Inadequate quantity and quality of pollen reaching the stigmas decreases the sexual reproductive output of plants, compromising yield. Still, the current extent of pollen limitation affecting yield (i.e., pollination deficits) is poorly quantified. This study is aimed at quantifying pollination deficits in kiwifruit orchards, a dioecious plant with a fruit caliber and market value largely dependent on pollination services. For that, we set up a pollination experiment and quantified services and yield provided by current pollination vectors, and under optimal pollination, over two years in a total of twenty-three orchards covering the kiwifruit production range in Portugal. We characterized nine fruit traits and used: (1) fruit weight to calculate pollination deficits and relate them with pollinator diversity and abundance, and environmental variables; and (2) production values, fruit caliber, and market values to calculate economic impact of pollination deficits. Results showed that pollination deficits were variable in time and space and were significantly and negatively correlated with pollinator abundance, while the opposite pattern was obtained for production, supporting the notion that a higher pollinator’s abundance is related to lower pollination deficits and higher yields. Understanding the factors affecting pollination deficits is crucial to depict the need for nature-based solutions promoting pollinators and to resort to management practices assisting pollination.
Arbutus unedo L. is a resilient tree with a circum-Mediterranean distribution. Besides its ecological relevance, it is vital for local economies as a fruit tree. Several microorganisms are responsible for strawberry tree diseases, leading to production constrictions. Thus, the development of alternative plant protection strategies is necessary, such as bacterial endophytes, which may increase their host’s overall fitness and productivity. As agricultural practices are a driving factor of microbiota, this paper aimed to isolate, identify and characterize endophytic bacteria from strawberry tree leaves from plants growing spontaneously in a natural environment as well as from plants growing in orchards. A total of 62 endophytes were isolated from leaves and identified as Bacillus, Paenibacillus, Pseudomonas, Sphingomonas and Staphylococcus. Although a slightly higher number of species was found in wild plants, no differences in terms of diversity indexes were found. Sixteen isolates were tested in vitro for their antagonistic effect against A. unedo mycopathogens. B. cereus was the most effective antagonist causing a growth reduction of 20% in Glomerella cingulata and 40% in Phytophthora cinnamomi and Mycosphaerella aurantia. Several endophytic isolates also exhibited plant growth-promoting potential. This study provides insights into the diversity of endophytic bacteria in A. unedo leaves and their potential role as growth promoters and pathogen antagonists.
1 January 2014 in Pesquisa Agropecuária Brasileira
O objetivo deste trabalho foi avaliar, por meio de marcadores SSR, a diversidade genética de Xylella fastidiosa no Estado da Bahia. Foram estudadas duas das principais regiões produtoras de citros no Estado, o Litoral Norte e o Recôncavo Sul. Para fins comparativos, utilizaram-se dez amostras provenientes do Estado de São Paulo. Foram empregados os seguintes iniciadores: ASSR20, OSSR9, OSSR17, CSSR4, CSSR12 e CSSR20, dos quais os quatro últimos permitiram identificar 22 loci polimórficos. As populações de X. fastidiosa presentes em citros no Estado da Bahia apresentam elevada diversidade genética, com base nos marcadores SSR, com pools gênicos distintos e agrupamento geográfico. No Litoral Norte, as populações do isolado apresentam maior diversidade genética do que as da região do Recôncavo Sul da Bahia.
Bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to global kiwifruit production. Copper-based bactericides remain widely used, but increasing resistance highlights the urgency of developing sustainable alternatives. Understanding the functional capabilities of phyllosphere bacteria under copper pressure is critical for designing microbiome-informed management strategies. This study provides a culture-based functional inventory of bacteria associated with Actinidia chinensis var. deliciosa leaves from Portuguese orchards under long-term copper management, aiming to identify native taxa with traits relevant to plant health and resilience. A total of 1058 isolates were recovered and grouped into 261 Random Amplification of Polymorphic DNA (RAPD) clusters, representing 58 species across 29 genera. Representative strains were screened for Plant Growth-Promoting (PGP) traits (Indole-3-acetic acid (IAA), siderophore production, phosphate solubilization, ammonia production), copper tolerance, and in vitro antagonism against Psa. Copper resistance was widespread (53.3% of isolates with MIC ≥ 0.8 mM), including the first evidence of a highly copper-resistant PSA strain in Portuguese kiwifruit orchards and an exceptionally resistant non-pathogenic strain closely related to Erwinia iniecta (MIC 2.8 mM). A subset of 25 isolates combined all four PGP traits, and several also exhibited antagonism against Psa in vitro, among them Bacillus pumilus consistently supressed pathogen growth. Notably, antagonistic and multifunctional traits co-occurred in some isolates, highlighting promising candidates for integrated biocontrol strategies. Overall, the findings reveal a functionally diverse and copper-resilient collection of cultured bacteria, offering both challenges and opportunities for microbiome-based disease management. This work establishes a robust functional basis for subsequent in planta validation and the development of sustainable, microbiome-informed approaches for Psa control.
Bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to global kiwifruit production. Copper-based bactericides remain widely used, but increasing resistance underscores the need for alternative strategies. Understanding the functional capabilities of phyllosphere bacteria under copper pressure is critical for designing sustainable alternatives. This study provides a culture-based functional inventory of bacteria associated with Actinidia chinensis var. deliciosa leaves from Portuguese orchards under long-term copper management, aiming to identify native taxa with traits relevant to plant health and resilience. A total of 1,058 isolates were recovered and grouped into 261 RAPD clusters, representing 58 species across 29 genera. Representative strains were screened for plant growth-promoting (PGP) traits (IAA, siderophore production, phosphate solubilization, ammonia production), copper tolerance, and in vitro antagonism against Psa. Copper resistance was widespread (53.3% of isolates with MIC ≥0.8 mM), including the first evidence of a highly copper-resistant PSA in Portuguese kiwifruit orchards and an exceptionally resistant non-pathogenic strain ( Erwinia iniecta , MIC 2.8 mM). A subset of 25 isolates combined all PGP traits. In parallel, several isolates exhibited antagonism against Psa, including Bacillus pumilus , which consistently inhibited pathogen growth. Notably, some antagonistic isolates overlapped with the multifunctional PGP subset, highlighting promising candidates for integrated biocontrol strategies. These findings reveal the kiwifruit phyllosphere as a reservoir of functionally diverse and copper-resilient bacteria, highlighting both ecological risks and opportunities for microbiome-based biocontrol innovation. This work establishes a functional baseline for future in planta validation and microbiome-informed disease management strategies.