油莎豆CePIP2;1的克隆、亚细胞定位与表达分析OA北大核心CSTPCD

Tigernut(Cyperus esculentus L.)is an herbaceous oil crop uniquely accumulating a high level of oil in the underground tubers.Water,which accounts for approximately 85％of immature tubers,is essential for tuber develop-ment and metabolism.Plasma membrane intrinsic proteins(PIPs)represent the main channel that mediates the efficient water transport across the cell membrane.This study presents the characterization of CePIP2;1,a PIP gene highly abundant in tigernut tubers.This gene with three introns was shown to encode 288 amino acids with the theoretical mo-lecular weight of 30.34 kDa,the isoelectric point of 8.60,the grand average of hydropathicity of 0.529,and the instabil-ity index of 29.60,implying it's stable,basic and hydrophobic characteristics.The protein was shown to possess one conservative MIP(major intrinsic protein)domain,and presence of the F-H-T-R ar/R selectivity filter and Q-S-A-F-W Froger's positions implies a putatively efficient water transport activity.Phylogenetic analysis revealed that CePIP2;1 clusters with OsPIP2;1,OsPIP2;2,and OsPIP2;3 with the similarities of 91.72％,90.31％and 84.98％,respectively,supporting its assignment into the PIP2 group of the PIP subfamily.Subcellular localization analysis showed that CePIP2;1 was localized to the cell membrane of Nicotiana benthamiana leaves.Although CePIP2;1 was characterized as a dominant isoform in tubers,expression analysis indicated that its transcripts were relatively more in leaves,leaf sheaths,rhizomes,and roots with the most in leaves,in contrast to a comparable level to that in shoot apexes.Among four typical stages(S1-S4)of tuber development examined in this study,CePIP2;1 was shown to exhibit a bell-shaped expression pattern,peaking at S2.These results laid a solid foundation for further uncovering the mechanism of water balance in tigernut.