Series-Spatial Transcriptome Profiling of Leafy Head Reveals the Key Transition Leaves for Head Formation in Chinese Cabbage

Abstract

Chinese cabbage is an important leaf heading vegetable crop. At the heading stage, its leaves across inner to outer show significant morphological differentiation. However, the genetic control of this complex leaf morphological differentiation remains unclear. Here, we reported the transcriptome profiling of Chinese cabbage plant at the heading stage using 24 spatially dissected tissues representing different regions of the inner to outer leaves. Genome-wide transcriptome analysis clearly separated the inner leaf tissues from the outer leaf tissues. In particular, we identified the key transition leaf by the spatial expression analysis of key genes for leaf development and sugar metabolism. We observed that the key transition leaves were the first inwardly curved ones. Surprisingly, most of the heading candidate genes identified by domestication selection analysis obviously showed a corresponding expression transition, supporting that key transition leaves are related to leafy head formation. The key transition leaves were controlled by a complex signal network, including not only internal hormones and protein kinases but also external light and other stimuli. Our findings provide new insights and the rich resource to unravel the genetic control of heading traits.

Transposable element insertion: a hidden major source of domesticated phenotypic variation in Brassica rapa

“…Moreover, we analyzed the expression levels of the TIP‐containing BrMYB18.1 gene in the leaves from inner to outer at Chinese cabbage heading stage; the expression of this gene suddenly enhanced significantly in the leaf L7 and keeping high level expression in the afterward leaves (Figure 7d). This specific leaf was considered to be the key transition leaf during the leafy head formation (Guo et al ., 2021). Unexpectedly, distribution of either the TIP or the gene haplotype of BrMYB18.1 in summer Chinese cabbage was like the nonheading morphotypes, suggesting that this locus had been re‐introduced into summer Chinese cabbage during the modern breeding.…”

Identification of YUC genes associated with leaf wrinkling trait in Tacai variety of Chinese cabbage

“…Analogous circumstances arise in the head formation of Chinese cabbage, with variations in leaf characteristics observed across different leaf positions. Studies indicate that the key transition leaf in the heading process of Chinese cabbage is the 7 th true leaf, regulated by an intricate signaling network ( Guo et al, 2022 ). Hence, we utilized leaf samples from the 1 st and 5 th leaves, which exhibited significant differences during both the juvenile and mature stages, to establish a comprehensive expression profile of BrYUCs during leaf wrinkling formation in Chinese cabbage.…”

The Roles of Gibberellins in Regulating Leaf Development

“…In addition, three families of auxin transport genes have been discovered to be expressed throughout the entire process of leafy head formation: auxin-resistant 1/like aux1 (AUX/LAX), pin-formed (PIN), and ATP-binding cassette subfamily B (ABCB/MDR/PGP), suggesting that these genes play important roles in the development of heads [ 8 ]. Besides dynamic auxin distribution, low temperatures, wide temperature differences, low light intensity, short light duration, and sufficient carbon, GA promotes leafy head induction and development [ 99 ]. The mechanism of GA in forming leafy heads is complex and still needs to be explored.…”