Abstract
BackgroundRubisco activase (RCA) regulates the activity of Rubisco and is a key enzyme of photosynthesis. RCA expression was widely reported to affect plant photosynthesis and crop yield, but the molecular basis of natural variation in RCA expression in a wide range of maize materials has not been fully elucidated.ResultsIn this study, correlation analysis in approximately 200 maize inbred lines revealed a significantly positive correlation between the expression of maize RCA gene ZmRCAβ and grain yield. A genome-wide association study revealed both cis-expression quantitative trait loci (cis-eQTLs) and trans-eQTLs underlying the expression of ZmRCAβ, with the latter playing a more important role. Further allele mining and genetic transformation analysis showed that a 2-bp insertion and a 14-bp insertion in the promoter of ZmRCAβ conferred increased gene expression. Because rice is reported to have higher RCA gene expression than does maize, we subsequently compared the genetic factors underlying RCA gene expression between maize and rice. The promoter activity of the rice RCA gene was shown to be stronger than that of the maize RCA gene, suggesting that replacing the maize RCA gene promoter with that of the rice RCA gene would improve the expression of RCA in maize.ConclusionOur results revealed two DNA polymorphisms regulating maize RCA gene ZmRCAβ expression, and the RCA gene promoter activity of rice was stronger than that of maize. This work increased understanding of the genetic mechanism that underlies RCA gene expression and identify new targets for both genetic engineering and selection for maize yield improvement.
Highlights
Rubisco activase (RCA) regulates the activity of Rubisco and is a key enzyme of photosynthesis
The variation range of grain yield was larger, 95% of lines fell in the range of 19.83–71.37 g/plant in 2015 and 17.32
We focused on ZmRCAβ transcript expression, and observed that during the two growing seasons of 2015 and 2016, the ZmRCAβ transcript expression displayed a significant correlation with the corresponding grain yield (P < 0.01)
Summary
Rubisco activase (RCA) regulates the activity of Rubisco and is a key enzyme of photosynthesis. Rubisco activity is regulated by a second enzyme named Rubisco activase (RCA) [1,2,3,4,5,6]. The endogenous levels of RCA have been widely reported to affect plant photosynthesis and crop yield. Characterization of the genetic elements regulating RCA gene expression could facilitate the modulation of the RCA gene for improving crop yield. For this purpose, genetic determinants that control the expression of RCA genes have been identified in various crops. Functional analysis of the rice RCA gene promoter revealed several cis-elements that regulate its expression [17]
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