Sexual reproduction increases the possibility that Phytophthora capsici will develop resistance to dimethomorph in China. (27th March 2014)

• Record Type: Journal Article
• Authors: Bi, Y.; Hu, J.; Cui, X.; Shao, J.; Lu, X.; Meng, Q.; Liu, X.
• Is Part Of: Plant pathology. Volume 63:Number 6(2014:Dec.)
• Page Start: 1365
• Page End: 1373
• Publication Date: 2014-03-27
• Subjects: Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/ppa.12220
• Languages: English
• ISSNs: 0032-0862

Abstract

<abstract abstract-type="main" id="ppa12220-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A total of 1511 isolates of <italic>Phytophthora capsici</italic> were collected from farms with no history of exposure to the carboxylic acid amide (CAA) fungicides in 32 provinces in China during 2006 to 2013. All 1511 isolates were assayed for mating type and 403 were assayed for sensitivity to dimethomorph (DMM) and metalaxyl. The DMM EC₅₀ values ranged from 0·126 to 0·339 <italic>μ</italic>g mL⁻¹. Both A1 and A2 mating types were detected on the same farms in four provinces and with a 1:1 ratio. Most isolates were sensitive to metalaxyl but a few exhibited intermediate resistance or resistance to metalaxyl. The segregation of DMM resistance and sensitivity among 337 progeny obtained from hybridization or self‐crossing <italic>in vitro</italic> indicated that the resistance of <italic>P. capsici</italic> to DMM is controlled by two dominant genes. Eighteen progeny that were derived from hybridization differed in DMM sensitivity and in fitness. Some progeny were as fit as parental isolates. Given the distribution of mating types and therefore the potential for sexual reproduction, the control of resistance by two dominant genes, and the fitness of hybrid progeny, the risk of <italic>P. capsici</italic> populations developing DMM resistance in China is substantial.</p> </abstract>