title: Methylation effect on IPT5b gene expression determines cytokinin biosynthesis in apple rootstock.
abstract: The molecular mechanism of dwarfing in the apple rootstock is poorly understood, and has been attributed to low root cytokinin biosynthesis levels. Here we identified differences in root trans-zeatin content and expression of cytokinin metabolic pathway genes between dwarfing and vigorous rootstocks. Specifically, a stable low expression of IPT5b was identified in the dwarfing rootstocks. Bisulfite sequencing showed that two CpG islands (CpG2 and CpG4) in the IPT5b promoter region showed higher methylation levels in the M9 rootstock (dwarfing) compared to the Mr (vigorous) rootstock. Furthermore, IPT5b expression increased when M9 rootstocks were treated with 5-azaC, a methylation blocker, indicating that methylation levels influence IPT5b expression. In conclusion, we found low IPT5b expression with high level methylations in promoter region, leading to poor root trans-zeatin biosynthesis in the M9 rootstock, which may induce dwarfing.
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China.
authors.forename: Xinzhong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Xu
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China.
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Han
authors.affiliation: Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China; Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, China; Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, China. Electronic address: wangyi@cau.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways; D018899:CpG Islands; D003583:Cytokinins / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D027845:Malus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008958:Models, Molecular; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015026:Zeatin / Q000235:genetics / Q000378:metabolism
chemical_list: D003583:Cytokinins; D010940:Plant Proteins; D015026:Zeatin; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase
keywords: Apple rootstock; Cytokinin; DNA methylation; Dwarfing; IPT