中国农业科学 ›› 2021, Vol. 54 ›› Issue (12): 2547-2558.doi: 10.3864/j.issn.0578-1752.2021.12.006

• 植物保护 • 上一篇    下一篇

四川玉米小斑病菌交配型组成与育性分析

孙小芳(),刘敏,潘婷敏,龚国淑()   

  1. 四川农业大学农学院,成都 611130
  • 收稿日期:2020-10-11 接受日期:2020-11-24 出版日期:2021-06-16 发布日期:2021-06-24
  • 通讯作者: 龚国淑
  • 作者简介:孙小芳,E-mail:sunxiaofang207@163.com
  • 基金资助:
    现代农业产业技术体系四川玉米创新团队-玉米病虫害绿色防控技术(SCCXTD-2020-02);省级大学生创新训练计划(201710626078)

Mating Type and Fertility of Cochliobolus heterostrophus Causing Southern Corn Leaf Blight in Sichuan Province

SUN XiaoFang(),LIU Min,PAN TingMin,GONG GuoShu()   

  1. College of Agronomy, Sichuan Agricultural University, Chengdu 611130
  • Received:2020-10-11 Accepted:2020-11-24 Online:2021-06-16 Published:2021-06-24
  • Contact: GuoShu GONG

摘要:

【目的】明确四川省玉米小斑病菌(Cochliobolus heterostrophus)自然群体的交配型和有性态形成能力(育性),探索小斑病菌有性生殖在自然界发生的可能性。【方法】利用多重PCR技术对2013—2018年间采自四川和云南的玉米小斑病菌的交配型进行检测,通过相反交配型菌株的两两杂交筛选一对高配合力的菌株作为标准菌株,采用与标准菌株对峙的方法对待测田间菌株进行育性测定,以假囊壳及子囊的形成情况判定菌株的育性水平。【结果】544株玉米小斑病菌中交配型MAT1-1菌株286株,交配型MAT1-2菌株258株,出现频率分别为52.57%和47.43%。卡方检验两种交配型的比例符合1﹕1的分离比(χ2=1.441,P=0.230),未出现偏离。两种交配型菌株在各采样区均有分布,不同年份间交配型结构基本一致。筛选得到MSRS-2-3(MAT1-1)和DY-12-1-2(MAT1-2)作为一对标准菌株,与标准菌株杂交能够产生子囊孢子的可育菌株比例为88.79%,不能产生子囊孢子的不育菌株比例为11.21%。可育菌株中存在育性的分化,高育性、中等育性和低育性菌株分别占测试菌株的12.32%、27.39%和49.08%。采自不同年份、不同地区的小斑病菌育性结构存在差异,2013—2018年可育菌株率分别为77.88%、78.57%、93.33%、94.87%、93.49%和88.76%。云南西双版纳地区的菌株可育率最高,达到100%;其次为四川北部、中部、南部和东部地区,菌株可育率分别为93.25%、89.87%、83.33%和79.31%;四川西部地区菌株可育率最低,为69.23%。【结论】玉米小斑病菌自然群体中普遍存在MAT1-1和MAT1-2两种交配型,两种交配型均衡分布且多为可育菌株。尽管未见自然条件下玉米小斑病菌有性世代的报道,但两种交配型菌株和高比例可育菌株的普遍存在表明有性生殖可能正在发生。

关键词: 玉米小斑病, 玉米小斑病菌, 有性生殖, 交配型, 育性分析, 多重PCR

Abstract:

【Objective】The objective of this study is to clarify the distribution of mating types and fertility of Cochliobolus heterostrophus (anamorph: Bipolaris maydis), and to elucidate the possibility of the sexual reproduction of C. heterostrophus isolates in natural fields.【Method】A total of 544 C. heterostrophus isolates were collected from different geographical regions in Sichuan and Yunnan provinces during 2013-2018. The mating type of these isolates was detected by a multiple PCR method, and two standard tested isolates with high combining ability were screened by cross of MAT1-1 and MAT1-2 isolates. Then the 544 C. heterostrophus isolates were tested for their mating type and fertility with two standard test isolates. The fertility was determined by the development of pseudothecia and asci.【Result】Among the 544 isolates, 286 ones were identified as MAT1-1 and 258 as MAT1-2, accounting for 52.57% and 47.43%, respectively. Chi-square test gave a good fit of 1﹕1 ratio (χ2=1.441, P=0.230), indicating that these two mating types distributed in balance in natural fields. In addition, the investigation also showed that two mating types were present in all sampling locations and they had a basically same population structure in different years. After crossing tested isolates with standard isolates MSRS-2-3 (MAT1-1) and DY-12-1-2 (MAT1-2), the percentage of fertile and sterile isolates was 88.79% and 11.21%, respectively, and an obvious fertility differentiation was observed, which were characterized by 12.32% of high fertile, 27.39% of medium fertile, and 49.08% of low fertile isolates, respectively. Fertility structures of isolates varied in different geographical locations and in different collection years. The frequencies of fertile isolates ranged from 77.88% to 94.87% in 2013-2018. The percentage of fertile isolates in Southern Yunnan was highest up to 100%, followed by those in Northern Sichuan, Central Sichuan, Southern Sichuan and Eastern Sichuan regions, accounting for 93.25%, 89.87%, 83.33% and 79.31%, respectively. The percentage of fertile isolates in Western Sichuan region was lowest (69.23%).【Conclusion】MAT1-1 and MAT1-2 achieved an equilibrium in quantity among C. heterostrophus field populations, and the cross combinations between MAT1-1 and MAT1-2 isolates were generally fertile. Although sexual generation was rarely reported in C. heterostrophus population in natural condition, the current results indicated that cryptic sexual cycle might contribute to the genetic diversity of C. heterostrophus.

Key words: southern corn leaf blight, Cochliobolus heterostrophus, sexual reproduction, mating type, fertility, multiple PCR