شناسايي و رده بندي عوامل فايتو پلاسمايي سيب زميني در ايران با استفاده از روش هاي مولكولي

چكيده انگليسي :

AbstractPhytoplasmas are known as plant pathogenic agents that cause great losses ineconomical plants Phytoplasma diseases in potato including potato whitches broomand potato purple top are documented worldwide but there is no informationconfirming the importance of these diseases in Iran In 2006 2007 symptoms typical ofphytoplasma induced diseases were observed in sprouted seed tubers and potato plantsin fields surveyed over an areas of Isfahan Tehran Kermanshah Hamedan Chaharmahal O Bakhtiari and East Azarbaijan provinces The diseases arecharacterized by stunting slight purple top discoloration of new growth leaf curl swollen nodes broken auxiliary buds and formation of aerial tubers similar to potatopurple top disease symptoms The potato sprouts emerged from generated tubers ofthese plants were spidle or hairy Planting these symptomatic tubers in green house promoted to produce potato purple top symptoms in generated plants except one ofthem which showed witches broom symptoms with general stunting yellowing andproliferation of auxiliary shoots To detect phytoplasmas associated with infected plants extracted DNA from sprouts of collected tubers or midrib of foliages was used as thetemplate for nested PCR assay primed by phytoplasma universal primers P1 P7 andP1 Tint in the first round amplification followed by R16F2n R16R2 and fU5 rU3 fornested reaction Except for few DNA samples no DNA amplification was observedwhen the P1 P7 and P1 Tint primers were used in first round PCR However whendirect PCR products were employed in nested PCR using R16F2n R16R2 and fU5 rU3primer pairs fragments sized approximately 1239bp and 879bp DNA fragment wereamplified respectively Characteristic banding patterns obtained from restriction analysisof PCR products using AluI EcoRI CfoI KpnI HinIII MseI RsaI and TaqI dendonucleases from positive samples confirmed significant genetic differences amongfragments of samples amplified in nested PCR assay indicating that divergent strains ofphytoplasma might be involved in promoting whiches broom and purple top symptomsin potato growing areas of Iran The representatives of strains with different PCR RFLPpatterns were subjected to DNA sequencing Nucleotide sequence comparison andalignment of a DNA base segment of 16S rRNA gene sequences revealed that containednucleotide sequences from representative isolates have high level similarity 98 99 to16S rRNA phytoplasma sequences that were previously reported Sequences analysis of16S rRNA gene sequences amplified by PCR indicated that the symptoms wereassociated with whitches broom in green house designated Candidatus Phytoplasmatrifolii Phytoplasmas includingCa Phytoplasma solani Ca Phytoplasma astris and Ca Phytoplasma trifolii were detected in potato plants showing purple top symptoms Among the associated phytoplasmas with purple top symptoms the high incidence ofCa Phytoplasma solani in potato fields was substantial showing that Ca Phytoplasmasolani is the prevalent phytoplasma in Iran to cause potato purple top symptoms This isin spite of the fact that there is no report of economic importance of Ca Phytoplasmasolani in world potatoes Confirming the transmission of Ca phytoplasma solani Ca Phytoplasma astris and Ca Phytoplasma trifolii through seed tubers in this study leadsto postulate that using certified seeds for prevention of disseminating the disease shouldbe considered

حسيني، پرهام

شناسايي و رده بندي عوامل فايتو پلاسمايي سيب زميني در ايران با استفاده از روش هاي مولكولي

واكنشPCR , باكتري E.Coli