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Ancient germplasm represents a reservoir of traits and genes that might maintain large the genetic diversity of a species, like pear, and help breeders to cope with climatic changes and the evolving demand of the market. This paper reports the analysis of 170 pear accessions profiled at 12 simple sequence repeat (SSR) markers. The collection was replicated in three different locations and the identification of matching profiles of duplicated genotypes reduced the dataset to 118 genotypes. Of these, 32 (27.1%) were shown to be triploid by flow cytometry, a result that was confirmed by the occurrence of triallelic profiles at molecular markers and the large leaf size. The geographic location of original plants explained very little molecular variance (2%), that was instead very high among genotypes (98%). This evidence confirms the extensive exchange of plant material among the different geographic areas of the region as well as with neighbouring countries as reported in historical documents. The analysis of synonymy revealed 38 duplicated genotypes and reduced the dataset to 80 unique genotypes, of which 12 were triploid (15.0%). The molecular metrics analysed on 70 unique diploid genotypes, including two commercial cultivars, 'Abate Fétél' and 'Conference' added as controls, revealed that the observed heterozygosity over all loci (Ho) was 0.742 (range 0.471–0.937 for individual loci), while the expected heterozygosity or gene diversity was 0.808 (range 0.534–0.912). The polymorphic information content was 0.784 on average (range 0.501–0.906 for individual loci). The probability of identity (PID) calculated for individual loci and unrelated genotypes ranged from 0.014 for the most discriminating locus, Ch01d09, to 0.250 for the least discriminating one, Ch04e03. The PID product over all loci was 2.50e−16 for unrelated genotypes and 4.86e−06 for full sibs. The analysis of data is integrated with a discussion on the use of SSR markers in pear genotyping and the origin and the frequency of triploids compared with data from the literature. Finally, a discussion on the resemblance of several groups of cultivars to those of the pomological treatises is included. [ABSTRACT FROM AUTHOR]

AINTEGUMENTA ( ANT) promotes initiation and growth of ovule integuments which cell fate is specified by ovule identity factors, such as SEEDSTICK ( STK), SHATTERPROOF1 ( SHP1) and SHATTERPROOF2 ( SHP2). To study the genetic interaction between ANT and the ovule identity genes, we have obtained a stk shp1 shp2 ant quadruple mutant. The molecular and morphological characterization of the quadruple mutant and its comparison with the stk shp1 shp2 triple mutant, the shp1 shp2 ant triple mutant and the stk ant double mutant are here presented. [ABSTRACT FROM AUTHOR]

The MADS box genes participate in different steps of vegetative and reproductive plant development, including the most important phases of the reproductive process. Here we describe the isolation and characterisation of two Asparagus officinalis MADS box genes, AOM3 and AOM4. The deduced AOM3 protein shows the highest degree of similarity with ZAG3 and ZAG5 of maize, OsMADS6 of rice and AGL6 of Arabidopsis thaliana. The deduced AOM4 protein shows the highest degree of similarity with AOM1 of asparagus, the SEP proteins of Arabidopsis and the rice proteins OsMADS8, OsMADS45 and OsMADS7. The high level of identity between AOM1 and AOM4 made impossible the preparation of probes specific for one single gene, so the hybridisation signal previously described for AOM1 is probably due to the expression of both genes. The expression profile of AOM3 and AOM1/AOM4 during flower development is identical, and similar to that of the SEP genes. Asparagus genes, however, are expressed not only in flower organs, but also in the different meristem present on the apical region of the shoot during the flowering season: the apical meristem and the three lateral meristems emerging from the leaf axillary region that will give rise to flowers and lateral inflorescences during flowering season, and to phylloclades and branches during the subsequent vegetative phase. The expression of AOM3 and AOM1/AOM4 in these meristems appears to be correlated with the reproductive function of the apex as the hybridisation signal disappears when the apex switches to vegetative function. [ABSTRACT FROM AUTHOR]

MADS box genes are implicated in different steps of plant development. Some of them are expressed in vegetative organs. Most of them, however, are expressed in flower tissues and are involved in different phases of flower development. Here we describe the isolation and characterization of an Asparagus officinalis MADS box gene, AOM1. The deduced AOM1 protein shows the highest degree of similarity with FBP2 of Petunia hybrida and AGL9 ( SEP3), AGL2 ( SEP1) and AGL4 ( SEP2) of Arabidopsis thaliana. In situ hybridization analyses, however, show that the expression profile of AOM1 is different from that of these genes: AOM1 is expressed not only in flower organs but also in inflorescence and flower meristems. These data indicate a possible function of AOM1 during flower development as well as in earlier stages of the flowering process. Asparagus officinalis is a dioecious species which bears male and female flowers on different individuals. AOM1, which is expressed very early during the process of flowering and has a similar expression profile in male and female flowers, does not seems to be involved in asparagus sex differentiation. [ABSTRACT FROM AUTHOR]