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Abstract
The selection of olive (Olea europaea L.) cultivars goes back to early biblical times. The main objectives were high oil content and regional adaptability. Subsequently, olive cultivars were selected also on a size basis for table consumption. In the last hundred years, form and size of green table olives became even more important than their oil content, but still, the minimum oil content was not lower than 7 to 8% oil of fresh wt for green ripe fruit. Selection for low-oil-content olives has not been attempted in the past. However, with diet consciousness and increased awareness of public health, the development of low-oil-content olive, particularly for dietetic use is of interest. This release describes a new olive named ‘Kadesh’ with extrem ely low oil content, yield stability, and relatively easy rooting (1).
Several groups of chemicals were tested for their effect on grapevine bud dormancy. Single-node cuttings were treated with hydrogen cyanamide and several of its derivatives, the respiratory inhibitors DNOC and azide, the alcohols 2-chloro ethanol and ethanol alone or in combination with cyanamide, the peroxide H2O2, Various sulfhydryls, the heribicides 3-amino triazol and paraquat and two inhibitors of polyamine biosynthesis. Although in each of these groups were active dormancy breaking agents which could be related to defined pathways, it became clear that the activity of these chemicals is specific and only partialy dependent on the common chemical configuration. It seems that in most cases the degree of activity could be related to their relation with peroxide scavenging activity or level of oxidation in the bud tissue.
The performance of five cv. Souri selections designated as “clones” were compared in two consecutive plots for ≈20 years each and three additional ones for 18 years. Fruit morphology, yield, oil production, and tree growth were monitored. The major results are presented as mean values of five sequential “on” years as well as the characteristic production of young and mature trees. The DNA identity was determined using both simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs). The performance of two “clones,” SLO and SBU, showed stable diverse production characteristics and could be designated as defined clones, although no clear differences of the DNA between them or the other “clones” were apparent. Another “clone,” SGS, was also designated as a true clone as a result of both unique fruit morphology and DNA markers. The differences between the other “clones” were minute in fruit production morphology and oil production as well as on a DNA basis and their designation as being true clones is doubtful.
A sequence-tagged site (STS) was developed to identify a genetic marker linked to resistance to olive leaf spot caused by the pathogen, Spilocea oleaginea (Cast) (syn. Cycloconium oleaginum Cast.). The STS was based on a randomly amplified polymorphic DNA (RAPD) marker of about 780 base pairs (bp) linked to olive leaf spot resistance. Several primer pairs were developed to flank the sequence, and one pair produced the expected polymorphism between resistant and susceptible individuals tested, and was used as an STS marker. This primer pair was tested against parents and 34 individuals from a population segregating for resistance to olive leaf spot, and 12 commercial olive (Olea europaea L.) cultivars showing various levels of resistance to the disease. The STS marker was present in 71.4% of the parents and progeny that were designated as resistant, and was absent in 87% of the parents and progeny showing susceptibility. These primers were also able to distinguish cultivars such as `Koroneiki' and `Leccino', that are reported to show resistance to olive leaf spot, from `Barouni' and `Mission', that are reported to be susceptible. This is the first report of a STS marker for olive, and its use will assist greatly in screening olive progeny for resistance to leaf spot in breeding programs.
Olive leaf spot is a disease of olive (Olea europaea L.) caused by the fungal pathogen, Spilocea oleaginea Cast. Progeny derived from crosses among susceptible, resistant, and semiresistant parental lines were assessed in the field for 8 years and classified as either resistant or susceptible. DNA from some of the progeny of this segregating population was used to identify molecular markers linked to olive leaf spot disease using the randomly amplified polymorphic DNA (RAPD) technique and bulked segregant analysis (BSA). Two DNA bulks were constructed, each containing 13 progeny showing either resistance or susceptibility for the disease, and screened for polymorphisms using 100 primers. One primer produced two polymorphic bands, one of ≈700 base pairs (bp) from the susceptible bulk and the other of ≈780 bp from the resistant bulk. The 780 bp marker appeared in 70.6% of the segregating progeny and 100% of parents showing resistance to leaf spot disease, while the 700 bp marker appeared in 47.1% of the segregating progeny and 100% of the parents showing susceptibility. These markers can be used as screening tools in olive improvement programs.