جستجوی مقالات مرتبط با کلیدواژه « واکنش زنجیره ای پلی مراز چندگانه » در نشریات گروه « گیاهپزشکی »

Cercospora leaf spot, caused by Cercospora beticola, is one of the most important foliar diseases of sugar beet. Due to the problems associated with traditional methods in the identification of Cercospora species, in the present study two sets of previously designed Cercospora beticola-specific primers based on calmodulin and actin genes were used for the molecular identification of C. beticola isolates. For this purpose, two standard isolates of C. beticola together with the other isolates recovered from sugar beet plants with leaf spot disease symptoms in present study were subjected to PCR amplification. Efficacy of primer sets were tested on the Cercospora isolates recovered from weed plants with leaf spot symptoms, in present study. Our results showed that the primer set based on actin gene amplified a 959 bp PCR product from the all of the isolates tested in this study. This primer set failed to distinguish C. beticola from the other Cercospora spp. isolated from weeds as well as other fungal groups. The results of multiplex PCR assay using primer sets based on calmodulin gene yielded 234 bp PCR product from all of the Cercospora spp. tested in this study and only a 176 bp PCR product from C. beticola isolates; such that successfully discriminated C. beticola from the other Cercospora isolates. The calmodulin genes primer sets can be used for the screening of Cercospora beticola from the other Cercospora spp. and for the detection and the determination of the host range of Cercospora beticola as well.

Sexual stage of Cercospora beticola has not yet been discovered; however, high levels of phenotypic and genetic diversity as well as resistance against fungicides have been reported in different populations of C. beticola. In present study, mating types of 70 Iranian isolates of C. beticola were determined using specific primer sets and formation of sexual reproduction cycle was evaluated under laboratory and greenhouse conditions. For this purpose, C. beticola isolates were recovered directly from sugar beet plants showing leaf spot disease symptoms in fields of Moghan region, Ardabil province. Pure cultures were established using a single spore technique and subsequently subjected to DNA extraction. Mating types were determined by a modification made in the already designed protocol using a multiplex PCR assay. Analysis of PCR products revealed a 400 bp amplicon specific only for Mat1-2 and an 800 bp amplicon specific for Mat1-1 isolates only. Six different methods were used to induce sexual structures by crossing opposite mating type strians under laboratory and greenhouse conditions. The results for the induction of sexual stage using different crossing protocols were unsuccessful. It seems that some unknown factors are involved in sexual induction or failure in other genes involved in sexual reproduction result in lack of sexual reproduction under field or controlled conditions.