Performance of Solanum phureja-derived bacterial-wilt resistant potato clones in a field naturally infested with Ralstonia solanacearum in Central Brazil

ABSTRACT Bacterial wilt (BW), or brown rot, caused by the soil and seed borne bacterium Ralstonia solanacearum, is one of the most devastating diseases of potatoes cultivated in warmer regions of the world. There are no potato cultivars with a desirable level of BW resistance, although it has been recognized that resistance can be an outstanding component for disease management. However, the sources of resistance available lack agronomic traits required by potato growers, therefore being of little interest to breeders. The objective of this work was to evaluate the performance of 11 clones selected for BW resistance and improved for tuber traits upon selection in the last two decades. The clones under test were compared with susceptible and resistant clones and cultivars, in a completely randomized blocks design with three replications of single lines of 10 plants, in a field naturally infested with race 1, biovar 1, phylotype II of R. solanacearum. BW incidence was assessed 60-70 days after planting and total tuber yield in each plot was recorded 110 days after planting. All the evaluated clones presented higher levels of resistance to BW compared with the commercial varieties, not differing from the resistant, not commercial, controls. In a next step, these clones will be characterized for other desirable traits and those which combine high level of resistance and commercial characteristics will be recommended for breeders for enriching the genotypic background in the search for commercial varieties. We also confirmed that the cultivar BRSIPR Bel displays an intermediate level of resistance, what makes it an interesting genitor for its good agronomic characteristics. The findings of this work demonstrate that the improved potato clones selected under tropical conditions in the Embrapa’s pre-breeding project possess high and stable levels of resistance to bacterial wilt, being a valuable resource for breeders.

摘要 由土壤及种子传播的青枯劳尔氏菌（Ralstonia solanacearum）引发的青枯病（Bacterial wilt, BW，又称褐腐病），是全球温暖地区马铃薯栽培中最具毁灭性的病害之一。尽管学界已公认抗病性是病害防控的核心手段之一，但目前尚无具备理想青枯病抗性水平的马铃薯栽培品种。现有抗源普遍缺乏马铃薯种植者所需的优良农艺性状，因此对育种者而言应用价值有限。本研究旨在评估近二十年通过选育获得的11个青枯病抗性优良且块茎性状改良的马铃薯无性系的田间表现。试验采用完全随机区组设计，以10株单株为重复单元，设置三次重复，在自然侵染了青枯劳尔氏菌1号小种（race 1）、1号生物型（biovar 1）、Ⅱ号系统型（phylotype II）的田块中开展，供试无性系与感病、抗病无性系及商业化品种进行对照比较。分别于种植后60~70天调查青枯病发病率，种植后110天记录各试验小区的块茎总产量。所有供试无性系的青枯病抗性水平均显著高于商业化品种，与非商业化抗病对照材料无显著差异。后续将对这些无性系的其他优良目标性状进行鉴定，筛选兼具高抗性与商业化优良性状的材料，推荐给育种者以丰富商业化品种的遗传背景。本研究同时证实，品种BRSIPR Bel的青枯病抗性水平为中等，其优良的农艺性状使其成为极具潜力的育种亲本。本研究结果表明，巴西农业研究公司（Embrapa）预育种项目中在热带条件下选育的改良马铃薯无性系，具备高且稳定的青枯病抗性，是育种者可利用的宝贵遗传资源。