Department of Plant Pathology, Punjab Agricultural University, Ludhiana-141004
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
Citrus is an important fruit crop grown in more than 140 countries and its productivity is often affected by a number of graft-transmissible viruses and virus-like pathogens. Citrus greening bacterium is important among these graft-transmissible viruslike pathogens causing greening or yellowing type of diseases in different citrus cultivars in several parts of India. Though the disease is known to produce foliar symptoms like interveinal chlorosis and various types of chlorotic mottling, the symptoms are often confused with nutritional deficiencies and other abiotic stresses. These type of symptoms were observed in different citrus growing areas of the Punjab state. Therefore, it is essential to have a reliable diagnostic procedure to be available to distinguish between abiotic stresses and citrus greening disease in the citrus nurseries and orchards. The samples were collected from different citrus cultivars and DNA was extracted from the midrib of the infected leaves as well as healthy and leaves showing symptoms of nutritional deficiencies. PCR amplification of DNA samples was done using a set of greening-specific primers(A2/J5) and PCR products were analyzed on 1% agarose gel in TAE buffer containing ethidium bromide. Approximately about 700 bp amplicon was observed from leaf samples showing symptoms of yellowing and mottling.
