UMH 916, UMH 972, UMH 1093, UMH 1127, and UMH 1139: Four Fresh- market Breeding Lines Resistant to Viruses Within the Muchamiel Tomato Type

Abstract

Muchamiel is a tomato (Solanum lycopersicum L.) landrace of Marmande type, very popular in southeastern Spain due to its excellent organoleptic fruit quality. Fruits of the Muchamiel cultivars are medium-large in size (150–300 g), multilocular (five or more locules), flattened and strongly ribbed, green shoulder, and red flesh. The melting texture and mild flavor of these fruits makes them highly valued in salads. However, the incidence of several viruses as Tomato mosaic virus (ToMV), Tomato spotted wilt virus (TSWV), and Tomato yellow leaf curl virus (TYLCV) can make the Muchamiel (and other) landraces cultivation nonviable in many areas, especially in open field (Picó et al., 2002). The Miguel Hernández University breeding program for the introgression of virus into Spanish landraces has resulted in the release of the UMH 1200 breeding line, homozygous for Tm-2a, Ty-1, and Sw-5 genes (García-Martínez et al., 2011). This breeding line allows farmers to obtain an acceptable harvest with intense virus incidence conditions. However, important yield decreases (ranging between 50% and 75%) have been reported for UMH 1200 with low virus incidence conditions (García-Martínez et al., 2011). This result is due to the introgressed genes and/or to the linkage drag, as previously has been reported in processing tomatoes (Tanksley et al., 1998). The introgression of the TYLCV resistance is responsible for most of the yield decrease obtained in fresh tomato (Rubio et al., 2012). For this reason, we have developed breeding lines without TYLCV resistance. UMH 916 and UMH 972 have genetic resistance to ToMV, whereas UMH 1127 and UMH 1139 have genetic resistance to ToMV and TSWV. The four breeding lines showed similar or better marketable yield than the traditional cultivar Muchamiel 18 (M18) and the breeding line UMH 1200.