油莎豆水通道蛋白基因CeTIP2;1的克隆与分析OA北大核心CSTPCD

Tigernut(Cyperus esculentus L.),most likely originated from Africa and Mediterranean,represents a novel herbaceous oil crop accumulating high levels of oil in its underground tubers.Water balance is essential for tuber de-velopment and metabolism in tigernut.Tonoplast intrinsic proteins(TIPs),which include five phylogenetic groups(i.e.TIP1-5),constitute a subfamily of aquaporin facilitating the fast and passive transport of water across vacuolar mem-branes.Based on available genome and transcriptome data,one TIP gene named CeTIP2;1 was isolated from tigernut tubers by using the RT-PCR technique.Sequence analysis showed that the full gene length of CeTIP2;1 is 3323 bp,in-cluding two introns with a coding sequence of 747 bp;the gene was predicted to encode 248 amino acids with the theo-retical molecular weight of 24.73 kDa,the isoelectric point of 5.09,the grand average of hydropathicity of 0.948,the aliphatic index of 114.60,and the instability index of 21.76,implying its stable,acidic,and hydrophobic features,which is consistent with its tonoplast-localization;presence of one conservative MIP domain was observed,which possesses six transmembrane helices,two half helices,and two typical NPA motifs.CeTIP2;1 was shown to exhibit the sequence similarity of 87.20％with AtTIP2;1,which was considerably higher than 46.23％with SoPIP2;1.Further phylogenetic analysis revealed that CeTIP2;1 belongs to the TIP2 group and is a true ortholog of AtTIP2;1.Interestingly,the phy-logenetic analysis also supported that TIP2 has diverged into two subgroups sometime before monocot-eudicot diver-gence.Tissue-specific expression analysis showed that CeTIP2;1 was highly expressed in all tissues examined in this study,i.e.,leaf,sheath,root,shoot apex,rhizome,and tuber,with most in tuber/rhizome and lowest in shoot apex.A bell-like expression pattern was observed during tuber development,peaking at the medium stage of swelling and lowest in maturation.Moreover,CeTIP2;1 was also detected in the tuber proteomes,implying its high abundance and key roles.These findings would lay a solid foundation for further uncovering the mechanism of water balance in tigernut tubers.