F. Dicenta and J.E. Garcia
P. Martínez-Gómez, M. Rubio, and F. Dicenta
The resistance to a Dideron isolate of Plum pox virus, which causes sharka disease, of four apricot (Prunus armeniaca L.) cultivars from North America (`Harlayne', `Henderson', `Sunglo', and `Veecot') and a Greek cultivar Lito (a cross of American cultivar Stark Early Orange × Greek cultivar Precoce Tirynthos) was evaluated. `Stark Early Orange' and `Canino', previously rated as resistant and susceptible respectively, were included as controls. Resistance, herein, was defined as inability to infect plants by graft-inoculation and negative assays by enzyme-linked immunosorbent assay. Cultivars found to be resistant were: `Harlayne', `Henderson', `Sunglo', `Lito', and `Stark Early Orange'. Cultivars Veecot and Canino were susceptible.
J. Egea, F. Dicenta, and L. Burgos
E. Ortega, J. Egea, and F. Dicenta
In almond [Prunus dulcis (Mill.) D.A. Webb], a high flower density and fruit set rate is important, because yield increases with higher fruit set ratio. Furthermore, because the ovule of some cultivars mature at anthesis, rapid pollination and pollen tube growth along the style are essential to ensure fertilization of a viable ovule. In this work, we studied the effective pollination period (EPP) of four almond cultivars of different bloom time by studying pollen tube growth and fruit set. EPP in almond was longer than in other fruit trees, and its duration was determined by stigma receptivity, which decreased with high temperature. An acceptable fruit set for all cultivars was obtained following pollination from day 0 to day 4 after emasculation.
P. Martínez-Gómez, M. Rubio, F. Dicenta, and T.M. Gradziel
Sharka [(plum pox virus (PPV)] mainly affects Prunus species, including apricot (Prunus armeniaca L.), peach (Prunus persica L.), plum (Prunus salicina Lindl., Prunus domestica L.), and, to a lesser degree, sweet (Prunus avium L.) and sour cherry (Prunus cerasus L.). Level of resistance to a Dideron isolate of PPV in seven California almond [P. dulcis (Miller) D.A. Webb], five processing peach cultivars, and two peach rootstocks was evaluated. In addition, almond and peach selections resulting from interspecific almond × peach hybridization and subsequent gene introgression were tested. Evaluations were conducted in controlled facilities after grafting the test genotypes onto inoculated GF305 peach rootstocks. Leaves were evaluated for PPV symptoms during three consecutive cycles of growth. ELISA-DASI and RT-PCR analysis were also employed to verify the presence or absence of PPV. Peach cultivars and rootstocks showed sharka symptoms and were ELISA-DASI or RT-PCR positive for some growth cycles, indicating their susceptibility to PPV. Almond cultivars and almond × peach hybrids did not show symptoms and were ELISA-DASI and RT-PCR negative, demonstrating resistance to PPV. Two (almond × peach) F2 selections as well as two of three backcrossed peach selections also showed a resistant behavior against the PPV-D isolate. Results demonstrate a high level of resistance in almond and indicate potential for PPV resistance transfer to commercial peach cultivars.
J. Egea, P. Martínez-Gómez, F. Dicenta, and L. Burgos
J. Egea, D. Ruiz, F. Dicenta, and L. Burgos
P. Martínez-Gómez, T.M. Gradziel, E. Ortega, and F. Dicenta
Almond [Prunus dulcis (Mill.) D.A. Webb] breeding programs require successful techniques for pollen storage. We studied the pollen viability of two almond cultivars, `Ramillete' and `Desmayo Largueta', during 8 weeks of storage, in conditions that simulated standard situations including storage at 4, 22, and 4 °C alternating with 22 °C (4 °C/22 °C). Viability remained at 60% or more for 2 weeks under all three conditions. After the second week, germination capacity decreased rapidly at 22 °C, but remained above 50% for as long as 8 weeks at 4 °C or 4 °C/22 °C.
F. Dicenta, P. Martínez-Gómez, E. Ortega, and H. Duval
The effect of pollinizer on sweet or bitter almond flavor was studied by tasting the seeds obtained from 32 crosses between sweet, bitter, and slightly bitter parents. Out of eight female parents, two were homozygous sweet (`Del Cid' and `Aï'); two were heterozygous sweet (`Marcona' and `Nonpareil'); one heterozygous with an almost undetectable slightly bitter flavor (`Ferrastar'); two heterozygous slightly bitter (`Garrigues' and `Marie Dupuy'); and one bitter homozygous (`S3067', self-compatible clone obtained in CEBAS). Each cultivar was hand-pollinated with four male cultivars: one homozygous sweet (`Ramillete'), one heterozygous sweet (`Atocha'), one heterozygous slightly bitter (`Garrigues'), and one homozygous (`S3067'). Since `Garrigues' is self-incompatible, the cross `Garrigues' × `Garrigues' was replaced by `Garrigues' × `S3065' (slightly bitter clone obtained in CEBAS). Tasting of the seeds resulting from each cross resulted in the complete absence of any influence of pollinizer on flavor, which only depended on the female parent.