Sheridan W F, Avalkina N A, Shamrov I I, Batygina T B, Golubovskaya I N
Department of Biology, University of North Dakota, Grand Forks 58202-9019, USA.
Genetics. 1996 Mar;142(3):1009-20. doi: 10.1093/genetics/142.3.1009.
The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (mac1) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In mac1 mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.
开花植物从营养生长向生殖发育途径的转变需要胚珠和花药的亚表皮细胞进入减数分裂途径。这些细胞，即皮下细胞，直接或间接地形成孢原细胞，而孢原细胞又分化为大孢子母细胞和小孢子母细胞。我们分离出了一个隐性多效突变体，将其命名为多孢原细胞1（mac1），并将其定位到10号染色体的短臂上。其细胞学表型表明，该基因座在玉米胚珠中皮下细胞从营养生长向减数分裂（产孢）途径的转变中起重要作用。在玉米正常胚珠发育过程中，只有一个皮下细胞发育成孢原细胞，并分化为单个大孢子母细胞。在mac1突变体胚珠中，几个皮下细胞发育成孢原细胞，产生的大孢子母细胞进行正常的减数分裂。四分体中有不止一个大孢子存活，每个胚珠中形成不止一个胚囊。突变植株的雌穗由于大孢子分化和胚囊形成异常而表现出部分不育。因此，该基因的孢子体表达对正常雌配子体发育也很重要。
