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福建省稻瘟病菌田间种群无毒基因的变异检测
Detection of Avirulence Gene Variation in the Field Population of Rice Blast Fungus in Fujian, China
【摘要】 稻瘟病严重威胁福建省水稻生产。稻瘟病菌田间种群无毒基因的变异监测是实现优质抗稻瘟病水稻品种合理布局和轮换、有效预防因抗性丧失导致的稻瘟病爆发成灾的重要措施。本研究以福建省3个水稻主产区采集并分离的113个稻瘟病菌单孢菌株为材料,检测其无毒基因的变异情况。首先,利用24个已知抗性的水稻单基因系对它们进行致病性测定,分析致病频率、毒力频率、无毒基因的存在频率和无毒基因的组合频率。结果显示,福建省建阳、宁化和上杭3个水稻主产区的稻瘟病田间菌株对24个水稻单基因系的致病频率分别为12.50%~95.83%、29.17%~100%和4.55%~86.36%。3个水稻主产区菌株均对Piks、Pib、Pi3和Pi12表现为强毒性,而建阳和宁化菌株还对其他12个抗性基因表现为强毒力(毒力频率≥70%),包括Pia、Pii、Piz、Pita、Pit、Pish、Pi5、Pi7、Pi19、Pi20、Pita2和Pi11。其次,本研究还设计了8个无毒基因Avr-Pita、Avr-Pib、Avr-Pik、Avr-Piz-t、Avr-Pii、Avr-Pi9、Avr-Pi54和Avr-Co39的特异性引物,对单孢菌株进行基因型鉴定。结果显示,所有菌株均未检测到Avr-Co39,表明这些稻瘟菌株中均不携带该无毒基因。此外,Avr-Pib的出现频率也很小,仅为37.17%,但是该比例仍远超致病性测定中推测的Avr-Pib所占比例,表明检测到的Avr-Pib中很大一部分存在突变。为此,对Avr-Pib基因部分扩增产物进行测序,发现这些菌株的Avr-Pib在启动子区发生了缺失、插入和替换等突变。此外,部分菌株的Avr-Pik或Avr-Piz-t也存在启动子单核苷酸变异,而上杭菌株Avr-Pi9和宁化菌株Avr-Piz-t则均存在编码区的突变。这些位点的突变均可能导致无毒基因功能的缺失。研究还表明,携带Pi1、Piz5、Pi9和Pik、Pikh、Pikm位点的水稻品种仍适合在福建地区种植。
【Abstract】 Rice blast is the major disease that threatens rice production in Fujian. Investigation of the variation of avrirulence genes(AVRs) in the field population of rice blast fungus could facilitate the release and rotation of the resistance varieties, and subsequently prevent the burst of rice blast disease caused by the loss of rice blast resistance. We firstly investigated the pathogenicity and genetic variation of a field population consisting of 113 Magnaporthe oryzae monoconidial strains isolated from three different major rice planting regions in Fujian province. For pathogenicity and virulence assays of the strains, spray inoculation was performed using 24 monogenic lines carrying 24 different major blast resistance genes. The results showed that the pathogenicity frequency of strains isolated from Jianyang, Ninghua and Shanghang were ranged from 12.50% to 95.83%, 29.17% to 100% and 4.55% to 86.36%, respectively. All strains showed strong pathogenicity toward the monogenic lines carrying Piks、Pib、Pi3 and Pi12, while strains isolated from Jianyang and Ninghua also showed strong pathogenicigy toward the monogenic lines carrying other 12 resistance genes,including Pia, Pii, Piz, Pita, Pit, Pish, Pi5, Pi7, Pi19, Pi20, Pita2 and Pi11. To investigate the genetic variation of AVR genes in the above strains, we performed genotyping of 8 AVR genes: Avr-Pia, Avr-Pib, Avr-Pik, Avr-Piz-t, Avr-Pii,Avr-Pi9, Avr-Pi54, and Avr-Co39. As expected, Avr-Co39 was absent in all the strains, indicating that all the strains collected in the three regions of Fujian province did not carry the AVR gene. The frequency of Avr-Pib in the 113 strains was also very low(37.17%). However, the ratio was much higher than that of the functional Avr-Pib(4.32%), indicating some loss-of-function mutations of Avr-Pib in the Fujian field population. We compared the sequence of selected AVR genes amplified from some field isolates to the reference sequences, and found variation in the promoter region of Avr-Pib, as well as Avr-Pik and Avr-Piz-t. Besides, we also found mutations in the coding region of Avr-Pik and Avr-Pita amplified from some of the Fujian field isolates. Our results suggested that rice cultivars carrying Pi1, Piz5, Pi9, Pik,Pikh and Pikm still could be used in Fujian Province.
- 【文献出处】 热带作物学报 ,Chinese Journal of Tropical Crops , 编辑部邮箱 ,2023年02期
- 【分类号】S435.111.41
- 【下载频次】23