The Ca2+-dependent DNases are Involved in Secondary Xylem Development in Eucommia ulmoides
The Ca2+-dependent DNases are Involved in Secondary Xylem Development in Eucommia ulmoides
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Ca2+依赖性DNA酶参与杜仲次生木质部发育
DOI：
10.1111/j.1744-7909.2012.01134.x
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发表时间：
2012-07-01
影响因子：
11.4
通讯作者：
He, Xin-Qiang
中科院分区：
文献类型：
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作者：
Chen, Hui-Min;Pang, Yu;He, Xin-Qiang
次生木质部发育一直被认为是植物细胞程序性死亡（PCD）的一个典型例子。在PCD过程中，基因组DNA的降解是由内切酶催化的。然而，到目前为止，还没有发现内切酶参与次生木质部的发育。从杜仲（Eucommia ulmoides Oliv）分化次生木质部中鉴定出两个新的Ca2+依赖性dna酶基因EuCaN1和EuCaN2。通过dna酶活性测定、原位杂交、蛋白免疫定位和病毒诱导基因沉默实验研究了它们的功能。EuCaN1和EuCaN2全长cdna包含一个987 bp的开放阅读框，编码两个328个氨基酸的蛋白，具有snase样功能域。EuCaN1基因组DNA序列不含内含子，而EuCaN2有8个内含子。在中性ph下，EuCaN1和EuCaN2酶切ssDNA和dsDNA，依赖于Ca2+。它们的表达局限于分化次生木质部细胞，蛋白定位于细胞核。它们的活性动态与次生木质部发育密切相关。次生木质部细胞分化受内切酶基因RNAi的影响。结果表明，Ca2+依赖性dna酶参与了次生木质部的发育。
Secondary xylem development has long been recognized as a typical case of programmed cell death (PCD) in plants. During PCD, the degradation of genomic DNA is catalyzed by endonucleases. However, to date, no endonuclease has been shown to participate in secondary xylem development. Two novel Ca2+-dependent DNase genes, EuCaN1 and EuCaN2, were identified from the differentiating secondary xylem of the tree Eucommia ulmoides Oliv., their functions were studied by DNase activity assay, in situ hybridization, protein immunolocalization and virus-induced gene silencing experiments. Full-length cDNAs of EuCaN1 and EuCaN2 contained an open reading frame of 987 bp, encoding two proteins of 328 amino acids with SNase-like functional domains. The genomic DNA sequence for EuCaN1 had no introns, while EuCaN2 had 8 introns. EuCaN1 and EuCaN2 digested ssDNA and dsDNA with Ca2+-dependence at neutral pH. Their expression was confined to differentiating secondary xylem cells and the proteins were localized in the nucleus. Their activity dynamics was closely correlated with secondary xylem development. Secondary xylem cell differentiation is influenced by RNAi of endonuclease genes. The results provide evidence that the Ca2+-dependent DNases are involved in secondary xylem development.