title: Impacts of strigolactone on shoot branching under phosphate starvation in chrysanthemum (Dendranthema grandiflorum cv. Jinba).
abstract: Chrysanthemum (Dendranthema grandiflorum cv. Jinba) shoot branching is determined by bud outgrowth during the vegetative growth stage. The degree of axillary bud outgrowth is highly influenced by environmental conditions, such as nutrient availability. Here, we demonstrated that phosphorus (Pi) starvation significantly reduces axillary bud outgrowth in chrysanthemum. A strigolactone (SL) biosynthesis gene, DgCCD7, was isolated and characterized as an ortholog of MAX3/DAD3/RMS5/D17. By using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS), three putative SLs were identified and levels of all three SLs showed strong increase under Pi starvation conditions. Determinations of the distribution of SLs and regulation of DgCCD7/8 in response to Pi changes in root indicate that SL acts systemically. However, temporal expression patterns of biosynthesis and signaling genes in nodes revealed that Pi starvation causes a local response of SL pathway. Treatment of node segments with or without auxin and Pi revealed that in the absence of exogenous auxin, Pi delayed axillary buds outgrowth and up-regulated local SL pathway genes. These data indicated that an auxin-SL regulatory loop responded to Pi starvation for delaying bud outgrowth locally, root biosynthesized SLs were transported acropetally and functioned in shoot branching inhibition under Pi starvation. We proposed that SLs contributed to chrysanthemum shoot branching control in response to Pi-limiting conditions in a systemic way.
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xi
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wen
authors.affiliation: National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Fang
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chen
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Nie
authors.affiliation: National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China.
authors.forename: JinFang
authors.initials: J
authors.lastname: Chu
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Cunquan
authors.initials: C
authors.lastname: Yuan
authors.affiliation: National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China.
authors.forename: Cunyu
authors.initials: C
authors.lastname: Yan
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Ma
authors.affiliation: Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University Beijing, China.
authors.forename: Liangjun
authors.initials: L
authors.lastname: Zhao
keywords: UPLC-MS; auxin; chrysanthemum bud outgrowth; local regulation; phosphorus starvation; strigolactone (SL); systemic regulation