Indentification Of Tomato Inbred Lines And Comparison Of The Crosses Resistance To Bacterial Wilt

The bacterial wilt (BW) in tomato, especially along Yangtze River and its south areas, leads to decreasing yield of tomato or even total production failure, bringing huge economic losses. The conventional methods to control bacterial wilt disease show no obvious effect, with high cost and environmental pollution. So far, one of the most effective methods is to cultivate bacterial wilt-resistant variety. In this study,58 inbred lines were characterized in terms of field performance, and resistance to BW and/or Tomato yellow leaf curl disease (TY). The disease resistance was assayed by pathogen inoculation, natural disease indexes and molecular markers. Based on BW resistance and other economic characters among inbred lines, we screened out 4 crossing combinations which showed resistance to BW and other diseases through three successive seasons of variety comparisons. The novel crossing combinations of tomato will provide foundation for breeding tomato cultivars resistant to BW. Main results are as follows:1. We made a comprehensive observation of 58 inbred lines, in terms of important traits such as field phenotype, agronomic characters, fruit performance, botanical traits, and disease resistances (BW and TY, etc). Molecular markers related to the disease resistance were utilized to investigate five disease resistance genes (1-2, TM-2a, Cf-9, Mi-1, Ty-1).Several disease resistant inbred lines were obtained including 1 inbred line resistant to 5 diseases,3 inbred lines resistant to 4 diseases, 7 inbred lines resistant to 3 diseases, and 23 inbred lines resistance to 2 diseases.2. Ten inbred lines were chosen for investigation for their resistance to BW through artificial inoculation during seedling stages. And we got 5 inbred lines highly-resistant to BWr, and 1 BW tolerant line.3. The inbred lines with BW resistance and high economic traits were utilized as parental lines for crossing combination, giving totally 36 hybrid combinations. Some of the crossing combinations were observed successively through 3 seasons (the fall of 2011, the spring of 2012 and the fall of 2012) in combination comparison tests. We obtained 4 hybrid combinations (HB-21, HB-22, HB-23, HB-25) with good economic characters, resistance to BW and TY, as well as fine fruit firmness and fruit shape. Crossing combinations of HB-5 and HB-24 show high field yield, soft fruit, and resistance to BW but not TY.