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Access type: UnknownSubject: search.filters.subject.Capsicum annuum L

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    Differential Biochemical Responses of Resistant and Susceptible Genotypes of Chili to Pepper Yellow Leaf Curl Thailand Virus
    (2025-09-01)
    Mueangkhong, Manthana
    ;
    Suwor, Patcharaporn
    ;
    Techawongstien, Suchila
    ;
    Teerarak, Montinee
    ;
    Tsai, Wen Shi
    Chili (Capsicum annuum L.) production is threatened by the pepper yellow leaf curl virus (PepLCV), transmitted by whiteflies, leading to reduced yields. This study investigated the biochemical changes in two chili genotypes, PEP6 (tolerant to PepLCV) and Homsuphan (susceptible to PepLCV), following inoculation with the Thailand strain of PepLCV (known as Pepper Yellow Leaf Curl Thailand Virus, PepYLCTHV). Inoculation was performed using whitefly transmission (WF) and graft transmission (GT) methods, and disease severity was evaluated using a standardized index. The level of total phenolic compounds and the activities of peroxidase (POD) and polyphenol oxidase (PPO) enzymes were analyzed in virus-infected plants and compared with those in uninoculated controls. Both chili genotypes exhibited a more rapid increase in disease severity when inoculated with WF than with GT. In PEP6, disease severity was lower than Homsuphan in both WF and GT inoculations. Disease severity in WT-inoculated PEP6 plants increased gradually, reaching 100% by day 36, whereas Homsuphan plants had a more rapid progression, attaining 100% by day 21. The GT method led to slower disease severity progression in both genotypes, reaching 80–85% by day 36. In PEP6 plants, total phenolic compound content increased significantly following WF, indicating an active defense response, whereas levels remained stable in GT plants. Phenolic content in the tolerant genotype Homsuphan remained stable across all conditions. Notably, peroxidase (POD) activity was elevated in GT plants of both genotypes, which correlated with reduced disease severity. Polyphenol oxidase (PPO) activity was lowest in control plants, but WT and GT increased the PPO level. Among the treatments, GT induced the highest PPO activity, which was associated with the lowest disease severity. These findings suggest that GT may enhance disease resistance by modulating phenolic compound accumulation and increasing POD and PPO activity.
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    Gene actions of resistance to anthracnose (Colletotrichum acutatum) of six F1 hybrid chili cultivars at the mature green fruit stage
    (2023-01-01)
    Sangarun, P.
    ;
    Suwor, P.
    ;
    Saetiew, K.
    ;
    Tsai, W. S.
    ;
    Techawongstien, S.
    Anthracnose is an economically important fungal disease affecting the yield and fruit quality of chili in the tropics. This study aimed to assess the anthracnose disease reaction in six hybrid chili pepper cultivars compared with their parental lines. Two male resistant lines were crossed with three commercial female parents by North Carolina mating design II. All chili genotypes were grown in the greenhouse in a randomized complete block design with three replications, 10 plants each. Five mature green fruit plant<sup>-1</sup> were harvested and inoculated with C. acutatum by using the microinjection method. ANT4 had smaller lesions than ANT10. Additionally, the F1-hybrids derived from ANT4 showed smaller disease lesions (7.47-9.82 mm) than on those derived from ANT10 (9.40-11.04 mm). However, the percentage heterosis of anthracnose disease traits in ‘Jindanil 80’ (JD) and ANT4 gave the lowest value to other parents. Hybrid JD × ANT4 showed the lowest anthracnose lesion size. However, the heterosis of cross the NM × ANT10 was the most negative at -43.68. The mode of gene action was found to be additive rather than involving dominant effects, with a narrow-sense heritability of 50.9% and broad sense heritability of 70.1%. Therefore, the resistant parent ANT4 cultivar is crucial for use as a resistant elite line for producing good F1 hybrid tolerance to anthracnose disease.