In plants external stimuli are perceived through a cascade of signals and signal transduction pathways. Protein phosphorylation and de-phosphorylation is one of the most important transduction paths for the perception of signals in plants. The highest concentrations of plant phospho-proteins are located in chloroplasts. This facilitates the protection of thylakoid membranes from stress-induced damage and augments adaptive strategies in plants. In this review, the protein kinases associated with phosphorylation of thylakoid membrane protein, and the adaptive changes in thylakoid membrane architecture and developmental cues are given. The presence of membrane bound kinases in thylakoid membranes have evolutionary implications for the signal transduction pathways and the photosynthetic gene expression for thylakoid membrane protein dynamics. and A. N. Misra, A. K. Biswal.
Responses to drought were studied using two maize inbred lines (B76 and B106) and a commercial maize hybrid (Zea mays L. cv. Silver Queen) with differing resistance to abiotic stress. Maize seedlings were grown in pots in controlled environment chambers for 17 days and watering was withheld from one half the plants for an additional 11 days. On the final treatment date, leaf water potentials did not differ among genotypes and were -0.84 and -1.49 MPa in the water sufficient and insufficient treatments, respectively. Greater rates of CO2 assimilation were retained by the stress tolerant maize inbred line, B76, in comparison to the other two genotypes 11 days after watering was withheld. Rates of CO2 assimilation for all three genotypes were unaffected by decreasing the measurement O2 concentration from 21 to 2% (v/v). Activities of phosphoenolpyruvate carboxylase (PEPC), NADP-malic enzyme (NADP-ME), and NADP malate dehydrogenase were inhibited from 25 to 49% by the water deficiency treatment. Genotypic differences also were detected for the activities of NADP-ME and for PEPC. Changes of transcript abundance for the three C4 pathway enzymes also varied among watering treatments and genotypes. However, examples where transcripts decreased due to drought were associated with the two stress susceptible genotypes. The above results showed that enzymes in the C4 photosynthetic pathway were less inhibited by drought in stress tolerant compared to stress susceptible maize genotypes., R. Sicher, J. Bunce, J. Barnaby, B. Bailey., and Obsahuje bibliografii