461 / 2019-02-26 23:22:30

Effects of visible-light wavelengths on the plastoquinone pool: photo-acclimation and gene regulation

photosynthesis,gene regulation,light acclimation,plastoquinone

全体主题 > Photosynthesis

Plastoquinone (PQ) molecules mediate electron flow from Photosystem II (PSII) to Photosystem I (PSI) via the cytochrome b6f -complex. Previous research has shown that the redox state of the PQ pool regulates photo-acclimation in plants. However, effects of individual visible-light wavelengths have not been systematically measured. By directly measuring the redox state of the PQ pool with a HPLC method, we found that in Arabidopsis 470–500, 560 and 650–660 nm light favor PSII and reduce the PQ pool whereas 420–440, 520 and 690 nm light favor PSI and oxidize the PQ pool. Already moderate reduction of the PQ pool induced State 2, which deepened if the PQ pool was highly reduced. Next, to understand how the PQ pool regulates gene expression, we isolated mRNA from leaves illuminated for 1 h with the PSI or PSII wavelengths. Expression of over 3000 genes were found to correlate (r2 > 0.7) with the redox state of the PQ pool, most of the genes correlating positively with oxidation of the PQ pool. Expression of only eight chloroplast genes correlated with the redox state, seven of them coding for the chloroplast NDH-like complex. Expression of over 30 mitochondrial genes (including several genes coding for Complex I) followed the redox state of the PQ pool, suggesting that the redox status of chloroplasts regulates mitochondrial functions. In addition, expression of many nuclear genes, including those involved in regulation of growth, correlated with the redox state of the PQ pool.