Abstract
BackgroundNADP-malic enzyme (NAPD-ME), and pyruvate orthophosphate dikinase (PPDK) are important enzymes that participate in C4 photosynthesis. However, the evolutionary history and forces driving evolution of these genes in C4 plants are not completely understood.ResultsWe identified 162 NADP-ME and 35 PPDK genes in 25 species and constructed respective phylogenetic trees. We classified NADP-ME genes into four branches, A1, A2, B1 and B2, whereas PPDK was classified into two branches in which monocots were in branch I and dicots were in branch II. Analyses of selective pressure on the NAPD-ME and PPDK gene families identified four positively selected sites, including 94H and 196H in the a5 branch of NADP-ME, and 95A and 559E in the e branch of PPDK at posterior probability thresholds of 95%. The positively selected sites were located in the helix and sheet regions. Quantitative RT-PCR (qRT-PCR) analyses revealed that expression levels of 6 NADP-ME and 2 PPDK genes from foxtail millet were up-regulated after exposure to light.ConclusionThis study revealed that positively selected sites of NADP-ME and PPDK evolution in C4 plants. It provides information on the classification and positive selection of plant NADP-ME and PPDK genes, and the results should be useful in further research on the evolutionary history of C4 plants.
Highlights
NADP-malic enzyme (NAPD-ME), and pyruvate orthophosphate dikinase (PPDK) are important enzymes that participate in C4 photosynthesis
This study investigated the evolutionary processes in NADPmalic enzyme (NADP-ME) and Pyruvate orthophosphate dikinase (PPDK) in algal, moss, Lycopodiophyta, monocotyledon and dicotyledon species, providing new information regarding C4 photosynthesis
Numbers of NADP-ME and PPDK genes in plants A total 162 NADP-ME and 35 PPDK sequences were found in 25 species, including one algal, one moss, one Lycopodiophyta, 10 monocot, and 12 dicot species (Additional file 1: Table S1; Additional file 2: Table S2)
Summary
NADP-malic enzyme (NAPD-ME), and pyruvate orthophosphate dikinase (PPDK) are important enzymes that participate in C4 photosynthesis. Photosynthesis is the process used by plants to convert solar energy into chemical energy. This enables them to produce their own food for development [1]. Photosynthesis in higher plants can be classified into C3, C4 and Crassulacean acid metabolism (CAM) based on how they fix carbon during the process that leads to different initial photosynthesized products. The majority of land plants use the C3 pathway, whereas C4 and CAM plants were evolved from C3 plants [2, 3]. C4 plants are more efficient than C3 plants in utilizing CO2 leading to superior adaptiveness to subtropical and tropical environments, lower concentrations of CO2, and more stressed environments [4].
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