Molecular Detection Of Chili Pepper Phytoplasma And Homology Analysis Between Paulowniaphytoplasma And Chili Pepper Phytoplasma In Shanxi Province

In order to provide a reference basis for effective prevention and control of chili pepper little leaf disease,92 and 86 diseased plant samples were collected from more than a dozen counties(cities)in main producing areas of Shaanxi Province,including Baoji city,Weinan city and Xianyang city in 2012 and 2013.By means of 2 primer pairs of P1/P7&R16F2/R16R2,the 16SrRNA gene of chili pepper samples was amplified by nested PCR.The analysis results of 2012 show that by means of 3 primer pairs of P1/P6&R16F2/R16R2,R16mF2/R16mR1&R16F2/R16R2,P1/P7&R16F2/R16R2,the 16SrRNA gene of 22 chili pepper samples and 1 bermuda grass(positive control)was amplified by nested PCR.PCR products were analyzed by agarose gel electrophoresis.Target fragment of 16 chili pepper samples and bermuda grass was amplified by P1/P7&R16F2/R16R2 primer pairs.Only target fragment of bermuda grass was amplified by P1/P6&R16F2/R16R2,R16mF2/R16mR1&R16F2/R16R2 primer pairs.The target fragment amplified with P1/P7&R16F2/R16R2 primer pairs was sequenced.The result showed the target fragment is 16SrRNA gene of bacillus;however,the analysis results of 2013 show that target fragments of phytoplasma were amplified from only 2 samples collected from Dan village,Baoji city.In this sampling locations,there was a paulownia tree with witches-broom disease nearby the chili pepper field,and at the same time we collected some plantago lanceolata with abnormal leaves in this field.We detected target fragments from them using same method and primer pairs.The target fragments were sequenced and the result showed the similary of 16SrRNA gene among the pepper,plantago lanceolata and plantago lanceolata was above 99%,respectively,they all belong to 16SrI group.Through the electron microscope,we just observed a few phytoplasma in phloem of pepper.so we come to the conclusion that phytoplasma is not the main pathogens of chili pepper little leaf disease and chili pepper is the natural host of paulownia witches-broom phytoplasma.