Identification and functional characterization of BrcLL1, a candidate gene controlling leaf lobing in non-heading Chinese cabbage (Brassica rapa subsp. chinensis)

IF 4.1 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Plant Science Pub Date : 2025-09-24 DOI:10.1016/j.plantsci.2025.112785

Zhihang Song, Zhaojun Yu, Haoming Li, Qingguo Sun, Hanqiang Liu, Maixia Hui

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引用次数: 0

Abstract

Leaf morphology is a key agronomic trait in non-heading Chinese cabbage (Brassica rapa subsp. chinensis), influencing both its commercial value and adaptability. The lobed leaf phenotype is of particular interest due to its implications for stress tolerance and breeding selection. In this study, a recombinant inbred line (RIL) population derived from a cross between the round-leaf line 14XS39B and the lobed-leaf line 14XS33H was used to fine-map the genetic basis of leaf lobing. A candidate gene, BrcLL1 (lobed-leaf 1), was identified within a 13.5 kb interval on chromosome A10, encodes a homeodomain leucine zipper class I (HD-ZIP I) transcription factor. Quantitative real-time PCR analysis showed that BrcLL1 expression was significantly elevated in the lobed-leaf parent 14XS33H, particularly at the cotyledon stage. Gene copy number analysis revealed that both 14XS39B and 14XS33H carry two copies of BrcLL1 (BrcLL1-A, BrcLL1-B). Sequence of BrcLL1-A showed no difference between the two parents, while the sequence of BrcLL1-B in 14XS33H has a 245 bp deletion in the intron region and four SNPs in the coding region. Transformation validation of the CDS sequences in Arabidopsis thaliana revealed distinct roles for the two alleles: overexpression of BrcLL1-A caused mildly serrated leaf margins, whereas overexpressing BrcLL1-B induced deeply lobed and highly dissected leaves with altered morphology. Furthermore, RNAi-mediated knockdown of BrcLL1 resulted in enlarged leaves, supporting the possibility of a positive regulatory role in the production of lobed leaves. These results indicate that the four SNPs in the coding region of the BrcLL1-B gene copy in the lobed-leaf parent, which lead to elevated expression of the B copy, serve as the primary driver enhancing the lobed-leaf phenotype, whereas the A copy likely plays only a minor role. Collectively, our work provides valuable insights into the molecular basis of lobed leaf formation and marker-assisted breeding in Brassica crops.

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无头甘蓝叶片裂变候选基因BrcLL1的鉴定与功能研究对)。

叶片形态是无头大白菜（Brassica rapa subsp）的关键农艺性状。影响其商业价值和适应性。由于其对胁迫耐受性和育种选择的影响，裂叶表型特别令人感兴趣。本研究利用圆形叶系14XS39B与浅裂叶系14XS33H杂交的重组自交系（RIL）群体，对叶片浅裂的遗传基础进行了精细定位。候选基因BrcLL1 （lobebeleaf 1）编码同源结构域亮氨酸拉链类I （HD-ZIP I）转录因子，位于A10染色体13.5kb的间隔内。实时荧光定量PCR分析显示，BrcLL1在小叶亲本14XS33H中表达显著升高，尤其是在子叶期。基因拷贝数分析显示，14XS39B和14XS33H均携带2个BrcLL1拷贝（BrcLL1- a, BrcLL1- b）。BrcLL1-A序列在两亲本之间没有差异，而14XS33H中BrcLL1-B序列在内含子区缺失245bp，编码区有4个snp。对CDS序列在拟南芥中的转化验证揭示了两个等位基因的不同作用：过表达BrcLL1-A导致叶片边缘呈轻微锯齿状，而过表达BrcLL1-B则导致叶片深裂和高度解剖，并改变叶片形态。此外，rnai介导的BrcLL1敲低导致叶片变大，这支持了BrcLL1在裂叶产生中的积极调节作用的可能性。这些结果表明，在小叶亲本BrcLL1-B基因拷贝编码区，导致B拷贝表达升高的4个snp是增强小叶表型的主要驱动因素，而A拷贝可能只起次要作用。总的来说，我们的工作为芸苔属作物裂叶形成和标记辅助育种的分子基础提供了有价值的见解。

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来源期刊

Plant Science 生物-生化与分子生物学

CiteScore

9.10

自引率

1.90%

发文量

322

审稿时长

33 days

期刊介绍： Plant Science will publish in the minimum of time, research manuscripts as well as commissioned reviews and commentaries recommended by its referees in all areas of experimental plant biology with emphasis in the broad areas of genomics, proteomics, biochemistry (including enzymology), physiology, cell biology, development, genetics, functional plant breeding, systems biology and the interaction of plants with the environment. Manuscripts for full consideration should be written concisely and essentially as a final report. The main criterion for publication is that the manuscript must contain original and significant insights that lead to a better understanding of fundamental plant biology. Papers centering on plant cell culture should be of interest to a wide audience and methods employed result in a substantial improvement over existing established techniques and approaches. Methods papers are welcome only when the technique(s) described is novel or provides a major advancement of established protocols.