Zhang Mengru, Song Mengfei, Cheng Feng, Han Xiaoxu, Cheng Chunyan, Yu Xiaqing, Chen Jinfeng, Lou Qunfeng
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Weigang Street No.1, Nanjing, 210095, China.
College of Horticulture and Landscape, Henan Institute of Science and Technology, Xinxiang, China.
Theor Appl Genet. 2024 Dec 24;138(1):12. doi: 10.1007/s00122-024-04785-9.
A dwarf mutant with short branches (csdf) was identified from EMS-induced mutagenesis. Bulked segregant analysis sequencing and map-based cloning revealed CsKAO encoding ent-kaurenoic acid oxidase as the causal gene. Plant architecture is the primary target of artificial selection during domestication and improvement based on the determinate function for fruit yield. Plant architecture is regulated by complicated genetic networks, more underlying mechanism remains to be elucidated. Here, we identified a dwarf mutant (csdf) in an EMS-induced cucumber population, and genetic analysis revealed the mutated phenotype is controlled by a single recessive gene. Optical microanalysis showed the decrease in cell length is mainly contribute to the dwarf phenotype. By strategy of BSA-seq combined with map-based cloning, CsaV3_6G006520 (CsKAO) on chromosome 6 was identified as the candidate gene for csdf. Gene cloning and sequence alignment revealed a G to A mutation in the sixth exon, which causes the premature stop codon in CsKAO of csdf. Expression analysis revealed CsKAO was expressed in various tissues with abundant transcripts, and has significant differences between WT and csdf. Gene annotation indicated CsKAO encodes a cytochrome P450 family ent-kaurenoic acid oxidase which functioned in GA biosynthesis. GA-relevant analysis showed that endogenous GA contents were significantly decreased and the dwarfism phenotype could be restored by exogenous GA treatment; while, some of the representative enzyme genes involved in the GA pathway were up-regulated in csdf. Besides, IAA content is decreased in the terminal bud and increased in the lateral bud in csdf as well as several IAA-related genes are differentially expressed. Overall, those findings suggest that CsKAO regulated plant height via the influence on GAs pathways, and IAA might interact with GAs on plant architecture morphogenesis in cucumber.
从甲基磺酸乙酯（EMS）诱变产生的突变体中鉴定出一个具有短枝的矮化突变体（csdf）。混合分组分析法测序和图位克隆表明，编码贝壳杉烯酸氧化酶的CsKAO是导致该性状的基因。基于果实产量的决定功能，株型是驯化和改良过程中人工选择的主要目标。株型受复杂的遗传网络调控，更多潜在机制仍有待阐明。在此，我们在EMS诱变的黄瓜群体中鉴定出一个矮化突变体（csdf），遗传分析表明该突变表型由单个隐性基因控制。光学显微分析显示细胞长度的减少是导致矮化表型的主要原因。通过混合分组分析法测序（BSA-seq）结合图位克隆的策略，确定6号染色体上的CsaV3_6G006520（CsKAO）为csdf的候选基因。基因克隆和序列比对显示，第六外显子发生了G到A的突变，导致csdf的CsKAO中出现提前终止密码子。表达分析表明，CsKAO在各种组织中均有表达且转录本丰富，在野生型和csdf之间存在显著差异。基因注释表明，CsKAO编码一种细胞色素P450家族的贝壳杉烯酸氧化酶，其在赤霉素（GA）生物合成中发挥作用。与GA相关的分析表明，内源GA含量显著降低，外源GA处理可恢复矮化表型；同时，GA途径中一些代表性的酶基因在csdf中上调。此外，csdf顶芽中的生长素（IAA）含量降低，侧芽中的IAA含量增加，并且几个与IAA相关的基因差异表达。总体而言，这些发现表明CsKAO通过影响GA途径调控株高，并且IAA可能在黄瓜株型形态发生过程中与GA相互作用。
