水稻黄单胞菌水稻致病变种rpfC缺失突变体在感病和抗病水稻品种中的繁殖和扩展

Multiplication and Spread of the rpf C Gene Deletion Mutant of Xanthomonas oryzae pv. oryzac in Susceptible and Resistant Cultivars of Rice

水稻黄单胞菌水稻致病变种（Ｘａｎｔｈｏｍｏｎａｓｏｒｙｚａｅｐｖ．ｏｒｙｚａｅ）中国菌株１３７５１和水稻品种广桂１１０和ＩＲ２６的相互作用分别为亲和和不亲和相互作用。１３７５１的ｒｐｆＣ基因缺失突变株ＳＬ３７５１在电镜下的形态和野生型没有显著差别，均为短杆状，大小为（０．５～０．８）×（１．０～２．０）μｍ。用１０８ｃｆｕ／ｍＬ或１０１０ｃｆｕ／ｍＬ的ＳＬ３７５１剪叶接种苗期和分蘖盛期的广桂１１０，接种后５ｄ内ＳＬ３７５１在广桂１１０中的生长繁殖和野生型相似，但接种５ｄ后ＳＬ３７５１在其中的活菌数均稳定在１０６－７ｃｆｕ／叶，最终ＳＬ３７５１的活菌数比１３７５１的低１００倍左右。在抗病品种ＩＲ２６上，接种后５ｄＳＬ３７５１也增殖到１０６－７ｃｆｕ／叶，之后也保持在这一水平，最终ＳＬ３７５１的活菌数比野生型的低１０倍左右。另外，ＳＬ３７５１在被接种到广桂１１０和ＩＲ２６后，它被主要局限在剪叶接种切口下３ｃｍ范围内。野生型接种在广桂１１０上，接种后３ｄ就迅速沿叶脉往下扩展，野生型１３７５１在抗病品种ＩＲ２６中的扩展速度显著慢于其在广桂１１０中的扩展速度。所有这些都进一步证实ｒｐｆＣ基因在１３７５１在致病过程中起?

The interactions between Chinese strain 13751 of Xanthomonas oryzae pv. oryzae and rice cultivars Guanggui 110 and IR26 are compatible and incompatible interactions,respectively.SL3751,the rpf C gene deletion mutant of 13751, was shortrod which was similar to that of 13751 under electronic microscope.Its size was about (0 5～0 8)×(1 0～2 0) μm.When Guanggui 110 plants at seedling or middle tillering stages were clippinginoculated with SL3751 at concentrations of 10 8 cfu/mL or 10 10 cfu/mL,SL3751 grew and multiplied similarly as the wild-type did within five days post inoculation.But five days after inoculation,the number of SL3751 in each leaf maintaining at about 10 6-7 cfu/leaf till the end of experiment.The final number of SL3751 was about 100 fold lower than that of 13751 in Guanggui 110.Whereas in the resistant cultivar IR26,SL3751 also multiplied to the level of 10 6-7 cfu/leaf five days post inoculation and also maintained at this level afterwards till the end of experiment.The final number of SL3751 was about 10 fold lower than that of 13751.The spread of SL13751 in both Guanggui 110 and IR26 was mainly limited in the region of 3cm away from the cutting tip.Whereas the wildtype could spread fast downwards along the veins in Guanggui 110 three days post inoculation.The spread of 13751 in the resistant cultivar IR26 was significantly slower than that of 13751 in Guanggui 110.All these data further confirmed that rpf C gene played important roles in the pathogenicity of Xoo13751.