USVL-380, a Zucchini yellow mosaic virus-resistant Watermelon Breeding Line

in HortScience
Authors: Amnon Levi1 and Kai-shu Ling1
View More View Less
  • 1 U.S. Department of Agriculture, Agricultural Research Service, U.S. Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414

USVL-380 is a watermelon breeding line [Citrullus lanatus (Thunb.) Matsum. & Nakai] with resistance to the Zucchini yellow mosaic virus-Florida strain (ZYMV-FL) (Provvidenti, 1991; Provvidenti et al., 1984). This new breeding line is homozygous for the recessive eukaryotic elongation factor eIF4E allele associated with ZYMV resistance, identified in United States Plant Introduction (PI) 595203 (Harris et al., 2009; Ling et al., 2009). This breeding line was developed at the USDA, ARS, U.S. Vegetable Laboratory, Charleston, SC.

Origin

Development of USVL-380 was initiated in 2009 with the observation that the eukaryotic elongation factor eIF4E allele of the watermelon PI 595203 is associated with ZYMV-FL resistance (Harris et al., 2009; Ling et al., 2009). The USVL-380 was developed through a breeding plan that initially involved the construction of an F2 population derived from a cross between the ZYMV-FL-resistant PI 595203 (globular fruits with light green gray rind and white flesh with dense texture and slightly bitter taste and white seeds; Guner, 2004) and the highly susceptible heirloom watermelon cultivar New Hampshire Midget (Fig. 1). The phenotyping procedure for ZYMV resistance included stringent evaluation of disease symptoms for plants inoculated with ZYMV-FL in the greenhouse, an enzyme-linked immuno-sorbent assay (ELISA), and marker-assisted selection using two cleaved amplified polymorphic sequence (CAPS) markers of the eIF4E gene locus (CAPS1, CAPS2) and a sequenced characterized amplified region (SCAR) marker (designated as ZYRP) associated with ZYMV-FL resistance (Harris et al., 2009; Ling et al., 2009).

Fig. 1.
Fig. 1.

Pedigree of USVL-380 showing the route of incorporating the Zucchini yellow mosaic virus resistance gene locus into the genome of the watermelon cultivar Charleston Gray (Citrullus lanatus var. lanatus).

Citation: HortScience horts 52, 10; 10.21273/HORTSCI12292-17

Young F2 plants (2–3 leaf stage) were inoculated two times with ZYMV-FL, at 1 week apart between the two inoculations. The plants were evaluated at the end of the third week after the first inoculation. Plants that did not have any ZYMV symptoms and no virus presence in the ELISA test were selected for additional evaluation. DNA samples were isolated from these resistant F2 plants and were tested with the two CAPS markers and the ZYRP-SCAR marker associated with ZYMV-FL resistance mentioned previously. In contrast with ZYMV-susceptible control plants, including ‘Charleston Gray’ and ‘Desert King’, that were homozygous for the susceptible eIF4E allele or susceptible F2 plants that were homozygous or heterozygous for the susceptible eIF4E allele, the ZYMV-resistant plants were all homozygous for the eIF4E allele derived from PI 595203 (as shown in Fig. 2). Each of the resistant F2 plants was self-pollinated to produce an F3 family. Resistance to ZYMV was confirmed in homozygous resistant F3 families, and an F3 plant that showed no virus symptoms and no virus presence in an ELISA test and was confirmed to be homozygous for the eIF4E allele derived from PI 595203 (Fig. 2) was selected and crossed to ‘Charleston Gray’.

Fig. 2.
Fig. 2.

Genotyping of plants throughout the breeding process of USVL-380 using the CAPS-2 marker for the eIF4E allele. Genotyping of CAPS-2 was performed using the primer pair KL08-03, 5′-AAAGCTACACCCACGGAAGA and KL08-04, 5′-CTCCAGAACTCCTCGACAGTAG and by digestion of their polymerase chain reactions amplicon with restriction enzyme Pas I (as described by Harris et al., 2009; Ling et al., 2009). From left to right, lanes 1 (P) is the Zucchini yellow mosaic virus (ZYMV)-resistant PI 595203 parent (211 bp fragment). Lane 2 (N) is the susceptible watermelon cultivar Charleston Gray (268 bp fragment). Lane 3 is the F1 hybrid derived from crossing PI 595203 and ‘New Hampshire Midget’. Lanes 4–12 are susceptible (S) and resistant (R) F2 progeny. The R progeny are homozygous for the eIF4E allele (211 bp fragment) derived from the ZYMV-resistant PI 595203, whereas the ZYMV-S plants are heterozygous for the eIF4E allele, or homozygous for the eIF4E allele derived from the parent cultivar.

Citation: HortScience horts 52, 10; 10.21273/HORTSCI12292-17

Ten F1 plants derived from this cross were genotyped, and a plant that was confirmed to have the eIF4E allele of PI 595203 was self-pollinated to produce F2 seeds. Thirty young F2 plants were tested for ZYMV resistance, and a plant that showed no ZYMV symptoms and no virus presence in an ELISA test and was homozygous for the PI 595203 eIF4E allele was selected and backcrossed with ‘Charleston Gray’ to produce BC1 plants. A BC1 plant that contained the PI 595203 eIF4E allele was self-pollinated to produce BC1F2 seeds (Fig. 1). As described in the previous stage, 30 BC1F2 plants were evaluated, and a plant that showed no ZYMV symptoms and no virus presence in the ELISA test and was homozygous for the PI 595203 eIF4E allele was selected and further backcrossed with ‘Charleston Gray’ to produce BC2 seeds. The selection process was further advanced to produce BC2F2 seeds, and a resistant BC2F2 plant was selected and advanced through the aforementioned selection criteria in four generations to produce BC2F7 resistant plants, designated as USVL-380.

In greenhouse tests at the U.S. Vegetable Laboratory (Charleston, SC) during 2013 and 2014, the USVL-380 plants showed significantly higher resistance to ZYMV compared with the heirloom watermelon cultivars Charleston Gray or Desert King that were used as susceptible controls (Table 1).

Table 1.

Virus disease severity (mean and sd) for plants of the Zucchini yellow mosaic virus (ZYMV)-susceptible watermelon cultivars Charleston Gray and Desert King, the ZYMV-resistant PI 595203, and USVL-380.z

Table 1.

Description

USVL-380 is a sister line of USVL-370 and has the same breeding scheme for this ZYMV-resistant line (Levi et al., 2016). However, in contrast with the ovular watermelon fruit of USVL-370, USVL-380 has an elongated fruit, similar to the recurrent backcross parent ‘Charleston Gray’. USVL-380 has a slightly thick rind, similar to USVL-370 (rind thickness is 2.2–2.5 cm) (Tables 2 and 3). In field trials in Charleston, SC (2014–15), USVL-380 plants produced on average 1.2 large mature fruits per plant (Tables 2 and 3; Figs. 3 and 4) in mid-late season (78–82 d post-planting), comparable with ‘Charleston Gray’ or ‘Crimson Sweet’. The mature fruits of USVL-380 have light green-gray dappled rind, resembling that of ‘Charleston Gray’ (Fig. 4), and light red flesh color with a sweet flavor, but with a lower solid soluble content compared with traditional cultivars. The USVL-380 watermelon flesh is firm with a slightly crispy texture and does not exhibit hollow heart (Fig. 4). The fruit contains light brown seeds (7.0 mm long and 4 mm width). USVL-380 should be useful in breeding programs aiming to enhance resistance to potyviruses in watermelon cultivars.

Table 2.

Watermelon fruit characteristics for USVL-380 and cultivars grown in a field of the U.S. Vegetable Laboratory, Charleston, SC, in the Summer of 2014. Mean ± (sem).

Table 2.
Table 3.

Watermelon fruit characteristics for USVL-380 and cultivars grown in a field of the U.S. Vegetable Laboratory, Charleston, SC, in the Summer of 2015. Mean ± (sem).

Table 3.
Fig. 3.
Fig. 3.

USVL-380 fruits harvested in the field in Charleston, SC (Summer 2014).

Citation: HortScience horts 52, 10; 10.21273/HORTSCI12292-17

Fig. 4.
Fig. 4.

USVL-380 fruits harvested in the field in Charleston, SC (Summer 2015).

Citation: HortScience horts 52, 10; 10.21273/HORTSCI12292-17

Seed Availability

Small samples of seed of USVL-380 are available for distribution to interested research personnel and plant breeders who make written request to Drs. Amnon Levi or Kai-shu Ling, U.S. Vegetable Laboratory, 2700 Savannah Highway, Charleston, SC 29414-5334. Seed of USVL-380 will also be submitted to the National Plant Germplasm System where it will be available for research purposes, including the development and commercialization of new cultivars. It is requested that appropriate recognition of the source be given when this germplasm contributes to research or development of a new breeding line or cultivar.

Literature Cited

  • Guner, N. 2004 Papaya ringspot virus watermelon strain and Zucchini yellow mosaic virus resistance in watermelon. Dept. Hort. Sci., North Carolina State Univ., Raleigh, PhD Diss

  • Harris, K.R., Ling, K.S., Wechter, W.P. & Levi, A. 2009 Identification and utility of markers linked to the Zucchini yellow mosaic virus resistance gene in watermelon J. Amer. Soc. Hort. Sci. 134 529 534

    • Search Google Scholar
    • Export Citation
  • Levi, A., Harris-Shultz, R.K. & Ling, K. 2016 USVL-370, a Zucchini yellow mosaic virus–resistant Watermelon Breeding Line HortScience 51 107 109

  • Ling, K.S., Harris, K.R., Meyer, J.D.F., Levi, A., Guner, N., Wehner, T.C., Bendahmane, A. & Havey, M.J. 2009 Non-synonymous single nucleotide polymorphisms in the watermelon eIF4E gene are closely associated with resistance to Zucchini yellow mosaic virus Theor. Appl. Genet. 120 191 200

    • Search Google Scholar
    • Export Citation
  • Provvidenti, R., Gonsalves, D. & Humaydan, H.S. 1984 Occurrence of Zucchini yellow mosaic virus in cucurbits from Connecticut, New York, Florida, and California Plant Dis. 68 443 446

    • Search Google Scholar
    • Export Citation
  • Provvidenti, R. 1991 Inheritance of resistance to the Florida strain of Zucchini yellow mosaic virus in watermelon HortScience 26 407 408

Contributor Notes

Corresponding author. E-mail: amnon.levi@ars.usda.gov.

  • View in gallery

    Pedigree of USVL-380 showing the route of incorporating the Zucchini yellow mosaic virus resistance gene locus into the genome of the watermelon cultivar Charleston Gray (Citrullus lanatus var. lanatus).

  • View in gallery

    Genotyping of plants throughout the breeding process of USVL-380 using the CAPS-2 marker for the eIF4E allele. Genotyping of CAPS-2 was performed using the primer pair KL08-03, 5′-AAAGCTACACCCACGGAAGA and KL08-04, 5′-CTCCAGAACTCCTCGACAGTAG and by digestion of their polymerase chain reactions amplicon with restriction enzyme Pas I (as described by Harris et al., 2009; Ling et al., 2009). From left to right, lanes 1 (P) is the Zucchini yellow mosaic virus (ZYMV)-resistant PI 595203 parent (211 bp fragment). Lane 2 (N) is the susceptible watermelon cultivar Charleston Gray (268 bp fragment). Lane 3 is the F1 hybrid derived from crossing PI 595203 and ‘New Hampshire Midget’. Lanes 4–12 are susceptible (S) and resistant (R) F2 progeny. The R progeny are homozygous for the eIF4E allele (211 bp fragment) derived from the ZYMV-resistant PI 595203, whereas the ZYMV-S plants are heterozygous for the eIF4E allele, or homozygous for the eIF4E allele derived from the parent cultivar.

  • View in gallery

    USVL-380 fruits harvested in the field in Charleston, SC (Summer 2014).

  • View in gallery

    USVL-380 fruits harvested in the field in Charleston, SC (Summer 2015).

  • Guner, N. 2004 Papaya ringspot virus watermelon strain and Zucchini yellow mosaic virus resistance in watermelon. Dept. Hort. Sci., North Carolina State Univ., Raleigh, PhD Diss

  • Harris, K.R., Ling, K.S., Wechter, W.P. & Levi, A. 2009 Identification and utility of markers linked to the Zucchini yellow mosaic virus resistance gene in watermelon J. Amer. Soc. Hort. Sci. 134 529 534

    • Search Google Scholar
    • Export Citation
  • Levi, A., Harris-Shultz, R.K. & Ling, K. 2016 USVL-370, a Zucchini yellow mosaic virus–resistant Watermelon Breeding Line HortScience 51 107 109

  • Ling, K.S., Harris, K.R., Meyer, J.D.F., Levi, A., Guner, N., Wehner, T.C., Bendahmane, A. & Havey, M.J. 2009 Non-synonymous single nucleotide polymorphisms in the watermelon eIF4E gene are closely associated with resistance to Zucchini yellow mosaic virus Theor. Appl. Genet. 120 191 200

    • Search Google Scholar
    • Export Citation
  • Provvidenti, R., Gonsalves, D. & Humaydan, H.S. 1984 Occurrence of Zucchini yellow mosaic virus in cucurbits from Connecticut, New York, Florida, and California Plant Dis. 68 443 446

    • Search Google Scholar
    • Export Citation
  • Provvidenti, R. 1991 Inheritance of resistance to the Florida strain of Zucchini yellow mosaic virus in watermelon HortScience 26 407 408

All Time Past Year Past 30 Days
Abstract Views 167 0 0
Full Text Views 295 114 14
PDF Downloads 113 58 17