A holistic analysis of photosynthetic acclimation to shade in C4 grass (Cynodon dactylon (L.) Pers.)

Abstract

Abstract Background: Lack of light in shady environment is the key factor affecting the growth and development of turf plants. However, it is shade avoidance rather than shade tolerance that has received more attention in past decades. In this study, we investigated the photosynthetic metabolisms of Bermuda grass exposed to deepening shade, aiming to provide a holistic perspective for understanding the shade acclimation strategies of C4 turfgrass. Results: The adjustments of pigment-proteins, photosynthetic electron transport and its coupling of carbon and nitrogen assimilation, ROS-scavenging enzyme activity in shade surroundings were detected. Mild shade enriched Chl b and LHC transcripts, while Chl a, carotenoids and photosynthetic electron transfer beyond QA- (ET0/RC, φE0, Ψ0) were enhanced by severe shade. In addition, differential impacts of shade on leaf and root were shown. Soluble sugar deficiency varied between the two, due shade reduced SPS, SUT1 while up-regulated BAM. Besides, Shading weakened the transcriptional level of genes involving in nitrogen assimilation (e.g. NR) and SOD, POD, CAT enzyme activities in leaf, but improved them in root. Conclusions: As the shade deepened, extensive changes had taken place in light energy conversion and photosynthetic metabolism process along the axis of electron transport chain. This study provided a theoretical basis for the photosynthetic acclimation of C4 grass to shade tolerance.