title: Cloning and characterization of miRNAs from maize seedling roots under low phosphorus stress.
abstract: MicroRNAs (miRNAs) are a class of small, non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition in plants and animals. In this study, a small RNA library was constructed to identify conserved miRNAs as well as novel miRNAs in maize seedling roots under low level phosphorus stress. Twelve miRNAs were identified by high throughput sequencing of the library and subsequent analysis, two belong to conserved miRNA families (miRNA399b and miRNA156), and the remaining ten are novel and one of latter is conserved in gramineous species. Based on sequence homology, we predicted 125 potential target genes of these miRNAs and then expression patterns of 7 miRNAs were validated by semi-RT-PCR analysis. MiRNA399b, Zma-miR3, and their target genes (Zmpt1 and Zmpt2) were analyzed by real-time PCR. It is shown that both miRNA399b and Zma-miR3 are induced by low phosphorus stress and regulated by their target genes (Zmpt1 and Zmpt2). Moreover, Zma-miR3, regulated by two maize inorganic phosphate transporters as a newly identified miRNAs, would likely be directly involved in phosphate homeostasis, so was miRNA399b in Arabidopsis and rice. These results indicate that both conserved and maize-specific miRNAs play important roles in stress responses and other physiological processes correlated with phosphate starvation, regulated by their target genes. Identification of these differentially expressed miRNAs will facilitate us to uncover the molecular mechanisms underlying the progression of maize seedling roots development under low level phosphorus stress.
authors.affiliation: Key Laboratory of Biology and Genetic Improvement of Maize in Southwest China, Ministry of Agriculture, Maize Research Institute, Sichuan Agricultural University, Chengdu Campus, 211 Huimin Road, Wenjiang 611130, Sichuan, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Zhang
authors.forename: Haijian
authors.initials: H
authors.lastname: Lin
authors.forename: Yaou
authors.initials: Y
authors.lastname: Shen
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.forename: Kui
authors.initials: K
authors.lastname: Xiang
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Haiping
authors.initials: H
authors.lastname: Ding
authors.forename: Guangsheng
authors.initials: G
authors.lastname: Yuan
authors.forename: Hai
authors.initials: H
authors.lastname: Lan
authors.forename: Shufeng
authors.initials: S
authors.lastname: Zhou
authors.forename: Maojun
authors.initials: M
authors.lastname: Zhao
authors.forename: Shibin
authors.initials: S
authors.lastname: Gao
authors.forename: Tingzhao
authors.initials: T
authors.lastname: Rong
authors.forename: Guangtang
authors.initials: G
authors.lastname: Pan
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D036226:Seedlings / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics*; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
chemical_list: D035683:MicroRNAs; D010758:Phosphorus