Summary: Mustard yield per plant is severely restricted by the seed number per silique. The seed number per silique in the Brassica juncea trilocular mutant J163‐4 is significantly greater than that in normal bilocular plants. However, how the trilocular silique of J163‐4 is formed remains unclear. Here, we studied the gene structure and function of mc2 in B. juncea and Arabidopsis using comparative morphology and molecular genetic experiments. We found that mc2 is a CLV1 ortholog, BjA7.CLV1. The deletion of cis‐regulatory region in mc2 promoter, which affects Mc2 expression in carpel margin meristem (CMM), led to trilocular silique formation. The BjCLV1 sequence with its complete promoter containing the cis‐regulatory region can restore the Bjclv1 and clv1 mutant phenotypes in B. juncea and Arabidopsis, respectively. Additionally, this cis‐regulatory region had a collinear segment in the promoter of CLV1 homologous gene in most Brassicaceae species. Our results are consistent with the report that BjCLV1 represents a conserved pleiotropic role in shoot meristem and CMM development, which contains a cis‐regulatory sequence specifically expressed BjCLV1 in CMM in its promoter, and this cis‐regulatory region is conserved in Brassicaceae species. These results offer a reliable approach for fine‐tuning the traits of seed yield in Brassicaceae crops.

Sugarcane (Saccharum spp.), a vital crop for sugar and bioenergy production, faces challenges in breeding due to its narrow genetic base and susceptibility to environmental stresses. To enhance genetic diversity, distant hybridization with wild relatives such as Erianthus rockii, known for its drought tolerance and strong ratooning ability, offers a promising strategy. However, identifying true intergeneric hybrids remains a critical challenge. This study identified true intergeneric hybrids from crosses between S. officinarum and E. rockii using tetra-primer ARMS-PCR and HRM curve analysis targeting SNPs in the nrDNA-ITS region, with genomic in situ hybridization (GISH) validating chromosome composition. The results confirmed 13 true hybrids among 16 progeny, showing a chromosome inheritance pattern of 40 chromosomes derived from S. officinarum and 15 from E. rockii. Hybrid plants, while exhibiting traits from both parents, displayed inferior yield and sugar content compared to the maternal parent, indicating the necessity for further backcrossing to improve agronomic performance. This study pioneers the application of ARMS-PCR and HRM in identifying E. rockii hybrids and underscores their potential in advancing sugarcane breeding by facilitating the introgression of beneficial traits from wild relatives.

Sugarcane (Saccharum spp.), a critical crop for sugar and bioenergy production, faces challenges in genetic improvement due to limited genetic diversity from selective breeding. Expanding genetic resources through intergeneric hybridization, particularly with Narenga porphyrocoma, offers a promising avenue to introduce traits like stress resistance and high biomass productivity. However, verifying true hybrids remains challenging with traditional morphological methods. This study employed tetra-primer ARMS-PCR and genomic in situ hybridization (GISH) to accurately identify intergeneric hybrids between S. officinarum and N. porphyrocoma. Species-specific primers were designed based on SNPs in the nrDNA-ITS region for ARMS-PCR, enabling effective differentiation of parental and hybrid genotypes, while GISH confirmed the chromosomal composition of hybrids, revealing an n + n inheritance pattern. The results demonstrated the potential of N. porphyrocoma to improve sugarcane’s tillering and leaf length, although sucrose content was lower in hybrids, suggesting the need for further breeding efforts. This study uniquely contributes to sugarcane breeding by providing an effective method for hybrid verification and laying a foundation for incorporating beneficial N. porphyrocoma genes into sugarcane cultivars.