Reynolds T L, Crawford R L
Department of Biology, The University of North Carolina at Charlotte, 9201 University City Boulevard, 28223, Charlotte, NC, USA.
Plant Cell Rep. 1997 Apr;16(7):458-463. doi: 10.1007/BF01092766.
A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
一个克隆的小麦（普通小麦）早期半胱氨酸标记的金属硫蛋白cDNA具有该植物花粉胚胎发生分子标记的许多特征。在培养时的单核小孢子或正常个体发育的任何阶段的花粉中均未检测到该转录本；其mRNA在培养6小时内开始在胚性小孢子中增加，在约24小时达到峰值，随后下降，然后在21日龄胚状体阶段趋于平稳。此外，富含胚状体的EcMt基因转录本的积累与胚性小孢子和发育中的花粉胚状体中ABA的增加呈直接正相关。用高强度白光、远红光或蓝光照射培养物，抑制了EcMt转录本的积累以及小孢子形成胚状体的能力；然而，光照在培养早期并不影响ABA浓度。这些结果表明，虽然ABA是面包小麦花粉胚胎发生的一个启动子，但仅ABA不能维持在体外受抑制光照条件下小孢子的孢子体分化。光照是直接还是间接抑制EcMt基因表达和花粉胚胎发生仍不清楚。
