Academic literature on the topic 'Peach germplasm'

Cultivated peach (Prunus persica) is an important fruit species worldwide. The wild relatives in Prunus, such as P. mira, P. davidiana, P. kansuensis, P. ferganensis, and P. persica, are valuable for peach breeding, and early and accurate identification of parental and hybrid genotypes is critical. In this study, 20 representative accessions of peach germplasm from the National Germplasm Repository of Peach in China were used to select a set of 18 simple sequence repeat (SSR) markers for accurate species discrimination. Eight unknown peach samples were successfully identified using the SSR panel and species genotype database. Interspecific hybrid genotypes of P. persica × P. davidiana, P. persica × P. kansuensis, and P. persica × P. ferganensis were also analyzed reliably. The markers were amenable to high-throughput fluorescent labeling and capillary electrophoresis (CE) analysis, allowing rapid and efficient species identification. The practical method described in this study will facilitate peach breeding and germplasm management.

Almond [Prunus dulcis (Mill.) D.A. Webb, syn. P. amygdalus, Batsch; P. communis (I.) Archangeli] represents a morphologically and physiologically variable group of populations that evolved primarily in central and southwest Asia. California cultivars have been developed from highly selected subgroups of these populations, while new breeding lines have incorporated germplasm from wild almond and closely related peach species. The genetic relatedness among 17 almond genotypes and 1 peach genotype was estimated using 37 RAPD markers. Genetic diversity within almond was found to be limited despite its need for obligate outcrossing. Three groupings of cultivar origins could be distinguished by RAPD analysis: bud-sport mutations, progeny from interbreeding of early California genotypes, and progeny from crosses to genotypes outside the California germplasm. A similarity index based on the proportion of shared fragments showed relatively high levels of 0.75 or greater within the almond germplasm. The level of similarity between almond and the peach was 0.424 supporting the value of peach germplasm to future almond genetic improvement.

A wide range of peach [Prunus persica (I,.) Batsch] germplasm was collected from the most important peach growing regions in Mexico and some Latin American countries, as well as from breeding programs in the United States, Europe, and South Africa. Budded trees, seedlings derived from selfing cultivars and selections, and seed samples from various growing regions were propagated and planted in central Mexico. Twenty eight morphological or phenological variables were recorded on 52 accessions representing different geographic regions. The highest degree of variability was observed for traits related to bud density and distribution, and to phenological variables associated with temperature requirements such as budbreak and harvest seasons, leaf fall, fruit development, and seed stratification period. Principal component analysis (PCA) integrated groups of phenotypes based mainly on growth habit, shoot diameter, bud and leaf size, as well as resistance to powdery mildew, rust, and frost. PCA provides support for the development of objectives and breeding strategies in the search for germplasm and cultivars for nontraditional peach growing regions.

Abstract Analysis of the pedigrees of selected eastern United States freestone peach [Prunus persica (L.) Batsch] cultivars reveals high degrees of inbreeding and coancestry. Commonly used parents include ‘Admiral Dewey’, ‘Elberta’, ‘Halehaven’, ‘J.H. Hale’, ‘Rio Oso Gem’, and ‘St. John’. These cultivars and their progeny were used as parents primarily for superior fruit quality. Selection for fruit quality has led to the intensive use of relatively few cultivars and a restriction in freestone peach germplasm. Future progress in the development of high quality, cold hardy, disease- and insect-resistant cultivars will depend upon expansion of the germplasm base, and identification and interfusion of genes conferring desired tree and fruit characters into existing eastern United States peach germplasm.

Peach latent mosaic viroid (PLMVd) is widely distributed (approximately 55%) in peach germplasm from Europe, Asia, North America, and South America. PLMVd, or a closely related viroid, was occasionally detected in cherry, plum, and apricot germplasm from countries in Europe or Asia. The cherry isolate of PLMVd is 337 nucleotides in length and is 91 to 92% homologous to PLMVd isolates from peach. Molecular hybridization experiments demonstrated that PLMVd is not related to the agent of peach mosaic disease. PLMVd was readily transmitted (50 to 70%) by contaminated blades to green shoots and lignified stems of peach GF-305 plants. These results indicate that the viroid may be transmitted in orchards with contaminated pruning equipment.

Peach (Prunus persica (L.) Batsch) is one of the most produced and studied stone fruits. Many genetic and genomic resources are available for this species, including a high-quality genome. More recently, a new high-density Illumina peach Single Nucleotide Polymorphism (SNP) chip (9+9K) has been developed by an international consortium as an add-on to the previous 9K array. In the current study, this new array was used to study the genetic diversity and population structure of the National Peach Germplasm Collection of the Agrifood Research and Technology Centre of Aragon (CITA), located in Zaragoza (northern Spain). To accomplish this, 90 peach accessions were genotyped using the new peach SNP chip (9+9K). A total of 9796 SNPs were finally selected for genetic analyses. Through Identity-By-Descent (IBD) estimate analysis, 15 different groups with genetically identical individuals were identified. The genetic diversity and population structure elucidated a possible exchange of germplasm material among regions, mainly in the northern regions of Spain. This study will allow for more efficient management of the National Peach Germplasm Collection by classifying valuable individuals for genetic diversity preservation and will benefit forthcoming Genome-Wide Association Studies (GWAS) of commercially important fruit traits in peach.

Peach [Prunus persica L. (Batsch.)] and apricot (Prunus armeniaca L.) are two Prunus species developing delicious fruits and they are mostly grown in temperate areas of the world. Both species have been cultivated since ancient times, being greatly appreciated for their unique taste and benefits to human health. Peaches and apricots can be consumed either fresh or processed through canning or drying, depending on the preference of a specific region and the use-purpose. So far, many efforts have been done in enhancing disease and pest resistance, in increasing the environmental adaptability to sub-tropical areas, in extending the harvest season or in improving fruits appearance. However, consumers frequently complain about the lack of taste in peach and apricot fruits sold on markets, encouraging the ongoing breeding projects to include organoleptic properties among their objectives. Among all the fruit quality-related traits, acidity plays a pivotal role affecting both consumers’ and market acceptance. To match with market trends, an extensive characterization of peach and apricot fruits attributes under the highlighted necessity of renewing the varieties cultivated worldwide is required. In this thesis, a peach and apricot collection of 201 and 164 accessions, respectively, was screened for many important fruit organoleptic attributes, with a specific focus on acidity and organic acids content. Fruits acidity was titrated and ten organic acids (cis-aconitate, citrate, fumarate, galacturonate, malate, oxalate, quinate, shikimate, succinate and tartrate) separation was accomplished by HPLC technique coupled to UHPLC-HRMS validation. Analyses were performed on peach pulp and on apricot pulp and peel. The final aim was in-depth dissecting the peach and apricot panel for these organoleptic parameters to exploit the existing variability within their germplasm. Malate and citrate were the most abundant organic acids in both species, with pattern more genotype than year dependent. Results suggested that seasonality effects on fruits acidity and almost all the considered-organic acids were very low. Among the other organic acids, quinate and succinate reached large concentrations in peach and apricot, respectively, while tartrate was interestingly present more in apricot peel than pulp. The availability of a reference genome in peach has allowed to further characterize peach fruit quality traits. Over the past, peach fruits acidity has been partially elucidated at genetics level, identifying one major locus and making it a breeding target. Although the great advances, the selection accuracy and the long-time required for releasing new varieties on markets still hamper peach breeding progress. To in-depth unravel acidity trait and to speed up the selection of newly developed individuals in peach, a total of 1,190 accessions were genotyped for performing genomics analyses. Two different studies were carried out in this thesis: genomic selection (GS) and genome wide association studies (GWAS). Results confirmed that GS seems feasible in peach not only for acidity but also for organic acids content, in particular for patterns of malate and citrate. GWAS confirmed the presence of one major locus acting as dominant in peach fruits but revealed other significant associations on chromosomes 1, 7 and 8. In summary, this thesis includes the first efforts in an in-depth and at multilevel dissection of acidity in peach and apricot, applying different approaches on a large panel of individuals. This thesis attempts to provide a complete overview with results that may be useful for future researches, studies and successful breeding programmes.

Research on the expression of fruit specific genes may allow breeders in the future to selectively manipulate through gene transfer in certain aspects of fruit development/quality in their advanced breeding lines thus reducing the time necessary for cultivar development. This would be particularly useful in breeding programmes, hybridizing standard cultivars with exotic germplasm of low fruit quality. The use of exotic germplasm will be important for the expansion of the peach germplasm base and the development of stress resistant cultivars. More immediate results of research on fruit specific gene expression will provide a better understanding of fruit development and quality. It is required to learn how the differences at the gene level correlate with quality characteristics. With the continued cooperation of fruit biochemists it is expected to obtain a better definition of fruit quality and a better understanding of fruit biochemistry. The potential will exit to generate a range of “anti-sense mutants” i.e. transgenic plants expressing anti-sense gene contstructs that reduce or nullify the effects of the normal gene. The phenotypes of these mutants could help to define the biochemistry, genetics and quality of peach fruit. The development of efficient regeneration and transformation system in peach will be useful not only for the modification of fruit characteristics, but also for the transfer and manipulation of genes affecting stress resistance and other economically important characters.

Almond (Prunus dulcis), a stone fruit belonging to a family Rosaceae (rose) is broadly cultivated for ornament and fruit. Within this genus, the almond is very much associated with the peach, and these two fruits share the same subgenus the Amygdalus. About 430 species are spread all through the northern temperate regions of the world. The Mediterranean climate region of the Middle East like Turkey and Pakistan eastward to Syria is native to the almond and its related species. Almond is one of the ancient fruit trees known to the Asian as well as European regions with the most primitive proof of cultivation dating about 2000 B.C. Prunus dulcis (Almond) is a nutrient-loaded nut crop. Almond possesses a great genetic diversity due to the genetically controlled self-incompatibility system which can be estimated by a morphological characteristic including molecular markers and isoenzymes with a wide range of marker techniques. Simple sequence repeats (SSR) involving RFLP or SNP are the most commonly used molecular techniques among the DNA-based molecular symbols. Particular agronomic characters, e.g. kernel bitterness or self-compatibility can also be traced by these molecular markers. The direct association between the level of diversity and the basis of the germplasm cannot be understood by the studies of genetic diversity. Genetic diversity cannot be seriously lost by self-compatibility in almonds. The breeding, conservation, and cultivation of wild-growing almonds may similarly advantageous after the genetic diversity research studies (especially those applying molecular markers).