CCS52A基因与核内复制在新疆野生樱桃李巨细胞发育中的作用

Roles of CCS52Agene and endoreduplication during the formation of giant cells in Xinjiang wild myrobalan

为探究新疆野生樱桃李在接种南方根结线虫形成根结的过程中,线虫建立的取食位点诱导巨细胞形成过程中常出现的核内复制现象的原因,以扦插繁殖的新疆野生樱桃李为材料接种南方根结线虫进一步鉴定其抗性,通过石蜡切片观察根结发育以及核内复制现象,并分析了相关酶活性变化以及CCS52A基因表达方面的差异。结果显示:新疆野生樱桃李实生群体中大约1/4的个体表现为抗病。抗病植株中的POD、SOD和GLU酶活性在接种南方根结线虫6d时达到峰值并明显高于感病植株,而CHI酶活性在接种后8d达到最高,一直到14d都明显高于感病植株。组织学观察发现,接种后5d巨细胞内可以观察到正在分裂的细胞,到7d巨细胞内细胞核开始聚集,这种状态一直维持到接种后21d。说明接种后5~7d是巨细胞核进行分裂的时期,而7~21d是进行核内复制的主要过程。CCS52A基因在接种后7d也开始大量表达并持续到21d,与核内复制过程正好吻合。同时原位杂交结果也显示CCS52A基因主要在巨细胞中表达。说明CCS52A基因在巨细胞进行的核内复制过程中起作用,其高表达有利于线虫取食位点的成功建立。

To investigate the mechanism on giant cell induction at nematodes feeding site during the formation of galls caused by the root knot nematode（Meloidogyne icognita）in Xinjiang wild myrobalan（Prunus sogdiana）,the cutting seedlings of myrobalans were inoculated with M.incognitato identify the level of resistance to nematode,and paraffin sections were made to demonstrate the development of galls and phenotype of endoreduplication.The change of associative enzyme ability and differential expression of CCS52 A gene were also analyzed.The results showed that：Only round 25% of tested Xinjiang wild myrobalans presented the resistant capacities.The enzyme ability of POD、SOD and GLU reached peaks at 6 dpi（day past inoculation）,which apparently were higher than those of susceptible ones.But the peak of CHI activity appeared at 8 dpi,and was higher than in susceptible lines until 14 dpi.Histological observation discovered that a number of nucleus were observed to undergo mitosis in giant cells at 5 dpi,and were subsequently assembling from 7 to 21 dpi.The results suggested that nuclear division in the absence of cytokinesis occurred at 5 to 7 dpi in gall,and the process of endoreduplication mainly took place from 7 dpi to 21 dpi.The expression of CCS52 A gene began to rise at 7 dpi and continued to 21 dpi,which was consistent with the occurrence of endoreduplication.And its expression in the giant cells was also confirmed by in situ hybridization.These resultsillustrated that the CCS52 A gene is involved in the development of giant cells to help the successful establishment of feeding sites and its up-regulation contributes to the establishment of nematode feeding sites.