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[ES]: Reducir la pérdida de variabilidad genética es un reto en los programas de mejora debido al repetido uso de un escaso número de genotipos. Para estudiar la variabilidad genética del almendro en su mejora a nivel mundial se utilizaron datos genealógicos de 222 variedades y selecciones provenientes de Argentina, Australia, Francia, Grecia, Israel, Italia, Rusia, España y EE. UU. Se calculó la consanguinidad, las relaciones por parejas y la contribución genética para todos los genotipos. Los resultados señalan dos principales líneas de mejora basadas en tres cultivares ‘Tuono’–‘Cristomorto’ y ‘Nonpareil’. Existen 75 descendientes directos (compartiendo 30) de ‘Tuono’ o ‘Cristomorto’ mientras que ‘Nonpareil’ tiene 72 descendientes directos. El coeficiente medio de consanguinidad de los genotipos analizados fue 0,036, con 13 presentando una elevada consanguinidad. Los programas de mejora de EE. UU. (0,06), Francia (0,05) y España (0,03) mostraron consanguinidad. De acuerdo con su contribución genética, las variedades modernas de Israel, Francia, EE. UU., España y Australia, se basan en seis, cinco, cuatro, cuatro y dos genotipos fundadores principales respectivamente. Entre el grupo de 65 genotipos con el alelo Sf de autocompatibilidad, el coeficiente medio de relación fue de 0,133, con ‘Tuono’ como principal fundador (23,75% de la contribución genética total)., [EN]: Loss of genetic variability is a challenge increasing when breeding due to the repeated use of a reduced number of founders. Pedigree data of 222 almond cultivars and selections were used to study worldwide genetic variability in modern programs from Argentina, Australia, France, Greece, Israel, Italy, Russia, Spain and USA. Inbreeding coefficients, pairwise relatedness and genetic contribution were calculated. The results reveal two mainstream breeding lines based in three cultivars: ‘Tuono’–‘Cristomorto’ and ‘Nonpareil’. Direct descendants from ‘Tuono’ or ‘Cristomorto’ account to 75 (sharing 30 descendants), while ‘Nonpareil’ has 72 direct descendants. The mean inbreeding coefficient of the analyzed genotypes was 0.036, with 13 genotypes presenting a high inbreeding coefficient. Breeding programs from USA (0.06), France (0.05) and Spain (0.03) showed inbreeding. According to their genetic contribution, modern cultivars from Israel, France, USA, Spain and Australia, trace back to six, five, four, four and two main founders respectively. Among the group of 65 genotypes with the Sf allele for self–compatibility, the mean relatedness coefficient was 0.133, with ‘Tuono’ as main founder (23.75% of total genetic contribution).

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La helada es el principal factor limitante para el cultivo del almendro en muchas zonas frías de España. Consecuencia del incremento del precio de la almendra, el cultivo está sufriendo una gran expansión en nuestro país. Esta expansión está teniendo lugar en gran medida en zonas frías, donde incluso las nuevas variedades de floración tardía presentan un elevado riesgo de helada. En este trabajo mostramos el valor real de la floración extra–tardía en estas zonas frías, reduciéndose a la mitad el riesgo de perder la producción por la helada, respecto a las variedades de floración tardía.

Nº 169, ejemplar dedicado a: Lleida Fruit: simposio internacional, frutos secos.

En: XII International Symposium on Apricot Culture and Decline, Avignon (France). Editor: J.M. Audergon., Prunus mandshurica [(Maxim.) Koehne] is a species related to apricot from Central Asia and grown in China and Mongolia. This species has been used in apricot breeding as a source of frost resistance. In addition, some authors suggested P. mandshurica as the possible origin of some North American apricot cultivars resistant to sharka (plum pox potyvirus, PPV). The aim of this work was to evaluate, under controlled conditions, the resistance to a Dideron PPV isolate of a P. mandshurica accession and the descendants from a cross with the Spanish apricot cultivar 'Currot'. The results showed the susceptibility to PPV of the P. mandshurica accession and the apricot cultivar. Furthermore, all the progeny behaved as very susceptible showing stronger sharka symptoms than both parents.

En: XIII GREMPA Meeting on almonds and pistachios = XIIIème Réunion du GREMPA sur l'amandier et le pistachier . Zaragoza : CIHEAM-IAMZ, 2005. Eds: Oliveira M.M., Cordeiro V.-- Meeting of the Mediterranean Research Group for Almond and Pistachio, 2003/06/01-05, Mirandela (Portugal).-- 5 pages, 2 figures., [EN] The effect of stratification, heat, and endocarp and tegument removal on the breaking of seed dormancy was studied in 3 almond cultivars. In the first assay, the nuts with endocarp were stratified at 7 degrees C for 15 weeks. In the second, the nuts with endocarp were stratified at 7 degrees C for 4 weeks. Then, non-germinated seeds were kept at 22 degrees C for 7 weeks more to promote germination. Then, the remaining non-germinated nuts were cracked and the tegument was removed. The percentage of germinated seeds of each cultivar was recorded weekly in both assays. The results showed a different effect of each treatment on seed germination for each cultivar, related to their flowering time. The removal of the endocarp and the tegument in seeds that had not fulfilled their chilling requirements, produced the same effect as stratification and, finally, similar percentages of seed germination were observed in comparison with the first treatment., [FR] "Influence de la stratification, de la chaleur, et de l'élimination des téguments sur la rupture de dormance des semis d'amandier". Au cours de ce travail nous avons étudié l'effet de la stratification, de la chaleur, et de l'élimination de l'endocarpe et du tégument dans la rupture de la dormance de 3 variétés ('Desmayo Largueta', 'Del Cid' et 'Wawona') d'amandier [P. dulcis (Mill.) D.A. Webb] avec des dates de floraison distinctes. Dans le premier traitement, les semis avec endocarpe ont été stratifiés pendant 15 semaines à 7ºC. Dans le second traitement, les semis avec endocarpe ont été stratifiés à 7ºC pendant 4 semaines. Les semis qui n'ont pas germé ont été exposés à 22ºC pendant 7 semaines et après cette exposition l'endocarpe et le tégument ont été supprimés des semis qui n'ont pas germé. Chaque semaine le pourcentage de germination des semis a été calculé. Les résultats ont mis en évidence une relation entre les besoins de stratification des semis et la date de floraison de chaque variété. Le traitement à la chaleur ne peut pas induire la germination des semis qui n´ont pas satisfait leurs besoins en froid. L'élimination de l'endocarpe et du tégument produit une augmentation de la germination similaire à l´effet de la stratification de telle façon que les pourcentages finaux de germination sont similaires dans les deux traitements., This work has been financed by the project “Mejora genética del almendro” (AGL2001-1054-C03- 01) from the Spanish Ministry of Science and Technology.

En: XIII GREMPA Meeting on almonds and pistachios = XIIIème Réunion du GREMPA sur l'amandier et le pistachier . Zaragoza : CIHEAM-IAMZ, 2005. Eds: Oliveira M.M., Cordeiro V.-- Meeting of the Mediterranean Research Group for Almond and Pistachio, 2003/06/01-05, Mirandela (Portugal).-- 6 pages, 4 tables., [EN] Variability and inheritance of six peach [Prunus persica (L.) Batsch] SSR (simple-sequence repeat) markers was studied in 21 almond [P. dulcis (Mill.) D.A. Webb] cultivars and in a progeny of 180 descendants from the cross between the French cultivar 'R1000' and the Spanish cultivar 'Desmayo Largueta'. The results showed the molecular identification of the 21 cultivars using the six SSR polymorphic sequences. The number of alleles revealed by the SSR analysis ranged from 4 to 13, with a high level of heterozygosity. A codominant segregation of the SSRs was observed in this progeny. These results establish the value of SSR markers for distinguishing different genetic lineages and characterize the extensive gene pool available for almond breeding programs. The application of these SSR sequences in the development of markers associated with genes or QTLs involved in the inheritance of agronomic traits in almond is also discussed., [FR] "Variabilité et hérédité des séquences SSR de pêcher dans les génotypes d'amandier". Au cours de ce travail nous avons étudié la variabilité et l'hérédité de six séquences SSR de pêcher [Prunus persica (L.) Batsch] dans 21 variétés d'amandier [P. dulcis (Mill.) D.A. Webb] et dans une génération de 180 descendants issus du croisement entre la variété française 'R1000' et la variété espagnole 'Desmayo Largueta'. Les résultats ont montré l'identification des 21 variétés avec les six SSRs étudiés. Le nombre d'allèles observés a varié entre 4 et 13, avec une grande hétérozygotie de ces loci. Nous avons observé une ségrégation codominante dans la génération étudiée. Les résultats ont montré la grande valeur des marqueurs moléculaires de tipe SSR pour l'identification variétale et la caractérisation de la grande variabilité génétique disponible pour les programmes d'amélioration de l'amandier. Nous avons discuté l'application de ces SSRs pour le développement de marqueurs moléculaires associés aux caractéristiques agronomiques., This work has been financed by the project AGL2001-1054-C03-01 from the Spanish Ministry of Science and Technology. The authors thank the collaboration of Dr. H. Duval, from INRA (Avignon, France) in the generation of the studied progeny. The authors also acknowledge the support of the Spanish Ministry of Science and Technology for the contract of Dr. P. Martínez-Gómez.

En: XIII GREMPA Meeting on almonds and pistachios = XIIIème Réunion du GREMPA sur l'amandier et le pistachier . Zaragoza : CIHEAM-IAMZ, 2005. Eds: Oliveira M.M., Cordeiro V.-- Meeting of the Mediterranean Research Group for Almond and Pistachio, 2003/06/01-05, Mirandela (Portugal).-- 6 pages, 4 tables., [EN] The correlations between seed germination or leafing time and flowering time in almond [P. dulcis (Mill.) D.A. Webb] were studied in a population of 502 seedlings from 13 families. The aim of the study was to discover the possibilities of an early selection of those seedlings with late flowering in relation to germination of seeds or leafing time in the following year. The crosses were conducted in 1997. The seeds obtained were germinated by conventional stratification at 7°C, and the number of weeks necessary for the germination of each seed recorded. The trees were planted in 1998. Between 1999 and 2002 their leafing time was recorded, and in 2001 and 2002 also their flowering time. The results indicated that these characteristics bear a relation when considering the population globally, but with a high variability. However, within each family, the correlations between these characteristics were not important and, in most cases, not significant. In the case of germinationflowering, the lack of correlation seems to be the consequence of the germination depending mainly on the female parent. In the case of leafing-flowering, the lack of correlation was due to the positive or negative correspondence between leafing and flowering and to the genotype x environment interaction. In our opinion, to obtain seedlings with an extra-late flowering time, the selection of parents with very late flowering time is essential, with subsequent selection of the seedlings during their first flowering. An early selection regarding the leafing period could be applied with a certain degree of success when, for any reason, interested in selecting late-flowering trees coming from parents with very late and very early-flowering periods. In such cases, the high variability expected could compensate, to a certain degree, for the differences between leafing and flowering., [FR] "Sélection précoce d'amandiers à floraison tardive". Les corrélations entre la germination de la graine ou la date de débourrement et la date de floraison chez l'amandier [P. dulcis (Mill.) D.A. Webb] furent étudiées dans une population de 502 plantes issues de 13 familles. L'objectif de l'étude était de découvrir les possibilités d'une sélection précoce de ces plantes ayant une floraison tardive en relation avec la germination des graines ou la date de débourrement dans l'année suivante. Les croisements furent réalisés en 1997. Les graines obtenues ont germé selon une stratification conventionnelle à 7°C, et le nombre de semaines nécessaires à la germination de chaque graine est enregistré. Les arbres furent plantés en 1998, et leur date de débourrement enregistrée entre 1999 et 2002, ainsi que leur date de floraison en 2001 et 2002. Les résultats indiquèrent que les caractéristiques ont mis en évidence une relation si l'on considère la globalité de la population, mais avec une forte variabilité. Cependant, dans chaque famille, les corrélations entre ces caractéristiques se sont avérées peu importantes et dans de nombreux cas, non signifiantes. Dans le cas de la germination-floraison, la faible corrélation semble être la conséquence du fait que la germination soit contrôlée principalement par le parent femelle. Dans le cas du débourrement-floraison, la faible corrélation serait due à une asynchronie positive ou négative entre le débourrement et la floraison, et aussi à l'interaction entre le génotype et l'environnement. Selon nous, afin d'obtenir des sélections aux dates de floraison très tardives, la sélection de parents avec une date de floraison très tardive est essentielle, avec la sélection de plantes pendant leur première floraison. Une sélection précoce prenant en compte la période de débourrement pourrait être appliquée avec un certain taux de réussite quand, quelle que soit la raison, nous voulons obtenir des sélections très tardives à partir d'un croisement entre un géniteur très précoce et un autre très tardif. Dans ce cas, la grande variabilité attendue pourrait compenser, à un certain degré, des différences entre le débourrement et la floraison., This work has been financed by the project AGL2001-1054-C03-01 ("Mejora Genética del Almendro") from the Spanish Ministry of Science and Technology. The authors also acknowledge the support of the Spanish Ministry of Science and Technology for the contract of Dr. P. Martínez-Gómez.

2 pages.

9 páginas., En este trabajo se analizan los principales aspectos relacionados con la aplicación de los marcadores moleculares tipo SSR en frutales como el coste del equipo y los reactivos, los métodos de análisis de los polimofismos obtenidos, además de su abundancia, naturaleza y transferibilidad entre especies del genero Prunus.

2 pages.

3 pages., Aspergillus flavus Link. is a filamentous fungus affecting almond [Prunus dulcis (Mill.) D.A. Webb] kernels in the field and during storage. This fungus can produce afla-toxins (carcinogenic and immunosuppressive mycotoxins), which prevent the marketability of almond kernels. Aspergillus flavus resistance has not been an objective in conventional almond breeding programs. Because the importance of this disease is increasing, evaluations of cultivar susceptibility are being performed. In this study, the screening for A. flavus resistance in 40 almond genotypes has been carried out in controlled inoculation conditions at 26 °C. Eighteen days after the inoculation, kernels of all the almond cultivars assayed showed susceptibility to A. flavus. Nevertheless, differences among cultivars in the percentage of kernel surface colonized by the fungus were observed. The Spanish cultivar Ramillette was the least susceptible. Susceptibility was not related to the geographic origin of the cultivar.

8 páginas.

6 pages, 1 table, 1 figure., Homozygous self-compatible almond cultivars have not been reported. It is unclear if they are more inferior than heterozygotes or simply have not yet been detected. To investigate if homozygous individual are generally inferior, the self-compatibility genotype, homozygous or heterozygous, was determined by stylar ribonuclease assay in a population of 241 almond trees obtained by self-fertilisation of self-compatible selections. The resulting zymograms showed that 129 of the seedlings were homozygous and 112 heterozygous. For three years the differences observed between these two classes of self-compatible individuals were analysed with respect to 16 agronomic characteristics. In general, there were no important differences between the two classes. Both showed a low degree of productivity, probably as a result of their inbred origin. Some selected homozygous individuals were used in crosses, which were planned so as to ensure the self-compatibility of 100% of the descendants and to eliminate the laborious task of testing the seedlings for self-compatibility., The work has been financed within the project ‘Mejora Genética del Almendro’ (AGF98-0211-C03-02) from the ‘Plan Nacional de I+D’ of the Spanish Ministry of Education and Culture.

2 pages, 2 figures., In almond [Prunus dulcis (Mill.) D.A. Webb], the appearance of multiple embryos within the same seedcoat has been described in seeds from different Californian cultivars including ‘Nonpareil’, ‘Price’, ‘Sonora’, ‘Jiml’, ‘Carmel’, ‘Johlyn’ and ‘Mission’ (Kester and Gradziel, 1996; Micke et al., 1996-2001)., The authors acknowledge the support of Spanish Ministry of Science and Technology.

3 pages., Multiple embryos (two or three embryos within the same seedcoat) occur spontaneously in certain almond [Prunus dulcis (Mill.) D.A. Webb] cultivars including ‘Nonpareil’ and ‘Mission’. Seedlings from the same multiple-seeded ovule are frequently viable, though often, one of the seedlings shows weak growth and develops poorly (aberrant seedlings). These aberrant seedlings have recently been identified as aneuploids, and so are useful for genetic studies of almond. In this work, we examine the success of in vivo micrografting for the early propagation of this weak material. Variables evaluated included genotype (aneuploid or diploid), type of micro-scion and growth stage of the rootstock. Micro-scions tested consisted of small (3 mm) micro-wedges from sprouted apical buds from two-weeks-old seedlings. In addition, both direct and inverse approach micrografts were assayed. Results showed a lower success for micrograft of aberrant seedlings (aneuploids) (5%) relative to normal seedlings (diploids) (42.5%). Inverse approach micrografts onto very young rootstocks showed the best results for aberrant seedlings (aneuploid) with a 15% success rate. Significant differences were observed in the growth of micrografted aberrant seedlings (aneuploid) as compared to seedlings growing on their own roots.

In this study, 34 apricot orchards in south-eastern Spain planted with the Spanish cultivar ‘Búlida’ and showing “viruela” symptoms were studied for 2 years. Leaf and fruit samples from four trees in each orchard, either with or without “viruela” symptoms, were collected and analysed by multiplex RT-PCR for the detection of American plum line pattern virus (APLPV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV), Apricot latent virus (ApLV), Plum bark necrosis and stem pitting-associated virus (PBNSPaV), Plum pox virus (PPV), Prune dwarf virus (PDV), and Prunus necrotic ring spot virus (PNRSV). In addition, molecular hybridization assays were performed for the detection of Hop stunt viroid (HSVd) and Peach latent mosaic viroid (PLMVd). All fruits showing “viruela” symptoms were infected with ACLSV and HSVd, suggesting that these pathogens may be responsible for “viruela” disease. Other viruses including PNRSV, PBNSPaV, ApLV, PDV, ApMV and PPV, were detected to a lesser degree. Detection of ACLSV and HSVd in samples without symptoms could be explained by the influence of environmental conditions and/or the physiological stage of fruits on the expression of symptoms.