Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560089, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Tomato is one of the most important vegetable crops cultivated throughout the world. World's acreage of tomato is 4.1 million hectares with a productivity of 26 tons/ha, while in India, it is cultivated in 0.52 million hectare with a productivity of 14 tons/ha. Low productivity of tomato in India is due to the occurrence of serious diseases such as tomato leaf curl disease (ToLCD), bacterial wilt and early blight. ToLCD is a destructive disease of tomato in many parts of India. The disease is caused by a begomvirus, transmitted naturally by whitefly vector (Bemisia tabaci). ToLCD has risen to alarming proportions in the plains of India and has become a limiting factor in tomato cultivation during the summer causing 100% infection and fruit yield losses exceeding 90 per cent. Thus, tomato cultivation is almost precluded during Autumn-summer in South India and summer in North India. Bacterial wilt caused by Ralstonia solanacearum, is also a devastating disease in India causing serious crop losses in tomato. This soil borne pathogen is reported to cause up to 90% losses in tomato. Early blight caused by Alternaria solani Sorauer is one of the most destructive diseases of tomato in tropical and sub-tropical regions of India. The loss due to this disease has been reported to range from 50–80%. The development of tomato cultivars with multiple disease resistance to ToLCV, BW and EB is currently the best approach to control the diseases they induce. Resistance to ToLCV and BW was identified in IIHR-2202 (CLN-2123-DC1F1-111-17-21-2-12) an advance breeding line received from AVRDC, Taiwan. Early blight resistant line IIHR-1816 (NCEBR-1) was crossed with IIHR-2202 to develop F1. Early blight resistant parent IIHR-1816 was backcrossed to F1 and BC1F1 was produced. BC1F1 was further advanced to BC1F7. Segregating progenies from BC1F1 to BC1F7 were artificially challenged with all the 3 pathogens. ToLCD was transmitted through virulent white flies in insect proof screen house at the seedling stages. ToLCV resistant plants were further confirmed by PCR using Ty-2 marker. ToLCV resistant plants were artificially inoculated with Alternaria solani spore suspension and the seedlings were planted in bacterial wilt sick soil (10-7 c.f.u./g.) followed by artificial inoculation with bacterial suspension through pinprick method. Four advanced breeding lines viz; TLBER-11-38-7, TLBER-11-7-12, TLBER-11-7-6 and TLBER-11-7-4 have been developed with triple resistance to ToLCV, BW and EB. All the four lines had good yield potential with good horticultural traits.
