Characterization of Rubisco Activase Genes in Maize: An α-Isoform Gene Functions alongside a β-Isoform Gene

Abstract

Rubisco activase (RCA) catalyzes the activation of Rubisco in vivo and plays a crucial role in regulating plant growth. In maize (Zea mays), only b-form RCA genes have been cloned and characterized. In this study, a genome-wide survey revealed the presence of an a-form RCA gene and a b-form RCA gene in the maize genome, herein referred to as ZmRCAa and ZmRCAb, respectively. An analysis of genomic DNA and complementary DNA sequences suggested that alternative splicing of the ZmRCAb precursor mRNA (premRNA) at its 39 untranslated region could produce two distinctive ZmRCAb transcripts. Analyses by electrophoresis and matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry showed that ZmRCAa and ZmRCAb encode larger and smaller polypeptides of approximately 46 and 43 kD, respectively. Transcriptional analyses demonstrated that the expression levels of both ZmRCAa and ZmRCAb were higher in leaves and during grain filling and that expression followed a specific cyclic day/night pattern. In 123 maize inbred lines with extensive genetic diversity, the transcript abundance and protein expression levels of these two RCA genes were positively correlated with grain yield. Additionally, both genes demonstrated a similar correlation with grain yield compared with three C 4 photosynthesis genes. Our data suggest that, in addition to the b-form RCA-encoding gene, the a-form RCA-encoding gene also contributes to the synthesis of RCA in maize and support the hypothesis that RCA genes may play an important role in determining maize productivity.

The Expression of TaRca2-α Gene Associated with Net Photosynthesis Rate, Biomass and Grain Yield in Bread Wheat (Triticum aestivum L.) under Field Conditions

“…These are in agreement with the previous findings in soybean, maize and other crops [16, 20, 28, 29, 34]. Grain-filling is a crucial stage for achieving optimum grain yield, the relatively stronger association of the expression levels of TaRca2-α with Pn at this stage suggested that higher expression may contribute more to grain yield, although Pn reduced greatly at this stage as shown in other studies [5, 17]. These results support the hypothesis that TaRca2-α contributed to photosynthesis substantially, detection of its expression levels could be utilized as a selection tool for the improvement of photosynthetic efficiency in bread wheat The genomic variations resulting in this expression difference should be further clarified for execution in marker assisted selection.…”

“…a large α isoform and a small β isoform with differences at the carboxy terminus [12] and also differing in maximal activity [14, 15] with Rca-α showing higher expression under most of the growth conditions [16]. The importance of Rca-α is also evident from the results of previous studies in different crops due its positive effect on plant productivity traits [16, 17] and therefore can also identify genotypes with improved phenotype under prevailing crop growth conditions. The success of crop plants depends on their final performance in the field where plants experience unpredictable changes in environmental conditions e.g.…”

Overexpression of the rubisco activase gene improves growth and low temperature and weak light tolerance in Cucumis sativus

“…Rubisco is the key factor that limits the carbon assimilation in plants through the C3 cycle; nevertheless, changes in Rubisco activity are unable to alter photosynthesis as expected (Mann , Spreitzer and Salvucci , Parry et al ). Only Rubisco that is activated by RCA can affect the normal operation of the Calvin cycle, resulting in higher yields (Singh et al , Yin et al ). In this study, the overexpression of CsRCA not only increased the RCA activity, but also enhanced the initial and total activities of Rubisco in cucumber leaves (Fig.…”

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…In other plant species the two isoforms are encoded in separate genes (Fig. 3, processes 2a and 2c; Salvucci et al, 2003;Yin et al, 2014).The longer redox-regulated α-isoform contains at the C-terminus an extension with two cysteine residues which are absent in the shorter β-isoform (Portis, 2003). These two residues can be reduced via the thioredoxin system (Portis, 2003).…”