Khanduri Priyanka, Sharma Roopam, Bhat Vishnu, Tandon Rajesh
Department of Botany, University of Delhi, Delhi, 110007, India.
Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada.
J Plant Res. 2016 Mar;129(2):241-50. doi: 10.1007/s10265-015-0771-2. Epub 2015 Dec 9.
Podostemaceae is an interesting family of angiosperms with unusual development and morphology. Among these, double fertilization, a defining feature of angiosperms is invariably missing in the family. Consequently, embryo development in the seeds takes place without endosperm. In recent years, the role of polycomb genes has garnered much interest because of their crucial role in seed development. Some of these genes have been reported from many unrelated species, underlining their high conservation. Thus, it becomes exciting to know the role of these genes in podostemads, which are devoid of double fertilization and endosperm. Here, we report the isolation, characterization and expression patterns of homologs of Fertilization Independent Endosperm (FIE) in two species of Podostemaceae, Zeylanidium olivaceum and Polypleurum stylosum. FIE like homologs could be identified in Z. olivaceum (ZoFIE) and P. stylosum (PsFIE). The predicted amino acid sequence of FIE homologs showed similarity to other homologs, containing the conserved seven WD40 repeats. Expression studies revealed that ZoFIE and PsFIE transcripts were present in the vegetative tissue (thallus in Podostemaceae) and the seedlings, similar to the model plants. However, the ZoFIE and PsFIE expression disappeared in the flowering stages. This unique pattern of expression suggests that in the absence of double fertilization and endosperm the expression of FIS complex genes perhaps is obliterated in Podostemaceae.
川苔草科是一个有趣的被子植物科，其发育和形态异常。其中，双受精作为被子植物的一个决定性特征，在该科中总是缺失。因此，种子中的胚胎发育在没有胚乳的情况下进行。近年来，多梳基因的作用因其在种子发育中的关键作用而备受关注。这些基因中的一些已在许多不相关的物种中被报道，这突出了它们的高度保守性。因此，了解这些基因在缺乏双受精和胚乳的川苔草科植物中的作用变得令人兴奋。在这里，我们报告了川苔草科两种植物——泽氏川苔草（Zeylanidium olivaceum）和长柄多肋草（Polypleurum stylosum）中自主胚乳（FIE）同源基因的分离、表征和表达模式。在泽氏川苔草（ZoFIE）和长柄多肋草（PsFIE）中可以鉴定出类似FIE的同源物。FIE同源物的预测氨基酸序列与其他同源物相似，包含保守的七个WD40重复序列。表达研究表明，ZoFIE和PsFIE转录本存在于营养组织（川苔草科的叶状体）和幼苗中，类似于模式植物。然而，ZoFIE和PsFIE的表达在开花阶段消失。这种独特的表达模式表明，在没有双受精和胚乳的情况下，FIS复合体基因在川苔草科中的表达可能被消除了。
