Erigeron breviscapus (Vant.) Hand.-Mazz. is a famous traditional Chinese medicine that has positive effects on the treatment of cardiovascular and cerebrovascular diseases. With the increase of market demand (RMB 500 million per year) and the sharp decrease of wild resources, it is an urgent task to cultivate high-quality and high-yield varieties of E. breviscapus. However, it is difficult to obtain homozygous lines in breeding due to the self-incompatibility (SI) of E. breviscapus. Here, we first proved that E. breviscapus has sporophyte SI (SSI) characteristics. Characterization of the ARC1 gene in E. breviscapus showed that EbARC1 is a constitutive expression gene located in the nucleus. Overexpression of EbARC1 in Arabidopsis thaliana L. (Col-0) could cause transformation of transgenic lines from self-compatibility (SC) into SI. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated that EbARC1 and EbExo70A1 interact with each other in the nucleus, and the EbARC1-ubox domain and EbExo70A1-N are the key interaction regions, suggesting that EbARC1 may ubiquitinate EbExo70A to regulate SI response. This study of the SSI mechanism in E. breviscapus has laid the foundation for further understanding SSI in Asteraceae and breeding E. breviscapus varieties.

Low temperature at the seedling stage adversely affects sorghum growth and development and limits its geographical distribution. APETALA2/Ethylene-Responsive transcription factors (AP2/ERFs), one of the largest transcription factor families in plants, play essential roles in growth, development, and responses to abiotic stresses. However, the roles of AP2/ERF genes in cold tolerance in sorghum and the mechanisms underlying their effects remain largely unknown. Here, transcriptome sequencing (RNA-seq) was performed on the leaves of sorghum seedlings before and after cold treatment. Several candidate genes for cold tolerance and regulation pathways involved in “photosynthesis” under cold stress were identified via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Additionally, the AP2/ERF family gene SbERF027, a novel regulator of cold tolerance, was functionally identified through a comprehensive analysis. The expression of SbERF027 was high in seedlings and panicles, and its expression was induced by low temperature; the cold-induced expression level of SbERF027 was markedly higher in cold-tolerant accession SZ7 than in cold-sensitive accession Z-5. SbERF027 was detected in the nucleus under both normal and cold stress conditions. In addition, the cold tolerance of SbERF027-overexpressing lines was higher than that of wild-type plants; while the cold tolerance of lines with SbERF027 silenced via virus-induced gene silencing (VIGS) was significantly lower than that of wild-type plants. Further research demonstrated that SNP-911 of the promoter was essential for enhancing cold tolerance by mediating SbERF027 expression. This study lays a theoretical foundation for dissecting the mechanism of cold tolerance in sorghum and has implications for the breeding and genetic improvement of cold-tolerant sorghum.

Cold stress poses a major threat to rice productivity and grain quality. WRKY transcription factors, one of the largest plant-specific gene families, play crucial roles in plant responses to abiotic stress. However, their functions in cold responses and the evolutionary mechanisms underlying cold adaptation during the long-term domestication of cultivated rice remain poorly understood. Here, we identified OsWRKY26 as an important regulator of cold adaptation in japonica subspecies through transcriptome sequencing (RNA-seq). Subcellular localization analysis showed that the OsWRKY26 protein is localized to the nucleus under both normal and cold-stress conditions. Expression analysis indicated that OsWRKY26 is significantly upregulated at low temperature. Moreover, transgenic validation and measurements of multiple physiological traits demonstrated that OsWRKY26 positively regulates seedling cold tolerance in rice. Evolutionary analyses of OsWRKY26 and OsMYB2, a previously reported positive regulator of rice cold tolerance, suggested that these two genes diverged in wild rice and subsequently experienced directional selection in temperate japonica cultivated in high-altitude and high-latitude regions. Together, these findings provide a theoretical foundation for dissecting cold-tolerance mechanisms in rice, as well as promising genetic resources for molecular breeding in low-temperature environments.