Abstract: Linseed flax (Linum usitatissimum L.) is one of the main oil crops in China, with strong drought tolerance, cold resistance and resistance to poverty characteristics. Plant height not only affects the yield of flax, but also relates to plant lodging and seed quality. This study used a recombinant inbred line population  consisting of 155 lines as experimental materials, which was constructed with Macbeth and Heiya 14 as parents, to analyze the plant height traits in Lanzhou and Jingtai at Gansu province, Yuanmou at Yunan province and Langfang at Hebei province. The QTL-seq based on high-throughput sequencing and the traditional QTL localization method were used to locate the QTL of flax plant height, and a main effect gene of plant height, LuCWINV1-1, was obtained. It belonged to the cell wall invertase of acid invertase and contained the conserved domains NDPNG, RDP and MWECP. There was mutation  in genome sequence of LuCWINV1-1 between the parents, which resulted the 21st glutamate and 523rd isoleucine in Macbeth were glycine and alanine in Heiya 14, respectively. By transformed into Arabidopsis, it was found that the plant height overexpressed LuCWINV1-1Mac became higher, while the plant height overexpressed LuCWINV-11 Hei became lower, which indicated that the gene controlled the plant height in flax. Those results laid a foundation for analyzing the mechanism of plant height in flax, and also explored that QTL-SEQ could be used to clone QTL candidate genes quickly and effectively in this small genome crop, which provided technical support for the subsequent identification of genes controlling the important agronomic characters of flax.

Key words: linseed flax, plant height, QTL-seq, cell wall invertase

摘要： 胡麻(Linum usitatissimum L.)是我国主要油料作物之一，具有较强的耐旱、耐寒、耐贫瘠特性，株高不仅影响胡麻产量，同时与植株倒伏性相关，对胡麻籽品质也有一定影响。以加拿大油用亚麻品种Macbeth和中国纤用亚麻品种黑亚14号为亲本构建的包含155个株系的重组自交系群体为试验材料，统计了该群体在甘肃兰州和景泰、云南元谋及河北廊坊四点的株高性状，挑选在四个环境株高表现一致的高、低单株构建混合池进行QTL-seq。将分析结果和QTL定位结果进行比较分析后确认了QTL候选区段，锁定了一个胡麻株高候选基因LuCWINV1-1，其属于酸性转化酶中的细胞壁转化酶，包含保守的结构域NDPNG、RDP和MWECP。亲本中LuCWINV1-1基因组序列发生突变，导致Macbeth中第21位谷氨酸和第523位异亮氨酸在黑亚14中分别为甘氨酸和丙氨酸。通过转化拟南芥发现，两个亲本的等位基因对株高起着不同的效应作用，LuCWINV1-1Mac转基因株系的株高变低，LuCWINV1-1Hei转基因株系变高，表明该基因在胡麻中控制株高。上述结果为解析胡麻株高机制奠定了基础，同时，也探索出在小基因组作物中利用QTL-seq快速能有效克隆QTL候选基因，为后续鉴定克隆控制胡麻重要农艺性状的基因提供技术支撑。

关键词: 胡麻, 株高, QTL-seq, 细胞壁转化酶