The main edible organ of snap bean (Phaseolus vulgaris L.) is the pod, whose color is a main characteristic affecting its commercial use. Golden pods are popular with consumers; however, color instability affects their commercial exploitation and causes economic losses to the planters. In this study, we focused on the different pod color of two varieties of snap bean. The golden yellow color of snap bean pods is controlled by a single recessive nuclear gene located at 1–4.24 Mb of chromosome 2. To explore the physiological and molecular mechanism of the golden pod color, the golden bean line ‘A18-1′ and the green bean line ‘Renaya’ were selected as experimental materials. We analyzed the pigment contents, detected the intermediate products of chlorophyll biosynthesis, and identified differentially expressed genes using RNA-seq. The formation of golden bean pods reflects a chlorophyll deficiency, which was speculated to be caused by impairment of the Mg-protoporphyrin IX to chlorophyllide step. In ‘A18-1′ and ‘Renaya’ pods on 10, 14, and 18 days, five genes related to this step were differentially expressed, all of which were protochlorophyllide oxidoreductase (POR) genes. Among them, the expression changes of the Phvul. 004G112700, Phvul.007G157500, and Phvul. 004G112400 genes were consistent with the color change and physiological data during pod development in ‘A18-1′ and ‘Renaya’. We speculated that the altered expression of these three POR genes might be related to changes in the chlorophyllide content. The results might provide insight into the understanding of chlorophyll biosynthesis and crop breeding for snap bean.

四季豆的主要食用器官（菜豆）L.）是豆荚，其颜色是影响其商业用途的主要特征。金豆荚深受消费者欢迎。但是，颜色的不稳定性会影响其商业开发并给种植者造成经济损失。在这项研究中，我们着眼于两种豆荚的不同豆荚颜色。四季豆荚的金黄色由位于2号染色体1–4.24 Mb处的单个隐性核基因控制。为探索金荚颜色，金豆系'A18-1'和大豆的生理和分子机理。选择绿豆品系“ Renaya”作为实验材料。我们分析了色素含量，检测了叶绿素生物合成的中间产物，并使用RNA序列鉴定了差异表达的基因。金豆荚的形成反映出叶绿素缺乏，据推测是由于Mg-原卟啉IX破坏了叶绿素步骤。在第10、14和18天的'A18-1'和'Renaya'豆荚中，差异表达了与该步骤相关的五个基因，所有这些基因均为原叶绿素内酯氧化还原酶（POR）基因。其中，Phvul的表达发生了变化。004G112700，Phvul.007G157500和Phvul。004G112400基因与'A18-1'和'Renaya'豆荚发育期间的颜色变化和生理数据一致。我们推测这三个POR基因表达的改变可能与叶绿素含量的变化有关。研究结果可能为深入了解绿豆的叶绿素生物合成和作物育种提供参考。在第10、14和18天的'A18-1'和'Renaya'豆荚中，差异表达了与该步骤相关的五个基因，所有这些基因均为原叶绿素内酯氧化还原酶（POR）基因。其中，Phvul的表达发生了变化。004G112700，Phvul.007G157500和Phvul。004G112400基因与'A18-1'和'Renaya'豆荚发育期间的颜色变化和生理数据一致。我们推测这三个POR基因表达的改变可能与叶绿素含量的变化有关。研究结果可能为深入了解绿豆的叶绿素生物合成和作物育种提供参考。在第10、14和18天的'A18-1'和'Renaya'豆荚中，差异表达了与该步骤相关的五个基因，所有这些基因均为原叶绿素内酯氧化还原酶（POR）基因。其中，Phvul的表达发生了变化。004G112700，Phvul.007G157500和Phvul。004G112400基因与'A18-1'和'Renaya'豆荚发育期间的颜色变化和生理数据一致。我们推测这三个POR基因表达的改变可能与叶绿素含量的变化有关。研究结果可能为深入了解绿豆的叶绿素生物合成和作物育种提供参考。004G112700，Phvul.007G157500和Phvul。004G112400基因与'A18-1'和'Renaya'豆荚发育期间的颜色变化和生理数据一致。我们推测这三个POR基因表达的改变可能与叶绿素含量的变化有关。研究结果可能为深入了解绿豆的叶绿素生物合成和作物育种提供参考。004G112700，Phvul.007G157500和Phvul。004G112400基因与'A18-1'和'Renaya'豆荚发育期间的颜色变化和生理数据一致。我们推测这三个POR基因表达的改变可能与叶绿素含量的变化有关。研究结果可能为深入了解绿豆的叶绿素生物合成和作物育种提供参考。