Genetic Effect of PUL Allelic Variation on Rice Cooking and Eating Qualities

Pullulanase (PUL) is a type of starch debranching enzymes involved in starch biosynthesis. To test the effect of PUL allelic variation on cooking and eating qualities in rice (Oryza sativa L.), 2 sets of near-isogenic lines (NILs) for PUL gene were developed by crossing and backcrossing Guichao 2 (indica) and Suyunuo (japonica glutinous) and selected with the help of the gene-specific STS marker on PUL gene. The NILs had no significant differences in amylose content, gel consistency, and starch crystalline structure compared with their corresponding recurrent parents. In contrast, the starch paste viscosity and starch thermal property changed obviously between the NILs and their recurrent parents. It was concluded that PUL gene plays an important role in determining rice grain cooking and eating qualities, and functional differentiation occurred at the PUL locus between indica variety Guichao 2 and japonica variety Suyunuo. The gene-specific molecular marker for PUL gene developed on the basis of genomic sequence diversity could be directly applied in rice good quality breeding program.

摘要为探讨PUL基因的变异对稻米蒸煮食味品质的影响, 分别以籼稻品种桂朝2号和粳型糯稻品种苏御糯互为供体和轮回亲本, 通过分子标记辅助选择, 经过多代回交构建了PUL基因的近等基因系, 分析了各近等基因系和轮回亲本的蒸煮品质指标。结果表明, 近等基因系与轮回亲本在直链淀粉含量、胶稠度和淀粉晶体结构等指标上没有显著差异, 而淀粉的热力学特性和淀粉黏滞性等指标存在显著的变化。说明PUL基因是影响稻米蒸煮品质的重要基因之一。来源于籼稻桂朝2号和粳稻苏御糯的PUL等位基因在功能上已经发生明显的分化。本研究中基于PUL基因序列差异设计的分子标记可以直接用于水稻品质的改良。