Molecular Identification Of TYLCV And Pathogenicity

Tomato(Lycopersicon esculentum M) is widly cultivated in the world as one of themain vegetables.But in recent years,tomato production is seriously affected result inhuge losses for Tomato yellow leaf curl virus,(TYLCV) large-scale outbreak TYLCV, akind of Geminiviruses transmitted by the whitefly Bemisia tabaci, can affect seriousinfluence to qulity and production of tomato even cause economic losses up to100%intomato crop.At present TYLCV has broke out widly in the Shanghai area and has beenone of the main obstacle to tomato growth. The researchers have been devoted to findeffective methods to solve this problem during recent years,which of disease-resistantbreeding is thought the most effective and direct method to deal with disease up tonow.Finding molecular markers linked to resistant genes and identifing and evaluatingvarieties resources,which is help to set up tomato molecular marker-assisted selectionbreeding system, so more and better resistant resources can be chosed and the level ofresistant breeding can be significantly improved. This study first began with thedetection of TYLCV in tomato from Shanghai area and Shandong area.Then identifythe resistant gene of tomato varieties provided by tomato breeding laboratory ofHorticultural Research Institute in Shanghai Academy of Agricultural Science.At lastthese lines were validated in the filed by nature infection.The varieties withhomozygous resistant gene chosed by this method could be used for cross breeding inthe order to cultivate many good varieties with complex resistant genes.Therefore,thisexperiment has a high value of practical application to tomato breeding for resistantdisease.Tomato samples showing leaf curl symptoms were colleeted in Shandong，Shanghai, Hebei Provinces of China.500-bp fragments were amplified from all thesamples by PCR using universal primer pair PA/PB specific for the genusBegomovirus.The full-length genomes of TYLCV isolates from different areas were sequenced and the high sequence identity (>98.9%), and less related to the other speciesof Begomovirus.20tomatovarietieswereeolleetedandresistanceloeusTy-1,Ty-2and Ty-3areassoeiated with these tomato varieties，respectively.When these tomato varieties wereagroinoeulated with TYLCV, different resistant phenotypes were found， and nocorelationship was found between infectivity and virus concentration.Infection clone of HaNHK7and PaLCCNV were constructed and agro-inoculatedinto Nicotiana benthamiana and S. lycopersicum. Leaf yellowing was observed inHaNHK7inoculated S. lycopersicum differed from PaLCCNV induced symptoms. In N.benthamiana and S. lycopersicum, HaNHK7inoculated plants displayed downward leafcurling as well as crinkling symptoms. However, PaLCCNV inoculated plants displayedupward leaf curling symptoms.