A proteome map of a quadruple photoreceptor mutant sustains its severe photosynthetic deficient phenotype.

FOX, ROMINA; BARBERINI, MARIA LAURA; PLOSCHUK; MUSCHIETTI, JORGE; MAZZELLA, MARIA AGUSTINA

JOURNAL OF PLANT PHYSIOLOGY

ELSEVIER GMBH

Año: 2015 vol. 185 p. 13 - 23

0176-1617

Light is the environmental factor that most affects plant growth and development through its impact onphotomorphogenesis and photosynthesis. A quadruple photoreceptor mutant lacking four of the mostimportant photoreceptors in plants, phytochromes A and B (phyA, phyB) and cryptochromes 1 and 2(cry1, cry2), is severely affected in terms of growth and development. Previous studies have suggestedthat in addition to a photomorphogenic disorder, the phyA phyB cry1 cry2 quadruple mutant might havesevere alterations in photosynthetic ability. Here, we investigated the photosynthetic processes alteredin the quadruple mutant and performed a proteomic profiling approach to identify some of the proteinsinvolved. The phyA phyB cry1 cry2 quadruple mutant showed reduced leaf area and total chlorophyllcontent. Photosynthetic rates at high irradiances were reduced approximately 65% compared to the wildtype (WT). Light-saturated photosynthesis and the response of net CO2 exchange to low and high internalCO2 concentrations suggest that the levels or activity of the components of the Calvin cycle and electrontransport might be reduced in the quadruple mutant. Most of the under-expressed proteins in the phyAphyB cry1 cry2 quadruple mutant consistently showed a chloroplastic localization, whereas componentsof the Calvin cycle and light reaction centers were overrepresented. Additionally, Rubisco expression wasreduced threefold in the phyA phyB cry1 cry2 quadruple mutant.Together, these results highlight the importance of the phytochrome and cryptochrome families inproper autotrophy establishment in plants. They also suggest that an overall limitation in the chlorophylllevels, expression of Rubisco, and enzymes of the Calvin Cycle and electron transport that affectribulose-1,5-biphosphate (RuBP) regeneration reduced photosynthetic capacity in the phyA phyB cry1cry2 quadruple mutant.