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Genetic diversity of Puccinia kuehnii, the causal agent of orange rust of sugarcane, from Brazil
Journal of Phytopathology ( IF 1.5 ) Pub Date : 2020-08-08 , DOI: 10.1111/jph.12937
Alfredo Seiiti Urashima 1 , Tatiane de Fátima Mistura 1 , Lis Natali Rodrigues Porto 1 , Paige Dariel Austin 2 , Renee Silvia Arias 2
Affiliation  

The use of resistant genotypes is the preferred method to control orange rust of sugarcane (Saccharum spp) caused by Puccinia kuehnii. This approach has been adopted in Brazil but outbreaks of the disease on previously resistant varieties showed that the efficacy of this method is limited and requires a better understanding of pathogen diversity. Nevertheless, adequate molecular markers for examining pathogen diversity at population level are not available, which limits the success of orange rust control by genetic resistance. Therefore, two independent investigations were conducted to examine genetic diversity of P. kuehnii from São Paulo state, the most important sugarcane growing state of Brazil. First, simple‐sequence repeat (SSR) markers were developed in the present work and genotypic diversity of orange rust isolates from different locations investigated. Second, phenotypic diversity was examined by the single‐pustule inoculation technique on P. kuehnii isolates retrieved from three susceptible commercial sugarcane cultivars. A total of 96 SSR markers were generated and tested for this species. Subsequently, 29 isolates of P. kuehnii were fingerprinted with nine SSR markers to estimate the genotypic diversity by neighbour‐joining and 3D principal coordinates. The 29 isolates of the pathogen clustered into four main groups, which were identified by three SSR markers (NPRL_PK_108a, NPRL_PK_162_spka and NPRL_PK_221_spka). Phenotypic data at 21 days after the single‐pustule inoculation showed that P. kuehnii from highly susceptible commercial cultivars harboured a small proportion of variants capable of causing disease on resistant cultivars. A differential reaction was demonstrated for the most virulent variant in a repeated experiment confirming the existence of races within P. kuehnii in Brazil.

中文翻译:

巴西甘蔗橙锈病的致病因子——Puccinia kuehnii的遗传多样性

抗性基因型的使用是控制由Puccinia kuehnii引起的甘蔗(Saccharum spp)橙锈病的首选方法在巴西已经采用了这种方法,但是在以前具有抗药性的品种上暴发该病表明该方法的效果有限,需要更好地了解病原体多样性。然而,没有足够的分子标记可用于在种群水平上检查病原体的多样性,这限制了通过遗传抗性控制橙锈病的成功。因此,进行了两项独立的调查,以检查库氏假单胞菌的遗传多样性来自巴西最重要的甘蔗种植国圣保罗州。首先,在本工作中开发了简单序列重复(SSR)标记,并研究了来自不同位置的橙色锈菌分离物的基因型多样性。其次,通过单药房接种技术对从三个易感商品甘蔗品种中回收的库氏假单胞菌分离株进行了表型多样性检查。总共产生了96个SSR标记并对该物种进行了测试。随后,分离到库氏假单胞菌29株用9个SSR标记对它们进行指纹识别,以通过邻域连接和3D主坐标估计基因型多样性。病原体的29种分离物分为四个主要组,通过三个SSR标记(NPRL_PK_108a,NPRL_PK_162_spka和NPRL_PK_221_spka)鉴定。单接种后21天的表型数据表明,高度易感商品品种的库氏假单胞菌含有一小部分能够在抗性品种上引起疾病的变体。在重复实验中证实了最强毒性变异体的差异反应,证实了巴西库氏假单胞菌中存在种族。
更新日期:2020-09-21
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