Pedigree analysis of 220 almond genotypes reveals two world mainstream breeding lines based on only three different cultivars

Loss of genetic variability is an increasing challenge in tree breeding programs due to the repeated use of a reduced number of founder genotypes. However, in almond, little is known about the genetic variability in current breeding stocks, although several cases of inbreeding depression have been reported. To gain insights into the genetic structure in modern breeding programs worldwide, marker-verified pedigree data of 220 almond cultivars and breeding selections were analyzed. Inbreeding coefficients, pairwise relatedness, and genetic contribution were calculated for these genotypes. The results reveal two mainstream breeding lines based on three cultivars: “Tuono”, “Cristomorto”, and “Nonpareil”. Descendants from “Tuono” or “Cristomorto” number 76 (sharing 34 descendants), while “Nonpareil” has 71 descendants. The mean inbreeding coefficient of the analyzed genotypes was 0.041, with 14 genotypes presenting a high inbreeding coefficient, over 0.250. Breeding programs from France, the USA, and Spain showed inbreeding coefficients of 0.075, 0.070, and 0.037, respectively. According to their genetic contribution, modern cultivars from Israel, France, the USA, Spain, and Australia trace back to a maximum of six main founding genotypes. Among the group of 65 genotypes carrying the Sf allele for self-compatibility, the mean relatedness coefficient was 0.125, with “Tuono” as the main founding genotype (24.7% of total genetic contribution). The results broaden our understanding about the tendencies followed in almond breeding over the last 50 years and will have a large impact into breeding decision-making process worldwide. Increasing current genetic variability is required in almond breeding programs to assure genetic gain and continuing breeding progress

Genetic analysis for physical nut traits in almond

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Engins de pêche pour l'ichthyoplancton : résultats des essais comparatifs réalisés en 1974 et 1975

The results of comparisons between several zooplankton samplers are summarised.Vengono riportate in modo coinciso le indicazioni emerse da numerose serie di prove comparative tra diversi attrezzi per la pesca dell'ittioplancton in due aree deI Mediterraneo occidentale

Relationship between almond bitterness and resistance to capnode

5 pages.-- En: ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds.Capnode (Capnodis tenebrionis L.) is one of the main pests that affect fruit trees in the Mediterranean basin and other semi-arid areas around the world. Some studies seem to show a relationship between kernel bitterness, presence of cyanogenic compounds in roots and resistance to capnode. In this work we studied prunasin content and the resistance to capnode grubs of almond descendants of different genotypes with respect to bitterness: SS (sweet) ['Peraleja' (SS) x 'Ramillete' (SS)]; ss (bitter) [S3064 (ss) x S3067 (ss)] and Ss (sweet or slightly bitter) [S3064 (ss) x 'Ramillete' (SS)]. Three months after having inoculated the plants with neonate grubs, incidence of damage in roots and presence of grubs were determined. Afterwards, prunasin content in the roots was determined by HPLC. The results showed that the damage level was similar in the three families. The prunasin contents seemed to be independent of kernel bitterness and behaved as a quantitative trait. The lack of relationship found between prunasin contents and damage in roots might be due to an anomalous low incidence of capnode grubs in the roots.Peer reviewe

Relationship between almond bitterness and resistance to capnode

5 pages.-- En: ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds.Capnode (Capnodis tenebrionis L.) is one of the main pests that affect fruit trees in the Mediterranean basin and other semi-arid areas around the world. Some studies seem to show a relationship between kernel bitterness, presence of cyanogenic compounds in roots and resistance to capnode. In this work we studied prunasin content and the resistance to capnode grubs of almond descendants of different genotypes with respect to bitterness: SS (sweet) ['Peraleja' (SS) x 'Ramillete' (SS)]; ss (bitter) [S3064 (ss) x S3067 (ss)] and Ss (sweet or slightly bitter) [S3064 (ss) x 'Ramillete' (SS)]. Three months after having inoculated the plants with neonate grubs, incidence of damage in roots and presence of grubs were determined. Afterwards, prunasin content in the roots was determined by HPLC. The results showed that the damage level was similar in the three families. The prunasin contents seemed to be independent of kernel bitterness and behaved as a quantitative trait. The lack of relationship found between prunasin contents and damage in roots might be due to an anomalous low incidence of capnode grubs in the roots.Peer reviewe

Susceptibility of almond seedling rootstocks to capnode

5 pages,-- En: ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds.Almond rootstocks, particularly the bitter almond, have been described as more resistant to capnode (Capnodis tenebrionis L.) than other species. This work looks into the susceptibility of seedling rootstocks of the almond cultivars 'Garrigues', 'Atocha' and 'Desmayo Largueta' to grubs of capnode. Three months after the plants were inoculated with neonate grubs, damage in roots and presence of grubs were observed. Subsequently, roots were analysed by HPLC to determine prunasin content. Although a large variability was observed, 'Desmayo Largueta' seedlings were the most susceptible whereas 'Garrigues' seedlings were the most resistant. The results showed a high correlation between presence of grubs and damage in roots but there was no correlation between root damage and the content of prunasin. Obtaining seedling rootstocks from open pollination could be a tool for breeding almond rootstocks for resistance to capnode, mainly using the traditional Garrigues as female parent.Peer reviewe

Susceptibility of ´real fino´and ´canino´apricot seedlings to capnode

En: XII International Symposium on Apricot Culture and Decline, Avignon (France). Editor: J.M. Audergon.Apricot (Prunus armeniaca L.) rootstocks have been described as more susceptible to capnode (Capnodis tenebrionis L.) than other species of Prunus. In Spain, ‘Real Fino’ and ‘Canino’ seedlings are the two most important rootstocks for apricot. In this work the susceptibility of seedlings of these cultivars to capnode grubs was studied. Damage and presence of grubs in roots were observed three months after inoculating the plants with eggs of capnode. Subsequently, roots were analysed by HPLC to determine the prunasin contents. The results showed a high variability among the seedlings in both cultivars regarding damage in roots and prunasin contents. Furthermore, a high correlation between resistance to capnode grubs and prunasin content in roots was observed. This relationship would allow the breeding of new resistant rootstocks from these cultivars, which could be propagated by vegetative reproduction.Peer reviewe

The influence of previous self-pollination on later cross-pollination in self-incompatible almond cultivars

3 pages.The effect of previous self-pollination in self-incompatible almond cultivars on later poflen germination, pollen tube growth. and fruit set when pollen of a cross-compatible cultivar reached the stigma, was studied. Two self-incompatible almond cultivars, Garrigues and Ramillete, were self-pollinated and later pollinated with pollen from the cross-compatible cultivar Desmayo Largueta. Pistils were collected up 72 h after pollination in the laboratory and 120 h after field pollination. The pistils were observed later by fluorescence microscopy. Ten weeks later, fruit set was determined in field. No important effect of previous self-pollination on the number of pollen grains germinated on the stigma, the number of pollen tubes in the ovary or fruit set was observed. So, the previous self-pollination of self-incompatible almond cultivars does not affect the fruition process in almond.Peer reviewe