Shoot rot of Zizania latifolia and the first record of its pathogen Pantoea ananatis in China

Abstract

The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai, widely cultivated in China. A new disease of Z. latifolia was found in Zhejiang Province, China. Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths. The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf, causing sheath rot and death of entire leaves on young plants. The pathogen was isolated and identified as the bacterium Pantoea ananatis, based on 16S ribosomal RNA (rRNA) gene sequencing, multilocus sequence analysis (atpD (β-subunit of ATP synthase F1), gyrB (DNA gyrase subunit B), infB (translation initiation factor 2), and rpoB (β-subunit of RNA polymerase) genes), and pathogenicity tests. Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths, forming biofilms on the inner surface of vessel walls, and extended between vessel elements via the perforated plates. To achieve efficient detection and diagnosis of P. ananatis, species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z. latifolia. This is the first report of bacterial sheath rot disease of Z. latifolia caused by P. ananatis in China.

摘要

目的

本文主要鉴定了引起茭白鞘腐病的病原菌和研发病原菌快速检测方法, 为病害防治提供病原菌的信息。

创新点

首次明确了引起茭白鞘腐病的病原菌是菠萝泛菌, 揭示了菠萝泛菌在茭白组织中与寄主互作的超微结构特性, 并研发了特异性引物可用于对引起该病害的病原菌进行早期检测和病害诊断。

方法

通过病原菌16S rRNA序列及结合多基因(atpD、gyrB、infB和rpoB)序列的系统发育分析, 以及致病性试验结果, 进行了病原菌鉴定;通过扫描电子显微镜, 对病原菌与寄主互作的超微结构特征进行观察;分析了病原菌属内种间同源基因的碱基差异, 设计出检测病原菌的专化性引物, 并进行验证。

结论

本文系统观察和描述了发生在浙江地区茭白鞘腐病的症状, 并通过系统发育分析和致病试验首次鉴定了引起引茭白鞘腐病的病原菌是菠萝泛菌。超微结构观察认为, 菠萝泛菌主要定殖于寄主叶鞘中的维管束组织, 形成生物膜, 是涉及致病性;并通过导管分子多孔板在导管中传播。设计的病原菌专化性引物对pagyrB-F/R可用于对引起该病害的病原菌进行早期检测和病害诊断。这为该病害的防治提供了病原菌种的重要信息。