2017 ASHS Annual Conference

Bacterial speck, caused by Pseudomonas syringae pv. tomato is one of the most important diseases of tomato. It is favored by the low temperature and high moisture conditions. There are two races of the pathogen, race 0 and race 1. In North Carolina, predominant race is race 0, and race 1 has not been reported yet. There is a major gene ‘Pto’ conferring resistance to the race 0 in tomato. We were interested to introgress the Pto gene from various sources including CULBPT-04-5 and Ontario 7710 into the NC-adapted tomato breeding lines and evaluate their performance at Mountain Horticulture Crops Research & Extension Center at Mills River, NC over the years. Crosses were made and three F2 populations were analyzed for their resistance to the bacterial speck using local isolate NC-C3 (Pst, race 0) under controlled conditions collected from NC. The populations analyzed were NC13267 (47NC-2 x CULBPT04-05), NC13271 (NC 714 x Ontario 7710) and NC13272 (NC 1CELBR x Ontario 7710) for the inheritance pattern of Pto and bacterial speck. The inheritance pattern of the Pto was confirmed to be a single gene (χ²=0.88, p>0.05) in all three populations. Bacterial speck resistance held up consistently well in the lines derived from these sources under field conditions. Resistant lines are being further evaluated for the advancement and improvement of horticultural traits. We believe that the lines advanced and selected from these populations will have useful to address the problem of bacterial speck.