the function of BnSIP1-1 and the ABA signaling mechanism in B. napus.

Expression Analysis of Trihelix Transcription Factor Family in Strawberries and Functional Characterization of FvTrihelix6

The Trihelix is a plant-specific transcription factor family and has critical roles in plant growth and development and stress resistance. There is less information about Trihelix transcription factor genes and their potential functions in strawberries (Fragaria vesca). In the present study, we performed a detailed bioinformatics analysis of the Trihelix family in strawberries including physicochemical properties, chromosomal location, exon–intron distribution, domain arrangement, and subcellular localization. Thirty Trihelix family members were identified and divided into five subfamilies. The expression of FvTrihelix genes in different tissues/organs, i.e., root, stolon, leaf, flower, and fruit, was measured in strawberries after infection with Colletotrichum. gloeosporioides and foliar applications of salicylic acid (SA) and jasmonic acid (JA). Most of the genes showed differential expression responses following C. gloeosporioides infection and hormone treatments (SA and JA), suggesting critical roles in disease resistance and hormonal signaling pathways. As anticipated, the ectopic expression of FvTrihelix6 in Arabidopsis thaliana increased resistance against Colletotrichum. higginsianum infection. FvTrihelix6 protein was localized in the nucleus. We surmise that FvTrihelix6 enhances resistance against pathogens through the SA and JA signaling pathways. This study provides novel insights into the strawberry Trihelix transcription factor genes and new candidates for disease-resistance breeding of strawberries.

Transcriptome-Wide Integrated Analysis of the PgGT25-04 Gene in Controlling Ginsenoside Biosynthesis in Panax ginseng.

Panax ginseng is a valuable medicinal herb of the Araliaceae family with various pharmacological activities. The Trihelix transcription factors family is involved in growth and secondary metabolic processes in plants, but no studies have been reported on the involvement of Trihelix genes in secondary metabolic processes in ginseng. In this study, weighted co-expression network analysis, correlation analysis between PgGTs and ginsenosides and key enzyme genes, and interaction network analysis between PgGTs and key enzyme genes were used to screen out the PgGT25-04 gene, which was negatively correlated with ginsenoside synthesis. Using ABA treatment of ginseng hair roots, PgGT genes were found to respond to ABA signals. Analysis of the sequence characteristics and expression pattern of the PgGT25-04 gene in ginseng revealed that its expression is spatiotemporally specific. The interfering vector pBI121-PgGT25-04 containing the PgGT25-04 gene was constructed, and the ginseng adventitious roots were transformed using the Agrobacterium-mediated method to obtain the pBI121-PgGT25-04 positive hairy root monocot line. The saponin contents of positive ginseng hair roots were measured by HPLC, and the changes in PgGT25-04 and key enzyme genes in positive ginseng hair roots were detected via fluorescence quantitative RT-PCR. These results preliminarily identified the role of the PgGT25-04 gene in the secondary metabolism of ginseng in Jilin to provide a theoretical basis for the study of Trihelix transcription factors in Panax ginseng.

Identification and analysis of differentially expressed trihelix genes in maize (Zea mays) under abiotic stresses.

Trihelix transcription factors play important roles in triggering plant growth and imparting tolerance against biotic and abiotic stresses. However, a systematical analysis of the trihelix transcription factor family under heat and drought stresses in maize has not been reported. PlantTFDB and TBtools were employed to identify the trihelix domain-containing genes in the maize genome. The heat-regulated transcriptome data for maize were obtained from NCBI to screen differentially expressed ZmTHs genes through statistical analysis. The basic protein sequences, chromosomal localization, and subcellular localization were analyzed using Maize GDB, Expasy, SOMPA, TBtools, and Plant-mPLoc. The conserved motifs, evolutionary relationships, and cis-elements, were analyzed by MEME, MEGA7.0 and PlantCARE software, respectively. The tissue expression patterns of ZmTHs and their expression profiles under heat and drought stress were detected using quantitative real-time PCR (qRT-PCR). A total of 44 trihelix family members were discovered, and members were distributed over 10 chromosomes in the maize genome. A total of 11 genes were identified that were regulated by heat stress; these were unevenly distributed on chromosomes 1, 2, 4, 5, and 10. ZmTHs encoded a total of 16 proteins, all of which were located in the nucleus; however, ZmTH04.1 was also distributed in the chloroplast. The protein length varied from 206 to 725 amino acids; the molecular weight ranged from 22.63 to 76.40 kD; and the theoretical isoelectric point (pI) ranged from 5.24 to 11.2. The protein's secondary structures were mainly found to be random coils and α-helices, with fewer instances of elongation chains and β-rotations. Phylogenetic relationship analysis showed that these can be divided into five sub-groups. The conserved domain of ZmTHs was GT1 or MyB_DNA-Bind_4. The protein and gene structure of ZmTHs differed greatly among the subfamilies, while the structures within the subfamilies were similar. The promoter of ZmTHs contained abundant tissue-specific expression cis-acting elements and abiotic stress response elements. qRT-PCR analysis showed that ZmTHs expression levels were significantly different in different tissues. Furthermore, the expression of ZmTH08 was dramatically up-regulated by heat stress, while the expression of ZmTH03, ZmTH04, ZmTH05, ZmTH06, ZmTH07, ZmTH09, ZmTH10, and ZmTH11 were down-regulated by heat stress. Upon PEG-simulated drought stress, ZmTH06 was significantly up-regulated, while ZmTH01 and ZmTH07 were down-regulated. We performed a genome-wide, systematic identification and analysis of differentially expressed trihelix genes under heat and drought stresses in maize.

Genome-wide characterization and identification of Trihelix transcription factors and expression profiling in response to abiotic stresses in Chinese Willow (Salix matsudana Koidz).

Trihelix transcription factors (TTF) are a class of light-responsive proteins with a typical triple-helix structure (helix-loop-helix-loop-helix). Members of this gene family play an important role in plant growth and development, especially in various abiotic stress responses. Salix matsudana Koidz is an allotetraploid ornamental forest tree that is widely planted for its excellent resistance to stress, but no studies on its Trihelix gene family have been reported. In this study, the Trihelix gene family was analyzed at the genome-wide level in S. matsudana. A total of 78 S. matsudana Trihelix transcription factors (SmTTFs) were identified, distributed on 29 chromosomes, and classified into four subfamilies (GT-1, GT-2, SH4, SIP1) based on their structural features. The gene structures and conserved functional domains of these Trihelix genes are similar in the same subfamily and differ between subfamilies. The presence of multiple stress-responsive cis-elements on the promoter of the S. matsudana Trihelix gene suggests that the S. matsudana Trihelix gene may respond to abiotic stresses. Expression pattern analysis revealed that Trihelix genes have different functions during flooding stress, salt stress, drought stress and low temperature stress in S. matsudana. Given that SmTTF30, as a differentially expressed gene, has a faster response to flooding stress, we selected SmTTF30 for functional studies. Overexpression of SmTTF30 in Arabidopsis thaliana (Arabidopsis) enhances its tolerance to flooding stress. Under flooding stress, the leaf cell activity and peroxidase activity (POD) of the overexpression strain were significantly higher than the leaf cell activity and POD of the wild type, and the malondialdehyde (MDA) content was significantly lower than the MDA content of the wild type. Thus, these results suggest that SmTTF30 enhances plant flooding tolerance and plays a positive regulatory role in plant flooding tolerance.