Inbred Lines Selected With Molecular Markers And Their Combining Ability In Tomato

Tomato is popular with consumers for its rich nutrition and good taste. However, it suffers from various diseases due to continuous cultivation. Although chemical control have certain effect on these diseases, it can result in food safety issues, and can not favor the sustainable development of modern agriculture; Therefore, the cultivation of resistant varieties of tomato, which can reduce production costs, environmental pollution, and pesticide residues in food, is the best way to solve the disease.Traditional resistant breeding is vulnerable to environmental conditions, and time-consuming, the breeding efficiency is not high. While using the molecular marker technology, we can choose the target genes directly without the impact of external environmental conditions, and it can also accelerate the breeding process and improve breeding efficiency.By using molecular marker-assisted selection technology, three inbred lines were improved for disease resistance. We used J1-18-2-1, A101, Zhong6 as receptor parents, and TOV-1-15-17, TOV-2-11-10, TOV-2-2-4 as the donor parents. Through two times inbred, three times backcross, we got 7 improved inbred lines, and then measured out the combining ability of these inbred lines. We hybridized different inbred lines and got some combinations, then compared and chose the excellent combinations, which can lay the foundation for the breeding of tomato varieties. The results are as follows:1. From TOV-1-15-17×J1-18-2-1, TOV-2-11-10×Zhong6, TOV-2-2-4×A101 of this backcross combination, we got BC3F1, BC4F1, BC3F2 groups. From the observation of traits in the field and by using molecular marker-assisted selection, seven copies of BC3F2 resistant strains were obtained, such as TJ-6-12-4-13-8, TJ-13-1-5-5-10, TZ-9-3-17-2-4, TZ-19-8-5-11-6, TZ-16-4-7-2-3, TA-1-10-3-11-7, and TA-8-9-3-16-7. By inoculation tobacco mosaic virus in the tomato seedling, the results showed that the seven inbred lines were all resistant to the diseases above the R level.2. Using one of the four inbred lines and three high-yielding inbred lines hybridized, we got 12 hybrid combinations. Through the varieties of comparative test, we got three good combinations, G2×B3 (TZ-19-8-5-11-6×A101), G3×B1 (TA-1-10-3-11-7×F-21-6),Gl×B1 (TJ-6-12-4-13-8×F-21-6). 3. We used seven disease-resistant inbred lines as female parents, four high-yielding inbred lines as male parents to carry out hybridization. Combining of the ability of period from transplanting to first flowering, ripe period, fruit weight, yield per plant, VC content, soluble solids content, flesh thickness, fruit hardness of 8 traits, the results showed that the general combining ability about the measured traits had reached a significant or very significant level. Above all, we got two new combinations:TZ-19-8-5-11-6×A101 and TJ-6-12-4-13-8×F-21-64. From the test of combinations and combining ability, we got three combinations, TZ-19-8-5-11-6×A101 is large fruit, pink; TA-1-10-3-11×F-21-6 is medium fruit, orange; TJ-6-12-4-13-8×F-21-6 is small fruit, yellow.