Genotypic and environmental effect on male flower production in Cupressus sempervirens clones and selection of genotypes with reduced pollen emission.

Common cypress (Cupressus sempervirens L.) is widespread in the Mediterranean area and is frequently planted as ornamental tree in parks and gardens. Like other species of Cupressus, common cypress releases a significant amount of the total annual airborne pollen in most regions and is known as responsible for winter pollinosis. Although variation in the production and release of pollen has been observed among C. sempervirens trees growing in urban areas, no information is available on effects due to genotype × environment interaction on this trait. In this study more than 150 C. sempervirens clones were analyzed for two to four consecutive years in clonal orchards situated in central Italy to evaluate variations in the production of male cones. Variance component ANOVA underscored an important genetic control of male flowering, with high repeatability (from 0.80 to 0.95) found in single environments. Analysis for combined sites or years (in a single site) showed significant effect of environment and genotype × environment interaction on the total variance. Intra-trait genetic correlations between environments were moderate to high (from 0.40 to 0.92), which indicates that male cone production of clones is fairly consistent across years and sites. Of the 10 clones characterized by the lowest mean male cone production, three showed good stability across environments based on the linear regression coefficient and Wricke's ecovalence. The mean cone production of these 10 clones was 5 to 10 times lower than the mean production observed in the same environment. These clones have both ornamental and hypoallergenic traits and hold promise for designing green spaces with low allergy impact.

Decline in diversity and abundance of endophytic fungi in twigs of Fagus sylvatica L. after experimental long-term exposure to sodium dodecylbenzene sulphonate (SDBS) aerosol.

Sodium dodecylbenzene sulphonate (SDBS) is an anionic synthetic detergent found in polluted sea aerosol and is known for its harmful effects on leaf surface ultrastructure on conifers and broadleaved trees. Four-year-old saplings of European beech were sprayed weekly for three consecutive growing seasons with either a 50 mg l(-1) solution of SDBS in deionized water or with pure deionized water (control). Two- to three- year-old twigs were collected from SDBS-treated and control plants during the growing season one year after the last treatment to isolate endophytic fungi. The frequency of colonization by endophytic fungi was significantly lower on SDBS-treated plants (63.8%) than on control plants (85.4%). Multiple colonization of twigs occurred more frequently and diversity of endophyte species was higher in control plants than in SDBS-treated plants. Thirty-six fungal species were isolated from 360 twigs. Cladosporium cladosporioides, Coryneum compactum, Phialocephala dimorphospora, and a species each of Mycosphaerella and Phomopsis were the most abundant endophytes with frequencies of colonization of more than 5%. The abundance of the Phomopsis species proved to be significantly reduced by the SDBS treatment. Within the limits of the indoor experimental conditions, the obtained results suggest that long-term exposure of aerial parts of beech to SDBS can affect the amount and composition of endophytic fungal communities of lignified twigs. Degradation of the leaf epicuticular wax layer and changes of the assimilation capacity and leaf water content (transpiration) of the crowns are presumed to be responsible for the reduction of endophytic fungi detected in twigs of SDBS-treated plants.