title: Auxin Biosynthesis, Accumulation, Action and Transport are Involved in Stress-Induced Microspore Embryogenesis Initiation and Progression in Brassica napus.
abstract: Isolated microspores are reprogrammed in vitro by stress, becoming totipotent cells and producing embryos and plants via a process known as microspore embryogenesis. Despite the abundance of data on auxin involvement in plant development and embryogenesis, no data are available regarding the dynamics of auxin concentration, cellular localization and the expression of biosynthesis genes during microspore embryogenesis. This work involved the analysis of auxin concentration and cellular accumulation; expression of TAA1 and NIT2 encoding enzymes of two auxin biosynthetic pathways; expression of the PIN1-like efflux carrier; and the effects of inhibition of auxin transport and action by N-1-naphthylphthalamic acid (NPA) and α-(p-chlorophenoxy) isobutyric acid (PCIB) during Brassica napus microspore embryogenesis. The results indicated de novo auxin synthesis after stress-induced microspore reprogramming and embryogenesis initiation, accompanying the first cell divisions. The progressive increase of auxin concentration during progression of embryogenesis correlated with the expression patterns of TAA1 and NIT2 genes of auxin biosynthetic pathways. Auxin was evenly distributed in early embryos, whereas in heart/torpedo embryos auxin was accumulated in apical and basal embryo regions. Auxin efflux carrier PIN1-like gene expression was induced in early multicellular embryos and increased at the globular/torpedo embryo stages. Inhibition of polar auxin transport (PAT) and action, by NPA and PCIB, impaired embryo development, indicating that PAT and auxin action are required for microspore embryo progression. NPA also modified auxin embryo accumulation patterns. These findings indicate that endogenous auxin biosynthesis, action and polar transport are required in stress-induced microspore reprogramming, embryogenesis initiation and progression.
authors.affiliation: Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas (CIB) CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Héctor
authors.initials: H
authors.lastname: Rodríguez-Sanz
authors.affiliation: Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas (CIB) CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: María-Teresa
authors.initials: MT
authors.lastname: Solís
authors.affiliation: Departamento de Ciencias Agrarias y del Medio Natural, Universidad Jaume I, Campus Riu Sec, 12071, Castellón, Spain.
authors.forename: María-Fernanda
authors.initials: MF
authors.lastname: López
authors.affiliation: Departamento de Ciencias Agrarias y del Medio Natural, Universidad Jaume I, Campus Riu Sec, 12071, Castellón, Spain.
authors.forename: Aurelio
authors.initials: A
authors.lastname: Gómez-Cadenas
authors.affiliation: Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas (CIB) CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: María C
authors.initials: MC
authors.lastname: Risueño
authors.affiliation: Pollen Biotechnology of Crop Plants group, Centro de Investigaciones Biológicas (CIB) CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain testillano@cib.csic.es.
authors.forename: Pilar S
authors.initials: PS
authors.lastname: Testillano
mesh_terms: D001692:Biological Transport; D053898:Biosynthetic Pathways / Q000235:genetics; D029688:Brassica napus / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D002995:Clofibric Acid / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D007210:Indoleacetic Acids / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D018613:Microscopy, Confocal; D008857:Microscopy, Interference; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000187:drug effects / Q000196:embryology* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D007210:Indoleacetic Acids; D010797:Phthalimides; D010937:Plant Growth Regulators; D010940:Plant Proteins; C002687:alpha-naphthylphthalamic acid; D002995:Clofibric Acid
keywords: Indole acetic acid; NPA; PCIB; PINs; Polar auxin transport (PAT); Rapeseed