New diversity of Ralstonia solanacearum strains associated with vegetable and ornamental crops in Florida
New diversity of Ralstonia solanacearum strains associated with vegetable and ornamental crops in Florida
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DOI：
10.1094/pdis-91-2-0195
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发表时间：
2007-02-01
期刊：
影响因子：
4.5
通讯作者：
Momol, A. Timur
中科院分区：
文献类型：
--
作者：
Ji, Pingsheng;Allen, Caitilyn;Momol, A. Timur
2003年和2004年，从佛罗里达南部的田间辣椒枯萎植株和盆栽绣球花上分离到15个青枯雷尔氏菌分离物。在北佛罗里达的商业苗圃和蓄水池中，诊断免疫测定和聚合酶链反应（PCR）分析确定所有分离株为R。青枯菌而不是3号生理小种2.对番茄、辣椒和烟草的致病性研究表明，15个菌株对番茄的致病力相似，均引起烟草萎蔫，但对烟草的致病力存在显著差异。一种本土的佛罗里达番茄品系，生理小种1生物变种1（Rs5），对烟草没有引起疾病，对辣椒几乎没有或没有引起疾病。3个辣椒品系对所有3个辣椒品种的攻击性均高于Rs5或2个绣球品系。基于内切葡聚糖酶基因序列的系统发育分析表明，这些菌株有三个不同的起源。这三个辣椒菌株属于辣椒I型生物变种3，并与来自亚洲不同宿主的菌株聚在一起，属于sequevar 13。6个天竺葵属菌株和4个绣球属菌株与sequevar 5中的菌株密切相关，sequevar 5是从法属西印度群岛和巴西分离的11个生物变型I菌株的一个不同的亚群。来自八仙花属的另外两个生物变型I菌株和菌株K60、AW和Rs5属于H型的sequevar 7，可能原产于北美。根据DNA序列分析和生物变种表型检测结果，佛罗里达分离株均不属于高度监管的选择性病原体小种3生物变种2亚组。然而，在实时PCR中，小种3生物变型2特异性B2引物弱扩增来自一些小种I生物变型I菌株的产物，表明该测定在某些条件下可能产生假阳性。考虑到误诊的高成本，似乎建议使用至少两种独立的诊断方法来确认可疑分离株是R。青枯菌R3B2。这是首次报道的R.青枯菌生理小种I生物变种3或青枯菌I型菌株的报道，首次证实了青枯菌的存在。引起佛罗里达绣球花自然感染的青枯菌。因此，R.在佛罗里达存在与假定的本土菌株完全不同的青枯菌菌株，并且能够感染不同的宿主。
In 2003 and 2004, 15 isolates of Ralstonia solanacearum were obtained from wilting plants of field-grown pepper (Capsicum annuum) in south Florida and from pot-grown hydrangea (Hydrangea paniculata and H. macrophylla) and geranium (Pelargonium x hortorum) in commercial nurseries and retention ponds in north Florida. Diagnostic immunoassays and polymerase chain reaction (PCR) analyses identified all the isolates as R. solanacearum but not race 3 biovar 2. Pathogenicity studies on tomato, pepper, and tobacco revealed that all 15 strains had similar high virulence on tomato and all caused wilting of tobacco, although there were significant differences among the strains in aggressiveness on tobacco. An indigenous Florida tomato strain, race 1 biovar 1 (Rs5), caused no disease on tobacco and little or none on pepper. The three pepper strains were more aggressive than Rs5 or two hydrangea strains on all three pepper cultivars studied. Phylogenetic analysis based on an endoglucanase gene sequence indicated that these strains had three distinct origins. The three pepper strains belonged to phylotype I biovar 3 and clustered with strains from diverse hosts in Asia belonging to sequevar 13. The six geranium strains and four of the hydrangea strains were closely related to strains in sequevar 5, a distinct subcluster of phylotype 11 biovar I strains isolated from the French West Indies and Brazil. Two other biovar I strains from hydrangea and strains K60, AW, and Rs5 belonged to sequevar 7 in phylotype H and probably are native to North America. None of the Florida isolates belong to the highly regulated Select Agent race 3 biovar 2 subgroup, according to both the DNA sequence analysis and the biovar phenotypic test results. However, the race 3 biovar 2-specific B2 primers weakly amplified a product from some race I biovar I strains in real-time PCR, indicating that this assay may give false positives under some conditions. Given the high cost of a misdiagnosis, it seems advisable to use at least two independent diagnostic methods to confirm that a suspect isolate is R. solanacearum R3B2. This is the first report of the presence of R. solanacearum race I biovar 3 or phylotype I strains in North America, and the first report confirming R. solanacearum causing natural infection of hydrangea in Florida. Thus, R. solanacearum strains that are quite distinct from presumably indigenous strains are present and can infect diverse hosts in Florida.