大豆斑疹病疱斑形成过程的电镜观察

 由(Xanthomonas campestris pv.glycines)所致大豆斑疹病病斑隆起成疱。盆栽大豆感病品种(Chippewa和Horosoy)和它们的抗病品系在二片真叶展开2/3时,用高压喷雾接种(Xanthomonas campestris pv.glycines),接种后的第3、6、9天分别取样;样本分二种处理分别在扫描电镜、透射电镜和普通光学显微镜下观察病斑形成过程.接种后3天,肉眼可见褪绿斑时,病斑部分的表皮细胞和薄壁细胞组织已开始膨大,病斑部分稍有隆起.第6天,肉眼能见疱斑时,表皮细胞和薄壁细胞膨大明显,少数细胞开始破裂.第9天病斑开始变褐,电镜下可见疱斑完全破裂,表皮细胞和薄壁细胞膨大数倍于正常细胞,且细胞破裂,大量细菌溢出。同时可以看到大豆斑疹病细菌在发病初期是在细胞间隙中存活和繁殖的,在表皮细胞和薄壁细胞破裂后进入细胞内,最后完全破坏细胞.从电镜切片中也可以看到疱斑形成主要是由于细胞体积增大所致.抗病品种只有褪绿斑,渐变褐,肉眼看不见疱斑,但在电镜下可见得下表皮稍隆起,有少数细菌存在于细胞间隙,未见有细菌溢出现象。

OBSERVATION ON THE FORMATION OF SOYBEAN BACTERIAL PUSTULE UNDER ELECTRON MICROSCOPE

2/3 expanded unifoliate leaves of susceptible varieties (Chippewa and Horosoy) and their resistant isolines of Soybean were spray-inoculated with cultures of Xanthomonas campestris pv.glycines.Samples were taken 3,6,9 days after inoculation respectively.Each sample was prepared for TEM and SEM.Three days after inoculation.partial epidermis and parenchyma cells enlarged when only chlorotic lesion can be seen by eyes.At sixth day,when we can see the pustule raised,the epidermic and parenchyma enlarged significantly,and partial cells were broken,in which some bacteria were present.At ninth day,the lesions became brown,the pustules were broken totally and the parenchyma cells broken too.An abundance of bacteria exuded.At the same time,we can found that the bacteria exist in the intercellular spaces and entered into the collapsing cells.The resistant lines showed only chlorotic lesions,no pustule,but under SEM,we can see the epidermic raised slightly,no bacteria exudate.