荚长是豇豆重要性状，其调控机制未明。申请人前期利用一个长荚×短荚品系衍生的RIL群体明确该群体荚长受1主效+1微效QTL控制，主效QTL Qpl-3解释的表型变异~40%，并将该QTL定位在一个0.44 cM的区间。本项目在此基础上1)从RIL群体筛选只携单个主效QTL（长荚)与不携长荚QTL（短荚)的典型植株，混成长、短荚两池进行比较转录组分析;2)构建整合遗传图谱、双亲深度重测序等在Qpl-3区间开发新标记，对扩大的RIL和F2大群体进行基因型和表型分析，结合重组体分析实现精细定位;3)筛选BAC文库将Qpl-3限定于含预测基因<10个的基因组区段;4)综合各预测基因在长、短荚间的表达水平、功能注释、转录组信息推定候选基因，利用转基因豇豆愈伤组织和拟南芥验证基因功能;5)分析该基因在豇豆自然群体中的序列变异，揭示其在育种驯化中的作用，探明其与其他物种已知荚长QTL或基因的关系。

Pod length is an important trait of asparagus bean, yet the mechanism controlling this trait remains unknown. Using a RIL population derived from the cross between a long-podded and a short-podded accessions, we have revealed that pod length was genetically controlled by one major QTL and one minor QTL in that population. The major QTL, Qpl-3 accounting for ~ 40% of the phenotypic variance, has been mapped to a 0.44 cM interval on LG3. In this project, we are planned to create a long-podded and short-podded RIL pools that harbor the single Qpl-3 and no pod length QTl, respectively. Comparative transcriptomic analysis will be conducted in pods between the two pools. Consensus genetic mapping and in-depth re-sequencing of the parental lines will be conducted to develop new DNA markers in the Qpl-3 interval. Fine mapping of Qpl-3 will be achieved by using the enlarged RIL population as well as a large F2 population, in combination with genotypic and phenotypic analysis of the recombinants. Through screening a BAC library , the Qpl-3 is expected to be confined to a genome region harboring no more than 10 predicted genes. To help determine most possible candidate genes, real-time RT-PCR　will be conducted for each predicted gene between the long-podded and short-podded pools. This information, together with the annotation of predicted genes and the transcriptomic data, will lead to the identification of one or a few more candidate genes. Transgenic approaches will be used to verify candidate gene functions using cowpea callus and Arabidopsis. Finally, natural variations of the cloned pod length gene will be investigated across the Chinese asparagus bean mini core to reveal the impact of human selection on the domestication of pod length in this species. A comparative analysis will also be performed for the pod length genes/QTLs between asparagus bean and the broader plant species.