Insufficient synthesis and acylation modification of anthocyanins causes
photoinactivation of the oxygen-evolving complex in Zostera marina
Zostera marina among seagrass suffering from global decline is a
representative species in temperate regions in the Northern Hemisphere.
Given our recent findings, the decline of seagrasses may be associated
with the photosensitivity of the oxygen-evolving complex (OEC).
Therefore, understanding the mechanism of OEC photosensitivity is key to
understanding the continued decline in seagrasses. Herein, we explored
the screening-based photoprotection function in Z. marina by
examining the inactivation spectrum of OEC and the differences in
photoresponse pathways following exposure to different spectrums. The
OEC inactivation was spectral-dependent. High-energy light significantly
reduced the PSII performance, OEC peripheral protein expression, and
photosynthetic O 2 release capacity. The increased
synthesis of carotenoids under blue light with severe OEC damage implied
its weak photoprotection property in Z. marina. However,
anthocyanins key synthetic genes were lowly expressed with inefficient
accumulation under high-energy light. Furthermore, the acylation
modifications of anthocyanins, especially aromatic acylation
modifications were insufficient, leading to poor stability and light
absorption of anthocyanins. Based on the role of blue light receptors in
regulating the synthesis of anthocyanins in vascular plant, we
hypothesized that the absence of blue light receptor CRY2 in Z.
marina causes the insufficient synthesis of anthocyanins and acyl
modifications, reducing the shielding against high-energy light,
subsequently causing OEC photoinactivation.