Molecular Characterization of Carbonic Anhydrase Genes in Lotus japonicus and Their Potential Roles in Symbiotic Nitrogen Fixation

Abstract

Carbonic anhydrase (CA) plays a vital role in photosynthetic tissues of higher plants, whereas its non-photosynthetic role in the symbiotic root nodule was rarely characterized. In this study, 13 CA genes were identified in the model legume Lotus japonicus by comparison with Arabidopsis CA genes. Using qPCR and promoter-reporter fusion methods, three previously identified nodule-enhanced CA genes (LjαCA2, LjαCA6, and LjβCA1) have been further characterized, which exhibit different spatiotemporal expression patterns during nodule development. LjαCA2 was expressed in the central infection zone of the mature nodule, including both infected and uninfected cells. LjαCA6 was restricted to the vascular bundle of the root and nodule. As for LjβCA1, it was expressed in most cell types of nodule primordia but only in peripheral cortical cells and uninfected cells of the mature nodule. Using CRISPR/Cas9 technology, the knockout of LjβCA1 or both LjαCA2 and its homolog, LjαCA1, did not result in abnormal symbiotic phenotype compared with the wild-type plants, suggesting that LjβCA1 or LjαCA1/2 are not essential for the nitrogen fixation under normal symbiotic conditions. Nevertheless, the nodule-enhanced expression patterns and the diverse distributions in different types of cells imply their potential functions during root nodule symbiosis, such as CO2 fixation, N assimilation, and pH regulation, which await further investigations.

Decoding the guardians of cotton resilience: A comprehensive exploration of the βCA genes and its role in Verticillium dahliae resistance

“…Extensive research has been conducted in recent decades to explore the functions of CAs in various physiological processes across photosynthetic organisms. Although genome-wide identification of CA gene families has been achieved in different species using whole-genome sequencing technologies (Fabre et al, 2007, Smith and Ferry, 2000, Tiwari et al, 2005, DiMario et al, 2017, Feng et al, 2015, Wang et al, 2021, Carbonic anhydrase (CA) is a universally occurring enzyme found in various organisms, playing a crucial role in facilitating the interconversion of CO 2 and HCO 3 À (bicarbonate ion) (Sanogo and Zhang, 2016).…”

Comparison of Carbonic Anhydrases for CO2 Sequestration

“…Expression yields were not reported. CAs from higher plants were mainly expressed in the original species for characterization, and hydratase activities were not reported [55,56]. For CO 2 capture, prominent α-CAs from other eukaryotes were human hCAII, which was produced using bacterial vectors [13], and BovCAII, which was simply purified from bovine erythrocytes [57].…”

A Changing Light Environment Induces Significant Lateral CO2 Diffusion within Maize Leaves

“…However, due to the low porosity, long lateral path lengthening, and low conductance of the intercellular airspace in the maize leaves ( Figure 1 and Figure 2 ), it was, therefore, possible that lateral CO 2 diffusion might be not completely dependent on gaseous diffusion through the intercellular space. Carbonic anhydrase (CA) plays an important role in the initial fixation of CO 2 [ 27 , 28 , 29 , 30 , 31 ]. More importantly, the CA activity in the mesophyll cytoplasm of C 4 plants is higher than that of C 3 plants, while CA in the leaves of C 3 plants is mainly distributed in the chloroplasts [ 32 , 33 , 34 , 35 ].…”