Nonomura Ken-Ichi, Miyoshi Kazumaru, Eiguchi Mitsugu, Suzuki Tadzunu, Miyao Akio, Hirochika Hirohiko, Kurata Nori
Experimental Farm/Plant Genetics Laboratory, National Institute of Genetics, Yata1111, Mishima, Shizuoka 411-8540, Japan.
Plant Cell. 2003 Aug;15(8):1728-39. doi: 10.1105/tpc.012401.
The function of the novel gene MSP1 (MULTIPLE SPOROCYTE), which controls early sporogenic development, was elucidated by characterizing a retrotransposon-tagged mutation of rice. The MSP1 gene encoded a Leu-rich repeat receptor-like protein kinase. The msp1 mutation gave rise to an excessive number of both male and female sporocytes. In addition, the formation of anther wall layers was disordered and the tapetum layer was lost completely. Although the mutation never affected homologous chromosome pairing and chiasma maintenance, the development of pollen mother cells was arrested at various stages of meiotic prophase I, which resulted in complete male sterility. Meanwhile, plural megaspore mother cells in a mutant ovule generated several megaspores, underwent gametogenesis, and produced germinable seeds when fertilized with wild-type pollen despite disorganized female gametophytes. In situ expression of MSP1 was detected in surrounding cells of male and female sporocytes and some flower tissues, but never in the sporocytes themselves. These results suggest that the MSP1 product plays crucial roles in restricting the number of cells entering into male and female sporogenesis and in initiating anther wall formation in rice.
通过对水稻反转录转座子标签突变体进行特征分析，阐明了控制早期孢子发生发育的新基因MSP1（多个孢子母细胞）的功能。MSP1基因编码一种富含亮氨酸重复序列的类受体蛋白激酶。msp1突变导致雄雌两性的孢子母细胞数量过多。此外，花药壁层的形成紊乱，绒毡层完全缺失。尽管该突变从未影响同源染色体配对和交叉维持，但花粉母细胞的发育在减数分裂前期I的各个阶段停滞，导致完全雄性不育。同时，突变胚珠中的多个大孢子母细胞产生了几个大孢子，经历了配子发生，并且在与野生型花粉受精时，尽管雌配子体紊乱，但仍产生了可萌发的种子。在雄雌孢子母细胞的周围细胞和一些花组织中检测到了MSP1的原位表达，但在孢子母细胞本身中未检测到。这些结果表明，MSP1产物在限制进入雄雌孢子发生的细胞数量以及启动水稻花药壁形成过程中起着关键作用。
