AtVAM3 is required for normal specification of idioblasts, myrosin cells
AtVAM3 is required for normal specification of idioblasts, myrosin cells
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DOI：
10.1093/pcp/pci232
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发表时间：
2006-01-01
影响因子：
4.9
通讯作者：
Hara-Nishimura, I
中科院分区：
文献类型：
--
作者：
Ueda, H;Nishiyama, C;Hara-Nishimura, I
山柑目植物中的黑芥子细胞是积累硫代葡萄糖苷葡萄糖水解酶（TGG，也称为黑芥子酶）的异细胞，其水解硫代葡萄糖苷以产生用于驱除害虫的有毒化合物。在这里，我们表明AtVAM 3参与myrosin细胞的发育。已经表明酵母VAM 3是Q.-参与液泡蛋白质的囊泡运输和液泡装配的SNARE。我们发现，两个拟南芥atvam 3等位基因，atvam 3 -3和atvain 3 -4/ssin，积累了大量的TGG 1和TGG 2的酶活性。免疫金分析显示，TGG特异性地定位于atvam 3突变体的myrosin细胞的液泡中。这一结果表明，TGG正常运输到液泡在这些突变体和AtVAM 3是不是必需的蛋白质的液泡运输。我们开发了考马斯亮蓝染色方法，通过其高TGG含量检测整个叶片中的myrosin细胞。该方法显示atvam 3叶具有比野生型叶更多数量的myrosin细胞。Myrosin细胞在野生型叶片中沿着叶脉分布，而在atvam 3叶片中分布异常。这些突变体在整个叶片中形成了一个Myrosin细胞网络：Myrosin细胞不仅沿着叶脉连续分布，而且独立于叶脉。atvam 3突变体中黑曲霉素细胞的过量可能是导致这些突变体中TGG异常丰富以及花序茎和叶伸长减少的原因。我们的研究结果表明，AtVAM 3在myrosin细胞的发育中具有植物特异性功能。
Myrosin cells in Capparales plants are idioblasts that accumulate thioglucoside glucohydrolase (TGG, also called myrosinase), which hydrolyzes glucosinolates to produce toxic compounds for repelling pests. Here, we show that AtVAM3 is involved in development of myrosin cells. It has been shown that yeast VAM3 is a Q.-SNARE that is involved in vesicle transport of vacuolar proteins and vacuolar assembly. We found that two Arabidopsis atvam3 alleles, atvam3-3 and atvain3-4/ssin, accumulate large amounts of TGG1 and TGG2 that are enzymatically active. An immunogold analysis revealed that TGGs were specifically localized in the vacuole of myrosin cells in atvam3 mutants. This result indicates that TGGs are normally transported to vacuoles in these mutants and that AtVAM3 is not essential for vacuolar transport of the proteins. We developed a staining method with Coomassie brilliant blue that detects myrosin cells in whole leaves by their high TGG content. This method showed that atvam3 leaves have a larger number of myrosin cells than do wild-type leaves. Myrosin cells were scattered along leaf veins in wild-type leaves, while they were abnormally distributed in atvam3 leaves. The mutants developed a network of myrosin cells throughout the leaves: myrosin cells were not only distributed continuously along leaf veins, but were also observe independent of leaf veins. The excess of myrosin cells in atvam3 mutants might be responsible for the abnormal abundance of TGGs and the reduction of elongation of inflorescence stems and leaves in these mutants. Our results suggest that AtVAM3 has a plant-specific function in development of myrosin cells.