Phloem cytochemical modification and gene expression following the recovery of apple plants from apple proliferation

Recovery of apple trees from apple proliferation was studied by combining ultrastructural, cytochemical, and gene expression analyses to possibly reveal changes linked to recovery-associated resistance. When compared with either healthy or visibly diseased plants, recovered apple trees showed abnormal callose and phloem-protein accumulation in their leaf phloem. Although cytochemical localization detected Ca2+ ions in the phloem of all the three plant groups, Ca2+ concentration was remarkably higher in the phloem cytosol of recovered trees. The expression patterns of five genes encoding callose synthase and of four genes encoding phloem proteins were analyzed by quantitative real-time reverse transcription- polymerase chain reaction. In comparison to both healthy and diseased plants, four of the above nine genes were remarkably upregulated in recovered trees. As in infected apple trees, phytoplasma disappear from the crown during winter, but persist in the roots, and it is suggested that callose synthesis/deposition and phloem-protein plugging of the sieve tubes would form physical barriers preventing the recolonization of the crown during the following spring. Since callose deposition and phloem-protein aggregation are both Ca2+-dependent processes, the present results suggest that an inward flux of Ca2+ across the phloem plasma membrane could act as a signal for activating defense reactions leading to recovery in phytoplasma-infected apple trees.L'articolo é disponibile sul sito dell'editore: http://www.apsjournals.apsnet.or

Intra-varietal variability of Romanesco variety (Vitis vinifera L.)

Most historical sources that describe the presence of Romanesco variety in vine-growing areas of Lazio Region (Italy) highlighted the variability of morphological traits within the variety. This partly justifies the presence of different synonyms, true or presumed, reported by many authors for this grape variety. With the aim of analysing this variability, eight accessions related to the variety, collected in Lazio Region and grown in the DAFNE grape germplasm collection, have been characterized over five productive seasons. The ampelographic description was carried out using 50 OIV morphological descriptors and ampelometric analyses were carried out on mature leaves by SuperAmpelo software. The DNA of the different accessions, extracted from young leaves, was analyzed using 14 microsatellite loci. Furthermore, at harvest, the grapes of each accession were sampled to assess main compositive characteristics. Results showed differences among accessions on some ampelographic descriptors of the mature leaf, of the bunch, and on phenological stages. Microsatellite profiles allowed for classification of the accessions into three distinct groups. Qualitative analysis of the berry skin showed differences among accessions in the content of the main classes of phenolic compounds

Molecular and phylogenetic analysis of MADS-box genes of MIKC type and chromosome location of SEP-like genes in wheat (Triticum aestivum L.).

Transcription factors encoded by MIKC-type MADS-box genes control many important functions in plants, including Xower development and morphogenesis. The cloning and characterization of 45 MIKC-type MADSbox full-length cDNA sequences of common wheat is reported in the present paper. Wheat EST databases were searched by known sequences of MIKC-type genes and primers were designed for cDNA cloning by RT-PCR. Full-length cDNAs were obtained by 5 and 3 RACE extension. Southern analysis showed that three copies of the MIKC sequences, corresponding to the three homoeologous genes, were present. This genome organization was further conWrmed by aneuploid analysis of six SEP-like genes, each showing three copies located in diVerent homoeologous chromosomes. Phylogenetic analysis included the wheat MIKC cDNAs into 11 of the 13 MIKC subclasses identiWed in plants and corresponding to most genes controlling the Xoral homeotic functions. The expression patterns of the cDNAs corresponding to diVerent homeotic classes was analysed in 18 wheat tissues and Xoral organs by RT-PCR, real time RT-PCR and northern hybridisation