Nadolska-Orczyk A, Gasparis S, Orczyk W
Plant Transformation and Cell Engineering Department, Plant Breeding and Acclimatization Institute, Poland.
J Appl Genet. 2009;50(3):185-97. doi: 10.1007/BF03195672.
Kernel hardness is an important agronomic trait that influences end-product properties. In wheat cultivars, this trait is determined by the Puroindoline a (Pina) and Puroindoline b (Pinb) genes, located in the Hardness locus (Ha) on chromosome 5DS of the D genome. Wild type alleles code puroindoline a (PINA) and puroindoline b (PINB) proteins, which form a 15-kDa friabilin present on the surface of water-washed starch granules. Both the proteins are accumulated in the starch endosperm cells and aleurone of the mature kernels. Puroindoline-like genes coding puroindoline-like proteins in the starch endosperm occur in some of the genomes of Triticeae and Aveneae cereals. Orthologs are present in barley, rye and oats. However, some genomes of these diploid and polyploid cereals, like that of Triticum turgidum var. durum (AABB) lack the puroindoline genes, having a very hard kernel texture. The two wild type alleles in opposition (dominant loci) control the soft phenotype. Mutation either in Pina or Pinb or in both leads to a medium-hard or hard kernel texture. The most frequent types of Pin mutations are point mutations within the coding sequence resulting in the substitution of a single amino acid or a null allele. The latter is the result of a frame shift determined by base deletion or insertion or a one-point mutation to the stop codon. The lipid-binding properties of the puroindolines affect not only the dough quality but also the plants' resistance to pathogens. Genetic modification of cereals with Puroindoline genes and/or their promoters enable more detailed functional analyses and the production of plants with the desired characteristics.
籽粒硬度是影响最终产品特性的重要农艺性状。在小麦品种中，该性状由位于D基因组5DS染色体硬度位点（Ha）上的麦醇溶蛋白类a（Pina）和麦醇溶蛋白类b（Pinb）基因决定。野生型等位基因编码麦醇溶蛋白类a（PINA）和麦醇溶蛋白类b（PINB）蛋白，它们形成一种存在于水洗淀粉颗粒表面的15 kDa friabilin蛋白。这两种蛋白都积累在成熟籽粒的淀粉胚乳细胞和糊粉层中。在一些小麦族和燕麦族谷物的基因组中存在编码淀粉胚乳中麦醇溶蛋白类蛋白的麦醇溶蛋白类基因。大麦、黑麦和燕麦中存在直系同源基因。然而，这些二倍体和多倍体谷物的一些基因组，如硬粒小麦（AABB）的基因组，缺乏麦醇溶蛋白基因，籽粒质地非常硬。两个相对的野生型等位基因（显性位点）控制软质表型。Pina或Pinb或两者的突变会导致籽粒质地为中硬或硬。Pin突变最常见的类型是编码序列内的点突变，导致单个氨基酸替换或无效等位基因。后者是由碱基缺失或插入或一个点突变至终止密码子导致的移码结果。麦醇溶蛋白的脂质结合特性不仅影响面团质量，还影响植物对病原体的抗性。用麦醇溶蛋白基因和/或其启动子对谷物进行基因改造能够进行更详细的功能分析，并培育出具有所需特性的植物。
