Becraft P W, Asuncion-Crabb Y
Zoology and Genetics Department, Iowa State University, Ames, IA 50011, USA.
Development. 2000 Sep;127(18):4039-48. doi: 10.1242/dev.127.18.4039.
A genetic analysis of maize aleurone development was conducted. Cell lineage was examined by simultaneously marking cells with C1 for anthocyanin pigmentation in the aleurone and wx1 for amylose synthesis in the starchy endosperm. The aleurone and starchy endosperm share a common lineage throughout development indicating that positional cues specify aleurone fate. Mutants in dek1 block aleurone formation at an early stage and cause peripheral endosperm cells to develop as starchy endosperm. Revertant sectors of a transposon-induced dek1 allele showed that peripheral endosperm cells remain competent to differentiate as aleurone cells until late in development. Ds-induced chromosome breakage was used to generate Dek1 loss-of-function sectors. Events occurring until late development caused aleurone cells to switch fate to starchy endosperm indicating that cell fate is not fixed. Thus, positional cues are required to specify and maintain aleurone fate and Dek1 function is required to respond to these cues. An analysis of additional mutants that disrupt aleurone differentiation suggests a hierarchy of gene functions to specify aleurone cell fate and then control aleurone differentiation. These mutants disrupt aleurone differentiation in reproducible patterns suggesting a relationship to endosperm pattern formation.
对玉米糊粉层发育进行了遗传分析。通过同时用C1标记糊粉层中用于花青素色素沉着的细胞和用wx1标记淀粉质胚乳中用于直链淀粉合成的细胞来检测细胞谱系。糊粉层和淀粉质胚乳在整个发育过程中具有共同的谱系，这表明位置线索决定了糊粉层的命运。dek1突变体在早期阻止糊粉层形成，并导致外周胚乳细胞发育成淀粉质胚乳。转座子诱导的dek1等位基因的回复突变区段表明，外周胚乳细胞在发育后期之前仍有能力分化为糊粉层细胞。利用Ds诱导的染色体断裂来产生Dek1功能缺失区段。直到发育后期发生的事件导致糊粉层细胞将命运转变为淀粉质胚乳，这表明细胞命运不是固定不变的。因此，需要位置线索来确定和维持糊粉层的命运，并且需要Dek1功能来响应这些线索。对其他破坏糊粉层分化的突变体的分析表明，存在一个基因功能层次结构来确定糊粉层细胞命运，然后控制糊粉层分化。这些突变体以可重复的模式破坏糊粉层分化，表明与胚乳模式形成有关。
