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Auxin response factor (ARF) is a transcription factor family that mediates auxin signaling and regulates various biological processes. To investigate the ARF gene family members and their roles in response to high temperature and drought stress, the phylogenetic and expression patterns of the ARF gene family members in Huperzia serrata were analyzed using full-length transcriptome and RNA-seq data. Based on bioinformatics analysis, the physicochemical properties, domains, conserved motifs, phylogeny, tissue expression patterns, and expression patterns of the ARF gene family under high temperature and drought stress were analyzed. The results were as follows:(1) A total of 24 ARF family members were screened in the full-length transcriptome of H. serrata, all of which were acidic proteins and hydrophilic proteins. (2) Subcellular localization prediction revealed that 24 HsARF were all localized in nucleus. (3) Phylogenetic analysis revealed that HsARF had a distant genetic relationship with angiosperms Arabidopsis and rice, and only share two common ARF ancestors with higher flowering plants. (4) Domain analysis revealed that, except for HsARF18/23/24, most HsARF had B3 domains. Analysis of secondary structure found that the highest proportion of HsARF protein was random curling, followed by elongated chains and α-helix. Three-dimensional (3D) protein structure prediction model used in the 24 HsARF proteins was only four. (5) RNA-seq analysis showed that the expression levels of 7 HsARF were high in all detected organs. The expression levels of 10 HsARF in stems were higher than those in roots and leaves. Otherwise, the expression levels of HsARF13 and HsARF14 in leaves were lower than those in roots and stems. (6) The expression levels of HsARF undergo significant changes under high temperature and drought stress, with 18 HsARF being induced to varying degrees by high temperature stress, 7 HsARF responded to drought stress, with 3 HsARF induced by drought, while 4 HsARF inhibited by drought. The results provide theoretical references for the functional and biological breeding study of ARF gene family in H. serrata.

Heading date is one of the most important agronomic traits of rice, which critically affects rice ecogeographical adaptation, yield and quality. In this study, a late heading date 3 (lhd3) mutant was screened from the 60Co-γ irradiation mutant library. The lhd3 delayed heading date in rice under both short day and long day conditions. Map-based cloning combined with Mutmap strategy was adopted to isolate the causal LHD3 gene. The LHD3 gene encodes a DNA_J domain protein, which was ubiquitously expressed in various plant organs, and dominant expressed in stems and leaves. Subcellular localization analysis showed that LHD3 was localized to nucleus, indicating that LHD3 may interact with other elements to regulate the expression of flowering genes. The transcriptions of the heading activators Ehd1, Hd3a and RFT1 significantly decreased in the lhd3 mutant, suggesting that LHD3 may control the heading date through the Ehd1-Hd3a/RFT1 photoperiodic flowering pathway. The variation and haplotype analyses of the genomic region of LHD3 showed that there were 7 haplotypes in the LHD3 region from 4 702 accessions. The haplotypes of LHD3 can be divided into two classes: class a and class b, and the heading dates of these two classes were significantly different. Further study showed that two single nucleotide polymorphisms (SNPs), SNP10 (G2100C) in Hap II and SNP3 (C861T) in Hap VII, may be the functional sites causing early and late heading in accessions. Nucleotide diversity analysis showed LHD3 had been selected in the indica population, rather than in the japonica population. Therefore, the present study sheds light on the regulation of LHD3 on heading date in rice and suggests that LHD3 is a novel promising new target for rice molecular design and breeding improvement.

Abstract: The interplay between abscisic acid (ABA) and salicylic acid (SA) influences plant responses to various (a)biotic stresses; however, the underlying mechanism for this crosstalk is largely unknown. Here, we report that type 2C protein phosphatases (PP2Cs), some of which are negative regulators of ABA signaling, bind SA. SA binding suppressed the ABA‐enhanced interaction between these PP2Cs and various ABA receptors belonging to the PYR/PYL/RCAR protein family. Additionally, SA suppressed ABA‐enhanced degradation of PP2Cs and ABA‐induced stabilization of SnRK2s. Supporting SA's role as a negative regulator of ABA signaling, exogenous SA suppressed ABA‐induced gene expression, whereas the SA‐deficient sid2‐1 mutant displayed heightened PP2C degradation and hypersensitivity to ABA‐induced suppression of seed germination. Together, these results suggest a new molecular mechanism through which SA antagonizes ABA signaling. A better understanding of the crosstalk between these hormones is important for improving the sustainability of agriculture in the face of climate change. [ABSTRACT FROM AUTHOR]