title: Morphological, cytological and metabolic consequences of autopolyploidization in Hylocereus (Cactaceae) species.
abstract: BACKGROUND
  Genome doubling may have multi-level effects on the morphology, viability and physiology of polyploids compared to diploids. We studied the changes associated with autopolyploidization in two systems of somatic newly induced polyploids, diploid-autotetraploid and triploid-autohexaploid, belonging to the genus Hylocereus (Cactaceae). Stomata, fruits, seeds, embryos, and pollen were studied. Fruit pulp and seeds were subjected to metabolite profiling using established gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography (UPLC) Q-TOF-MS/MS (time of flight)-protocols.
  
  
  RESULTS
  Autopolyploid lines produced lower numbers of tetrads, larger pollen grains with lower viability, larger stomata with lower density, and smaller fruits with lower seed numbers and decreased seed viability. The abundance of sugars was lower in the fruits and seeds of the two duplicated lines than in their donor lines, accompanied by increased contents of amino acids, tricarboxylic acid (TCA) cycle intermediates, organic acids and flavonoids. Betacyanins, the major fruit pigments in diploid and triploid donors, decreased following genome doubling. Both autopolyploid Hylocereus lines thus exhibited unfavorable changes, with the outcome being more dramatic in the autohexaploid than in the autotetraploid line.
  
  
  CONCLUSIONS
  Induced autotetraploid and autohexaploid lines exhibited morphological and cytological characteristics that differed from those of their donor plants and that were accompanied by significant metabolic alterations. It is suggested that a developmental arrest occurs in the fruits of the autohexaploid line, since their pericarp shows a greater abundance of acids and of reduced sugars. We conclude that genome doubling does not necessarily confer a fitness advantage and that the extent of alterations induced by autopolyploidization depends on the genetic background of the donor genotype.
authors.forename: Hagai
authors.initials: H
authors.lastname: Cohen
authors.forename: Aaron
authors.initials: A
authors.lastname: Fait
authors.affiliation: French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer Campus, Midreshet Ben-Gurion, Beer-Sheva 84990, Israel. telzur@bgu.ac.il.
authors.forename: Noemi
authors.initials: N
authors.lastname: Tel-Zur
mesh_terms: D029421:Cactaceae / Q000033:anatomy & histology / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D004171:Diploidy; D005434:Flow Cytometry; D005638:Fruit / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D018525:Germination; D055432:Metabolomics; D056771:Ovule / Q000378:metabolism; D054046:Plant Stomata / Q000033:anatomy & histology / Q000166:cytology / Q000378:metabolism; D011058:Pollen / Q000378:metabolism; D011123:Polyploidy; D025341:Principal Component Analysis; D019655:Quantitative Trait, Heritable; D064210:Secondary Metabolism; D012639:Seeds / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D013194:Staining and Labeling