甘肃省玉米大斑病菌生理小种结构组成与交配型测定

Structural composition of physiological races and mating types ofSetosphaeria turcica in Gansu

为了明确甘肃玉米大斑病菌生理小种与交配型的结构组成,采用单基因鉴别寄主测定了甘肃4个典型生态区57株玉米大斑病菌的抗、感反应型,对峙培养显微观测法测定了它们与标准菌株杂交是否产生有性态子囊壳。结果表明,甘肃玉米大斑病菌生理小种结构组成十分复杂,57株病菌中共发现0、1、12、23、123、N、1N、2N、3N、123N共10个生理小种,0号以61.40%分布频率成为优势生理小种,1号以17.54%分布频率成为次优势生理小种,23号生理小种出现频率仅为5.26%、123和N号生理小种出现频率仅为3.51%,12、1N、2N、3N、123N生理小种出现频率仅为1.75%,4个典型生态区中河西灌溉绿洲生态区生理小种结构组成最为复杂,15株病菌中共检出0、1、N、12、1N、2N、3N、123N 8个生理小种,中部干旱雨养、陇东半湿润半干旱和南部湿润生态区生理小种结构组成相对简单,42株病菌共检出0、1、23、123和N号5个生理小种。相对而言,甘肃玉米大斑病菌交配型结构组成简单,57株病菌中共检出A型22株、a型24株, Aa型11株,分布频率分别为38.6%、42.1%和19.3%;其中河西灌溉绿洲、中部干旱雨养和陇东半湿润半干旱生态区45株病菌共检出18株A型、18株a型和9株Aa型,A∶a比例完全符合1∶1,南部湿润生态区12株病菌共检出4株A型、6株a型和2株Aa型,A∶a比例小于1∶1。

To understand the virulence and sexual structure of the causal agent of northern corn leaf blight in Gansu,the reaction types of 57 isolates of Setosphaeria turcica collected from Gansu on two sets of differential hosts were tested,and their mating types were also determined by using standard strains.The results showed that their structural composition of natural populations of S.turcica was complex.A total of 10 races were found in 57 strains,including 0,1,12,23,123,N,1N,2N,3N and 123N.Race 0 was dominant with a frequency of 61.40%;race 1 was subdominant with a frequency of 17.54%;race 23 accounted for only 5.26%;races 123 and N accounted for 3.51%,and races 12,1N,2N,3N and 123N accounted for 1.75%.The race composition of S.turcica in irrigated oasis of Hexi was the most complicated:eight races were found in 15 isolates of S.turcica,including 0,1,N,12,1N,2N,3N,and 123N.The structural composition of S.turcica races in central rainfed drylands,eastern semi-humid and semi-arid regions and southern humid region was comparatively simple in the four typical ecoregions in Gansu:a total of five races were found in 42 isolates of S.turcica,including 0,1,23,123 and N.In contrast,the structural composition of mating types was very simple:22 isolates of A type,24 isolates of a type and 11 isolates of Aa type were detected in 57 isolates,accounting for 38.60%,42.10%and 19.30%,respectively.Among them,18 A type,18 a type and nine Aa type were detected among 45 isolates in the irrigated oasis of Hexi,central rainfed drylands and eastern semi-humid and semi-arid regions,with an approximately 1∶1 proportion of A to a.Moreover,four A type,six a type and two Aa type were detected in 12 isolates from the southern humid region,with a proportion less than 1∶1 of A to a.