Tissue-Specific Differential Expression of Two β-carbonic Anhydrases in Leucaena leucocephala Under Abiotic Stress Conditions

This is the authors' abstract. We don't add key points for this paper.

Besides carbon fixation in plants, β-carbonic anhydrases (β-CAs) have been shown to be involved in plant adaptation against some abiotic stress conditions. The objective of this research was to determine the expression levels of two isoforms of β-CAs under various stress conditions in different tissues of Leucaena leucocephala , a highly stress-tolerant tree-legume of tropics. The cDNAs for two β-CAs isoforms, one chloroplastic ( cacp ) and other cytoplasmic ( cacyt ) were isolated. These isoforms have 79% similarities at amino acid level, and their secondary structures, active site residues including zinc ligands, and the three-dimensional (3D) quaternary structures were found to be highly conserved and similar to those of the β-CA from Pisum sativum , which is structurally well-characterized. The 3D-model of the two leucaena β-CAs predicted them as octameric proteins like the β-CA from P. sativum . The transcripts for cacp was found to be more abundant than the transcripts for cacyt in leaf and stem tissues, however the transcripts level of both β-CAs were similar in root tissues. The drought, salt, and light conditions caused up-regulation, and dark resulted down regulation of the cacp and cacyt transcripts. However, the changes in the expression levels of cacp was more pronounced than those of cacyt , except in salt-stressed root tissues, which showed more pronounced up regulation of cacyt than that of cacp . This study suggests that abiotic stress conditions affecting the photosynthesis potential of plants also affect expression of different isoforms of β-CAs from C 3 plants differentially, which may contribute to plants’ survival under stress conditions.