水稻橙叶植原体在病株中积累及其经电光叶蝉传播的主要特征

Accumulation in infected rice and transmission characteristics via Recilia dorsalis of rice orange leaf phytoplasma

【目的】探究水稻橙叶植原体(Rice orange leaf phytoplasma,ROLP)在水稻植株体内的扩散和积累以及其经由主要介体电光叶蝉传播的特征,以加深对水稻橙叶病发生规律的认识,为病菌继代保存和田间病害防控提供科学依据。【方法】采用半定量PCR和实时荧光定量PCR检测ROLP在感病水稻植株不同部位积累动态及在叶蝉体内的增殖动态;以2~3龄电光叶蝉若虫为传菌介体,测定其在病程约20 d的菌源病株上取食不同时间的获菌率;采用稻苗感病试验测定病菌在叶蝉体内的循回期;通过单虫单苗共培养试验测定病菌经电光叶蝉向3~4叶期水稻幼苗传播的效率。【结果】水稻幼苗感病后,病菌先在受侵染叶片中缓慢增殖,10~15 d后经主茎向下扩展,随后在分蘖的茎和叶组织中大量增殖,约30 d后引致分蘖发病;病株受侵染叶片的上部茎和叶组织中仅有微量或没有病菌存在,根部仅实时荧光定量PCR检测到微量病菌。2~3龄电光叶蝉在菌源植株上取食15、25和35 d的获菌率分别为26.67%、71.11%和85.56%。病菌在叶蝉体内的循回期为25 d左右,度过循回期的带菌叶蝉单虫单苗取食12、24和48 h可分别使24.44%、46.67%和47.78%的水稻苗染病。【结论】ROLP在水稻植株体内呈不均匀分布,以感病30 d前后的分蘖茎和叶组织中含量最高,受侵叶片的上部茎和叶组织中无病菌分布。病菌经电光叶蝉高效传播的获菌取食时间、体内循回期和传菌取食时间分别为15 d、25 d和24 h。

【Objective】In this study,the diffusion and accumulation of rice orange leaf phytoplasma(ROLP)in rice plants and its transmission characteristics by its main vector,Recilia dorsalis,were investigated.This would enhance the understanding of the occurrence patterns of rice orange leaf disease and provide scientific basis for pathogen preservation and field disease control.【Method】Semi-quantitative PCR and real-time fluorescence quantitative PCR were used to detect the accumulation dynamics of ROLP in different tissues of infected rice plants and its proliferation dynamics in R.dorsalis.Second-to third-instar nymphs of R.dorsalis were used as vectors.The ROLP acquisition efficiency of R.dorsalis at approximately 20 days post infection(dpi)feeding on ROLP source plants for varying durations was determined.The circulative period of ROLP in R.dorsalis was determined through rice seedling infection experiment.The transmission efficiency of ROLP from R.dorsalis to three-to four-leaf stage rice seedlings was determined by single-insect and singleseedling co-culture experiment.【Result】After rice seedlings were infected,ROLP initially proliferated slowly in the infected leaves,and expanded downward through the main stem after 10 to 15 d.Subsequently,it proliferated extensively in the stem and leaf tissues of tillers,causing tiller disease onset after about 30 d.Only trace amount of strains or no strains were detected in the upper stem and leaf tissue of infected leaves,and only trace amounts of strains were detected by real-time fluorescence quantitative PCR in the root.The ROLP acquisition rates of second-to third-instar R.dorsalis after feeding on source plants for 15,25 and 35 d were 26.67%,71.11%and 85.56%respectively.The circulative period of ROLP in R.dorsalis was approximately 25 d.Inoculative single R.dorsalis that completed the circulative period could transmit ROLP to 24.44%,46.67%and 47.78%rice seedlings after feeding on single plant for 12,24,and 48 h respectively.【Conclusion】The distribution of ROLP is uneven in rice plants,with the highest content in the stem and leaf tissues of tillers around 30 dpi.No ROLP is found in the upper stems and leaf tissues of infected leaves.ROLP acquisition feeding time,circulative period and transmission feeding time of ROLP for efficient transmission by R.dorsalis are 15 d,25 d and 24 h respectively.