Two divergent genes encoding L-myo-inositol 1-phosphate synthase1 (CaMIPS1) and 2 (CaMIPS2) are differentially expressed in chickpea.
L-myo-inositol 1-phosphate synthase (MIPS; EC5.5.1.4) catalyses the rate-limiting step in inositol biosynthetic pathway, and is extremely widespread in living organisms including plants. Several plants possess multiple copies of MIPS gene(s) indicating a possibility of differential expression of each gene to perform distinct physiological functions. To explore this, two MIPS genes (CaMIPS1 and CaMIPS2) were isolated from a drought-tolerant plant chickpea. Both genes are extremely divergent in respect to their introns, at the same time retaining 85% identity to their exons and functionally complementing inositol auxotroph Schizosaccharomyces pombe. Expression analysis showed both genes were expressed in all organs except seed, where only CaMIPS2 transcript was detected. Under environmental stresses, only CaMIPS2 was induced whereas CaMIPS1 expression remained same, which could be explained by the divergence of their 5' upstream regulatory sequences. Remarkably, both gene products exhibited similar biochemical characteristics; however, CaMIPS2 retained higher activity than CaMIPS1 at a high temperature and salt concentration. Furthermore, functional expression of CaMIPS2 in S. pombe results better growth response than CaMIPS1 under stress environment. Taken together, our results suggest that CaMIPS1 and CaMIPS2 are differentially expressed in chickpea to play discrete though overlapping roles in plant; however CaMIPS2 is likely to be evolved through gene duplication to function under environmental stresses.
Kaur
Harmeet
H
National Institute for Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.
Shukla
Rakesh Kumar
RK
Yadav
Gitanjali
G
Chattopadhyay
Debasis
D
Majee
Manoj
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D029863:Cicer / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D019295:Computational Biology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D007294:Inositol / Q000378:metabolism; D008969:Molecular Sequence Data; D007296:Myo-Inositol-1-Phosphate Synthase / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature
D018749:RNA, Plant; D012965:Sodium Chloride; D007294:Inositol; D007296:Myo-Inositol-1-Phosphate Synthase