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Chromosomal inversion is an important structural variation that usually suppresses recombination and is critical for key genotype fixation. In a previous study, an 11.47 Mb recombination suppression region was identified in the yellow–green leaf locus BoYgl-1on chromosome 1, but the cause of recombination suppression is still unclear. In this study, chlorophyll and carotenoid contents were found to be significantly decreased in the yellow–green leaf mutant YL-1. Genome assembly and comparative analysis revealed that two large inversions in YL-1 were responsible for the severe recombination suppression in the BoYgl-1locus. Analyses with inversion-specific markers revealed that the inversions were present in 44 (including all wild cabbage; INV1 and INV2) of 195 cabbage inbred lines and 15 (INV1) ornamental kale inbred lines, indicating that these species with INV1 or INV2 may have evolved much earlier than other types of cabbage. Analyses with inversion-correlated markers revealed that the genotypes of CoINV1, CoINV2 and CoINV3 were highly correlated with INV1 and INV2, indicating that INVs could fix the key genotypes of the involved region. In addition, a 5.87 Mb assembly inversion was identified at the BoYgl-1locus in the TO1000 genome by genome comparative analysis. This study provides new insight into the recombination suppression mechanism of chromosomal inversion and the application of genome fragment fixation in cabbage breeding.

Leaf color is an important agronomic trait in cabbage (Brassica oleraceaL. var. capitata), but the detailed mechanism underlying leaf color formation remains unclear. In this study, we characterized a Brassica oleracea yellow-green leaf 2(BoYgl-2) mutant 4036Y, which has significantly reduced chlorophyll content and abnormal chloroplasts during early leaf development. Genetic analysis revealed that the yellow-green leaf trait is controlled by a single recessive gene. Map-based cloning revealed that BoYgl-2encodes a novel nuclear-targeted P-type PPR protein, which is absent in the 4036Y mutant. Functional complementation showed that BoYgl-2from the normal-green leaf 4036G can rescue the yellow-green leaf phenotype of 4036Y. The C-to-U editing efficiency and expression levels of atpF, rps14, petLand ndhDwere significantly reduced in 4036Y than that in 4036G, and significantly increased in BoYgl-2overexpression lines than that in 4036Y. The expression levels of many plastid- and nuclear-encoded genes associated with chloroplast development in BoYgl-2mutant were also significantly altered. These results suggest that BoYgl-2participates in chloroplast C-to-U editing and development, which provides rare insight into the molecular mechanism underlying leaf color formation in cabbage.

Four theories have predominated in historical literature as to when Li Zongren (1890-1969), a Guangxi warlord who went on to become a top political leader during the republican era, joined the Nationalist Party. These theories make claims for the following dates: 1) at the beginning of 1926; 2) in July 1925; 3) at the end of 1923, based on Li’s own recollections during his last years; and 4) at the end of 1924. This article examines all four of these theories and shows that only the fourth one is viable. Based chiefly on the memoirs of Huang Shaohong (1895-1966), Li’s immediate subordinate in the control of the Guangxi Clique during the early 1920s, Li joined the Nationalists in December 1924. [ABSTRACT FROM CONTRIBUTOR]