云南疣粒野生稻抗白叶枯病鉴定及叶片组织学观察

 本研究采用水稻白叶枯病菌强致病性代表菌株,评价了云南省自然分布的疣粒野生稻代表生态居群18份材料的抗病性,观察叶片组织学结构,初步分析了疣粒野生稻的抗性基因。结果表明,16份材料表现中抗、高抗甚至免疫;9份材料对4个菌株的抗性有一定差异;同时发现云南地方代表菌株X1和CN9404的致病性比C1和BD8438强。叶片组织学结构表明,高抗材料与感病的栽培稻米泉黑芒都无蜡质层,二者的叶肉组织、薄壁细胞和表皮细胞相同,表皮毛、维管束、厚壁组织等的差异也不明显,不足以引起抗病性差异。疣粒野生稻高抗或免疫白叶枯病并非借助其特殊叶片结构的物理作用,而主要是抗病基因的作用。参试疣粒野生稻中没有与Xa1、Xa21同源的基因,加之独立进化,推断其具有新的优异抗白叶枯病基因,值得深入研究和发掘利用。

Identification of Oryza granulata for resistance to Xanthomonas oryzae pv.oryzae and observation of leaf tissue

Bacterial blight caused by Xanthomonas oryzae pv.oryzae(Xoo)is the most severe bacteria disease in rice worldwide.In order to breed new resistant rice varieties,it is very important to identify and find new resistance genes.Eighteen typical populations of Oryza granulata from different ecosystems of Yunnan were inoculated and analyzed by using four representative strains of Xoo from several areas.At the same time,the leaf surface and anatomical structure of O.granulata plants resistant to Xoo and susceptible O.sativa cultivar miquanheimang were compared by observation under microscope.It was also analyzed whether O.granulata carrying Xa21 gene and Xa1 gene or their homologous genes and checked by PCR.It was found that most of O.granulata populations were moderateltly or highly resistant or even immune to the four strains of Xoo.Some O.granulata populations showed significantly difference of resistance to different Xoo strains.The virulence varied among the Xoo strains used on both O.granulata and susceptible control.Xoo strains X1 and CN9404 from Yunnan were usually severer than strains C1 and BD8438 from other provinces in O.granulata.Both the wild Oryza and the rice cultivar had no long fuzz or wax cover on leaf surface by observing under microscope,and had similar mesophyll structure,top cells and thin-wall cells.Even though the wild rice and the cultivar had different short fuzz,vescular and thick-wall cells in number and shape,these differences were not enough to cause significant difference in disease resistance ability between the wild rice and the cultivars.Therefore it was concluded that the strong resistance of O.granulata to Xoo was not caused by physical structure of leaf but by resistance genes.It is also found that O.granulata did not have the genes or homologous sequences of Xa1,Xa21 which were isolated from other wild rice or cultivar.It is putative that Yunnan O.granulata has one or more new genes resistant or immune to some severe strains of Xoo.Those resistant genes are valuable for improving disease resistance ability of rice cultivars.This is the first time to report systematical identification of Yunnan O.granulata to Xoo as well as leaf surface structure and anatomical structure of O.granulata worldwide to confirm that O.granulata of Yunnan has new genes strongly resistant to Xoo.