Phaseolin Induction on Common-Bean Cultivars and Biological Control of Colletotrichum lindemuthianum 89 Race by Baccharis trimera (Less) Dc

Abstract The objective of this work was to evaluate the fungitoxic effect of the aqueous extracts of Baccharis trimera on the mycelial growth of Colletotrichum lindemuthianum 89 race, as well as its effect on the accumulation of phaseolin in hypocotyls of different cultivars and common bean varieties. It was obtained 20% aqueous extract from plants collected in municipalities of the Western Region of Paraná. Blocks containing C. lindemuthianum mycelium were transferred to Petri dishes containing medium with the different extracts and incubated at 25 °C. The colonies diameter was measured until the 12th day. Effects of aqueous extracts on phaseolin production was evaluated in hypocotyls of Carioca, Cnpf 8104, Soberana, Tibatã, Uirapurú cultivars, as well as Rosinha and Vermelho varieties. Each one cultivar and variety hypocotyl was transferred separately to test tubes containing 500 μL of 20% aqueous extracts. Sterile water, Bion®, and UV was used as controls. The phaseolin production was measured in spectrophotometer [280 nm]. Results of the evaluation of the antifungal activity of aqueous extracts of Baccharis sp. specimens collected indicate that approximately 50% of the samples presented capacity to reduce between 74 and 92% of C. lindemuthianum growth. Cultivar Tibatã and Vermelho variety showed greater sensitivity over the applied treatments. Results of fungal filtrates and vegetal aqueous extracts presented a low capacity to induce the production of phaseolin in hypocotyls.

CO2 Fertilizer Effect on Growth, Polyphenols, and Endophytes in Two Baccharis Species

Abstract In a climate change context, the buildup of CO2 will affect plant communities worldwide. This study evaluated the effects of CO2 enrichment on the development and defense of two Cerrado native species Baccharis dracunculifolia and B. platypoda and their associated endophytic fungi richness. The study took place in Open-Top Chambers, two with ambient CO2 concentration (~400 ppm) and two in an enriched environment (~800 ppm). Baccharis platypoda developed 20% more leaves under enriched CO2 conditions, whereas B. dracunculifolia was 30% taller and showed 27% more leaves than those under ambient conditions. In both species, leaf polyphenol concentration did not differ between treatments. Nevertheless, polyphenol content had a positive correlation with plant height on both species' individuals grown under CO2 enriched conditions. Endophytic fungi richness and colonization rate on both plant species did not differ between ambient and enriched conditions. Our results show the positive effect of CO2 fertilizer in at least one of the measured growth parameters. An important new finding was a synergistic increase in growth and chemical defense in both studied species under enriched CO2 conditions, suggesting higher carbon assimilation and accumulation. This study suggests that the effects on primary productivity and secondary metabolites of Baccharis species will potentially reflect on the diversity and distribution of Cerrado plants and their associated animal communities.