Alkaloids (emetine and cephalin) production - affected by full sunlight stress in Carapichea ipecacuanha.

This study evaluated the responses of Carapichea ipecacuanha to sunlight stress-induced changes in the electron transport chain and its extended effects on alkaloid production (emetine and cephalin). The treatments consisted of: (i). 50, 70, and 90% shading (controls) and their respective exposure to full sunlight; besides, full sunlight (55 days of direct sun exposure). Photosynthetic pigments, chlorophyll a fluorescence transient, antioxidant enzymatic system, and quantification of cephalin and emetine were analyzed. Several changes in the Chl a fluorescence induction were observed, such as a decline in the quantum yield of the conversion of photochemical energy and photosynthetic performance and; an increase in emetine production of plants exposed to full sunlight. These results demonstrated that ipecac plants are extremely sensitive to full exposure to solar radiation, especially in periods with high temperatures, such as in summer, however with increment in emetine production.

Potassium supply promotes the mitigation of NaCl-induced effects on leaf photochemistry, metabolism and morphology of Setaria viridis.

Soil salinity has the potential to severely affect crop performance. To maintain cell functioning and improve salt tolerance, the maintenance of K+ homeostasis is crucial in several plant metabolism processes. Besides, potassium fertilization can efficiently alleviate the perilous effects of salinity. We characterized impacts in Setaria viridis exposed to NaCl and KCl to underlying photochemistry mechanisms, K+ and Na+ shoot contents, enzymatic activity, electrolytic leakage, and morphological responses focusing on non-stomatal limitation of photosynthesis. Plants were exposed to sodium chloride (NaCl; 0, 150 and 250 mM) and potassium chloride (KCl; 0, 5, 9 mM). The exposure to NaCl affected S. viridis leaves morphological and physiologically. Plants submitted to 150 mM showed reductions in performance indexes (PIabs and PItotal; JIP-test), and the presence of positive K- and L-bands. Plants exposed to 250 mM exhibited blockage in electron flow further than QA within 48h and permanent photoinhibition at 96 h. The presence of 9 and 5 mM of KCl counteracted the effects of NaCl on plants submitted to 150 mM, concomitant with increases in K+ accumulation and cell turgidity conservation, causing positive effects in plant growth and metabolism. Neither KCl concentrations were effective in reducing NaCl-induced effects on plants exposed to 250 mM of NaCl. Our results support the conclusion that greater availability of K+ alleviates the harmful effects of salinity in S. viridis under moderate stress and that application of KCl as means of lightning saline stress has a concentration and a salt level limit that must be experimentally determined.