Genetic diversity of Xylella fastidiosa in citrus producing regions in the state of Bahia, BrazilAbstract -The objective of this work was to evaluate, by SSR markers, the genetic diversity of Xylella fastidiosa in the state of Bahia, Brazil. Two of the main citrus producing regions of the state were evaluated, Litoral Norte and Recôncavo Sul. Ten samples from the state of São Paulo, Brazil, were used for comparison. The following primers were used: ASSR20, OSSR9, OSSR17, CSSR4, CSSR12, and CSSR20, of which the last four allowed the identification of 22 polymorphic loci. The citrus populations of X. fastidiosa in the state of Bahia have high genetic diversity, based on SSR markers, with distinct gene pools and geographical grouping. In Litoral Norte, the populations of the isolate show higher genetic diversity than those in the Recôncavo Sul region of Bahia.
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.
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