CULTIVAR AND GERMPLASM RELEASES The U.S. Department of Agriculture, Ag- ricultural Research Service, announces the release of three novel watermelon [Citrullus lanatus (Thumb.) Matsum. & Nakai] breeding lines:USVL-200, USVL-205, and USVL-2 10. These lines contain the nuclear genome of cultivated watermelon (C. lanatus var. lanatus) and chloroplast and mitochondrial genomes derived from the desert species C. colocynthis (L.) Schrad. Efforts to develop these breeding lines were initiated in 1999 with our greenhouse observation of plants derived from reciprocal crosses between U.S. plant introductions (PIs) of the wild desert species and watermelon cultivars. We observed that when a watermelon cultivar was the female parent, all F, plants produced one female flower for every 5 to 9 male flowers. In contrast, when a wild desert plant (P1 386015 or P1 386016) was the female parent, all F, plants (8 to 12 F, plants in each cross) produced a higher number of female flowers (one female for every 2 to 4 male flowers). This ratio of one female for every 2 to 4 male flowers was retained in the BC, and BC, when the F, plant was used as the female parent and a watermelon cultivar ('Allsweet', 'Charleston Gray', 'Crimson Sweet', or 'New Hampshire Midget') was the recurrent male parent. However, the ratio of female flowers was reduced to one female flower for every 4 to 7 male flowers in BC, through BC,. These results suggest that, in addition to nuclear genes, the maternal plant cytoplasm [most likely chloroplast or mitochondrial genes, which are known to be maternally inherited in most plant species (Havey et al. 1998)] may affect female flower production in watermelon. Nucleo- cytoplasmic interaction in sex inheritance has been observed in various plant species (Ehlers et al., 2005; Van der Hulst et al. 2004; Wade and McCauley, 2005). Received for publication 23 Oct. 2005. Accepted for publication 11 Nov. 2005. Use of trade names does not imply endorsement of the products names nor criticism of similar ones not named. 'Corresponding author; e-mail_alevi@saa.ars.usda. gov. Chloroplasts and mitochondria are mater- nally inherited in crosses between cultivated watermelon and the related subspecies C. lanatus var. citroides (Havey et al., 1998). Our experiments, using DNA markers, confirmed that chloroplast and mitochondria are mater- nally inherited in crosses between cultivated watermelon and the wild desert species (Levi andThomas, 2005). In addition, this study con- firmed that the chloroplast and mitochondrial genomes ofthe wild desert species are retained in successive backcrosses, where a watermelon cultivar is the recurrent male parent and the backcross plant (carrying the the wild desert species chloroplast and mitochondrial ge- nomes) is the female parent (Levi and Thomas, 2005; A. Levi, unpublished data). Origin USVL-200 was produced by first cross- ing an F, hybrid ['New Hampshire Midget' (C. lanatus var. lanatus) x Griffin 14113 (C. lanatus var. citroides)] with the wild desert Pt 386015 as the female parent. Then, most of the nuclear genes of the F, hybrid plant were replaced with the nuclear genes of cultivated watermelon through a series of successive backcrosses with different watermelon culti- vars. The watermelon cultivars that were used as the male (pollinator) parents in the eight successive backcrosses were 1) 'Allsweet', 2) 'Charleston Gray', 3) 'Minilee', 4) 'Allsweet', 5) 'Charleston Gray', 6) 'Black Diamond', 7) 'New Hampshire Midget', and 8) 'Black Dia- mond'. Then, a BC,-S, was self-pollinated and a plant with yellow flesh fruit was selected in five successive generations to produce USVL- 200 seeds (BC5S6). USVL-205 is a sister line of USVL-200. It was developed by self-pollinating a BC5S, plant, and a plant with red flesh fruit was se- lected in six successive generations to produce USVL-205 seeds (BC, S7)' USVL-210 was produced by first cross- ing 'Charleston Gray' with the wild desert P1386016 (female parent). Then, most of the nuclear genes of the F, hybrid plant were re- placed with those of the cultivated watermelon through a series of six successive backcrosses with watermelon cultivars that were used as the male parents. The watermelon cultivars that were used in the six successive back- crosses to replace the the wild desert species nuclear genome were 1) 'Charleston Gray', 2) 'Calhoun Gray', 3) 'Charleston Gray', 4) 'Crimson Sweet', 5) 'NewflampshireMidget', and 6) 'Charleston Gray'. A BC 6 S, plant was self-pollinated, followed by self-pollination and selection of the plant with best fruit qual- ity in five successive generations to produce USVL-210 seeds (BC656). Description and Performance USVL-200 and USVL-205 produce one female flower for every 5 to 7 male flowers. Each of the plants of these breeding lines pro- duced three fruit in the field in Charleston, S.C., during Summers 2004 and 2005. USVL-200 and USVL-205 produce globular fruit with a thick, dark-green rind. USVL-200 has a yel- low-pink flesh with a firm texture devoid of hollow heart, while USVL-205 has the same fruit characteristics except for having a red flesh (Table 1, Fig. I). The fruit of USVL-200 and USVL-205 have an intermediate solid soluble content (Table 1) and are not as sweet as the cultivars used in their development ('Alls- weet', 'Charleston Gray', 'Minilee', 'Black Diamond', and 'New Hampshire Midget'). The fruit of these two lines are ready for har- vest in early to midseason, similar to 'New Hampshire Midget'. USVL-210 is a 'Charleston Gray'-type watermelon. Typical fruit are oblong with light green to gray rind and a pink flesh color (Fig. 1). The flesh has a pleasant flavor and an intermediate-high content of soluble sol- ids (Table 1). USVL-210 plants produce one female flower for every 7 to 10 male flowers, similar to 'Charleston Gray'. An average yield of USVL-2 10 plants, in the field in Charleston (during Summers 2004 and 2005), was 2.6 to 3 fruit per plant. Overall, fruit of USVL-210 have thick rind, crispy flesh texture, and do HORTSCIENCE 41(2):463-464. 2006. Novel Watermelon Breeding Lines Containing Chioroplast and Mitochondrial Genomes derived from the Desert Species Citrullus colocynthis Amnon Levi,' Claude E. Thomas, Judy A. Thies, Alvin M. Simmons, Kai-Shu Ling, and Howard F. Harrison U. Department ofAgriculture, Agricultural research Service, U. Vegetable Laboratory, 2700 Savannah Highway Charleston, SC 29414 Richard Hassell and Anthony P. Keinath Clemson University, Coastal Research and Education Center 2700 Savannah Highway, Charleston, SC 29414 Table I. Fruit characteristics of the three breeding lines. Characteristic USVL-200 USVL-205 USVL-2 10 Fruit shape Globular Globular Elongated Fruit size (cm) 25 x 23 25 X 23 42 x18 Fruit weight (lb) 17.5 17.5 14.3 Rind color Dark green Dark green Light green—gray Flesh color Yellow—pink Pink—red Pink Flesh texture Firm Firm Slightly crispy Soluble solids (%)Z 6-8.5 6-8.5 8.5-10 Seeds Larce. brown Large, brown Small, light brown 'Measured by a refractometer. 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