title: Hormonal requirements for effective induction of microspore embryogenesis in triticale (× Triticosecale Wittm.) anther cultures.
abstract: Effective microspore embryogenesis in triticale is determined by a specific hormonal homeostasis: low value of IAA/cytokinins, IAA/ABA and cytokinins/ABA ratios as well as proper endogenous/exogenous auxin balance, which favours androgenic structure formation and green plant regeneration ability. The concentration of plant growth regulators (PGRs): auxins (Auxs), cytokinins (CKs) and abscisic acid (ABA) was measured in anthers of eight DH lines of triticale (× Triticosecale Wittm.), and associated with microspore embryogenesis (ME) responsiveness. The analysis was conducted on anthers excised from control tillers at the phase optimal for ME induction and then after ME-initiating tillers treatment (21 days at 4 °C). In control, IAA predominated among Auxs (11-39 nmol g(-1) DW), with IBA constituting only 1 % of total Auxs content. The prevailing isoforms of CKs were cis isomers of zeatin (121-424 pmol g(-1) DW) and zeatin ryboside (cZR, 146-432 pmol g(-1) DW). Surprisingly, a relatively high level (10-64 pmol g(-1) DW) of kinetin (KIN) was detected. Cold treatment significantly changed the levels of all analysed PGRs. The anthers of 'responsive' DH lines contained higher concentrations of IBA, cis and trans zeatin, cZR and ABA, and lower amount of IAA and KIN in comparison with 'recalcitrant' genotypes. However, the effects of exogenous ABA, p-chlorophenoxyisobutyric acid (PCIB) and 2,3,5-triiodobenzoic acid treatments suggest that none of the studied PGRs acts alone in the acquisition of embryogenic competency, which seems to be an effect of concerted PGRs crosstalk. The initiation of ME required a certain threshold level of ABA. A crucial prerequisite for high ME effectiveness was a specific PGRs homeostasis: lower Auxs level in comparison with CKs and ABA, and lower CKs/ABA ratio. A proper balance between endogenous Auxs in anthers and exogenous Auxs supplied by culture media was also essential.
authors.affiliation: The Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 30-239, Kraków, Poland, zur@ifr-pan.krakow.pl.
authors.forename: Iwona
authors.initials: I
authors.lastname: Żur
authors.forename: Ewa
authors.initials: E
authors.lastname: Dubas
authors.forename: Monika
authors.initials: M
authors.lastname: Krzewska
authors.forename: Piotr
authors.initials: P
authors.lastname: Waligórski
authors.forename: Michał
authors.initials: M
authors.lastname: Dziurka
authors.forename: Franciszek
authors.initials: F
authors.lastname: Janowiak
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D002995:Clofibric Acid / Q000494:pharmacology; D003080:Cold Temperature; D003583:Cytokinins / Q000378:metabolism / Q000494:pharmacology; D002523:Edible Grain / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D005838:Genotype; D007150:Immunohistochemistry; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D010937:Plant Growth Regulators / Q000378:metabolism* / Q000494:pharmacology; D058439:Plant Somatic Embryogenesis Techniques / Q000379:methods; D006109:Poaceae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D025341:Principal Component Analysis; D012038:Regeneration / Q000187:drug effects / Q000235:genetics; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D003583:Cytokinins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D014283:Triiodobenzoic Acids; D002995:Clofibric Acid; D000040:Abscisic Acid; C052968:2,3,5-triiodobenzoic acid