Arabidopsis plants expressing only the redox‐regulated Rca‐α isoform have constrained photosynthesis and plant growth

Autor: Martin H. Spalding, David A. Wright, Sang Yeol Kim, Dan J. Stessman, Donald R. Ort, Steven C. Huber
Rok vydání: 2020
Předmět:
Zdroj: The Plant Journal. 103:2250-2262
ISSN: 1365-313X
0960-7412
DOI: 10.1111/tpj.14897
Popis: Rubisco activase (Rca) facilitates the release of sugar-phosphate inhibitors from the active sites of Rubisco and thereby plays a central role in initiating and sustaining Rubisco activation. In Arabidopsis, alternative splicing of a single Rca gene results in two Rca isoforms, Rca-α and Rca-β. Redox modulation of Rca-α regulates the function of Rca-α and Rca-β acting together to control Rubisco activation. Although Arabidopsis Rca-α alone less effectively activates Rubisco in vitro, it is not known how CO2 assimilation and plant growth are impacted. Here, we show that two independent transgenic Arabidopsis lines expressing Rca-α in the absence of Rca-β ('Rca-α only' lines) grew more slowly in various light conditions, especially under low light or fluctuating light intensity, and in a short day photoperiod compared to wildtype. Photosynthetic induction was slower in the Rca-α only lines, and they maintained a lower rate of CO2 assimilation during both photoperiod types. Our findings suggest Rca oligomers composed of Rca-α only are less effective in initiating and sustaining the activation of Rubisco than when Rca-β is also present. Currently there are no examples of any plant species that naturally express Rca-α only but numerous examples of species expressing Rca-β only. That Rca-α exists in most plant species, including many C3 and C4 food and bioenergy crops, implies its presence is adaptive under some circumstances.
Databáze: OpenAIRE
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