The Asteraceae family has achieved considerable progress through the implementation of hybridization techniques. However, the special complex capitulum of its members severely hinders the breeding process. Therefore, male sterility is crucial for the hybrid seed production in Asteraceae. Here, we identified that a retrotransposon insertion in the third intron of TePI gene co-segregated with the male sterility in five F₂ segregating population of marigold (Tagetes erecta) and down-regulation of TePI gene by RNAi generated pappus-like corollas and pistil-like stamens, resulting in male sterility. The male sterile mutant showed distinct down-regulation of TePI and altered expression of other ABCE genes. The K domain of the Tepi protein was altered due to the insertion of four amino acids. Nevertheless, Tepi, like wild-type TePI, retained the capacity to form homo- and heterodimers, as well as several higher-order complexes with other floral homeotic proteins. Notably, this structural disruption specifically impaired the interaction strength between Tepi and TeAP3. Taken together, the analysis of different expression patterns and protein interaction patterns suggests that tetramer complexes determining the corolla and stamen identities may not form in male sterile plants. This research elucidates the molecular mechanism underlying male sterility in marigold and provides potential applications for hybrid breeding improvement.

Rose is sensitive to high temperature which will make the rose go into a semi-dormancy state. Grafting is an excellent way to enhance rose heat tolerance. Here, heat-tolerant Rosa multiflora ‘Huanong Wuci 1′ (W) and heat-sensitive Rosa chinensis ‘Old Blush′ (X) were selected as experimental materials. The RNA-seq technique was used to investigate the transcriptomes of self-root grafting line (XX0), heterogeneous grafting line (XW0), self-root grafting line under 6 h heat stress (XX6), and heterogeneous grafting line under 6 h heat stress (XW6). Under high temperature stress, multiple signaling pathways were activated, moreover, a large number of transcription factors and functional genes were induced, especially the HSFs and HSPs with remarkably upregulated expression levels. The GO analysis showed that the differences in the expressions of the genes related to fatty acids and carbohydrates were observed between self-root grafting line and heterogeneous grafting line. In addition, 14 P450s were differentially expressed, and one lectin gene was up-regulated in XW0 vs XW6, but down-regulated in XX0 vs XX6. Considering physiological and biochemical traits such as relative electrolyte leakage, SOD activity, proline, and total soluble sugars, DEGs involved in these processes may be key factors to resist high temperature. The present study provides an insight into the complex mechanism underlying grafting in response to heat stress. Our results indicate that grafting is an effective way to improve rose heat resistance.