UMH 1422 and UMH 1415: Two Fresh-market Tomato Breeding Lines Resistant to Tomato Mosaic Virus and Tomato Spotted Wilt Virus

Abstract

The incidence of several viral diseases such as those caused by Tomato mosaic virus (ToMV) and Tomato spotted wilt virus (TSWV) makes tomato landrace cultivation practically nonviable in many areas of southeastern Spain, especially in open-field conditions (Ruiz et al., 2005). ‘De la Pera’ and ‘Muchamiel’ are two tomato landraces that are very appreciated as a result of their organoleptic fruit quality. The Miguel Hernández University breeding program for the introgression of virus resistance into Spanish landraces has already resulted in the release of two breeding lines, UMH 1200 and UMH 1203, both homozygous for Tm-2a, Ty-1, and Sw-5 genes (García-Martínez et al., 2011, 2012). These breeding lines allow farmers to obtain acceptable harvest under intense virus infection conditions. However, when compared with the original landraces under low virus incidence conditions, important yield decreases were obtained for these breeding lines, ranging between 50% and 75% decrease for UMH 1200 and between 40% and 50% for UMH 1203 (García-Martínez et al., 2011, 2012). These results are the result of the introgressed genes and/or to the linkage drag, as previously reported in processing tomatoes (Tanksley et al., 1998) and in fresh tomato (Rubio et al., 2012), although the yield problems are mainly the result of the introgression of the Ty-1 gene for Tomato yellow curl virus (TYLCV) resistance. For this reason, we have developed the breeding lines UMH 1422 and UMH 1415 without TYLCV resistance. The two lines are useful for tomato cropping in the spring to summer growing cycle, when the incidence of the viruses caused by TYLCV is less intense. Both lines have medium-sized fruits (70 to 90 g) with a bell shape and green shoulders (Fig. 1). Organoleptic characteristics of the fruits are similar to those of the original landrace. UMH 1422 is homozygous only for the Tm-2a resistance gene, whereas UMH 1415 is homozygous for the Tm-2a and Sw-5 resistance genes. These breeding lines obtained yields similar to the original landrace in several trials.