title: Physiological and transcriptional analyses of developmental stages along sugarcane leaf.
abstract: BACKGROUND
  Sugarcane is one of the major crops worldwide. It is cultivated in over 100 countries on 22 million ha. The complex genetic architecture and the lack of a complete genomic sequence in sugarcane hamper the adoption of molecular approaches to study its physiology and to develop new varieties. Investments on the development of new sugarcane varieties have been made to maximize sucrose yield, a trait dependent on photosynthetic capacity. However, detailed studies on sugarcane leaves are scarce. In this work, we report the first molecular and physiological characterization of events taking place along a leaf developmental gradient in sugarcane.
  
  
  RESULTS
  Photosynthetic response to CO2 indicated divergence in photosynthetic capacity based on PEPcase activity, corroborated by activity quantification (both in vivo and in vitro) and distinct levels of carbon discrimination on different segments along leaf length. Additionally, leaf segments had contrasting amount of chlorophyll, nitrogen and sugars. RNA-Seq data indicated a plethora of biochemical pathways differentially expressed along the leaf. Some transcription factors families were enriched on each segment and their putative functions corroborate with the distinct developmental stages. Several genes with higher expression in the middle segment, the one with the highest photosynthetic rates, were identified and their role in sugarcane productivity is discussed. Interestingly, sugarcane leaf segments had a different transcriptional behavior compared to previously published data from maize.
  
  
  CONCLUSIONS
  This is the first report of leaf developmental analysis in sugarcane. Our data on sugarcane is another source of information for further studies aiming to understand and/or improve C4 photosynthesis. The segments used in this work were distinct in their physiological status allowing deeper molecular analysis. Although limited in some aspects, the comparison to maize indicates that all data acquired on one C4 species cannot always be easily extrapolated to other species. However, our data indicates that some transcriptional factors were segment-specific and the sugarcane leaf undergoes through the process of suberizarion, photosynthesis establishment and senescence.
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6192, 13083-970, Campinas, SP, Brazil. lucia@lgf.ib.unicamp.br.|Laboratório de Genoma Funcional, Instituto de Biologia, Universidade Estadual de Campinas Campinas, Caixa Postal 6109, Campinas, 13083-862, SP, Brazil. lucia@lgf.ib.unicamp.br.
authors.forename: Lucia
authors.initials: L
authors.lastname: Mattiello
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6192, 13083-970, Campinas, SP, Brazil. diego.riano@bioetanol.org.br.
authors.forename: Diego Mauricio
authors.initials: DM
authors.lastname: Riaño-Pachón
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6192, 13083-970, Campinas, SP, Brazil. marina.martins@bioetanol.org.br.
authors.forename: Marina Camara Mattos
authors.initials: MC
authors.lastname: Martins
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6192, 13083-970, Campinas, SP, Brazil. larissa.cruz@bioetanol.org.br.
authors.forename: Larissa Prado
authors.initials: LP
authors.lastname: da Cruz
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Caixa Postal 6192, 13083-970, Campinas, SP, Brazil. denis.bassi@bioetanol.org.br.
authors.forename: Denis
authors.initials: D
authors.lastname: Bassi
authors.affiliation: Laboratório de Fisiologia de Plantas "Coaracy M. Franco", Centro de Pesquisa e Desenvolvimento em Ecofisiologia e Biofísica, Instituto Agronômico, Caixa Postal 28, Campinas, 13020-902, SP, Brazil. marchiori.paulo@gmail.com.
authors.forename: Paulo Eduardo Ribeiro
authors.initials: PE
authors.lastname: Marchiori
authors.affiliation: Departamento de Biologia de Plantas, Universidade Estadual de Campinas, Caixa Postal 6109, Campinas, 13083-970, SP, Brazil. rvr@unicamp.br.
authors.forename: Rafael Vasconcelos
authors.initials: RV
authors.lastname: Ribeiro
authors.affiliation: Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Universidade de São Paulo, Caixa Postal 83, Piracicaba, 13400-970, SP, Brazil. mtvlabate@gmail.com.
authors.forename: Mônica T Veneziano
authors.initials: MT
authors.lastname: Labate
authors.affiliation: Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Universidade de São Paulo, Caixa Postal 83, Piracicaba, 13400-970, SP, Brazil. calabate@usp.br.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Labate
authors.affiliation: Laboratório de Genoma Funcional, Instituto de Biologia, Universidade Estadual de Campinas Campinas, Caixa Postal 6109, Campinas, 13083-862, SP, Brazil. menossi@unicamp.br.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Menossi
mesh_terms: D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D031786:Saccharum / Q000235:genetics* / Q000254:growth & development*; D017422:Sequence Analysis, DNA
chemical_list: D010940:Plant Proteins