title: Roles of Aquaporins inSetaria viridisStem Development and Sugar Storage.
abstract: Setaria viridisis a C4grass used as a model for bioenergy feedstocks. The elongating internodes in developingS. viridisstems grow from an intercalary meristem at the base, and progress acropetally toward fully expanded cells that store sugar. During stem development and maturation, water flow is a driver of cell expansion and sugar delivery. As aquaporin proteins are implicated in regulating water flow, we analyzed elongating and mature internode transcriptomes to identify putative aquaporin encoding genes that had particularly high transcript levels during the distinct stages of internode cell expansion and maturation. We observed thatSvPIP2;1was highly expressed in internode regions undergoing cell expansion, andSvNIP2;2was highly expressed in mature sugar accumulating regions. Gene co-expression analysis revealedSvNIP2;2expression was highly correlated with the expression of five putative sugar transporters expressed in theS. viridisinternode. To explore the function of the proteins encoded bySvPIP2;1andSvNIP2;2, we expressed them inXenopus laevisoocytes and tested their permeability to water. SvPIP2;1 and SvNIP2;2 functioned as water channels inX. laevisoocytes and their permeability was gated by pH. Our results indicate that SvPIP2;1 may function as a water channel in developing stems undergoing cell expansion and SvNIP2;2 is a candidate for retrieving water and possibly a yet to be determined solute from mature internodes. Future research will investigate whether changing the function of these proteins influences stem growth and sugar yield inS. viridis.
authors.affiliation: Centre for Plant Science, School of Environmental and Life Sciences, University of Newcastle, CallaghanNSW, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, University of Adelaide, Glen OsmondSA, Australia.
authors.forename: Samantha A
authors.initials: SA
authors.lastname: McGaughey
authors.affiliation: Australian Research Council Centre of Excellence for Translational Photosynthesis, College of Medicine, Biology and Environment, Australian National University, Canberra ACT, Australia.
authors.forename: Hannah L
authors.initials: HL
authors.lastname: Osborn
authors.affiliation: Centre for Plant Science, School of Environmental and Life Sciences, University of Newcastle, CallaghanNSW, Australia; Australian Research Council Centre of Excellence for Translational Photosynthesis, College of Medicine, Biology and Environment, Australian National University, CanberraACT, Australia.
authors.forename: Lily
authors.initials: L
authors.lastname: Chen
authors.affiliation: Centre for Plant Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan NSW, Australia.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Pegler
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond SA, Australia.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Tyerman
authors.affiliation: Australian Research Council Centre of Excellence for Translational Photosynthesis, College of Medicine, Biology and Environment, Australian National University, Canberra ACT, Australia.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Furbank
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute and School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond SA, Australia.
authors.forename: Caitlin S
authors.initials: CS
authors.lastname: Byrt
authors.affiliation: Centre for Plant Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan NSW, Australia.
authors.forename: Christopher P L
authors.initials: CP
authors.lastname: Grof
keywords: aquaporin; grasses; stem; sugar accumulation; water transport