Details

Autor(en) / Beteiligte

• DE OLIVEIRA, Ana Claudia B
• MALUF, Wilson R
• PINTO, José Eduardo B. P
• AZEVEDO, Sebastiao M

Titel

Resistance to papaya ringspot virus in summer squash Cucurbita pepo L. introgressed from an interspecific C. pepo x C. moschata cross

Ist Teil von

• Euphytica, 2003-07, Vol.132 (2), p.211-215

Ort / Verlag

Dordrecht: Springer

Erscheinungsjahr

2003

Link zum Volltext

Quelle

SpringerLink (Online service)

Beschreibungen/Notizen

• Early infections of the papaya ringspot virus-watermelon strain (PRSV-W) in summer squash Cucurbita pepo may cause marketable yield losses of up to 100%. Because control of the viral disease via management of vector insects is not efficient, incorporation of PRSV-W genetic resistance into C. pepo cultivars would be highly desirable. Although resistant accessions have been described in C. ecuadorensis, C. foetidissima, C. maxima and C. moschata, resistant accessions of C. pepo are rare. This paper reports on interspecific hybridization between C. pepo and a PRSV-W-resistant C. moschata squash accession, and on the early steps in introgression of this resistance into the former species. C. pepo cv. Asmara was crossed with two PRSV-W resistant C. moschata accessions. Immature F sub(1) (C.pepo x C.moschata) embryos were excised 20 days after pollination, and cultured asseptically in two different culture media, each under two different light regimes. No adult plants could be recovered from immature embryos of the cross C. pepo cv. Asmara x C. moschata cv. Piramoita. From the cross C. pepo cv. Asmara x C. moschata cv. Duda, 4 seedlings were recovered from 6 embryos incubated in a growth chamber [25 degree to 28 degree C, 16 hours of light with 1500-2000 lux/ 8 h dark period] immediately after excision and inoculation in a culture medium [= Murashige and Skoog (MS) + 0.01 mg/L of IAA (indolacetic acid) + 0.1 mg/L of Kinetin], without an intervening dark period. F sub(1) (C. pepo x C. moschata) plants were fertile, and upon selfing yielded viable F sub(2) seeds. PRSV-W resistance was assessed in the F sub(2) (C. pepo x C. moschata) population, using C. pepo cv. Asmara and C. moschata cv. Duda, respectively, as the susceptible and resistant (tolerant) checks. Plants were mechanically inoculated with a known PRSV-W isolate. The F sub(2) population showed a PRSV-W response intermediate between those of the parental accessions, and estimates of the mean degree of dominance indicates incomplete dominance in the direction of susceptibility. The mean broad-sense heritability estimate of PRSV-W resistance was 0.48, a medium to high value, indicating the likelihood of a significant response to selection for resistance. The introgression of the resistance to PRSV-W of C. moschata into C. pepo seems to be technically viable.