Cloning and expression of GDP-D-mannose pyrophosphorylase gene and ascorbic acid content of acerola (Malpighia glabra L.) fruit at ripening stages
Cloning and expression of GDP-D-mannose pyrophosphorylase gene and ascorbic acid content of acerola (Malpighia glabra L.) fruit at ripening stages
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DOI：
10.1016/j.plaphy.2007.07.003
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发表时间：
2007-09-01
影响因子：
6.5
通讯作者：
Esaka, Muneharu
中科院分区：
文献类型：
--
作者：
Badejo, Adebanjo A.;Jeong, Seok T.;Esaka, Muneharu
针叶蝉(Malpighiaoplra L.)是L-抗坏血酸(AsA)最丰富的天然来源之一。GDP-D-甘露糖焦磷酸化酶(GMP；EC 2.7.7.13)是植物体内抗坏血酸(AsA)合成途径的重要组成部分，该基因点突变的拟南芥vtc1-1突变体具有较低的AsA含量。利用RACE技术从针叶树果实中分离到GMP基因，命名为MgGMP，并对其在果实成熟过程中的表达进行了研究。该基因全长为1083bp，编码361个氨基酸的多肽。对预测的氨基酸序列进行电子分析，等电点为6.45，相对分子质量为39.7kD。与其他植物GMP同源物的氨基酸序列同源性超过80%。系统进化树显示，与寄生虫、酵母菌和哺乳动物的GMP相比，其他植物的GMP与其亲缘关系较近。Southern分析表明，光滑木霉含有不少于两个拷贝的GMP基因。Northern印迹分析表明，在针叶菊属各器官中均有丰富的转录本表达，其中果实中的表达水平最高。果实中的相对转录丰度随着果实成熟进程的进展而变化，未成熟的绿色果实相对转录丰度最高，后期果实的相对转录丰度最低。果实成熟过程中，针叶的相对含量与其相对含量之间也存在很强的相关性。(C)2007年爱思唯尔·马森公司。版权所有。
Acerola (Malpighia glabra L.) is one of the richest natural sources Of L-ascorbic acid (AsA; vitamin Q. GDP-D-mannose pyrophosphorylase (GMP; EC 2.7.7.13) was found to play a major role in the proposed AsA biosynthetic pathway in plants, considering that Arabidopsis vtc1-1 mutant with point mutation in this gene has a highly reduced AsA content. GMP cDNA was isolated from acerola fruits, designated MgGMP, using rapid amplification of cDNA ends (RACE), and its expression was monitored during fruit ripening. The full-length cDNA was found to have an ORF of 1083 bp encoding a polypeptide of 361 amino acids. In silico analysis of the predicted amino acid sequence showed a pI of 6.45 and molecular mass of 39.7 kD. MgGMP showed over 80% amino acid sequence identity with other plant GMP homologues. The phylogenetic tree shows the close relation of MgGMP to the GMP of other plants as against those from parasite, yeasts and mammals. Southern analysis indicated that M. glabra contains not less than two copies of GMP genes. Northern blot analysis showed the transcript abundance of MgGMP in all the organs of acerola examined, with the fruit having the highest expression. The relative transcript abundance of MgGMP mRNA levels in the fruits changes as the ripening process progresses, with the unripe green fruits having the highest relative mRNA level, and the lowest was found in the fruits at advanced ripening stage. A strong correlation was also observed between the relative MgGMP mRNA levels and the AsA contents of acerola during fruit ripening. (C) 2007 Elsevier Masson SAS. All rights reserved.