In savanna ecosystems, the seasonal effects of nitrogen forms and availability, as well as their utilization by plants, influence the abundance and distribution of herbaceous species in grassland communities. This study examines seasonal effects on nitrogen availability and utilization by native grass species in the Cerrado, a savanna ecosystem in Brazil. Ammonium and nitrate levels in soil, nitrate acquisition and transport, and Nitrate Reductase Activity (NRA) in different plant parts during dry and wet periods were assessed. Results indicated higher soil nitrate availability during the wet period, influenced by precipitation, with leaves showing a higher nitrate content compared to roots. There was seasonal modulation in nitrate reduction, with leaves being the primary site during the dry period and roots during the wet period. The studied grass species exhibited heterogeneous responses to seasonal nitrogen availability, potentially affecting community abundance patterns. Findings suggest that edaphoclimatic seasonality plays a crucial role in nitrogen distribution and utilization capacity by grass plants in the Cerrado, contributing to the understanding of these ecosystems' ecology.

Background: Heavy metal toxicity affects plant growth and alters physiological processes. Soils in many areas are often contaminated by cadmium and zinc which show varied response on plants by their interactive effects. The experiment was done to study the effect of cadmium and zinc as sole presence and in combination in groundnut seedlings. Methods: The laboratory experiment was conducted on groundnut cultivar TG 51 in sand culture using modified Hoagland solution. After initial screening, three concentrations of cadmium (Cd 100, Cd 300 and Cd 500 mu M) and two concentrations of zinc (Zn 50 and Zn 150 mu M) were selected for studying their effects individually and in combination on physiological and biochemical parameters. Result: The reduction in root length increased over control as the concentration of cadmium in the medium increased. Cadmium or zinc alone led to a decrease in chlorophyll a, b and relative water content of the leaf. Zinc supplement at 150 pM not only mitigated the negative effect of Cd 100 pM and 300 pM, but also increased the chlorophyll content above control level. Zinc supplement not only increased the protein content over the control but also mitigated to some extent the adverse effects of cadmium in protein content when applied in combination. Under both cadmium and zinc treatment, the inhibition of nitrate reductase (NR) activity over unstressed control was found. Different treatment combinations, however, reduced the negative effects of cadmium, although zinc could not completely override such damage, change the level of toxicity. Treatment with Cd 100 pM and 300 pM induced an increase in phenol content over the control, while higher concentration (500 pM) of the metal led to a decrease in this potent antioxidant compound. Presence of Zinc in the growing medium significantly enhanced the accumulation of phenolic compounds highlighting its protective role against oxidative damage.

Cinnamaldehyde is a natural compound extracted from cinnamon bark essential oil, acclaimed for its versatile properties in both pharmaceutical and agricultural fields, including antimicrobial, antioxidant, and anticancer activities. Although potential of cinnamaldehyde against plant pathogenic bacteria like Agrobacterium tumefaciens and Pseudomonas syringae pv. actinidiae causative agents of crown gall and bacterial canker diseases, respectively has been documented, indepth studies into cinnamaldehyde's broader influence on plant pathogenic bacteria are relatively unexplored. Particularly, Pectobacterium spp., gram -negative soil -borne pathogens, notoriously cause soft rot damage across a spectrum of plant families, emphasizing the urgency for effective treatments. Our investigation established that the Minimum Inhibitory Concentrations (MICs) of cinnamaldehyde against strains P. odoriferum JK2, P. carotovorum BP201601, and P. versatile MYP201603 were 250 pg/ml, 125 pg/ml, and 125 pg/ml, respectively. Concurrently, their Minimum Bactericidal Concentrations (MBCs) were found to be 500 pg/ml, 250 pg/ml, and 500 pg/ml, respectively. Using RNA -sequencing analysis, we identified 1,907 differentially expressed genes in P. carotovorum BP201601 treated with 500 pg/ml cinnamaldehyde. Notably, our results indicate that cinnamaldehyde upregulated nitrate reductase pathways while downregulating the citrate cycle, suggesting a potential disruption in the aerobic respiration system of P. carotovorum during cinnamaldehyde exposure. This study serves as a pioneering exploration of the transcriptional response of P. carotovorum to cinnamaldehyde, providing insights into the bactericidal mechanisms employed by cinnamaldehyde against this bacterium.