风信子再生花芽中胚珠特征基因homads1的表达

Expression Analysis of Ovule Identity Gene homadsl During in Vitro Flowering of Hyacinthus orientalis L.

以风信子花被片为外植体,通过控制外源植物生长调节剂6-BA和2,4-D浓度诱导再生胚珠的分化。细胞学观察显示,离体条件下胚珠的发育过程与自然状态下基本一致。利用原位杂交技术分析风信子胚珠特征基因homadsl在再生胚珠分化过程中的表达模式。在胚珠形态发生之前,homadsl mRNA就已在心皮状结构边缘的某些细胞中积累,之后集中在由此处产生的胚珠原基和幼嫩的胚珠中,表明homadsl mRNA在启动再生胚珠的分化的过程中起重要作用。分别提取不同发育时期再生花芽的总RNA,以hom- adsl的特异序列设计引物,进行RT-PCR分析。结果显示,在降低6-BA和2,4- D浓度后5d的再生花芽中即检测到了homadsl mRNA的积累,而在高浓度6-BA和2,4-D条件下持续培养的花芽中均未检测到该基因的转录产物,表明低浓度6-BA和2,4-D诱导homadsl在再生花芽中的表达。

Tepals of Hyacinthus orientalis L. were used as explants to induce the formation of ovules through controlling the level of 6-BA and 2,4-D in the media. Anatomical studies using light microscopy showed that the development of in vitro ovules resembled that of in planta. To investigate the temporal and spatial expression pattern of homads1 during in vitro ovule initiation, which is involved in the determination of ovule identities in Hyacinthus, RNA in situ hybridization was carried out. The hybridization signals were first detected in some cells along the edge of carpel-like organ, from which the ovules were derived, and then restricted to the ovule primordial and ovules. The results indicated that homadsl plays an important role in the initiation and development of in vitro ovules. Further expression analysis by RT-PCR indicated that homadsl is induced by low level of 6-BA and 2,4-D during in vitro ovule initiation and development. This study may provide some clues to understand the molecular mechanism of ovule development regulated by hormones.