title: Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.
abstract: Cold-induced sweetening (CIS) in potato is detrimental to the quality of processed products. Conversion of starch to reducing sugars (RS) by amylases is considered one of the main pathways in CIS but is not well studied. The amylase genes StAmy23, StBAM1, and StBAM9 were studied for their functions in potato CIS. StAmy23 is localized in the cytoplasm, whereas StBAM1 and StBAM9 are targeted to the plastid stroma and starch granules, respectively. Genetic transformation of these amylases in potatoes by RNA interference showed that β-amylase activity could be decreased in cold-stored tubers by silencing of StBAM1 and collective silencing of StBAM1 and StBAM9. However, StBAM9 silencing did not decrease β-amylase activity. Silencing StBAM1 and StBAM9 caused starch accumulation and lower RS, which was more evident in simultaneously silenced lines, suggesting functional redundancy. Soluble starch content increased in RNAi-StBAM1 lines but decreased in RNAi-StBAM9 lines, suggesting that StBAM1 may regulate CIS by hydrolysing soluble starch and StBAM9 by directly acting on starch granules. Moreover, StBAM9 interacted with StBAM1 on the starch granules. StAmy23 silencing resulted in higher phytoglycogen and lower RS accumulation in cold-stored tubers, implying that StAmy23 regulates CIS by degrading cytosolic phytoglycogen. Our findings suggest that StAmy23, StBAM1, and StBAM9 function in potato CIS with varying levels of impact.
authors.affiliation: Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, People's Republic of China.|National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Hou
authors.affiliation: Huazhong Agricultural University, Wuhan 430070, People's Republic of China.|Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Wuhan 430070, People's Republic of China.|College of Forestry, Henan University of Science and Technology, Luoyang 471003, People's Republic of China.
authors.forename: Huiling
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, People's Republic of China.|National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Biochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany.
authors.forename: Stephen
authors.initials: S
authors.lastname: Reid
authors.affiliation: National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.|Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Wuhan 430070, People's Republic of China.
authors.forename: Tengfei
authors.initials: T
authors.lastname: Liu
authors.affiliation: National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.|Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Wuhan 430070, People's Republic of China.
authors.forename: Shijing
authors.initials: S
authors.lastname: Xu
authors.affiliation: National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.|Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Wuhan 430070, People's Republic of China.
authors.forename: Zhendong
authors.initials: Z
authors.lastname: Tian
authors.affiliation: Biochemistry Division, Department of Biology, Friedrich-Alexander-University Erlangen-Nuernberg, 91058 Erlangen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Sonnewald
authors.affiliation: National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.|Key Laboratory of Horticultural Plant Biology (HZAU), Ministry of Education, Wuhan 430070, People's Republic of China.
authors.forename: Botao
authors.initials: B
authors.lastname: Song
authors.affiliation: Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, People's Republic of China.|National Center for Vegetable Improvement (Central China), Wuhan 430070, People's Republic of China.|Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
authors.forename: Conghua
authors.initials: C
authors.lastname: Xie
mesh_terms: D000681:Amylases / Q000235:genetics* / Q000378:metabolism; D061353:Food Storage; D020868:Gene Silencing; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D035281:Plant Tubers / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D011198:Solanum tuberosum / Q000235:genetics / Q000502:physiology*; D013213:Starch / Q000378:metabolism*; D000073893:Sugars / Q000032:analysis
chemical_list: D010940:Plant Proteins; D000073893:Sugars; D013213:Starch; D000681:Amylases
keywords: cold-induced sweetening; potato; reducing sugar; starch degradation; tuber.; α-Amylase; β-amylase