Expression of virulence-related genes in variants of Fusarium oxysporum f. sp. niveum
| Autor: | Yu-Ling Wan, 萬宥伶 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Watermelon is one of the most important vegetable crops in Taiwan. Fusarium wilt of watermelon is a soil-borne disease which affects watermelon production severely. Watermelon wilt fungal pathogen, Fusarium oxysporum f. sp. niveum, tends to develop cultural variability from sporodochial type (abundant in aerial mycelium and sporodochia formation ) to mycelial type (only abundant in aerial mycelium) and pionnotal type (lack in aerial mycelium) during sequential culture transfers. According to the previous studies, reduced virulence of the pathogen accompanied with cultural variation when inoculated with infested soil. The aim of this research is to study the effects of cultural variability on the mycelia growth, conidiation, chlamydospore formation, and virulence (by root-dipping inoculation) toward host plant Grand Baby watermelon. The results showed that there were differences in the growth rate between the cultures of sporodochial and the mycelial or pionnotal variants. The pionnotal variant culture, however, produced the most abundant conidia. Nevertheless, during nutrition deficiency in the soil extract, the pionnotal variant produced the least amount of chlamydospores, which are the survival structure of the pathogen. In the results of root-dipping inoculation (105 spores / mL) of Grand Baby watermelon seedlings, the pionnotal variant cultures remained highly virulent, even slightly higher than the sporodochial variant culture. On the molecular biology respect, the RAPD patterns of different cultural variants of Fon-H0103 were identical, showing that the compositions of genomic DNA of these cultural variants were not different. According to the expression results of several virulence-related genes, the pionnotal and mycelial variant cultures showed higher level of expression of some genes in the RT-PCR analysis, which is correlated to the results of root-dipping inoculation. The effects of cultural variability on the pathogen might be the reduced survival ability and colonization to the host roots in the soil. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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