การประเมินความต้านทานโรคเหี่ยวเขียวที่เกิดจากเชื้อแบคทีเรีย Ralstonia solanacearum ในมะเขือยาว

Abstract

Field survey and sample collection were conducted in the production area of tomato, marigold, eggplant, pepper, potato, tobacco, and cucumber from 8 provinces: Chiang Mai, Chiang Rai, Phrae, Nan, Ratchaburi, Chonburi, Ubon Ratchathani, and Nakhon Si Thammarat. These 46 isolates of pathogens were obtained from wilting symptoms. Pathogenicity tests in eggplant (Top Gun F1 hybrid) and pepper (Yok Thep hybrid) seedlings can be separated into three groups; 13 highly virulent isolates, 21 moderately virulent isolates, and 12 less virulent isolates. Moreover, the reaction on tobacco (Nicotiana tabacum L.) leaf was studied by infiltrating suspension of the pathogen into tobacco leaf and the results showed that all of the isolates developed necrosis or hypersensitivity reaction (HR). Phylotype analyses all of 46 isolates were determined by phylotype-specific multiplex PCR (Pmx-PCR) assay revealed that all isolates confirmed that R. solanacearum was classified as Phylotype I, sequevar 12, 13, 14, 15, 17, 34, and 47 which is a strain original from Asia corresponding based on partial endoglucanase (egl) and hypersensitive reaction and pathogenicity (hrpB) genes sequences. Biovar determination confirmed that 42 isolates belonged to biovar 3, while 2 isolates belonged to biovar 4, and 2 isolates were classified as biovar 2. The screening of eggplant for resistance to bacterial wilt selected 3 isolates of PE-N3, EPP26, and MA-CM52 for resistant evaluation in 9 eggplant cultivars under greenhouse conditions, tested in two periods of the season. In the summer season, which was tested in April-June 2021. Results showed that all 9 cultivars were susceptible to R. solanacearum isolates EPP26 and PE-N3, except EW-03925 cultivars, which showed resistance. The result tested in August-October 2021, most eggplant cultivars were susceptible to EPP26 isolate, except EW-03925. While eggplant cultivars, EW-03925, EW-03127, EW-04439, and EW-14403 are resistance to R. solanacearum isolate PE-N3. Moreover, the MA-CM52 isolate revealed that all nine eggplant cultivars showed resistance. In addition, 11 cultivars of pepper have been evaluated for resistance to 7 isolates including; PEP-FLP, PE-N3, PE-UB1-15, EP.NST10, EPP26, MA-CM52, and TOM-FLP. The results showed that only 2 cultivars of pepper; PE-23566 and PE-08041 were resistant to all 7 isolates of R. solanacearum. Then 3 cultivars of pepper; PE-08177, PE- 22128, and PE- 21228 are relatively resistant to bacterial wilt disease. Furthermore, the invasion of R. solanacearum on survival plants of eggplant after inoculation at 21 days in greenhouse conditions was examined. The resistant (EW-03925) and susceptible cultivars (EW-17271) to the isolate EPP26 observed the invasion of R. solanacearum in the stems. The results showed that in the resistant cultivar, the invasion was found only three parts of all nine parts of the stems, and counted the R. solanacearum as 1.0x105–2.5x105 cfu/ml. While the susceptible cultivar, R. solanacearum was found distributed throughout all nine parts of stems and the amount of R. solanacearum counted was 1.1x105–2.1x107 cfu/ml.