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‘Guara’ has been the most planted almond cultivar in Spain in recent years. The introducers of this cultivar reported its origin as unknown and suggested that it is related to the Italian almond cultivar ‘Tuono’. Indeed, the experience of farmers and researchers has revealed strong similarities between ‘Guara’ and ‘Tuono’. In order to compare the identity of the two cultivars, their genetic profiles (fingerprints) were determined with a set of 12 SSR markers used to analyse the INRA clones of ‘Guara’ and ‘Tuono’ as well as two clones considered synonymous with ‘Tuono’, namely ‘Supernova’ and ‘Mazzetto’. A supplementary set of 23 SSRs was also analysed in ‘Guara’ and ‘Tuono’ samples from different reference collections of CEBAS-CSIC (Murcia, Spain), INRA (Avignon, France), IRTA (Constantí, Spain), and the University of Bari (Bari, Italy). The results confirmed that ‘Guara’ and ‘Tuono’ present identical DNA fingerprints for the 35 SSRs analysed. This genotypic information together with the similar characteristics of the two cultivars demonstrates that Spanish ‘Guara’ is actually the same cultivar as the Italian ‘Tuono’. [ABSTRACT FROM AUTHOR]

Self-incompatibility (SI) in almond [Prunus dulcis (Miller) D.A. Webb] is of the gametophytic-type and is controlled by the S-locus, which is highly polymorphic and includes two tightly-linked genes expressed in the pistil (as an S-RNase) and in the pollen [as an S haplotype-specific F-box (SFB) protein]. Experimental evidence indicates that other proteins are also needed for the functioning of self-incompatibility. However, to date, S-RNase and SFB are the only components of the SI system identified in almond. Moreover, the cause(s) of a lack of S-RNase activity in self-compatible almonds remain(s) unclear. This work aimed to identify the other proteins involved in the self-(in)compatible response in almond by comparative quantitative analysis of the differential expression of proteins following incompatible and compatible pollinations. Four self-incompatible almond cultivars were self-pollinated or cross-pollinated, and a homozygous self-compatible almond selection was self-pollinated. Proteins were extracted from the pollinated pistils and analysed by two-dimensional difference gel electrophoresis (2D-DIGE) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Searches were performed against the NCBI database using the MASCOT and SEQUEST search engines and Proteome Discoverer vl.4 software. A total of 43 proteins, some with a key role in pollen-pistil interactions, were identified as being differentially expressed following incompatible or compatible pollination. These results provide the first profiles of differential protein expression during self-(in)compatibility in almond. [ABSTRACT FROM AUTHOR]

Several pollination studies carried out on different, self-incompatible almond cultivars and seedlings have shown the presence of variable levels of fruit set following self-pollination that could be attributed to partial self-incompatibility (PSI). PSI is an intermediate reproductive behaviour, described in some angiosperm species, which indicates that self-incompatibility is a quantitative and plastic trait. The present study was performed to substantiate the occurrence of PSI in almond by studying ten cultivars that are traditionally considered to be self-incompatible (four of which had previously shown fruit set after self-pollination). These cultivars were analysed by microscopic observations of the progression of pollen tubes through the pistil following controlled self-pollination, determinations of fruit set after bagging flower buds, and molecular identification of the parentage of the fruits obtained using consensus PCR-primers for Prunus S-RNase alleles. The results showed that, in nearly all cases, the pollen tubes did not enter the ovary and, from a total of 5,349 bagged flower buds, only 17 fruits were obtained. In all cases, PCR analysis of the plants obtained after germination of these seeds showed a band corresponding to an S-RNase allele not present in the maternal progenitor, clearly indicating that they could only have arisen from cross-pollination. Therefore, the low fruit set values observed in some of the cultivars studied were not due to a breakdown in the self-incompatibility response that confers PSI, but to very low rates of contamination with foreign pollen. These results corroborate the self-incompatibility phenotype of the cultivars studied here, and highlight the importance of ascertaining the identity of the parentage in any progeny obtained after bagging. [ABSTRACT FROM AUTHOR]

With 1 table The behaviour of 31 plum cultivars (Prunus salicina, Prunus cerasifera, P. domestica, P. cerasifera × P. salicina and P. salicina × P. armeniaca) against a Dideron‐type isolate of Plum pox virus (PPV) (sharka) was evaluated in an insect‐proof greenhouse, grafted onto 'Adesoto' diseased rootstocks, during three growing cycles. All plum cultivars showed the symptoms of sharka or were ELISA positive in at least one of the replications evaluated. However, the behaviour of cultivars was different. Most of the Japanese plums were very sensitive or sensitive, showing strong sharka symptoms and being ELISA positive. Only the Japanese plums 'Black Star', 'Calita', and 'Laroda' showed tolerance to PPV, with mild sharka symptoms and a very low percentage of infected plants. In addition, among the four P. cerasifera studied, 'J9' was very sensitive, 'Kometa' was sensitive, and 'P16'and 'P2980' were tolerant to sharka. Finally, the inter‐specific hybrids 'J300' and 'Flavor Supreme' were sensitive, and 'Obilnaya' was tolerant to the disease. [ABSTRACT FROM AUTHOR]

Six tree traits (self-compatibility, blooming date, blooming density, productivity, leafing date and ripening time) and five pomological traits (kernel taste, in-shell weight, shell hardness, kernel weight and double kernel) were studied in an F1 almond progeny of 167 seedlings from the cross between the French cultivar ‘R1000’ and the Spanish cultivar ‘Desmayo Largueta’. In addition, a set of 135 codominant microsatellites or simple-sequence repeat (SSR) markers developed from peach, cherry and almond were used for the molecular characterization of the progeny. A genetic linkage map was constructed with 56 of these SSRs. Cosegregation analysis allowed the identification of the map positions of two major genes to be confirmed for kernel taste ( Sk) in linkage group five (G5) and for self-incompatibility ( S) in G6. QTLs mapped include two for leafing date ( Lf-Q1 and Lf-Q2) in G1 and G4, one for shell hardness ( D-Q) in G2, one each for double kernel ( Dk-Q) and productivity ( P-Q) in G4, one for blooming date ( Lb-Q) in G4, two for kernel weight ( Kw-Q1 and Kw-Q2) in G1 and G4, and two for in-shell weight ( Shw-Q1 and Shw-Q2) in G1 and G2. Four SSR loci (BPPCT011, UDP96-013, UDP96-003 and PceGA025) were linked to the important agronomic traits of leafing date, shell hardness, blooming date and kernel taste. Finally, the development of efficient marker-assisted selection strategies applied to almond and other Prunus breeding programmes was also discussed. [ABSTRACT FROM AUTHOR]

Obtaining new. late-flowering almonds by crossing is a very long process, mainly due to the long juvenile period of the seedlings obtained. It would be very useful to have an early selection method to identify the late-flowering genotypes, which would increase the efficiency of the breeding programmes. In this work, a study was made of the possibility of using the chilling requirements of seeds for germination and the leafing time of seedlings as criteria for early selection of flowering time, in 502 seedlings belonging lo 13 families, over a four-year period. Crossings were carried out in 1997. Seeds were stratified at 7°C. and the number of weeks necessary for germination was determined. Seedlings were planted in 199S. Between 1999 and 2002 the leafing time was recorded, and in 2001 and 2002 the time of flowering was also recorded. The results showed that, although some correlation was observed between the germination or leafing time and the flowering time, these correlations were not strong enough to be used as efficient criteria for early selection of late-flowering seedlings within each family, for which variability was limited. To obtain late-flowering cultivars, the best method is to cross progenitors which flower as late as possible, and later select the seedlings according to their flowering time. Leafing time could be used for early selection with certain success when progenitors have very different flowering times (very early and very late), since the expected variability within families will be very large. [ABSTRACT FROM AUTHOR]

The work aimed to develop a reliable and convenient PCR approach for determining incompatibilitySgenotypes in almond. Initially, genomic DNAs of 24 accessions of knownSgenotype were amplified with novel consensus primers flanking the first and second introns of theS-RNase gene. The PCR products separated on agarose showed length polymorphisms and correlated well with the reference allelesS 1– S 23 andS f. In addition, to improve discrimination between alleles of similar sizes, the same sets of primers but fluorescently labelled were used, and the products sized on an automated sequencer. These fluorescent primers were particularly informative in the case of the first intron, variation in the length of which has not been used previously forSgenotyping in almond. Some reference alleles showed the same patterns with first and second intron primers, and others showed a microsatellite-like trace. Subsequently, theSgenotypes of 26 cultivars not genotyped previously and of four of uncertain genotype were determined. An allele described in Australian work as putativeS 10 was shown to be a‘new’ allele and ascribed toS 24 and evidence of five more‘new’ Salleles was found, for which the labelsS 25– S 29 are proposed. This PCR approach should be useful for genotyping in otherPrunuscrops. [ABSTRACT FROM AUTHOR]

Sharka (Plum pox virus, PPV) severely affects the production of mostPrunusspecies in the areas affected by the disease. In this study, the resistance of 15Prunusrootstocks to a Dideron type isolate of PPV was evaluated under controlled conditions in an insect-proof greenhouse. After four cycles of study,‘GF677’ almond × peach hybrid,‘Myrobolan 29C’ plum and‘L2’ cherry did not show any symptoms and were ELISA-DASI and RT-PCR negative. These were considered resistant to PPV. The rest of the rootstocks assayed showed symptoms of sharka (confirmed by ELISA-DASI or RT-PCR), although the level of susceptibility was different for each rootstock.‘GF305’ peach,‘Puebla de Soto’ plum and‘Real Fino’ apricot, were highly susceptible to PPV, showing strong sharka symptoms and being ELISA and RT-PCR positive.‘Marianna 2624’ plum,‘AC 9921-07’ hybrid and‘CP-2’ plum showed susceptibility to PPV confirmed by ELISA-DASI and RT-PCR positives.‘Nemaguard’ and‘Nemared’ hybrids,‘Torinel’ plum and‘STN2’ hybrid showed an intermediate susceptibility to PPV with slight sharka symptoms and were ELISA-DASI and RT-PCR positive. Whereas,‘Montclar’ peach and‘Evrica’ hybrid showed moderate resistance to PPV with slight sharka symptoms and were ELISA positive but RT-PCR negative. The results open new possibilities in the search for different sources of resistance to PPV withinPrunus. [ABSTRACT FROM AUTHOR]

Localisation and movement of Plum pox virus (PPV), sharka disease, in stem tissues of susceptible and resistant apricot (Prunus armeniaca L.) cultivars was studied. Two different assays were performed. In the first assay, apricot cultivars were grafted on to a non-inoculated GF305 peach rootstock and, after two months, the sprouted apricot was inoculated by chip-grafting. In the second assay, apricot cultivars were grafted on to a previously chip-inoculated GF305 showing strong PPV symptoms. Localisation of virus was studied in apricot stem by immuno-tissue printing and sharka symptoms in GF305 and apricot leaves were also observed. Virus was mainly localised in the xylem, and sometimes in the cortex and pith. Results revealed that, while all the cultivars allowed limited virus movement from the inoculation point, only the susceptible cultivars (Screara, Bebeco and Colomer) allowed long distance movement and even showed symptoms in leaves. [ABSTRACT FROM AUTHOR]

Pollen tubes reaching the ovary, fruit set and the main fruit characteristics of six self-compatible genotypes (`Marta', `Antoñeta', `Guara', `Lauranne', `S2332' and `S4017') of almond were studied after self- or cross-pollination. No significant differences after self- or cross-pollination were found in the number of pollen tubes reaching the ovary, the percentage of ovaries finally penetrated, fruit set and fruit characteristics. The results showed the possibility of obtaining suitable fertilization, yields and quality of fruits by self-pollination of self-compatible almond cultivars in a single cultivar orchard. [ABSTRACT FROM AUTHOR]

Recent evidence has indicated that activated oxygen species (AOS) may function as molecular signals in the induction of defence genes. In the present work, the response of antioxidative enzymes to the plum pox virus (PPV) was examined in two apricot (Prunus armeniaca L.) cultivars, which behaved differently against PPV infection. In the inoculated resistant cultivar (Goldrich), a decrease in catalase (CAT) as well as an increase in total superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were observed. Ascorbate peroxidase (APX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) did not change significantly in relation to non-inoculated (control) plants. In the susceptible cultivar (Real Fino), inoculation with PPV brought about a decrease in CAT, SOD and GR, whereas a rise in APX, MDHAR and DHAR activities was found in comparison to non-inoculated (control) plants. Apricot leaves contain only CuZn-SOD isozymes, which responded differently to PPV depending on the cultivar. Goldrich leaves contained 6 SODs and both SOD 1 and SOD 2 increased in the inoculated plants. In leaves from Real Fino, 5 SODs were detected and only SOD 5 was increased in inoculated plants. The different behaviour of SODs (H2O2-generating enzymes) and APX (an H2O2-remover enzyme) in both cultivars suggests an important role for H2O2 in the response to PPV of the resistant cultivar, in which no change in APX activity was observed. This result also points to further studies in order to determine if an alternative H2O2-scavenging mechanism takes place in the resistant apricot cultivar exposed to PPV. On the other hand, the ability of the inoculated resistant cultivar to induce SOD 1 and SOD 2 as well as the important increase of DHAR seems to suggest a relationship between these activities and resistance to PPV. This is the first report about the effect of PPV infection on the antioxidative enzymes of apricot plants. It opens the way for the further studies, which are necessary for a better understanding of the role of antioxidative processes in viral infection by PPV in apricot plants. [ABSTRACT FROM AUTHOR]

2483 almond seedlings developed from 42 crosses between 12 parents were studied for three years (1989, 1990 and 1991). General and specific combining ability was determined for six traits (all years) and eight traits (1989 only). Additive factors are largely responsible for the genetic control of all traits, non-additive factors being of importance for the density of flowering and particularly for thedensity of production, time and duration of maturation and double kernels. The results permit the correct choice of parents and crosses for future breeding programmes and provide a better insight into the genetic control of the traits studied. [ABSTRACT FROM AUTHOR]

Reciprocal differences were determined in 18 inter-varietal crosses of almond (9 direct and its 9 reciprocals) obtained from 6 varieties by means of hand pollination. Five traits were analyzed over three years (1989--1991) and seven traits over one year (1989). No reciprocal differences were detected for blossom density, percentage of double kernels and kernel smoothness. For flowering times (start, full and end) the differences were nearly inexistent. They were of varying importance for production density, time of ripening, kernel/in-shell ratio and integument colour intensity in some crosses. In these cases, the direction of the cross must be kept in mind in order to improve the efficacy of future breeding programmes. [ABSTRACT FROM AUTHOR]

With 2 tables The breeding of new late-flowering almond cultivars is a long process, due mainly to the long juvenile phase of the seedlings. Early selection methods would improve the efficiency of breeding programmes. In this work, we investigated the use of seed germination time to select for late-flowering almonds in 136 seedlings representing six progeny from controlled pollinations performed in 2002. Germination time for seeds with mesocarp and endocarp removed was recorded during stratification, and time of leaf budbreak and flowering were recorded in the fourth and fifth leaf. Within the six progeny evaluated over 2 years, correlations between seed germination and leaf budbreak of the seedlings ranged from 0.02 to 0.43, and for the pooled data averaged 0.48. Correlations between seed germination and seedling flowering time ranged from 0.06 to 0.55, and for the pooled data were 0.50. These results indicate a relationship between times of germination of the seeds and flowering of the resulting seedlings, but the low correlations indicate that the usefulness of selection based in seed germination time will be limited. [ABSTRACT FROM AUTHOR]

Abstract Sharka, a disease caused by Plum pox virus (PPV), mainly affects some Prunus species, including apricot, peach and plum, and to a lesser degree, sweet cherry and sour cherry. In almond, different PPV isolates have been transmitted experimentally to the ‘Aï’ cultivar. In this study, the resistance of 10 almond cultivars to a Dideron PPV isolate was evaluated in controlled conditions by grafting the cultivars on to inoculated GF305 peach rootstocks. The results demonstrated a high level of resistance to PPV in all the almond cultivars assayed. They did not show any symptoms and were ELISA and RT-PCR negative, despite the strong symptoms observed in their GF305 rootstocks. The implications of these results for the dispersion of PPV, and the potential role of almond as a source of resistance to PPV in other Prunus species such as peach, are also discussed. [ABSTRACT FROM AUTHOR]