The rice genome encodes two vacuolar invertases with fructan exohydrolase activity but lacks the related fructan biosynthesis genes of the Pooideae
The rice genome encodes two vacuolar invertases with fructan exohydrolase activity but lacks the related fructan biosynthesis genes of the Pooideae
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DOI：
10.1111/j.1469-8137.2006.01896.x
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发表时间：
2007-01-01
期刊：
影响因子：
9.4
通讯作者：
Bennett, John
中科院分区：
文献类型：
--
作者：
Ji, Xuemei;Van den Ende, Wim;Bennett, John
果聚糖在几个植物科(禾本科、芦笋科和菊科)中被认为与耐寒和干旱有关，但为什么在一些属(如小麦)中发现了积累这些聚合物的能力，而在另一些属(如水稻)中没有发现。由于果聚糖生物合成酶(FBE)是由液泡转化酶(VINS)进化而来的，因此我们在水稻基因组序列中寻找与小麦和Pooideae其他成员的FBE和VIN基因相关的基因。我们对它们在毕赤酵母中表达后的外显子-内含子结构、蛋白质序列以及重组蛋白的酶学性质进行了比较，发现大米中含有两个VIN基因(OsVIN1和OsVIN2)，而不含FBE基因。FBE基因似乎是通过一系列来自小麦TaVIN3祖先的基因复制而出现在Pooideae中的。重组TaVIN2、OsVIN1和OsVIN2表现为转化酶，不具有FBE活性，但具有较高的果聚糖外水解酶活性，尤其是OsVIN1。在水稻中积累果聚糖以提高抗逆性的工程可以建立在内源外水解酶的基础上，但OsVIN1转录本在水分充足和干旱胁迫的植物的花序梗中缺失的事实消除了这一努力的一个潜在障碍。
Fructans are believed to contribute to cold and drought tolerance in several plant families (Poaceae, Asparagaceae and Asteraceae), but it is not clear why the ability to accumulate these polymers is found in some genera (e.g. Triticum) but not in others (e.g. Oryza).As fructan biosynthesis enzymes (FBEs) evolved from vacuolar invertases (VINs), we searched the rice genome sequence for genes related to both FBE and VIN genes of wheat and other members of the Pooideae. We compared them at the levels of exon-intron structure, protein sequence, and the enzymatic properties of recombinant proteins after expression in the yeast Pichia pastoris.We found that rice possesses two VIN genes (OsVIN1 and OsVIN2) and no FBE genes. FBE genes appear to have arisen in the Pooideae by a series of gene duplications from an ancestor of wheat TaVIN3. Recombinant TaVIN2, OsVIN1 and OsVIN2 behaved as invertases with no FBE activity, but possessed high fructan exohydrolase activity, especially OsVIN1.The engineering of fructan accumulation into rice for greater stress tolerance could founder on endogenous exohydrolases, but the fact that OsVIN1 transcripts are absent from peduncles of well watered and drought-stressed plants removes one potential obstacle to this endeavour.