title: The potato amylase inhibitor gene SbAI regulates cold-induced sweetening in potato tubers by modulating amylase activity.
abstract: Potato cold-induced sweetening (CIS) is critical for the postharvest quality of potato tubers. Starch degradation is considered to be one of the key pathways in the CIS process. However, the functions of the genes that encode enzymes related to starch degradation in CIS and the activity regulation of these enzymes have received less attention. A potato amylase inhibitor gene known as SbAI was cloned from the wild potato species Solanum berthaultii. This genetic transformation confirmed that in contrast to the SbAI suppression in CIS-resistant potatoes, overexpressing SbAI in CIS-sensitive potatoes resulted in less amylase activity and a lower rate of starch degradation accompanied by a lower reducing sugar (RS) content in cold-stored tubers. This finding suggested that the SbAI gene may play crucial roles in potato CIS by modulating the amylase activity. Further investigations indicated that pairwise protein-protein interactions occurred between SbAI and α-amylase StAmy23, β-amylases StBAM1 and StBAM9. SbAI could inhibit the activities of both α-amylase and β-amylase in potato tubers primarily by repressing StAmy23 and StBAM1, respectively. These findings provide the first evidence that SbAI is a key regulator of the amylases that confer starch degradation and RS accumulation in cold-stored potato tubers.
authors.affiliation: Key Laboratory of Horticultural Plant Biology (HAU), Ministry of Education, National Centre for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, China; College of Forestry, Henan University of Science and Technology, Luoyang, China.
authors.forename: Huiling
authors.initials: H
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Juan
authors.initials: J
authors.lastname: Hou
authors.forename: Ying
authors.initials: Y
authors.lastname: Yao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lin
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Ou
authors.forename: Botao
authors.initials: B
authors.lastname: Song
authors.forename: Conghua
authors.initials: C
authors.lastname: Xie
mesh_terms: D000595:Amino Acid Sequence; D000681:Amylases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D003080:Cold Temperature; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D013213:Starch / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D013213:Starch; D000681:Amylases
keywords: SbAI; amylase activity; cold-induced sweetening; potato; starch degradation