A new mechanistic understanding of light-limitation in the seagrass Zostera muelleri

In this study we investigated the effect of light-limitation (similar to 20 mu mol photons M-2 s(-1)) on the southern hemisphere seagrass, Zostera muelleri. RNA sequencing, chlorophyll fluorometry and HPLC techniques were used to investigate how the leaf-specific transcriptome drives changes in photosynthesis and photo-pigments in Z. muelleri over 6 days. 1593 (7.51%) genes were differentially expressed on day 2 and 1481 (6.98%) genes were differentially expressed on day 6 of the experiment. Differential gene expression correlated with significant decreases in rETR(Max), I-k, an increase in Yi (initial photosynthetic quantum yield of photosystem II), and significant changes in pigment composition. Regulation of carbohydrate metabolism was observed along with evidence that abscisic acid may serve a role in the low-light response of this seagrass. This study provides a novel understanding of how Z. rnuelleri responds to light-limitation in the marine water column and provides potential molecular markers for future conservation monitoring efforts.