黄瓜是我国主要蔬菜作物之一，不同类型的黄瓜品种对侧枝多少有着不同的要求。目前在黄瓜上关于多侧枝性状的研究还比较落后，虽然已经利用RAPD、AFLP、SRAP等标记对多侧枝QTL进行了初步定位，但是这些定位结果不够精细，标记可靠性也有待提高，难以在育种中满足分子标记辅助选择的需要。本项目在利用SSR标记对重组自交系多侧枝QTL初步定位的基础上，将对亲本进行深度重测序及从头组装，通过电子PCR和序列比对的方法在QTL区域筛选多态性SSR、SNP和Indel等标记对多侧枝主效QTL进行精细定位，并通过进一步对主效QTL在F2:3大群体中验证，最终克隆控制多侧枝主效QTL候选基因，进而研究该基因的表达模式及其在葫芦科作物中的分子进化。这不仅对改良黄瓜品种株型，提高分子标记辅助育种选择效率具有重要意义，同时为揭示黄瓜侧枝发育分子机理、深入研究侧枝发生和调控机制提供研究基础和理论依据。

Cucumber is one of the most important vegetable crops in China.The lateral branch number is an important agronomic trait for cucumber production and different types of cucumber have different requirements for branch number. Though preliminary QTL mapping have been studied for multiple lateral branch number (MLB) in cucumber by RAPD, AFLP and SRAP markers, molecular biology studies on cucumber are still dropping behind when compared with other plants. The current QTL mapping for MLB is not acurate and linked markers are not reliable in the lab test, which made it difficult for marker-assisted selection in breeding. In this study, the QTL for MLB have been primarily mapped by SSR markers in a RIL population, and deep resequenced and de nove assembly have been made for the two mapping parents. To fine mapping the major QTL for MLB, new SSR, SNP and Indel markers will be identified and selected by in silico PCR and genome alignment. The major QTL for MLB will be further validated by a large F2:3 population for final identification of the candidate gene controlling MLB. Furthermore, the expression porfile of candidate gene will be investigated in different tissue and molecular evolution in cucurbitceace family will be also investigated in this study. Therefore, studies on map-based cloning of the major QTL for MLB will not only help to increase the efficiency of marker-assisted selection in improving cucumber plant architecture, but also provide good foundation to explore the possible branching mechanism in cucumber.