93 research outputs found
Effect of a traditional control method (tree removal) on the spread of sharka in an apricot orchard in Southeastern Spain
The spatial spread of sharka disease (Plum pox virus, PPV) was studied from 1990 to 2002 in a traditional
apricot (Prunus armeniaca L.) orchard located in Murcia (Southeast of Spain). The occurrence of sharka was
determined by the visual observation of symptoms on leaves and fruits during the ripening stage, when symptoms
are most visible. To ascertain PPV in doubtful samples, an ELISA-DASI assay was applied to the leaves. All trees
infected the previous year were pulled up and were not replanted. Results showed that the virus was introduced to
the farm by natural vectors (aphids) from a neighbouring sharka-infected plum orchard. It was then transmitted
from these infected trees mainly to nearby trees by the same vectors, although also often to trees standing quite a
distance away. The long interval between infection and symptom appearance makes eradication of the disease more
difficult. Pulling up infected trees as a control method reduced the percentage of trees ultimately lost, and over the
long term could stop the further spread of the disease
Effect of a traditional control method (tree removal) on the spread of sharka in an apricot orchard in Southeastern Spain
The spatial spread of sharka disease (Plum pox virus, PPV) was studied from 1990 to 2002 in a traditional
apricot (Prunus armeniaca L.) orchard located in Murcia (Southeast of Spain). The occurrence of sharka was
determined by the visual observation of symptoms on leaves and fruits during the ripening stage, when symptoms
are most visible. To ascertain PPV in doubtful samples, an ELISA-DASI assay was applied to the leaves. All trees
infected the previous year were pulled up and were not replanted. Results showed that the virus was introduced to
the farm by natural vectors (aphids) from a neighbouring sharka-infected plum orchard. It was then transmitted
from these infected trees mainly to nearby trees by the same vectors, although also often to trees standing quite a
distance away. The long interval between infection and symptom appearance makes eradication of the disease more
difficult. Pulling up infected trees as a control method reduced the percentage of trees ultimately lost, and over the
long term could stop the further spread of the disease
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: âTuonoâ, âCristomortoâ, and âNonpareilâ. Descendants from âTuonoâ or âCristomortoâ number 76 (sharing 34 descendants), while âNonpareilâ 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 âTuonoâ 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
Peer ReviewedPublishe
CaracterizaciĂłn de embriones mĂșltiples en almendro
Multiple embryos within the same tegument occur spontaneously in certain almond [Prunus dulcis (Mill.) D.A. Webb]cultivars including Nonpareil and Mission. Seedlings from the same polyembryonic seed are frequently viable, thoughoften one of the seedlings shows weak growth and develops poorly. These dwarf seedlings have been characterised in aprevious work as haploid. In this work, we have characterised 450 seedlings from polyembryonic seeds of the Californiancultivar Nonpareil, and 100 seedlings from polyembryonic seeds of the Spanish selections D97396 and D97407,including their germination and later growth. Isozyme and Simple Sequence Repeat markers were used to geneticallyanalyse seedling genetic structure. In addition, individual mitotic karyotypes were determined following staining of roottips. The percentage of twin embryos showing aberrant growth was approximately 25% with mortality rates of about 90%.Results suggested the sexual origin of both embryos. Seedlings from the same seed are genetically identical with a similargrowth, though often one of the seedlings from the secondary embryo loses part of the genomic contents and becomesan aneuploid plant and showed a weak development. The use of this material in almond breeding is also discussed.La apariciĂłn de embriones mĂșltiples dentro del mismo tegumento es un fenĂłmeno espontĂĄneo que ocurre en semillas de algunas variedades de almendro [Prunus dulcis (Mill.) D.A. Webb] como "Nonpareil" o "Mission". Las plĂĄntulas procedentes de estas semillas poliembriĂłnicas son viables, aunque a menudo muestran un crecimiento mĂĄs debil y retrasado. Estas plĂĄntulas enanas han sido caracterizadas como haploides en trabajos previos. En este trabajo hemos estudiado 450 plĂĄntulas procedentes de semillas poliembriĂłnicas de la variedad californiana "Nonpareil" y 100 plĂĄntulas procedentes de semillas poliembriĂłnicas de las selecciones españolas "D97396" y "D97407", observando su germinaciĂłn y posterior crecimiento. Estas plĂĄntulas han sido caracterizadas molecularmente mediante marcadores isoenzimĂĄticos y microsatĂ©lites (...
Breaking dormancy of GF305 peach and Real Fino apricot trees during the evaluation of resistance to sharka (plum pox potyvirus)
In countries like Spain or France, where sharka (plum pox potyvirus) is not as
widespread as it is in Greece or Central Europe, experiments to evaluate apricot
resistance have to be carried out in controlled conditions using insect-proof
greenhouses. One of the most important aspects of such growth conditions is the
application of periods of artificially induced dormancy in cold chambers so that tree
species from temperate zones can undergo the necessary endodormancy-breaking step. In
the experiment described in this paper, GF305 peach and Real Fino apricot seedlings
were exposed to artificial periods of cold (7 C) and darkness lasting 3 to 12 weeks
(between 504 and 2016 hours of cold) in order to determine the optimum period for
subsequent good vegetative growth. After removal from the cold chamber, the plants
were placed in a greenhouse and weekly recordings were made of the percentage of leaf
buds sprouted and vegetative growth. The optimal periods were found to be 5 weeks
(840 hours of cold) for GF305 and 8 weeks (1344 hours of cold) for Real Fino.LevĂ©e de dormance du pĂȘcher GF305 et de l'abricotier Real Fino pendant l'Ă©valuation de
la résistance à la sharka (plum pox potyvirus). Dans des pays comme la France ou
l'Espagne, oĂč la sharka n'est pas aussi rĂ©pandue qu'en GrĂšce ou en Europe Centrale,
les expĂ©riences pour Ă©valuer la rĂ©sistance de l'abricotier doivent ĂȘtre conduites
dans des conditions contrÎlées en utilisant des serres indemnes d'insectes. Un des
aspects les plus importants des ces conditions de culture est la nécessité d'appliquer
des périodes d'induction artificielle de dormance pour que ces arbres des zones tempérées
puissent passer l'étape indispensable de la levée de dormance. Dans l'expérience décrite,
des plantules du pĂȘcher GF305 et de l'abricotier Real Fino ont Ă©tĂ© exposĂ©es Ă des pĂ©riodes
artificielles de froid (7 C) et d'obscurité durant 3 à 12 semaines (entre 504 et 2016
heures de froid) pour définir la période optimale permettant une bonne croissance
végétative subséquente. A la sortie de la chambre froide, les plantes ont été placées en
serre et des mesures hebdomadaires ont été faites du pourcentage de bourgeons de feuilles
démarrés et de la croissance végétative. Les périodes optimales ont été de
5 semaines (840 heures de froid) pour GF 305 et de 8 semaines (1344 heures de froid)
pour Real Fino
Behaviour of apricot (Prunus armeniaca L.) cultivars in the presence of sharka (plum pox potyvirus): a review
Information concerning the evaluation of apricot resistance to sharka (plum pox potyvirus) has in many
cases been published in journals of limited circulation. In an attempt to assess the actual status of this
resistance, a global review has been made, including 222 cultivars, 175 of which can be considered as
susceptible, 27 as resistant and 20 as cultivars of uncertain classification. Such a doubtful
classification could be due to differences in evaluation methods, the isolates used, or to the
authenticity of the plant material. The results seem to indicate that the main origin of resistance to
sharka could be North American cultivars, although other resistant sources have been found in Central
Europe.Comportement des cultivars d'abricotier (Prunus armenica L.) Ă la sharka (plum pox potyvirus) :
une revue. Les informations concernant l'Ă©valuation du comportement de l'abricotier Ă la sharka sont
fréquemment publiées dans des journaux à faible audience. La présente revue se propose de synthétiser ces
informations dispersĂ©es : 222 cultivars sont pris en compte, 175 d'entre eux pouvant ĂȘtre considĂ©rĂ©s comme
sensibles, 27 comme résistants et 20 pour lesquels la classification est incertaine. Cette classification
douteuse peut ĂȘtre due Ă des diffĂ©rences dans les mĂ©thodes d'Ă©valuation, aux isolats utilisĂ©s ou Ă
l'authenticité du matériel végétal. Les résultats semblent indiquer que la principale source de résistance
à la sharka aurait pour origine les cultivars nord-américains bien que d'autres sources de résistance ont
été trouvées en Europe centrale
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