Genetic diversity in local Spanish pear cultivars assessed by molecular characterization with SSRs

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Genetic diversity of the Spanish apple genetic resources using SSRs

The Spanish Program of Plant Genetic Resources integrates, among others, the collections located at Public University of Navarre, Centro de Investigaciones Agrarias de Mabegondo, Cabildos (Tenerife, La Palma and Gran Canaria), University of Lleida, Estación Experimental de Aula Dei-CSIC and CITA of Aragon. Those collections include mainly local cultivars from their respective regions, covering most of the Spanish apple-growing areas. Though some previous studies about the genetic variability of apple genetics resources from Spain were already performed, a complete analysis is needed in order to evaluate the complete diversity of Malus spp. in Spain. For doing that, the Spanish Government funded the project ¿Harmonization of the methodology of characterization, assessment of genetic diversity and definition of the core collection of the apple germplasm conserved in Spanish genebanks¿. In total, we have evaluated 1206 accessions using standardized methodologies, with SSR markers and morphological descriptors. SSR fingerprinting was performed with 13 SSR markers. SSR profiles were obtained independently and allele sizes were compared using a common set of cultivars selected as references. Results showed 601 genotypes for 1206 accessions. Most of the genotypes (438) were identified only in one accession. The other 163 genotypes were repeated in two to 81 accessions (involving 767 accessions in total). The harmonization of morphological descriptors will allow us to determine if the accessions with the same genotype are synonymies or closely related individuals. Results of this study highlight the interest of coordinated actions in order to optimize the management of germplasm collections and to evaluate the complete genetic diversity of Malus spp. in Spain.Peer Reviewe

Genetic diversity of the Spanish apple genetic resources using SSRs: abstract

PublishedPoster number 6

Mecanismos reproductivos que regulan la fructificación en peral (Pyrus communis L.) cv. "Agua de Aranjuez"

202 Pag., Tabl., fig.[ESP] El peral (Pynss communis) es un cultivo con una marcada tendencia a las producciones erráticas cuyas causas no están bien establecidas. Esto puede deberse a la escasa información disponible acerca tanto de su fructificación como de su biología reproductiva. En EspaÑa, al principal cultivar, ‘Agua de Aranjuez’, se le reconoce una marcada tendencia a bajos cuajados, hecho que fue controlado mediante el uso de ácido giberélico, hasta el punto que en la actualidad su producción es totalmente dependiente de este tratamiento. Sin embargo recientemente, la reducción en el uso de hormonas en fluticultura, pone en peligro la producción de este cultivar. La búsqueda de una alternativa, supone el conocimiento de las causas que limitan las producciones, El objetivo de este trabajo ha sido en primer lugar, el de sentar las bases de la fluctificaeión y de la biología reproductiva en peral. En segundo lugar, la evaluación de la receptividad floral y su repercusión en la producción Por último, la búsqueda de una alternativa agronómica para ‘Agua de Aranjuez’ libre del uso de ácido giberélico. Para llevar a cabo este trabajo, se ha utilizado una combinación histoquímica y microscópica, con una caracterización en campo del cuajado.Peer reviewe

Characterization of length polymorphisms at the 3'UTR of the maloideae S-RNase and its application for S.Genotyping in european pear (abstract)

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Aplicación para la obtención y análisis automático de noticias en el ámbito financiero

Este trabajo desarrolla el análisis, diseño e implementación de un prototipo para un sistema de obtención y análisis automático de noticias, estando enfocado al uso en el ámbito de los mercados financieros.This work develops the analysis, design and prototyping, of a system for the automatic extraction and analysis of news from the Internet; the use of the system will be within the scope of the financial markets.Aquest treball desenvolupa l'anàlisi, disseny i implementació d'un prototip per a un sistema d'obtenció i anàlisi automàtica de notícies, estant enfocat a l'ús en l'àmbit dels mercats financers

Asynchronous development of stigmatic receptivity in the pear (Pyrus communis; Rosaceae) flower

The editor version is available at: http://www.amjbot.org/cgi/content/full/90/1/78While stigma anatomy is well documented for a good number of species, little information is available on the acquisition and cessation of stigmatic receptivity. The aim of this work is to characterize the development of stigma receptivity, from anthesis to stigma degeneration, in the pentacarpellar pear (Pyrus communis) flower. Stigma development and stigmatic receptivity were monitored over two consecutive years, as the capacity of the stigmas to offer support for pollen germination and pollen tube growth. In an experiment where hand pollinations were delayed for specified times after anthesis, three different stigmatic developmental stages could be observed: (1) immature stigmas, which allow pollen adhesion but not hydration; (2) receptive stigmas, which allow proper pollen hydration and germination; and (3) degenerated stigmas, in which pollen hydrates and germinates properly, but pollen tube growth is impaired soon after germination. This developmental characterization showed that stigmas in different developmental stages coexist within a flower and that the acquisition and cessation of stigmatic receptivity by each carpel occur in a sequential manner. In this way, while the duration of stigmatic receptivity for each carpel is rather short, the flower has an expanded receptive period. This asynchronous period of receptivity for the different stigmas of a single flower is discussed as a strategy that could serve to maximize pollination resources under unreliable pollination conditions.J. Sanzol was supported by an INIA fellowship and financial support for this work was also provided by INIA (Project grants SC98-049 and RTA 01-103).Peer reviewe

Fructificación del cultivar del peral Agua de Aranjuez. Necesidades de polinización

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Self-incompatibility and self-fruitfulness in pear cv. Agua de Aranjuez

Most pear (Pyrus communis L.) cultivars are impaired to set fruit under self-pollination, because self-fertilization is prevented by a gametophytic self-incompatibility system. However, accumulated information in this species shows that often for a same cultivar, after self-pollination, a variable response in fruit set can be obtained in different years or growing conditions. In this work, we characterize self-incompatibility and self-fruitfulness in 'Agua de Aranjuez', the main Spanish pear cultivar, which also shows a variable response to self-pollination. Two years with a different fruit setting response after self-pollination, one with no fruit set and the other with a moderate fruit set, were compared for parthenocarpic fruit development and for pollen tube performance. Results show that in both years, this cultivar behaves as self-incompatible with absence of parthenocarpy. In selfed flowers, most pollen tubes are arrested in the upper half of the style, although in a small proportion of the styles, a pollen tube can reach the base of the style and eventually effect fertilization. Self-fertilization, although occurring at a low level, can explain the fruit set levels obtained under self-pollination given that flowers with just one fertilized ovule are able to set fruit. This behavior could explain confusing results about self-fruitfulness in 'Agua de Aranjuez' and other pear cultivars.Peer reviewe

The “effective pollination period” in fruit trees

The effective pollination period (EPP) concept, was developed by Williams [J. Hort. Sci. 40 (1965) 31] to asses flower receptivity. It is defined as the number of days during which pollination is effective in producing a fruit and is determined by the longevity of the ovules minus the time lag between pollination and fertilisation. Over 30 years have elapsed since this concept was first introduced and, during this time, a good number of experiments have been carried out to study the EPP in different species and cultivars and under different environmental conditions. The results obtained indicate that the EPP plays a clear role controlling cropping in fruit trees and, consequently, it is a useful parameter to dissect and locate the factors limiting fruit set. In this paper, the information built up around the EPP is reviewed in temperate fruit trees. Since EPP is conditioned by three main processes - stigmatic receptivity, pollen tube kinetics and ovule development - the role played by each of them is examined. Finally, the influence of a number of factors - temperature, flower quality and chemical treatments - that affect those parameters is evaluated.JS was supported by an INIA fellowship and financial support for this work was also provided by INIA (project grant SC98-049).Peer reviewe