The genome dynamics and function in higher plants

近红、紫红和三色紫红的自发突变体分别开出红色的花，野生型的花呈蓝色或深紫色。我们已经证实，这些突变体在编码类黄酮3‘-羟基酶的F3’H基因中携带点突变或转座子插入，该酶在花青素色素生物合成中介导柚皮素和脱氢山奈酚B环3‘位的羟基化。野生一号的花蕾呈紫红色，花朵呈蓝色开放，花色的变化与花上皮细胞液泡pH的升高有关。在液泡Na/H逆向转运蛋白NHX1基因缺失的突变体中，液泡只发生了部分碱化，红紫色的花蕾变成了紫色的开放花。我们已经鉴定出一个新的液泡Na/H逆向转运蛋白基因NHX2，它是在没有NHX1活性的情况下通过部分提高液泡pH来将红紫色的花蕾转化为紫色开放花的基因之一。花色为红棕色或紫灰色的暗色突变体缺乏一种新的花青素生物合成糖基化酶UDP-葡萄糖：花青素3-O-葡萄糖苷-2“-O-葡萄糖基转移酶(3GGT)，该酶介导花青素3-O-葡萄糖苷的糖基化反应生成3-O-苦参皂苷。所有被检测的暗色突变体都通过在3GGT基因的相同位置插入来携带4，并且这些插入引起移码突变。通过同源重组修饰基因被称为基因打靶是表征基因功能的最直接的方法，我们成功地通过强正负选择来重复性地修改了水稻蜡质基因的基因组序列。我们还发现了一个新的水稻DNA转座子nDART，它可以用于水稻的基因标记。

The spontaneous magenta, pink and fuchsia mutants in I. nil, I. purpurea and I. tricolor exhibit reddish flowers, respectively, while their wild-type flowers display blue or dark purple flowers. We have identified that these mutants carry either point mutations or transposon insertions within the F3'H gene encoding flavonoid 3'-hydroxylase that mediates hydroxylation of the 3' position of the B-ring of naringenin and dehydrokaempferol in anthocyanin pigment biosynthesis. The reddish-purple buds of the wild-type I. nil change into blue open flowers, and the shift in the flower coloration correlates with an increase in the vacuolar pH of the flower epidermal cell. In the mutant deficient in the NHX1 gene for the vacuolar Na+/H+ antiporter, the vacuolar alkalization occurs only partially, and reddish-purple buds become purple open flowers. We have identified a novel vacuolar Na+/H+ antiporter gene NHX2, which is one of the genes responsible for converting reddish-purple buds into purple open flowers by partially increasing vacuolar pH in the absence of the NHX1 activity. The dusky mutants of I. nil displaying reddish-brown or purplish-gray flowers were found to be deficient in a novel glycosylation enzyme for anthocyanin biosynthesis, UDP-glucose : anthocyanidin 3-O-glucoside-2"-O-glucosyltransferase (3GGT), which mediates the glucosylation of anthocyanidin 3-O-glucosides to yield 3-O-sophorosides. All of the dusky mutants examined were shown to carry 4 by insertions at the identical position in the 3GGT gene, and the insertions caused frameshift mutations.Modification of genes through homologousrecombination termed gene targeting is the most direct method to characterize gene function, and we have succeeded in modifying the rice genomic sequence of the Waxy gene reproducibly by using a strong positive-negative selection. We also identified a novel rice DNA transposon, nDart, which can be used for gene tagging in rice.