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Among Citrus species, lemon is one of the most susceptible to mal secco disease, a tracheomycosis caused by the mitosporic fungus Plenodomus tracheiphilus, which induces chlorosis followed by leaf drop and progressive desiccation of twigs and branches. Severe infection can cause the death of the plant. Since no effective control strategies are available to efficiently control the pathogen spread, host tolerance is the most desirable goal in the struggle against mal secco disease. To date, both traditional breeding programs and biotechnological techniques were not efficient in developing novel varieties coupling tolerance to mal secco with optimal fruit quality. Furthermore, the genetic basis of host resistance has not been fully deciphered yet, hampering the set-up of marker-assisted selection (MAS) schemes. This paper provides an overview of the biotechnological approaches adopted so far for the selection of mal secco tolerant lemon varieties and emphasizes the promising contribution of marker-trait association analysis techniques for both unraveling the genetic determinism of the resistance to mal secco and detecting molecular markers that can be readily used for MAS. Such an approach has already proved its efficiency in several crops and could represent a valuable tool to select novel lemon varieties coupling superior fruit quality traits and resistance to mal secco.

Background: Anthocyanin pigmentation characterizes a number of tissues of Citrus and its relatives. The gain and loss of pigmentation is intriguing and is inherited variously among species. Methods: Citrus germplasm was used to investigate the anthocyanin pigmentation of tissues never before considered, including stamen, style and stigma, and of young leaves, petals, rind and flesh of 28 genotypes belonging to 14 species. Citrus genotypes encompassed citron, lemon, sweet orange, lime, and Citrus relatives included Microcitrus, Murraya, and Severinia. A relative qRT-PCR analysis was carried out on the structural and regulatory genes: phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3&prime, hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), uridine diphosphate glucose flavonoid glucosyl-transferase (UFGT), glutathione S-transferase (GST), Ruby and Noemi. Image analysis and a genomic approach were employed to evaluate how the red pigmentation is inherited among tissues and species. Results: Pigmentation of young leaves and petals is specific to citron and its hybrids. Ruby controls the pigmentation of petals, but not of leaves. The red color of the rind and flesh is a trait that particularly characterizes a diversity of sweet oranges, citron hybrids and Citrus relatives. Color expression depends on external factors and also on developmental stage. The coloration of stamen and style is citron-specific, while a red stigma is exclusive to Moro orange and its hybrids. Conclusion: It is hypothesized that there is a relationship among Citrus species and genes controlling anthocyanin pigmentation.

According to projects and practices that the Italian botanists and ecologists are carrying out for bringing “more nature in the city”, new insights for a factual integration between ecological perspectives and more consolidated aesthetic and agronomic approaches to the sustainable planning and management of urban green areas are provided.

Green infrastructure and in particular green roofs are crucial to meet the challenge of sustainable urbanisation fostered by the current European Research and Innovation agenda. Several documents were issued in the last decades in Europe for regulating the design, construction and up-keep of roof greening. In particular, the actual German guidelines have been widely adopted as a reference basis for green roof design and regulation worldwide, because of its exhaustiveness and proven building- and landscaping tradition. With the aim to assess the effectiveness of green roof guidelines and norms in supporting plant and soil biodiversity in different ecoregions, and particularly of the Mediterranean one, the German guidelines, the Swiss and Italian norms are screened and discussed in this paper. The German guidelines were chosen for their traditional referential role, the Swiss norm for its peculiar biodiversity approach, the Italian one for its application on a territory with remarkably heterogeneous environmental conditions, stretching from Alpine to Mediterranean ecosystems. Even if the three documents at comparison addressed to some extent biodiversity-related matters, none of them deepened the relationship between plant species selection (local ecotypes), growing medium composition (materials, granular size and thickness) and system build-ups (multi-layers and/or single-layer systems). This is a crucial point for countries, like Italy, encompassing very different climatic conditions. It was concluded that at the current knowledge a guideline/norm taking into account the peculiarities of green roof design in the Mediterranean ecoregion has to be widely refined.

courtesy of the publisher for "Conservation Biology" - reviews are Open Access.

The variations in species composition and assemblage of unmanaged simple-intensive green roofs in Hannover, Germany, were investigated over a thirty year period, in order to assess the persistence of the initial seed mixture and to evaluate floristic changes. The roofs were greened in 1985 with soil-based turf rolls sown with a mixture of five grasses (Festuca rubra, Festuca ovina, Agrostis capillaris, Lolium perenne and Poa pratensis). Three sets of 120 phytosociological releves, sampled in 1987, 1999 and 2014, have been compared to assess: (1) nestedness vs spatial turnover, (2) functional diversity and (3) the importance of vegetation dynamics on green roof performance and design. Results demonstrated that from 1987 to 1999 the species diversity increased and the species turnover prevailed over nestedness, due to the progressive niche occupation by new species. In contrast, from 1999 to 2014 species diversity remained steady, suggesting that nestedness prevailed over species turnover. The main driver of the observed functional changes was a shift towards relatively more thermoxeric conditions. In terms of plant life strategies, the competitive species sown on the roof gradually gave way to stress-tolerant and ruderal species, along with a progressive increase in species with shortdistance seed dispersal strategies. It is concluded that: (a) to create resilient green roofs, spontaneous colonisation should be accepted and considered as a design factor; and (b) regional plant communities could serve as a model for seed recruitment and installations.