Lobed leaves are advantageous for gas exchange, canopy architecture, and high-density planting; however, the genetic mechanisms of leaf lobe formation in Brassica crops remains poorly understood. Here, lob10.1, our previously identified major QTL controlling the presence/absence of leaf lobes in B. rapa (AA), was fine mapped to a confidence interval of 69.8 kb. REDUCED COMPLEXITY ORGAN (BrRCO, BraA10g032440.3c), a homeodomain leucine zipper class I (HD ZIP I) transcription factor, was predicted to be the most likely candidate gene underlying lob10.1. Null mutations of BrRCO by CRISPR/Cas9 in the lobed-leaf parent RcBr and over-expression in the counter-part near isogenic lines (NILRcBr) lead to entire and lobed leaves, respectively. Analysis of the gene evolution revealed that A10. RCO functions as a core gene and was generally negatively selected in B. rapa. Moreover, BrRCO function as a negative regulator by directly binding to promoters of BrACP5 and repressing its expression. The function of ACID PHOSPHATASE TYPE 5 (BrACP5) was subsequently confirmed as VIGS-BrACP5 produced entire leaves in RcBr. This study identified the core gene BrRCO to be involved in the development of leaf lobes in B. rapa and elucidated a new pathway for leaf lobe formation by the BrRCO-BrACP5 module. These findings provide a theoretical basis for the formation of leaf lobes in Brassica crops.

Leaf shape is an important determinant of photosynthesis, yield and quality in plants. In this study, we obtained a curled leaf mutant, cl1, from an ethyl methanesulfonate (EMS)-induced mutagenesis population. It was designated the Brcl1^YS locus. Bulk segregant RNA sequencing combined with recombinant screening identified the candidate interval responsible for Brcl1^YS in a 97.5 kb region on chromosome A02. Twelve genes were identified within the candidate region. Sequence differences and co-separation verification confirmed that BraA02g017030.3C was the most promising candidate gene underlying the Brcl1^YS locus. It is homologous to Arabidopsis AT1G66350 (RGL1), which has been shown to act as a negative regulator of the gibberellin pathway. Combined with cell morphology observation, it is speculated that the loss of function of Brcl1^YS results in differences in cell development, ultimately leading to changes in leaf morphology. The results will contribute to the understanding of the molecular mechanisms underlying leaf curling in B. rapa.

Considering that the presence of a leafy head is a key morphological characteristic that determines the yield and quality of Chinese cabbage, identifying the major genes regulating the formation of a leafy head is crucial for variety improvement. A heading-related gene, BrKS, was previously predicted from a non-heading mutant, nhm1, derived from a heading variety, which encodes a key enzyme involved in gibberellin biosynthesis. Here, another mutant, nhm2, was identified from the same EMS-mutagenized population, and the phenotype of nhm2 was consistent with that of nhm1. We crossed mutants nhm1 and nhm2, and their F₁ plants exhibited the mutant phenotype, which indicated that their mutant genes were allelic. A single non-synonymous mutation in the fourth exon of BrKS in mutant nhm1 and another single non-synonymous mutation in the tenth exon of BrKS in mutant nhm2. The same gene mutation in mutants nhm1 and nhm2 produced a similar non-heading phenotype, which confirmed the role of BrKS in the leafy head formation of Chinese cabbage. RNA-Seq analysis indicated that a transcription factor gene, BrERF1A, which is associated with leaf development, significantly down-regulated expression in mutant nhm1, and after the mutant was treated with GA₃, the expression level of BrERF1A was recovered, which indicated that BrKS might be involved in leafy head formation through regulating the expression level of BrERF1A. Our findings provide important clues for revealing the molecular mechanism of leafy head formation in Chinese cabbage.

In crops such as Brassica rapa, the agronomic trait plant height affects the leaf light absorption rate, benefits substance accumulation, and increases production by increasing the biological yield of the population. The mechanism of plant height was adequately studied in Brassica napus and Arabidopsis, while Brassica rapa had been rarely reported. Herein, we studied a B. rapa dwarf mutant Brcd1^YS. Compared with its wild-type, Yellow sarson, Brcd1^YS showed shorter hypocotyls and slow growth, with inhibited root elongation and reduced numbers of lateral roots. Chlorophyll content determination and pollen viability detection indicated that the mutant’s chlorophyll content was higher than that of the wild-type; however, its pollen was inactive. Cytological identification showed that the number of cells in Brcd1^YS leaves was significantly reduced and were arranged irregularly compared with those of the wild-type. Bulked Segregant RNA sequencing combined with conventional linkage mapped the dwarf mutation Brcd1^YS to Chromosome A06, at position 21,621,766 to 24,683,923 bp. Application of exogenous gibberellic acid (GA) partially rescued the dwarf phenotype of Brcd1^YS. GA-related genes BraA06g034110.3C and BraA06g033010.3C were identified as the most promising candidate genes. These results make a valuable contribution to our understanding of the mechanism of plant height determination in B. rapa, paving the way for further breeding of dwarf B. rapa.

Schisandra chinensis (Turcz.) Baill. (S. chinensis) is a traditional Chinese medicinal plant whose fruits are rich in bioactive constituents, including lignans, organic acids, and flavonoids. Nevertheless, the biochemical dynamics underlying fruit development remain insufficiently characterized, limiting the effective cultivation, harvest, and utilization of S. chinensis. Here, we applied widely targeted metabolomics, together with a dynamic assessment of fruit growth, to profile temporal changes in major metabolites and to identify the optimal harvest window. The results show that the morphological changes in fruit mainly occurred from 70 to 110 days after fruit set; fresh fruit mass peaked at 110 days after fruit set. During the harvest period, the fruits are deep red and firm, showing no signs of softening. Meanwhile, fruit cluster weight, single fruit weight, and fruit longitudinal diameter all reached their peak values. Over the course of maturation, lignan levels declined markedly, whereas terpenoids, organic acids and flavonoids increased significantly. The most pronounced shifts were observed for schizandrin, gomisin N, shikimic acid, citric acid, gamma-terpinene and cyanidin 3-sophoroside, key marker compounds of S. chinensis fruit. Network pharmacology predicts that ESR1, RXRA, GATM, NCOA2, and SONEA are core targets. These findings provide a basis for determining timely harvest and for establishing quality evaluation criteria for S. chinensis.