Phakopsora euvitis Causes Unusual Damage to Leaves and Modifies Carbohydrate Metabolism in Grapevine.

Asian grapevine rust (Phakopsora euvitis) is a serious disease, which causes severe leaf necrosis and early plant defoliation. These symptoms are unusual for a strict biotrophic pathogen. This work was performed to quantify the effects of P. euvitis on photosynthesis, carbohydrates, and biomass accumulation of grapevine. The reduction in photosynthetic efficiency of the green leaf tissue surrounding the lesions was quantified using the virtual lesion concept (ß parameter). Gas exchange and responses of CO2 assimilation to increasing intercellular CO2 concentration were analyzed. Histopathological analyses and quantification of starch were also performed on diseased leaves. Biomass and carbohydrate accumulation were quantified in different organs of diseased and healthy plants. Rust reduced the photosynthetic rate, and ß was estimated at 5.78, indicating a large virtual lesion. Mesophyll conductance, maximum rubisco carboxylation rate, and regeneration of ribulose-1,5-bisphosphate dependent on electron transport rate were reduced, causing diffusive and biochemical limitations to photosynthesis. Hypertrophy, chloroplast degeneration of mesophyll cells, and starch accumulation in cells close to lesions were observed. Root carbohydrate concentration was reduced, even at low rust severity. Asian grapevine rust dramatically reduced photosynthesis and altered the dynamics of production and accumulation of carbohydrates, unlike strict biotrophic pathogens. The reduction in carbohydrate reserves in roots would support polyetic damage on grapevine, caused by a polycyclic disease.

The sarsaparilla market in the state of São Paulo (Brazil) and the challenges of cultivation

This study aimed to present information about the sarsaparilla sold in establishments in the state of São Paulo, Brazil, assess the genetic diversity of Smilax brasiliensis Spreng., Smilacaceae, and examine the growing conditions and productivity of five species of Smilax. The amount of sarsaparilla sold per month at most pharmacies was 0.4 kg on average. Herbal stores and markets sold averages of 9 kg and 8 kg per month, respectively. The weight of the underground biomass of S. fluminensis (188.3 g) is significantly higher than those of other species (28.3-79.6 g). The study demonstrated that high genetic diversity among the Smilax brasiliensis plants belonging to the CPQBA germplasm bank, which was confirmed by the results of the genotyping study that used a SSR marker on S. brasiliensis. The high consumption of sarsaparilla and the low yield of young plants cultivated from seeds with high genetic variability reinforce the need for further studies on the production of Smilax species.