Dogra Vivek, Sharma Ruchika, Yelam Sreenivasulu
Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, 176061, India.
Laboratory of Photosynthesis and Stress Signaling, Shanghai Center for Plant Stress Biology, CAS, Shanghai, China.
Planta. 2016 Aug;244(2):505-15. doi: 10.1007/s00425-016-2520-8. Epub 2016 Apr 20.
Xyloglucan endo-transglycosylase/hydrolase ( Ph XET/H) regulates Podophyllum seed germination via GA mediated up-accumulation of Ph XET protein and subsequent endosperm weakening. Xyloglucan endo-transglycosylase/hydrolase (XET/H) belong to glycosyl hydrolase family 16, which play an important role in endosperm weakening and embryonic expansion during seed germination. Podophyllum hexandrum is a high altitude medicinal plant exploited for its etoposides which are potential anticancer compounds. During seed germination in Podophyllum, accumulation of XET/H transcripts was recorded. This data confirmed its possible role in determining the fate of seed for germination. Full length cDNA of a membrane bound XET/H (here onwards PhXET) was cloned from the germinating seeds of Podophyllum. Analysis of nucleotide sequence revealed PhXET with an open reading frame of 720 bp encoding a protein of 239 amino acids with a molecular mass of 28 kDa and pI of 7.58. In silico structure prediction of PhXET showed homology with that of Populus tremula (1UN1). PhXET was predicted to have a potential GPI-anchor domain and was located in plasma membrane. It was found that the exogenously applied phytohormones (GA and ABA) regulate the expression of PhXET. The obtained data showed that the PhXET regulates seed germination in Podophyllum by supplementing its activity along with other endosperm weakening and embryo expansion genes.
木葡聚糖内转糖基酶/水解酶（PhXET/H）通过赤霉素介导的PhXET蛋白上调积累及随后的胚乳弱化来调节鬼臼种子萌发。木葡聚糖内转糖基酶/水解酶（XET/H）属于糖基水解酶家族16，在种子萌发过程中的胚乳弱化和胚胎扩展中起重要作用。喜马拉雅鬼臼是一种高海拔药用植物，因其含有的潜在抗癌化合物鬼臼毒素而被开发利用。在鬼臼种子萌发过程中，记录到了XET/H转录本的积累。该数据证实了其在决定种子萌发命运方面可能发挥的作用。从鬼臼萌发种子中克隆了一种膜结合型XET/H（以下简称PhXET）的全长cDNA。核苷酸序列分析显示，PhXET的开放阅读框为720 bp，编码一个239个氨基酸的蛋白质，分子量为28 kDa，等电点为7.58。PhXET的计算机结构预测显示与欧洲山杨（1UN1）具有同源性。PhXET被预测具有潜在的糖基磷脂酰肌醇锚定结构域，并位于质膜上。研究发现，外源施加的植物激素（赤霉素和脱落酸）可调节PhXET的表达。所得数据表明，PhXET通过补充其活性以及其他胚乳弱化和胚胎扩展基因来调节鬼臼种子的萌发。
