Catalases (CATs) are present in almost all living organisms and play important roles in plant development and response to various stresses. However, there is relatively little information on CAT genes in wheat and related Triticeae species. A few studies on CAT family genes in wheat have been reported. In this study, ten CAT proteins (TaCATs) were identified in wheat and classified into three groups based on their phylogenetic features and sequence analysis. The analysis of the structure and motif composition of the TaCAT proteins suggested that a segmental duplication event occurred in the TaCAT gene family. Collinearity relationship analysis among different species showed that there were three orthologous CAT genes in rice and in maize. By analyzing the cis-elements in the promoter regions, we speculated that TaCAT genes expression might be regulated by light, oxygen deficit, methyl jasmonate and abscisic acid, and by transcription factors such as MYB. A Gene Ontology (GO)-based analysis showed that TaCAT proteins may be related to the response to various stresses, are cytoplasm localized, and may function as antioxidant enzymes. RT-qPCR and transcriptome data analyses exhibited distinct expression patterns of TaCAT genes in different tissues and in response to various treatments. In this study, a comprehensive analysis of wheat CAT genes was performed, enriching our knowledge of CAT genes and providing a foundation for further functional analyses of this gene family in wheat.

In flowering plants, anther dehiscence and pollen release are essential for sexual reproduction. Anthers dehisce after cell wall degradation weakens stomium cell junctions in each anther locule, and desiccation creates mechanical forces that open the locules. Either effect or both together may break stomium cell junctions. The microRNA miR167 negatively regulates ARF6 and ARF8 encoding Auxin Response transcription Factors. Arabidopsis mARF6 or mARF8 plants with mutated miR167 target sites have defective anther dehiscence and ovule development. Null mir167a mutations recapitulated mARF6 and mARF8 anther and ovule phenotypes, indicating that MIR167a is the main miR167 precursor gene that delimits ARF6 and ARF8 expression in these organs. Anthers of mir167a or mARF6/8 plants overexpressed genes encoding cell wall loosening functions associated with cell expansion, and grew too large starting at flower stage 11. Experimental desiccation enabled dehiscence of miR167-deficient anthers, indicating competence to dehisce. Conversely, high humidity conditions delayed anther dehiscence in wild-type flowers. These results support a model in which miR167-mediated anther growth arrest permits anther dehiscence. Without miR167 regulation, excess anther growth delays dehiscence by prolonging desiccation.

Heat stress (HS) seriously restricts the growth and development of plants. When plants are exposed to extreme high temperature, the heat stress response (HSR) is activated to enable plants to survive. Sessile plants have evolved multiple strategies to sense and cope with HS. Previous studies have established that PHYTOCHROME INTERACTING FACTOR 4 (PIF4) acts as a key component in thermomorphogenesis; however, whether PIF4 regulates plant thermotolerance and the molecular mechanism linking this light transcriptional factor and HSR remain unclear. Here, we show that the overexpression of PIF4 indeed provides plants with a stronger basal thermotolerance and greatly improves the survival ability of Arabidopsis under severe HS. Via phylogenetic analysis, we identified two sets (six) of PIF4 homologs in wheat, and the expression patterns of the PIF4 homologs were conservatively induced by heat treatment in both wheat and Arabidopsis. Furthermore, the PIF4 protein was accumulated under heat stress and had an identical expression level. Additionally, we found that the core regulator of HSR, HEAT SHOCK TRANSCRIPTION FACTOR A2 (HSFA2), was highly responsive to light and heat. Followed by promoter analysis and ChIP-qPCR, we further found that PIF4 can bind directly to the G-box motifs of the HSFA2 promoter. Via effector–reporter assays, we found that PIF4 binding could activate HSFA2 gene expression, thereby resulting in the activation of other HS-inducible genes, such as heat shock proteins. Finally, the overexpression of PIF4 led to a stronger basal thermotolerance under non-heat-treatment conditions, thereby resulting in an enhanced tolerance to severe heat stress. Taken together, our findings propose that PIF4 is linked to heat stress signaling by directly binding to the HSFA2 promoter and triggering the HSR at normal temperature conditions to promote the basal thermotolerance. These functions of PIF4 provide a candidate direction for breeding heat-resistant crop cultivars.

Background: Short internodes contribute to plant dwarfism, which is exceedingly beneficial for crop production. However, the underlying mechanisms of internode elongation are complicated and have been not fully understood.Results: Here, we report a maize dwarf mutant,dwarf2014(d2014), which displays shortened lower internodes. Map-based cloning revealed that thed2014gene is a novelbr2allele with a splicing variation, resulting in a higher expression ofBR2-T02instead of normalBR2-T01. Then, we found that the internode elongation ind2014/br2exhibited a pattern of inhibition-normality-inhibition (transient for the ear-internode), correspondingly, at the 6-leaf, 12-leaf and 14-leaf stages. Indeed,BR2encodes a P-glycoprotein1 (PGP1) protein that functions in auxin efflux, and our in situ hybridization assay showed thatBR2was mainly expressed in vascular bundles of the node and internode. Furthermore, significantly higher auxin concentration was detected in the stem apex ofd2014at the 6-leaf stage and strictly in the node region for the ear-internode at the 14-leaf stage. In such context, we propose that BR2/PGP1 transports auxin from node to internode through the vascular bundles, and excessive auxin accumulation in the node (immediately next to the intercalary meristem) region suppresses internode elongation ofd2014.Conclusions: These findings suggest that low auxin levels mediated by BR2/PGP1 in the intercalary meristem region are crucial for internode elongation.

The MADS-box transcription factor (TF) family constitutes a critical class of transcriptional regulators in plants, playing pivotal roles in diverse developmental processes. MIKC-type proteins represent Type II MADS-box TFs that widely function in regulating floral organ development and reproductive growth in plants. In this study, a total of 38 MIKC-type MADS TFs were identified from the sorghum genome, distributed across nine chromosomes. Based on sequence alignments and phylogenetic analysis, these 38 SbMIKC genes (SbMIKCs) were further classified into 10 distinct subfamilies. The expression profiles of these SbMIKCs across multiple tissues revealed five major patterns, among which SbMIKC17 exhibited relatively abundant transcript levels during grain development in sorghum. Further assays confirmed that the protein encoded by SbMIKC17 localizes to the nucleus without self-transactivation activity in yeast. Integrated results from DAP-seq, dual-luciferase assays, and yeast one-hybrid experiments demonstrated that SbMIKC17 binds to and activates the promoter of SbAGPS1, as well as enhancing the promoter activities of SbBt1, SbGBSSI, SbSSIIa, and SbISA1 simultaneously. Collectively, these findings suggest that the MIKC-type MADS gene SbMIKC17 may play a crucial role in starch biosynthesis in sorghum.