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Chiang Mai, Thailand

Wang J.-F.,The World Vegetable Center | Ho F.,The World Vegetable Center | Truong H.T.H.,The World Vegetable Center | Truong H.T.H.,Hue University | And 5 more authors.
Euphytica | Year: 2013

Bacterial wilt caused by Ralstonia solanacearum is one of the most devastating diseases of tomato. Tomato cultivar 'Hawaii 7996' has been shown to have stable resistance against different strains under different environments. This study aimed to locate quantitative trail loci (QTLs) associated with stable resistance using 188 recombinant inbred lines (RILs) derived from 'Hawaii 7996' and 'West Virginia 700.' A new linkage map with good genome coverage was developed, mainly using simple sequence repeat markers developed from anchored bacterial artificial chromosome or scaffold sequences of tomato. The population was evaluated against phylotype I and phylotype II strains at seedling stage or in the field in Indonesia, Philippines, Taiwan, Thailand, and Reunion. Two major QTLs were identified to be associated with stable resistance. Bwr-12, located in a 2.8-cM interval of chromosome 12, controlled 17.9-56.1 % of total resistance variation. The main function of Bwr-12 was related to suppression of internal multiplication of the pathogen in the stem. This QTL was not associated with resistance against race 3-phylotype II strain. Bwr-6 on chromosome 6 explained 11.5-22.2 % of the phenotypic variation. Its location differed with phenotype datasets and was distributed along a 15.5-cM region. The RILs with the resistance allele from both Bwr-12 and Bwr-6 had the lowest disease incidence, which was significantly lower than the groups with only Bwr-12 or Bwr-6. Our studies confirmed the polygenic nature of resistance to bacterial wilt in tomato, and that stable resistance in 'Hawaii 7996' is mainly associated with Bwr-6 and Bwr-12. © 2012 Springer Science+Business Media Dordrecht. Source


Mahasuk P.,Kasetsart University | Struss D.,East West Seed Company | Mongkolporn O.,Kasetsart University
Molecular Breeding | Year: 2016

Two SNP maps were constructed from two chili populations including Capsicum annuum ‘Bangchang’ × C. chinense ‘PBC932’, and C. baccatum ‘PBC80’ × ‘CA1316’, aiming to identify QTLs for anthracnose resistance. The ‘PBC932’-derived map contained 12 linkage groups (LG) with 214 SNPs and 824 cM coverage. The ‘PBC80’-derived map contained 12 LGs with 403 SNPs and 1270 cM coverage. Based on the ‘PBC932’ map, two QTLs corresponding to the anthracnose resistances in mature green and ripe fruit stages were identified on the same location of LG2 between two SNPs within 14 cM. Based on the ‘PBC80’ map, total five QTLs (three major and two minor QTLs) were identified in the ripe fruit stage, which corresponded to different resistance traits that were assayed by different inoculation methods [microinjection (MI) and high-pressure spray (HP)] with two different pathotypes (PCa2 and PCa3). All the three major QTLs for the resistance traits assayed by PCa2/MI, PCa3/MI, and PCa3/HP were located on LG4 between two SNP markers within 17 cM, while the two minor QTLs for the traits assayed by PCa3/MI and PCa3/HP were on LG12 and LG9 between two SNP markers within 6 and 3 cM, respectively. All the SNP markers flanking the identified QTLs will be helpful for marker-assisted selection for the anthracnose resistance traits in the chili populations derived from ‘PBC932’ and ‘PBC80’. © 2016, Springer Science+Business Media Dordrecht. Source


Relevante C.A.,East West Seed Company | Relevante C.A.,University of the Philippines at Los Banos | Cumagun C.J.R.,University of the Philippines at Los Banos
Archives of Phytopathology and Plant Protection | Year: 2013

Fusarium wilt disease is a growing concern in cucurbit crops in the Philippines. Most often than not, farmers highly depend on commercial fungicides for control but these chemicals are very expensive and not environment-friendly. Biofumigation and green manuring using Brassica plants is a potential alternative for sustainable management of this destructive disease. A study was conducted to evaluate the efficacy of mustard var. Montevede as a biofumigant and green manure to control Fusarium wilt disease of bittergourd (Momordica charantia L.) and bottlegourd (Lagenaria siceraria (Mol.) Standl.). In vitro assay of mustard slurry resulted in 100% suppression of the mycelial growth of F. oxysporum f. sp. momordicae and F. oxysporum f. sp. lagenariae isolates after exposure to 5, 10 and 15 g of mustard slurry compared with the control. Similarly, incorporation of the macerated mustard leaves in the infested soil reduced Fusarium wilt incidence by 100% in bittergourd and bottlegourd. The effect of mustard was comparable to Bavistin® fungicide both in vitro and in vivo. © 2013 Copyright Taylor and Francis Group, LLC. Source


Cumagun C.J.R.,University of the Philippines at Los Banos | Aguirre J.A.,Bureau of Plant Industry | Relevante C.A.,East West Seed Company | Balatero C.H.,East West Seed Company
Plant Protection Science | Year: 2010

Fusarium oxysporum is responsible for a large range of diseases on economically important crops such as bitter gourd and bottle gourd. Pathogenicity and aggressiveness of F. oxysporum in bitter gourd and bottle gourd isolated from two breeding stations of East-West Company in the Philippines namely San Ildefonso, Bulacan and Lipa, Batangas were tested. Eleven F. oxysporum isolates from bitter gourd and 12 isolates from bottle gourd were inoculated on 7-day and 1-month-old bitter gourd and bottle gourd plants in the greenhouse. All F. oxysporum isolates from bitter gourd were pathogenic on 7-day-old and 1-month-old bitter gourd and nine out of 12 isolates from bottle gourd were pathogenic on bottle gourd. Three isolates from the infested soil were non-pathogenic on bottle gourd. There was a significant difference in aggressiveness of the isolates on their natural hosts (P ≤ 0.05). There also was a significant difference in the aggressiveness of isolates pathogenic on bitter gourd from Batangas and Bulacan (P ≤ 0.05) but isolates from Batangas and Bulacan had similar aggressiveness as bottle gourd (P ≥ 0.05). Aggressiveness of F. oxysporum on 7-day-old bitter gourd and bottle gourd was significantly different compared to those on 1-month-old plants, demonstrating an effect of the host age onaggressiveness. Correlations between aggressiveness of F. oxysporum isolates on 7-day-old and 1-month-old bitter gourd and bottle gourd were moderate (r = 0.63, 0.78). Out of 12 isolates from bottle gourd, only one isolate was pathogenic on 7-day-old bitter gourd. Four of the isolates from bitter gourd were pathogenic on 7-day-old bottle gourd but not on 1-month-old bottle gourd. No cross infection was observed on mature plants. Source


Hassani-Mehraban A.,Wageningen University | Cheewachaiwit S.,East West Seed Company | Relevante C.,East West Seed Company | Kormelink R.,Wageningen University | Peters D.,Wageningen University
European Journal of Plant Pathology | Year: 2011

Two tospovirus isolates collected from tomato and bell pepper in Thailand were studied. The isolates induced severe necrotic mottling and/or necrotic spots and rings on the leaves and fruits of the respective plants as confirmed by back-inoculation. A polyclonal antiserum raised against its nucleocapsid (N) protein reacted only with an extract from plants infected with the homologous virus. Analysis of the nucleocapsid (N) gene sequence and its deduced amino acid sequence (Mw ~31 kDa) showed 99% amino acid sequence homology with that of Tomato necrotic ring virus (TNRV). The nucleotide sequence of the 5' untranslated region and intergenic region flanking the N gene revealed typical features of the S RNA segment of tospoviruses. Mechanical inoculation of the virus on some plant species showed that most of the tested solanaceous species were susceptible to this virus. The biological, serological and molecular data presented here indicate that both isolates are identical to TNRV, a recently described tospovirus species in Thailand. © 2011 KNPV. Source

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