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Savage, Linda J.

Publications and source records attributed to Savage, Linda J..

PhenoCurve: capturing dynamic phenotype-environment relationships using phenomics data

MOTIVATION: Phenomics is significant for understanding the mechanisms that regulate or influence growth, fitness, and development. Techniques have been developed to conduct high-throughput large-scale phenotyping on animals, plants and humans, aiming to bridge the gap between genomics, gene functions and traits. Although new developments in phenotyping techniques are exciting, we are limited by the tools to analyze fully the massive phenotype data, especially the dynamic relationships between phenotypes and environments. RESULTS: We present a new algorithm called PhenoCurve, a knowledge-based curve fitting algorithm, aiming to identify the complex relationships between phenotypes and environments, thus studying both values and trends of phenomics data. The findings on both real and simulated data showed that PhenoCurve has the best performance among all the six tested methods. Its application to photosynthesis hysteresis pattern identification reveals new functions of core genes that control photosynthetic efficiency in response to varying environmental conditions, which are critical for understanding plant energy storage and improving crop productivity.

Yang, Yifan↗

Multi-level regulation of the chloroplast ATP synthase: the chloroplast NADPH thioredoxin reductase C (NTRC) is required for redox modulation specifically under low irradiance

The chloroplast ATP synthase is known to be regulated by redox modulation of a disulfide bridge on thec-subunit through the ferredoxin–thioredoxin regulatory system. We show that a second enzyme, therecently identified chloroplast NADPH thioredoxin reductase C (NTRC), plays a role specifically at low irradi-ance. Arabidopsis mutants lacking NTRC (ntrc) displayed a striking photosynthetic phenotype in which feed-back regulation of the light reactions was strongly activated at low light, but returned to wild-type levels asirradiance was increased. This effect was caused by an altered redox state of the c-subunit under low, butnot high, light. The low light-specific decrease in ATP synthase activity in ntrc resulted in a buildup of thethylakoid proton motive force with subsequent activation of non-photochemical quenching and downregu-lation of linear electron flow. We conclude that NTRC provides redox modulation at low light using the rela-tively oxidizing substrate NADPH, whereas the canonical ferredoxin–thioredoxin system can take over athigher light, when reduced ferredoxin can accumulate. Based on these results, we reassess previous modelsfor ATP synthase regulation and propose that NTRC is most likely regulated by light. We also find that ntrcis highly sensitive to rapidly changing light intensities that probably do not involve the chloroplast ATP syn-thase, implicating this system in multiple photosynthetic processes, particularly under fluctuating environ-mental conditions.

59 BASIC BIOLOGICAL SCIENCES↗