摘要
为了揭示嫁接提高西瓜抗枯萎病的机制,该研究以嫁接西瓜为材料,采用扫描电镜观察了枯萎病菌侵染下寄主的组织结构变化,荧光定量分析了相关防卫基因的表达,比较了嫁接西瓜对枯萎病菌侵染的抗感反应。结果显示:(1)枯萎病菌侵染后,与自根西瓜相比,嫁接西瓜的根部木质部导管通过快速形成膜状物、侵填体及细胞壁增厚阻塞菌丝入侵;自根西瓜防御反应较嫁接西瓜晚,严重侵染时薄壁细胞降解,导管组织脱落导致维管系统空洞,从而使植株呈现萎蔫症状,该现象在嫁接西瓜中没有发现。(2)枯萎病菌侵染后,嫁接西瓜比自根西瓜具有较高的防卫基因表达水平,其中:嫁接西瓜中,CHI、APX和PPO基因的表达随枯萎病菌侵染时间的延长而升高,而PAL呈现先升高后降低的表达趋势,但仍高于本底表达;自根西瓜中,仅PPO基因在枯萎病菌侵染后表达上调,而其他基因的表达则是先升高后降低,与嫁接西瓜中的PAL基因表达一致。研究表明,嫁接植株一方面通过快速的组织结构响应,另一方面从转录水平提高了相关防卫基因的表达,最终使植株具有抗病性;推测防御基因在嫁接植株与枯萎病菌互作中的强烈诱导响应可能是嫁接植株抗病的分子机制之一。
To explore the defense mechanisms involved in disease resistance of grafted watermelon to Fusarium oxysporum,we compared the histological responses using microscope and expression of defence genes of grafted and self-rooted watermelon infected by F.oxysporum.The results showed that：（1）F.oxysporum caused a quick defense response by formatting gums and tylosis in infected xylem vessels,and the thickening of xylem parenchyma cell wall in roots of grafted plants.These histological changes appeared later in roots of self-rooted plants.Serious infection resulted in wall disintegration of xylem parenchyma cell,the diseased vascular finally became hollow and plants developed wilt symptoms,which did not observed in grafted watermelon.（2）Highly induced expression of defence genes were observed in grafted plants than that in self-rooted plants,among which,the transcription of CHI,APX and PPO genes in grafted watermelon accumulated along the F.oxysporum inoculation,while transcription of PAL significantly increased and then sharply declined,but still with high expression level than base level.Different from the expression manner in grafted watermelon,only the transcription of PPO gene was up-regulated after F.oxysporum inoculation,in self-rooted watermelon,whereas expression of CHI,APX and PAL genes increased first and then sharply declined,which is consistent with PAL gene expression pattern in grafted watermelon.These results indicating that the resistance mechanism of grafted plants to F.oxysporum infection is because of the quick response in histological level and the high expression of defence genes in transcription level,which finally protect the grafted plant from infection by F.oxysporum;and that the significantly responses of defence genes in the interaction between grafted plants and F.oxysporum might be one of the important molecular mechanisms involving the resistance of grafting plants.
出处
《西北植物学报》
CAS
CSCD
北大核心
2013年第8期1605-1611,共7页
Acta Botanica Boreali-Occidentalia Sinica
基金
国家西甜瓜产业技术体系(CARS-NO.8)
江苏省农业科技自主创新基金[cx(11)1001]
江苏省农业科学院博士后基金(006046511105)
关键词
嫁接西瓜
西瓜枯萎病
组织结构
防卫基因表达
grafted watermelon
Fusarium oxysporum f.sp.niveum
anatomy
defense gene expression
