番茄圆纹病病原菌侵入、扩展及叶斑形成的研究

STUDIES ON PENETRATION,SPREAD AND LEAF SPOT FORMATION OF Phoma destructiva PLOWR

番茄圆纹病分生孢子在２０～２５℃温度下在水中需要４～６ｈ才开始萌发，病原菌大多数从气孔侵入，也可以从表皮直接侵入。病原菌菌丝在叶片栅栏组织中以纵向扩展为主，而在海绵组织中则以横向扩展为主。病原菌菌丝在病斑的栅栏组织中集结形成分生孢子器，成熟的分生孢子器有孔口的部分突出于病斑上表面，因而病原菌从叶片上表面侵入的机会比下表面大。菌丝在病斑栅栏组织中分布不均匀，使病斑上表现形成轮纹，而在海绵组织中分布较均匀，使病斑下表面没有轮纹出现。粗大的叶脉对病斑菌丝扩展有阻碍作用致使病斑扩展遇到粗大的叶脉时会呈不规则状。根据番茄圆纹病病原菌侵入、扩展及病斑形成的规律，可以初步认为番茄叶片形态结构对圆纹病抗性会有一定的关系。

The conidia of Phoma destructiva plowr.(Syn : Phyllostita lycopersici Peck)beginto sprout at 20～25℃ ,after immersing them in water in 4 to 6 hrs.It may penetrate muchmore in stamtaes and or so through epidermis cells.Its hyphae spread in vertial way in pal-isade tissue but in horizontal way in spongy tissue Hyphae allways mass to form pycidium inspots palisade tissu,and the part with hole of mature pycnium stricke out abaxial epidermiasof spot.The leaves were infected by P.destructiva much more from abaxial epidermis thanfrom adaxial epidermis.The adaxial epidermis of spot have lines because of the uneven distri-bution of hypha ,but the adaxial have not lines because of even distribution.After spot spreadto large vein,the vein can hinder the spread of hypha ,it made the spot to become irregular.on the basis of the rule of the penetration,spread and formation of P.destructiva,it'spreliminarily made out that the leaf's morphological character of tomato may be relation toresistance to P.destructiva.