水稻抗白葉枯病生理及遺傳之研究

Abstract

本研究主要探討肥培管理對水稻白葉枯病之影響及抗病水稻品種其 生化與遺傳之特性。供試材料為不同抗、感病性的水稻品種(系)，主要 包括感病品種台中在來一號(TN1)與抗病品系台秈糯育七號(TSWY7)。抗 、感病性測試之接種源採用本省白葉枯病菌菌系XM42或XF13。主要試驗 內容可分成三部份：溫室中營養要素對水稻葉片成份及其對白葉枯病之 抵抗力的影響、生長箱水耕系統之水稻幼苗罹病過程中生化特性的改變 、以及水稻抗白葉枯病之遺傳分析等。茲將所得到的結果敘述如下： 1.利用溫室水耕系統之不同氮、鈣及矽肥處理下，探討比較不同品種對 白葉枯病之反應情形，結果發現施用高濃度矽肥(150 ppm) 可使感病 品種TN1罹病度減少二至三倍，而抗病品種TSWY7之抗性則增加三倍以 上。矽及可溶性醣含量與抗病性有密切的關係，故若能適當的調控水 稻葉片矽的含量，應有助於降低此病害的發生。 2.於生長箱水耕培育水稻幼苗為抗病性測試系統中，發現抗病品系TSWY7 植株於接種XF13菌系後四天中，乙烯產生及葉片中過氧化?@活性有明 顯增加的現象，而TN1(感病)植株則未見之。以等電點焦集電泳分析 TSWY7可溶性蛋白質成分，結果顯示等電點分別為8.91及9.23兩個陽離 子性過氧化酵素同功?@之產生與抗病性寄主病原交互作用有明顯的關 連。 3.為探究本省秈型稻與梗型稻抗白葉枯病之遺傳特性，於溫室與田間之 白葉枯病遺傳試驗中，均顯示抗病性對感病性為部份顯性。基因之加 性及顯性作用均參與此抗病性，且加性作用大於顯性作用。狹義遺傳 率均在80 %以上，無母性效應的現象存在。由秈型稻與梗型稻之世代 分析顯示F2族群分布成正歪度分布，基因的作用為複合式基因的作用， 基因之加性與顯性作用在此性狀中殊為重要。

The thesis explored mainly the effect of nutrients on the biochemical and physiological characteristics associated with, and the genetic studies of bacterial blight resistance in rice (Oryza sativa L.). The rice materials included susceptible variety such as TN1 TCS10, TC189, and TNG67, and resistant variety (strain) such as TCSW1, TSWY1157, TSWY7, and TKY6287. The clipping inoculation methods of Kauffman et al. (1973) was adopted to evaluate the resistance performance of test rices using the XM42 and XF13 strains of Xanthomonas oryzae pv. oryzae as challenging pathogen. The results obtained are summsrized as follows : 1. Under the hydroponic culture system, the application of silicate at 150 ppm, on the contrarily, greatly enhanced the resistance of both TSWY7 and TN1 plants. An adjunct chemical analysis during the investigation revealed that the enhansive effect of silicate application was clearly associated with the increases of silicon and the decrease of soluble sugar contents among tested rices. 2. In order to explore the physiological characteristics associated with bacterial blight resistance, seedlings of both TSWY7 and TN1 plants were grown by hydroponic culture in a growth chamber as a model system for the resistance evaluation. Artificial inoculation of TSWY7 plants with the XF13 strain of this pathogen generally led to an enhanced rate of ethylene production throughout a four days experimental period. Where plant, the enhancement of pathogenesis related ethylene production was not observed. In accompany with the increased ethylene production, continued increase of peroxidase activity was detected from the soluble protein contents of the XF13 pathogen inoculated TSWY7 plants for 4 days after inoculation. And likewise, the enhanced peroxidase activity was not observed in the compared TN1 plants. 3. In order to explore the genetic behavior of bacterial blight resistance among the Indica and Japonica rices, two sets of diallel crosses were undertaken in which 5 Indica rices (namely TN1, TCS10, TCSW1, TSWY7 and TSWY1157) and 4 Japonica rices (namely TC189, TNG67, TN5 and TKY6287) were used. The disease resistance performance of their F1 progenies were evaluated by challenge inoculation with the XF13 and XM42 strains of X. oryzae pv. oryzae by the clipping method in both greenhouse and field trials. In addition to the diallel crosses, backcrosses were also conducted among two sets of Indica rice crosses (TN1TSWY7, TN1TSWY1157) and two sets of Japonica rice crosses (TKY6287TC189, TKY6287TNG67). The P1, P2, F1, F2, BC1 and BC2 backcrosses progenies were likewise evaluated for their bacterial blight resistance both in greenhouse and field trials as stated above. The resistance performance of all tested rice plants were determined by lesion lengths developed 14 days (for greenhouse trial) or 21 days (for field trial) after artificial inoculation. Statistic analysis of the results obtained from both the diallel crosses trial and the backcrosses trial generally indicated that the resistance of tested rice strains were characteristic of incomplete dominance. The additive and dominance effects both appeared to be significant for the two types of rice varieties tested; and among them, the additive effect was evidently greater than the dominance effect. The heritability of the resistance characteristic was over 80 % in all diallel crosses tested; the maternal effect was clearly not involved. The data obtained from generation mean analysis indicated that the continuous distribution of disease resistance among the F2 progenies of both types test rices were positively skewed. Morever, the disease resistance among the F2 appeared to be confered by genes in a multiplicative way in which the additive and dominance effect were of great importance.