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- Author or Editor: U. Lavi x
In examining the adenosine triphosphate (ATP) synthesizing system in seeds, an inhibitory effect of seeds on luciferase activity was detected (4). This study describes possible use of the luciferin-luciferase system for a better definition of the amount of seed traces in grape berries. With growing consumer preference for seedless table grapes and raisins, breeding of stenospermocarpic grape cultivars is of great interest. Stenospermocarpic grapes yield considerably larger seedless berries than parthenocarpic ones, but also often possess seedcoats that develop into hard, stony tissue (2). An objective definition of the amount of seed rudiments would be of considerable value in breeding for seedlessness and in assessing environmental or plant growth regulator effects.
Shortening the juvenile period is highly important for fruit tree breeding projects. Four girdling dates were tested in an attempt to shorten the juvenile period in 9 crosses of 3-year-old avocado (Persea americana Mill.) seedlings. Early September girdling was more effective than later or no girdling. It increased flowering intensity significantly, increased the percentage of seedlings that set from 15% to 66%, and increased 7-fold the number of fruits harvested per seedling as compared with the ungirdled control.
Application of four DNA fingerprint probes to avocado (Persea americana Mill.) resulted in identification of various cultivars, characterization of the three avocado races, and a genetic analysis of family structure. Genomic DNA from 14 cultivars was probed with four DNA fingerprint probes. Three of the probes gave well-resolved bands. The individual-specific patterns obtained for each cultivar validate the use of this technique for definitive cultivar characterization, with the probability of obtaining a similar pattern for two different cultivars being 2 × 10-9. DNA mixes representing either Mexican, Guatemalan, or West-Indian avocado races were hybridized with the DNA fingerprint probes, and a band pattern characteristic for each race was obtained. Progeny of a cross between the cultivars Ettinger and Pinkerton were analyzed. Their DNA fingerprints revealed one pair of linked bands and another band allelic to one of them. The application of these observations to identification, evolutionary studies, and breeding is discussed.
DNA fingerprint information was used for identification of mango (Mangifera indica L.) cultivars for genetic relatedness analysis of20 mango cultivars and for genetic analysis of a family structure. Genomic DNA was extracted from young leaves, digested with Hind III or Dra I, and hybridized with 10 different DNA probes. Jeffreys' minisatellite probe 33.6 was the most useful, resulting in well-resolved bands representing highly polymorphic loci. Specific patterns were obtained for each cultivar. The probability of obtaining a similar pattern for two different cultivars was 9.4 × 10-6. Based on DNA fingerprint information, genetic distances between 20 mango cultivars were evaluated and an evolutionary tree was established. Analysis of DNA fingerprint band patterns of 12 progeny resulting from a cross between `Tommy Atkins' and `Keitt' mango revealed neither linked nor allelic bands. Application of the reported results for identification, genetic analyses, and mango breeding is discussed.
Normal embryos and seedling plants were obtained from abortive ovules and seeds of seedless grape cultivars ‘Perlette’, ‘Flame Seedless’ and ‘Sultanina’. Plant development was accompanied by callus formation only in ‘Perlette’. The best medium was Nitsch’s with the addition of 10-5 m IAA and 10-6 m GA3. Excision and culturing of ‘Flame Seedless’ ovules 49 days after anthesis gave higher germination percentages and more viable plants than excision and culturing at anthesis plus 28. Selfed ‘Perlette’ and ‘Perlette’ × ‘Flame Seedless’ ovules cultured at 52 days gave 11%, and the reciprocal cross over 16% well developed seedlings. The significance of the findings for breeding stenospermocarpic grapes is discussed.