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• gma-miR169c is widely expressed in soybean tissues and induced by polyethylene glycol, high salt levels, cold stress and abscisic acid. • Arabidopsis overexpressing gma-miR169c is more sensitive to drought stress, with reduced survival, accelerated leaf water loss, and shorter root length than the wild-type plants. • gma-miR169c negatively regulates the drought stress response by inhibiting the expression of the targets AtNFYA1 and AtNFYA5 and reducing the transcript levels of the stress response genes AtRD29A , AtRD22 , AtGSTU25 and AtCOR15A. The miR169 family, a large-scale microRNA gene family conserved in plants, is involved in stress responses, although how soybean miR169 functions in response to drought stress remains unclear. We show that gma-miR169c exerts a negative regulatory role in the response to drought stress by inhibiting the expression of its target gene, nuclear factor Y–A (NF-YA). A real-time RT-PCR analysis indicated that gma-miR169c is widely expressed in soybean tissues and induced by polyethylene glycol (PEG), high salt, cold stress and abscisic acid (ABA). Histochemical ß-glucuronidase (GUS) staining showed that the gma-miR169c promoter drives GUS reporter gene expression in various transgenic Arabidopsis tissues, and the stress-induced pattern was confirmed in transgenic Arabidopsis and transgenic soybean hairy roots. Arabidopsis overexpressing gma-miR169c is more sensitive to drought stress, with reduced survival, accelerated leaf water loss, and shorter root length than wild-type plants. We identified a precise cleavage site for 10 gma-miR169c targets and found reduced transcript levels of the AtNFYA1 and AtNFYA5 transcription factors in gma-miR169c -overexpressing Arabidopsis and reduced expression of the stress response genes AtRD29A , AtRD22 , AtGSTU25 and AtCOR15A. These results indicate that gma-miR169c plays a negative regulatory role in drought stress and is a candidate miRNA for improving plant drought adaptation. [ABSTRACT FROM AUTHOR]

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]

Abstract Drought is the most serious meteorological disaster affecting wheat production. Members of the R2R3-MYB gene subfamily play a crucial role in the regulation of the wheat drought stress response. In this study, the function of polyethylene glycol (PEG)-induced expression of the wheat R2R3-MYB gene TaSIM in response to drought stress was characterized. β-Glucuronidase (GUS) histochemical staining revealed that the TaSIM promoter can drive the expression of the GUS gene in the flowers, roots, stems and rosette leaves. Moreover, TaSIM was expressed in the stamens, pistils, roots, stems and leaves of wheat. The TaSIM promoter contains a known stress-responsive cis -acting element and is inducible by stress, PEG and abscisic acid (ABA). Under drought stress, compared with wild-type (WT) Arabidopsis , transgenic Arabidopsis overexpressing TaSIM presented significantly lower leaf water loss rates and increased survival. Moreover, the content of soluble sugars and proline and the expression of stress-related genes (RD29A and RD22) in transgenic Arabidopsis overexpressing TaSIM were higher than those in WT Arabidopsis under drought stress. Our results indicate that TaSIM plays a positive role in the drought stress response and can be used as a candidate gene for the genetic engineering of wheat drought resistance. Highlights • TaSIM is expressed in the stamens, pistils, roots, stems and leaves of wheat. • ABRE and CRT/DRE cis -acting elements are present in the TaSIM promoter, which is induced by stress, PEG and ABA. • Transgenic Arabidopsis overexpressing TaSIM has a low water loss rate, accumulates relatively high contents of soluble sugars and proline, and expresses RD22 and RD29A , thereby enhancing Arabidopsis tolerance to drought stress. [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]

• The GmNF-YA10 gene encodes an NF-YA transcription factor located in the nucleus that responds to PEG and ABA treatment at the transcription level. • Overexpression of the GmNF-YA10 gene increases the drought resistance of transgenic Arabidopsis by accumulating osmotic substances, slowing membrane lipid peroxidation, enhancing photosynthesis, regulating ABA-mediated stomatal closure, reducing the leaf water loss rate, and affecting the transcript levels of stress-related genes. • GmNF-YA10 gene participates in Arabidopsis response to drought stress through two pathways, ABA-dependent and ABA-independent. Nuclear factor (NF)-Y is composed of three subunits, NF-YA, NF-YB and NF-YC, and plays important roles in the regulation of plant abiotic stress response gene expression. However, the function of individual soybean NF-YA proteins in response to drought stress is unclear. In this study, the soybean NF-YA subunit gene GmNF-YA10 was cloned, and its function in response to drought stress was identified. GmNF-YA10 is broadly expressed in soybean tissues and is specifically located in the nucleus. In soybean roots, the transcription level of the GmNF-YA10 gene was induced by polyethylene glycol (PEG)-simulated drought stress and abscisic acid (ABA) treatment. Under mannitol stress, the germination rate of transgenic Arabidopsis overexpressing GmNF-YA10 was higher than that of wild-type (WT) Arabidopsis. After drought stress, the survival rate, relative water content, ABA content, proline content and chlorophyll content of transgenic Arabidopsis overexpressing GmNF-YA10 were higher than those of WT Arabidopsis while the rate of water loss and the contents of malondialdehyde and sucrose were lower than those of WT Arabidopsis , indicating that transgenic Arabidopsis overexpressing GmNF-YA10 has better drought resistance than WT Arabidopsis. Under the ABA treatment, the root length of transgenic Arabidopsis overexpressing GmNF-YA10 was shorter than that of WT Arabidopsis and the degree of stomatal closure was greater than that of WT Arabidopsis , indicating that transgenic Arabidopsis overexpressing GmNF-YA10 was more sensitive to ABA at the post-germination stage. Transcriptome sequencing and real-time quantitative PCR analysis showed that GmNF-YA10 affected the expression of both ABA-dependent and ABA-independent signalling pathway genes. These results indicate that GmNF-YA10 significantly improves the drought resistance of transgenic Arabidopsis through ABA-dependent and ABA-independent signal transduction pathways. [ABSTRACT FROM AUTHOR]

• GmFBX176 encodes a nuclear-localized F-box protein that responds to PEG treatment, ABA treatment, and salt stress at the transcriptional level. • Stress tolerance analysis of heterologous GmFBX176-overexpressing Arabidopsis revealed that GmFBX176 is a negative regulatory protein that improves tolerance to drought and salt stress. • GmFBX176-overexpressing Arabidopsis displayed reduced sensitivity to ABA. • Constitutive heterologous overexpression of the GmFBX176 gene affects stress-related physiological indicators and the transcript levels of stress response genes in transgenic Arabidopsis. As key components of the E3 ubiquitin ligase in the Skp1/Cullin or CDC53/F-box (SCF) complex, F-box proteins are involved in plant abiotic stress responses. However, the functions of F-box proteins in soybean in response to abiotic stress remain unclear. In this study, the soybean F-box protein-encoding gene GmFBX176 was cloned and functionally analyzed. GmFBX176 localized to the nucleus, was widely expressed in tissues (with the highest level in the roots), and responded to polyethylene glycol (PEG) treatment, abscisic acid (ABA) treatment, and salt stress at the transcriptional level. GmFBX176 -overexpressing Arabidopsis had lower survival rates; faster water loss rates; lower proline, sucrose and chlorophyll contents; greater malondialdehyde (MDA) contents; greater relative electrical conductivity (REC); and greater drought stress sensitivity than did wild-type (WT) Arabidopsis. Moreover, GmFBX176 -overexpressing Arabidopsis had lower survival rates, lower chlorophyll content, lower superoxide dismutase (SOD) activity, greater sensitivity to salt stress, longer roots, greater stomatal opening rates, and lower sensitivity to ABA than did WT Arabidopsis. Transcriptome sequencing and quantitative real-time PCR (qPCR) analyses revealed that GmFBX176 affects the transcript levels of stress response genes. These results indicate that GmFBX176 regulates ABA-mediated responses to drought and salt stress. [ABSTRACT FROM AUTHOR]