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Teosinte branched1/cycloidea/proliferating cell factor1 (TCP) is a plant-specific protein family member involved in plant growth and development. However, the functions of most members of the cotton TCP family are unknown. In this study, the GbTCP5 gene encodes a sea-island cotton class II TCP CIN subclass transcription factor. The GbTCP5 transcription factor is located in the nucleus, has transcriptional activation activity, and can bind to TCP II cis-acting elements. GbTCP5 was widely expressed in tissues with the highest transcript level in the calyx. GbTCP5 is expressed at different developmental stages of the fiber and has significantly high transcriptional level expression in the fibers at 20, 30 and 35 days post anthesis (DPA). Heterologous overexpression of the GbTCP5 gene increased root hair length, root hair and stem trichome density, and stem lignin content in transgenic Arabidopsis compared to the wild type (WT). GbTCP5 binds the promoters of the GL3, EGL3, CPC, MYB46, LBD30, CesA4, VND7, CCOMT1, and CAD5 genes to upregulate their expression. Moreover, the homologous genes of these genes are expressed in the fibers of different developmental stages of the sea-island cotton fiber. These results indicate that GbTCP5 regulates root hair development and secondary wall formation in Arabidopsis and may be a candidate gene for improving cotton fiber quality., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Two class I family teosinte branched1/cycloidea/proliferating cell factor1 (TCP) proteins from allotetraploid cotton are involved in cotton fiber cell differentiation and elongation and root hair development. However, the biological function of most class II TCP proteins is unclear. This study sought to reveal the characteristics and functions of the sea-island cotton class II TCP gene GbTCP4 by biochemical, genetic, and molecular biology methods. GbTCP4 protein localizes to nuclei, binding two types of TCP-binding cis -acting elements, including the one in its promoter. Expression pattern analysis revealed that GbTCP4 is widely expressed in tissues, with the highest level in flowers. GbTCP4 is expressed at different fiber development stages and has high transcription in fibers beginning at 5 days post anthesis (DPA). GbTCP4 overexpression increases primary root hair length and density and leaf and stem trichomes in transgenic Arabidopsis relative to wild-type plants (WT). GbTCP4 binds directly to the CAPRICE ( CPC ) promoter, increasing CPC transcript levels in roots and reducing them in leaves. Compared with WT plants, lignin content in the stems of transgenic Arabidopsis overexpressing GbTCP4 increased, and AtCAD5 gene transcript levels increased. These results suggest that GbTCP4 regulates trichome formation and root hair development in Arabidopsis and may be a candidate gene for regulating cotton fiber elongation.

Sea-island cotton (Gossypium barbadense) has drawn great attention in the textile industry for its comprehensive resistance and superior fiber properties. However, the mechanisms involved in fiber growth and development are unclear. As TCP transcription factors play important roles in plant growth and development, this study investigated the TCP family genes in G. barbadense (GbTCP). We identified 75 GbTCP genes, of which 68 had no introns. Phylogenetic analyses categorized the GbTCP transcription factors into 11 groups. Genomic analyses showed that 66 genes are located on 21 chromosomes. Phylogenetic analyses of G. arboreum, G. raimondii, G. hirsutum, G. barbadense, Theobroma cacao, Arabidopsis thaliana, Oryza sativa, Sorghum bicolor, and Zea mays, Picea abies, Sphagnum fallax and Physcomitrella patens, categorized 373 TCP genes into two classes (Classes I and II). By studying the structures of TCP genes in sea-island cotton, we identified genes from the same evolutionary branches that showed similar motif patterns. qRT-PCR results suggested that the GbTCPs had different expression patterns in fibers at various developmental stages of cotton, with several showing specific expression patterns during development. This report helps lay the foundation for future investigations of TCP functions and molecular mechanisms in sea-island cotton fiber development.

MYB transcription factors are a large family of proteins involved in plant development and responses to stress. In this study, the wheat salinity-induced R2R3-MYB transcription factor TaSIM was functionally characterized, with a focus on its role in salt stress tolerance. TaSIM protein enters the nucleus and binds to the MYB-binding site II motif. Expression analysis revealed that TaSIM was induced by drought, high salinity, low temperature, and abscisic acid treatment. Overexpression of TaSIM improved salt stress tolerance in transgenic plants. Furthermore, the transcript levels of genes involved in abscisic acid (ABA)-dependent (RD22) and ABA-independent (RD29A) signaling were higher in TaSIM-overexpressing plants than in the wild type. These results suggest that TaSIM positively modulates salt stress tolerance and has potential applications in molecular breeding to enhance salt tolerance in crops., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Drought seriously affects the yield and quality of soybean. Previous studies have shown that the gma-miR394a / GmFBX176 module regulates the response of Arabidopsis to drought stress. However, whether the gma-miR394a / GmFBX176 module is involved in the regulation of the soybean drought stress response remains unclear. Here, the function of the gma-miR394a / GmFBX176 module in the soybean drought stress response was evaluated. In soybean hairy roots, drought stress induced the transcription of gma-miR394a and inhibited the transcription of GmFBX176. GUS histochemical staining showed that transgenic GmFBX176p:GUS soybean hairy root staining was weak and that GUS transcript levels decreased under drought stress. A transient expression experiment in tobacco showed that gma-miR394a inhibited GmFBX176 transcription. Under drought stress, composite soybean plants overexpressing gma-miR394a showed increased drought resistance compared with control K599 composite soybean plants (K599); their survival rate and peroxidase activity were higher than those of K599, and their malondialdehyde content was lower. In contrast, composite soybean plants overexpressing GmFBX176m3 (gma-miR394a complement site mutation) presented lower drought resistance than K599 plants. Transcriptomic sequencing showed that the gma-miR394a / GmFBX176 module affected the transcript levels of stress response genes and transcription factors. These results indicate that the gma-miR394a / GmFBX176 module can be used to improve the drought resistance of soybean. • gma-miR394a is upregulated and its target GmFBX176 is downregulated in 10% PEG-simulated drought-stressed soybean hairy roots. • Overexpression of gma-miR394a increased the tolerance of composite soybean plants to drought stress, while overexpression of GmFBX176m3 decreased the tolerance of composite soybean plants to drought stress. • Under PEG treatment, the gma-MIR394a / GmFBX176 module regulates the transcript levels of stress-related genes. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) have important functions in the plant salt stress response. However, the functions of nonconserved miRNAs in soybean salt stress adaptation remain unclear. In this study, the soybean nonconserved miRNA gma-miR4359b and its target mRNA F-box gene GmFBX193 were functionally identified in response to salt stress. gma-miR4359b responded to salt stress in soybean hairy roots, stems, and leaves. Under salt stress, the root length ratio, root surface area ratio, root volume ratio, root tip number, survival rate, chlorophyll content, soluble sugar content, proline content, superoxide dismutase activity, and peroxidase enzyme activity of soybean hairy roots overexpressing gma-miR4359b (MIR4359b) were increased compared to those of the K599 (control) soybean hairy roots, while the relative electrolyte leakage and malondialdehyde content of the MIR4359b soybean hairy roots decreased. In contrast, soybean hairy roots in which target mimicry (MIM4359b) and short tandem target mimic (STTM4359b) inhibited gma-miR4359b exhibited a salt-sensitive phenotype. The transcription level of GmFBX193 was decreased in MIR4359b soybean hairy roots, while the transcription level of GmFBX193 was increased in MIM4359b and STTM4359b soybean hairy roots. GmFBX193 responded to salt stress in soybean roots, and GmFBX193 was identified as a nuclear-localized protein. Under salt stress, soybean hairy roots overexpressing GmFBX193 had a similar phenotype to MIM4359b and STTM4359b soybean hairy roots. Compared with K599 (control) soybean hairy roots, MIR4359b soybean hairy roots had 172 differentially expressed genes (DEGs), and MIM4359b soybean hairy roots had 2129 DEGs. Some known stress-related transcription factors were included among the DEGs. Taken together, these results suggest that gma-miR4359b plays a positive role in the soybean salt stress response by negatively regulating GmFBX193. • The nonconserved soybean miRNA gma-miR4359b and its target mRNA F-box gene GmFBX193 responded to salt stress. gma-miR4359b positively regulates the soybean response to salt stress by targeting GmFBX193. • gma-miR4359b is a positive regulator of salt tolerance in soybean. • GmFBX193 negatively regulates soybean tolerance to salt stress. • Transcriptome sequencing showed that gma-miR4359b could affect the transcription levels of some transcription factors related to the salt stress response. [ABSTRACT FROM AUTHOR]

TCP transcription factors play important regulatory roles in plant growth and development; however, their function in response to salt and drought stress in sea-island cotton (Gossypium barbadense) is unknown. Here, GbTCP4 expression was induced by abscisic acid (ABA), drought, and NaCl treatments. Under drought stress, compared to wild-type (WT) Arabidopsis , transgenic GbTCP4 -overexpressing Arabidopsis showed increased seed germination rate, root length and survival rate; additionally, it was ABA-insensitive at the germination stage but ABA-sensitive at the seedling stage, showing reduced stomatal opening and ABA enrichment. Under salt stress, compared to WT Arabidopsis , transgenic GbTCP4- overexpressing Arabidopsis showed greater root length, survival rate, and SPAD value and lower malondialdehyde (MDA) content. Conversely, under drought or salt stress, virus-induced gene-silenced GbTCP4 cotton showed decreased root length, area and volume and increased MDA content and sensitivity to drought and salt stress compared with control cotton. RNA-seq and quantitative real-time PCR analyses showed that GbTCP4 affected the transcription levels of genes across multiple abiotic stress-related metabolic pathways. Furthermore, GbTCP4 activated the transcription of GbUVR8 and GbbHLH130 by binding to their promoters. These results suggest that GbTCP4 positively regulates drought and salt stress responses and is a suitable candidate gene for improving plant drought and salt tolerance. • The sea-island cotton class II TCP gene GbTCP4 is induced by drought, salt, and ABA treatments. • Overexpression of GbTCP4 in Arabidopsis and silencing of GbTCP4 in cotton indicated that GbTCP4 is a positive regulator of drought and salt stress. • GbTCP4 regulates abiotic stress responses in an ABA-dependent manner. • The GbTCP4 transcription factor can affect the expression of key genes in multiple stress-related metabolic pathways. [ABSTRACT FROM AUTHOR]