New Breeding Lines Resistant to Tomato Mosaic Virus and Tomato Spotted Wilt Virus within the ‘De la Pera’ Tomato Type: UMH 1353 and UMH 1354

Abstract

‘De la pera’ is a tomato landrace that is very popular in a limited area in southeastern Spain. The fruits from this landrace are juicy and have a firm texture, a strong flavor, and a high proportion of seeds and mucilage. The fruit weight ranges between 75 and 125 g, and fruits are elongated-oval to bell-like in shape, with dark green shoulders and no ribs. Like all tomato landraces, De la pera cultivars are highly susceptible to several viruses, such as Tomato mosaic virus (ToMV), Tomato spotted wilt virus (TSWV), and Tomato yellow leaf curl virus (TYLCV) (Picó et al., 2002). A breeding program for introgression of resistance to ToMV, TSWV, and TYLCV into several tomato landraces has been carried out over the last 15 years at the Miguel Hernández University (Spain). The breeding line UMH 1203, homozygous for Tm-2a, Ty-1, and Sw-5 genes, was the first obtained within the ‘De la pera’ tomato type (García-Martínez et al., 2012). This breeding line has enabled farmers to obtain acceptable harvests despite intense virus incidence conditions. Nevertheless, important decreases in yield have been reported for this breeding line, ranging between 40% and 50% at low virus incidence conditions (García-Martínez et al., 2012). These results are likely due to introgressed genes and/or linkage drag from the wild tomato species from which the resistance genes originally come, as has been previously reported in processing tomatoes (Tanksley et al., 1998) and in tobacco (Lewis et al., 2007). Previous work indicates that the introgression of TYLCV resistance has been responsible for most of the decrease in yield obtained in fresh tomatoes (Rubio et al., 2012). For this reason, breeding lines UMH 1422 (with only ToMV resistance) and UMH 1415 (with ToMV and TSWV resistance) were developed (García-Martínez et al., 2014). These lines have shown better marketable yields than UMH 1203 and yields similar to those of the traditional De la pera cultivar 21 (P21). Furthermore, the new breeding lines UMH 1353 and UMH 1354 are available for cropping in the spring-summer crop cycle, when the level of TYLCV incidence is lower. These new breeding lines UMH 1353 and UMH 1354, with genetic resistance to ToMV and TSWV, have shown higher marketable yields than the previously developed breeding lines UMH 1422 and UMH 1415 (around 35% greater in open field trial and ranging between 15% and 20% greater in mesh-covered net house trials) (Table 1).