Studies On The Detecting Technique And The Genetic Diversities Of Curvularia Lunata In Maize

Recenily there have been many reports all over the world about fungi diseasecaused by Curvularia lunata [Cochliobolus Iunana]. The economic importanceand the wide range of its hosts can be found from these reports. The biggestcomznedty of the host of C.lunata is gramineous plants such as rice, malze,wheat and sorghurn. Othedrise, cotton, cowpea,sunflower, onion etc could beinfected by C lunata too. C lunata is one of the importan seed-bome mycelialfungus pathogen. Microscopic examination showed C.lunata could be deectedin all components of maize seeds.Maize is the third importan food crop in addition to rice and wheat in China.Com northem leaf blight (Helminthosporium turcicum) and com southern leafblight (Cochliobolus heterostrophus) were the main maize diseases in China inthe past. But recentiy a new disease named maize cedaria leaf spot or malzeyellow spot caused by C.lunata (infrequentiy by C hoequais), is becomingprevalent in north China and is spreadin to south China.The disease ischaraterized by chlorotic spot symptoms on leaves: chlorotic pin points appearedin the beginning, then yellow spots with a white center and a chlorotic halofollowed,and finaly leaves bligh when a lot of spotS joined togetheL Size of thespot usually is 1 × 2mm-2mm. Maize cedaria leaf spot is easy to cothee withcom southem leaf bligh and com helrninthosporium leaf spot (Co. carbonum) insymptoms. C lunata can be found on the sdse of seeds, the spores andmycelium were also found on the buttrss roots, and on the soil surface but not at4dePths of 5 or 10crn. So isolation of the causal agent C lunata is the main methodfOr diagnoses at presen though there are variabilihes of cultural cforteristics ofC lUnata isolates and coWons by other sdriilar fungi occur frequently inthe Process of isolation. There are some reportS on the variabi1ity growh andsPOrulation of isolates from differen geograPhical locations, and on theulbetrUM of C IUnaha. So far there is still laCk of a raPid, sPecific andsensitive tecboque for the diagnosis of C lunata and there are few stUdies on thegenetic baskground of Ans pathogen.ln order to exPlore the differences betWeen C Iunata and otlier sbolar fungiand establish a specific and sensihve diagnostic method fOr C lunata, this stUdyhas compared the moboometrics including the fungi colony and in medium andthe sPores of C Iunata in maize and Othr swhlar forgi aPPearing bequently byisolation. We have compared their protein SDS polyacrytalde gelelectrophoresis pattems too. An immunological detection tecboque of C lunatafrOm cultUre and on the seed based on the assays of Proteins is established. Wealso study the genetic diversihes using amPlified fragYnent 1ength polyInorphismand comPared the molecular markers of C Iunata, the sbolar strains. Six specificPOlymorphic frgnents of AFLP have been found srochronously. They wiIl bethe twrtan molecular markers for idenopg C lunata. The main resultS arefollowed.First we collected 73 pure isolates of C IunaIa and their sindlar stains fromabroad, our councy and the main areas of maize in Sichuan, including 34 isolatesof C Iunata, 3 isolates of CO. Carbonum, l3 isolates of CO. heterosmphus, and 8isolates of A. alternata. TWlve isolates of C Iunata and six sbolar sPecie strainsfrom haze or other hoSt plants wer exaInined for the analysis of mycelioidcolony morphometrics, sPores morphometrics and SDS polyaCryamide geleleCtrOPhoresis pattemS of their soluble proteins. The diffeences of colonymorphometrics of l8 isolates existed arnong differen SPeCies and the same speciebu they wer no W and special. Th differences of SDS POlyaCrylndde geleleCtrphoresis pattems ekisted sighficantiy among differen Species and the5saxne sPecie. There was a sPecific protein band for CimIaria at relative mobilityvalue 0.l77 W0.177) and a sPeCial PrOtein band for C bo at Rf0.225.Second, we have set uP the bological detection tecboque to ide...