Expression of MsLEC1 transgenes in alfalfa plants causes symbiotic abnormalities
Expression of MsLEC1 transgenes in alfalfa plants causes symbiotic abnormalities
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DOI：
10.1094/mpmi.2004.17.1.16
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发表时间：
2004-01-01
影响因子：
3.5
通讯作者：
Hirsch, AM
中科院分区：
文献类型：
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作者：
Brill, LM;Fujishige, NA;Hirsch, AM
豆科植物凝集素在根瘤菌与豆科植物的共生中起着重要的作用。为了验证这一假设，在接种野生型梅氏中华根瘤菌1021后，分析了在反义或正义方向上表达部分推测的苜蓿凝集素基因MsLEC1或MsLEC2的转基因苜蓿植株的共生反应。mslec1 -反义（LEC1AS）植株发育迟缓，表现为超结瘤，不仅发育异常的大结节，而且发育大量的小结节，两者都过早衰老。mslec2反义植株在生长和根瘤数量上均处于中等水平。MsLEC1-sense转基因植株的共生异常与LEC1AS植株相似，但反应较轻，而MsLEC2-sense转基因植株的共生异常与载体和非转基因对照植株的共生异常相同。Northern blot分析未检测到MsLEC1 mRNA在结节RNA中积累，但原位杂交发现MsLEC1 mRNA定位于苜蓿结节分生组织及侵袭区邻近细胞；在根分生组织中也检测到转录本。使用全载原位杂交程序发现了类似的MsLEC2表达的空间模式。此外，在白甜三叶草（Melilotus alba）根瘤和根尖中检测到一种同源凝集素基因（MaLEC）的mrna。
Legume lectins have been proposed to have important symbiotic roles during Rhizobium-legume symbioses. To test this hypothesis, the symbiotic responses of transgenic alfalfa plants that express a portion of the putative alfalfa lectin gene MsLEC1 or MsLEC2 in either the antisense or sense orientation were analyzed following inoculation with wild-type Sinorhizobium meliloti 1021. MsLEC1-antisense (LEC1AS) plants were stunted, exhibited hypernodulation, and developed not only abnormally large nodules but also numerous small nodules, both of which senesced prematurely. MsLEC2-antisense plants were intermediate in growth and nodule number compared with LEC1AS and vector control plants. The symbiotic abnormalities of MsLEC1-sense transgene plants were similar to but milder than the responses shown by the LEC1AS plants, whereas MsLEC2-sense transgene plants exhibited symbiotic responses that were identical to those of vector and nontransgenic control plants. MsLEC1 mRNA accumulation was not detected in nodule RNA by Northern blot analysis but was localized to alfalfa nodule meristems and the adjacent cells of the invasion zone by in situ hybridization; transcripts were also detected in root meristems. A similar spatial pattern of MsLEC2 expression was found by using a whole-mount in situ hybridization procedure. Moreover, mRNAs for an orthologous lectin gene (MaLEC) were detected in white sweetclover (Melilotus alba) nodules and root tips.