Identification and Functional Analysis of KH Family Genes Associated with Salt Stress in Rice.

Salinity stress has a great impact on crop growth and productivity and is one of the major factors responsible for crop yield losses. The K-homologous (KH) family proteins play vital roles in regulating plant development and responding to abiotic stress in plants. However, the systematic characterization of the KH family in rice is still lacking. In this study, we performed genome-wide identification and functional analysis of KH family genes and identified a total of 31 KH genes in rice. According to the homologs of KH genes in Arabidopsis thaliana, we constructed a phylogenetic tree with 61 KH genes containing 31 KH genes in Oryza sativa and 30 KH genes in Arabidopsis thaliana and separated them into three major groups. In silico tissue expression analysis showed that the OsKH genes are constitutively expressed. The qRT-PCR results revealed that eight OsKH genes responded strongly to salt stresses, and OsKH12 exhibited the strongest decrease in expression level, which was selected for further study. We generated the Oskh12-knockout mutant via the CRISPR/Cas9 genome-editing method. Further stress treatment and biochemical assays confirmed that Oskh12 mutant was more salt-sensitive than Nip and the expression of several key salt-tolerant genes in Oskh12 was significantly reduced. Taken together, our results shed light on the understanding of the KH family and provide a theoretical basis for future abiotic stress studies in rice.

Genome-Wide Identification and Expression Analysis of ent-kaurene synthase-like Gene Family Associated with Abiotic Stress in Rice.

Rice (Oryza sativa) is one of the most important crops for humans. The homologs of ent-kaurene synthase (KS) in rice, which are responsible for the biosynthesis of gibberellins and various phytoalexins, are identified by their distinct biochemical functions. However, the KS-Like (KSL) family's potential functions related to hormone and abiotic stress in rice remain uncertain. Here, we identified the KSL family of 19 species by domain analysis and grouped 97 KSL family proteins into three categories. Collinearity analysis of KSLs among Poaceae indicated that the KSL gene may independently evolve and OsKSL1 and OsKSL4 likely play a significant role in the evolutionary process. Tissue expression analysis showed that two-thirds of OsKSLs were expressed in various tissues, whereas OsKSL3 and OsKSL5 were specifically expressed in the root and OsKSL4 in the leaf. Based on the fact that OsKSL2 participates in the biosynthesis of gibberellins and promoter analysis, we detected the gene expression profiles of OsKSLs under hormone treatments (GA, PAC, and ABA) and abiotic stresses (darkness and submergence). The qRT-PCR results demonstrated that OsKSL1, OsKSL3, and OsKSL4 responded to all of the treatments, meaning that these three genes can be candidate genes for abiotic stress. Our results provide new insights into the function of the KSL family in rice growth and resistance to abiotic stress.

Genome-Wide Identification and Expression Analysis of TGA Family Genes Associated with Abiotic Stress in Sunflowers (Helianthus annuus L.).

Sunflower (Helianthus annuus L.) is an important, substantial global oil crop with robust resilience to drought and salt stresses. The TGA (TGACG motif-binding factor) transcription factors, belonging to the basic region leucine zipper (bZIP) family, have been implicated in orchestrating multiple biological processes. Despite their functional significance, a comprehensive investigation of the TGA family's abiotic stress tolerance in sunflowers remains elusive. In the present study, we identified 14 TGA proteins in the sunflower genome, which were unequally distributed across 17 chromosomes. Employing phylogenetic analysis encompassing 149 TGA members among 13 distinct species, we revealed the evolutionary conservation of TGA proteins across the plant kingdom. Collinearity analysis suggested that both HaTGA01 and HaTGA03 were generated due to HaTGA08 gene duplication. Notably, qRT-PCR analysis demonstrated that HaTGA04, HaTGA05, and HaTGA14 genes were remarkably upregulated under ABA, MeJA, and salt treatments, whereas HaTGA03, HaTGA06, and HaTGA07 were significantly repressed. This study contributes valuable perspectives on the potential roles of the HaTGA gene family under various stress conditions in sunflowers, thereby enhancing our understanding of TGA gene family dynamics and function within this agriculturally significant species.

Whole-Transcriptome Sequencing Reveals the Global Molecular Responses and NAC Transcription Factors Involved in Drought Stress in Dendrobium catenatum.

Dendrobium catenatum is a highly drought-tolerant herb, which usually grows on cliffs or in the branches of trees, yet the underlying molecular mechanisms for its tolerance remain poorly understood. We conducted a comprehensive study utilizing whole-transcriptome sequencing approaches to investigate the molecular response to extreme drought stress in D. catenatum. A large number of differentially expressed mRNAs, lncRNAs, and circRNAs have been identified, and the NAC transcription factor family was highly enriched. Meanwhile, 46 genes were significantly up-regulated in the ABA-activated signaling pathway. In addition to the 89 NAC family members accurately identified in this study, 32 members were found to have different expressions between the CK and extreme drought treatment. They may regulate drought stress through both ABA-dependent and ABA-independent pathways. Moreover, the 32 analyzed differentially expressed DcNACs were found to be predominantly expressed in the floral organs and roots. The ceRNA regulatory network showed that DcNAC87 is at the core of the ceRNA network and is regulated by miR169, miR393, and four lncRNAs. These investigations provided valuable information on the role of NAC transcription factors in D. catenatum's response to drought stress.