No abstract

Evidence from a preliminary survey highlighted that ‘Candidatus Phytoplasma solani’, the etiological agent of bois noir (BN) disease of grapevine, infects grapevine varieties in Georgia, a country of the South Caucasus. In this study, field surveys were carried out to investigate the BN symptom severity in international and Georgian native varieties. ‘Ca. P. solani’ was detected and identified by polymerase chain reaction-based amplification and restriction fragment length polymorphism analysis of 16S ribosomal DNA, and further characterized by multiple gene typing analysis (vmp1 and stamp genes). Obtained data highlighted that the majority of Georgian grapevine varieties showed moderate and mild symptoms, whereas international cultivars exhibited severe symptoms. Molecular characterization of ‘Ca. P. solani’ from grapevine revealed the presence of 11 distinct phytoplasma types. Only one type (VmGe12/StGe7) was identical to a strain previously reported in periwinkle from Lebanon; the other ‘Ca. P. solani’ types are described here for the first time. Phylogenetic analyses of vmp1 and stamp gene concatenated nucleotide sequences showed that ‘Ca. P. solani’ strains in Georgia are associated mainly with the bindweed-related BN host system. Moreover, the fact that ‘Ca. P. solani’ strains are distributed in grapevine cultivars showing a range of symptom intensity suggests a different susceptibility of such local cultivars to BN.

Seed longevity is a complex trait that depends on numerous factors. It varies among species and populations, and within different seed morphs produced by the same plant. Little is known about variation in longevity in different seed morphs or the physiological and molecular basis of these differences. We evaluated the longevity and oxidative stress status in heteromorphic seeds aged in two different storage conditions.• We compared controlled ageing tests (seed storage at 45°C and 60% relative humidity; a method of accelerated ageing used to estimate longevity in genebank conditions) with storage in a genebank for up to 40 years (À18°C and 8% seed moisture content). We employed as study species two wild wheats characterized by seed heteromorphism: Aegilops tauschii and Triticum monococcum subsp. aegilopoides. We estimated the ROS content and the expression of genes coding for enzymes related to the H 2 O 2 scavenging pathway.• Results confirmed that seed longevity varies between different seed morphs. Different storage environments resulted in different longevity and survival curves. ROS levels, even if with variable patterns, were higher in several aged seed lots. We observed consistency in the expression of two genes (GSR and CAT) related to ROS scavenging in the late phase of pre-germinative metabolism.• Differences in seed longevity between morphs were observed for the first time under genebank conditions. Our results suggest also that controlled ageing tests should be used with caution to infer ranks of longevity under cold storage.

Italian maize germplasm is particularly rich in local materials and each region is characterized by the presence of peculiar local varieties deriving from centuries of adaptation, selection and cultivation. While the introduction of hybrids, during the 1950s, led to the disappearing of many of these varieties, some have been maintained in cultivation by farmers, frequently in marginal areas, as a kind of family heritage. Local varieties were identified throughout field surveys carried out in recent years. The discovery of a traditional popcorn variety over the most common flint and semi-flint materials used for production of polenta was interesting. Since these varieties have never been adequately described and reported in scientific literature, this study was aimed to solve this lack of knowledge on recently discovered local maize populations. Characterization represents the first step of a process focused on the preservation and possible exploitation of important genetic resources. Traditional materials are a useful reservoir of genes for adaptation to local conditions and climate changes. Adequate breeding programs can use such germplasm for developing new and more resilient varieties. These local materials have been characterized at the morphological level highlighting plant, ear and kernel differences. Genetic characterization, carried out on 455 individuals by the use of 10 SSR markers, revealed 62 different alleles ranging from four for markers phi127, phi076 and phi084 to nine for marker p-bnlg176. The landraces are well distinguishable at genetic level since 40% of genetic variability is present among accessions. Five landraces are characterized by the presence of private alleles and heterozygosity levels are generally good. These findings support the possibility to correctly preserve local materials through in situ conservation. Phylogenetic analysis evidenced the presence of varietal clusters, the clearest one formed by three red-pigmented accessions. STRUCTURE analysis revealed that five landraces have a well-defined genetic attribution while the remaining two (EMR04-Mais Rosso di Rasora and EMR10-Mais del Principe di Scavolino) are both constituted by two different backgrounds.

No abstract