水稻白叶白穗突变体wlwp7的鉴定与基因定位

水稻叶穗色泽突变体为解析不同器官叶绿素生物合成之间的内在联系提供了优良的遗传材料。本研究鉴定了1份白叶白穗突变体wlwp7（white leaf and white panicle 7）,分析了wlwp7的形态、生理和遗传特点。结果表明：wlwp7对低温敏感,当环境温度为20 ℃时苗期叶片白化,但温度升高至30 ℃后叶色正常;大田环境下wlwp7抽穗后颖壳白化,叶绿素含量降低至野生型的40.73%;除结实率较野生型T98B下降6.28%外,其他产量性状不受影响;遗传分析发现,wlwp7与T98B的正反杂交F₂群体中都未出现白叶绿穗和绿叶白穗重组单株,经卡方检测白叶白穗突变单株与绿叶绿穗野生型单株的理论分离比符合1∶3,表明白叶白穗性状受同一隐性核基因控制;利用BSA策略进一步将wlwp7定位在第3染色体上一个280 kb的区域内,该区域未有已报道的白叶白穗基因。本研究发现了wlwp7同时控制叶部和穗部叶绿素合成,精细定位结果为最终克隆wlwp7奠定了基础。

Identification and Gene Mapping of a White Leaf and White Panicle Mutant wlwp7 in Rice

Rice mutants varied both in leaf color and panicle color are valuable genetic resources for revealing the link of chlorophyll biosynthesis between different organs. Here, a white leaf and white panicle 7 mutant (wlwp7) was identified and analyzed from morphological, physiological and genetic levels. It showed that the seedling plants of wlwp7 was sensitive to low temperature with white leaves at 20 ℃. While, it became green at a high temperature of 30 ℃. The paddy plants of wlwp7 was observed to present white hulls at heading. The chlorophyll content in the hulls of wlwp7 was reduced to 40.73% of its wild type T98B. Except for the seed-setting rate (with a decrease of 6.28%), other yield traits remained unaffected. Further genetic analysis confirmed there was no recombinant plant with a phenotype of white leaf/green panicle or green leaf/white panicle in two F₂ groups derived from wlwp7/T98B and T98B/wlwp7. Moreover, it found the theoretical segregation ratio of mutant plants to wild-type plants was consistent with 1:3 by chi square test, supporting wlwp7 would be controlled via one recessive nuclear gene. Finally, wlwp7 was mapped within 280Kb on chromosome 3 using BSA strategy, and there is no reported gene controlling white leaf and white panicle in this area. This study reveals that wlwp7 functions in regulating the chlorophyll bio-synthesis in leaves and panicles, and the gene mapping results provides a basis for the cloning of wlwp7.