Simultaneous silencing of isoamylases ISA1, ISA2 and ISA3 by multi-target RNAi in potato tubers leads to decreased starch content and an early sprouting phenotype

Journal article


Publication Details

Author(s): Ferreira SJ, Senning M, Fischer-Stettler M, Streb S, Ast M, Neuhaus HE, Zeeman SC, Sonnewald S, Sonnewald U
Journal: PLoS ONE
Publisher: PUBLIC LIBRARY SCIENCE
Publication year: 2017
Volume: 12
Journal issue: 7
ISSN: 1932-6203


Abstract


Isoamylases hydrolyse (1-6)-alpha-D-glucosidic linkages in starch and are involved in both starch granule formation and starch degradation. In plants, three isoamylase isoforms with distinct functions in starch synthesis (ISA1 and ISA2) and degradation (ISA3) have been described. Here, we created transgenic potato plants with simultaneously decreased expression of all three isoamylases using a chimeric RNAi construct targeting all three isoforms. Constitutive expression of the hairpin RNA using the 35S CaMV promoter resulted in efficient silencing of all three isoforms in leaves, growing tubers, and sprouting tubers. Neither plant growth nor tuber yield was effected in isoamylase- deficient potato lines. Interestingly, starch metabolism was found to be impaired in a tissue- specific manner. While leaf starch content was unaffected, tuber starch was significantly reduced. The reduction in tuber starch content in the transgenic plants was accompanied by a decrease in starch granules size, an increased sucrose content and decreased hexose levels. Despite the effects on granule size, only little changes in chain length composition of soluble and insoluble glucose polymers were detected. The transgenic tubers displayed an early sprouting phenotype that was accompanied by an increased level of sucrose in parenchyma cells below the outgrowing bud. Since high sucrose levels promote sprouting, we propose that the increased number of small starch granules may cause an accelerated turnover of glucan chains and hence a more rapid synthesis of sucrose. This observation links alterations in starch structure/degradation with developmental processes like meristem activation and sprout outgrowth in potato tubers.



FAU Authors / FAU Editors

Senning, Melanie
Graduiertenzentrum der FAU
Sonnewald, Sophia PD Dr.
Department Biologie
Sonnewald, Uwe Prof. Dr.
Lehrstuhl für Biochemie


External institutions with authors

Eidgenössische Technische Hochschule Zürich (ETHZ) / Swiss Federal Institute of Technology in Zurich
Technische Universität Kaiserslautern


How to cite

APA:
Ferreira, S.J., Senning, M., Fischer-Stettler, M., Streb, S., Ast, M., Neuhaus, H.E.,... Sonnewald, U. (2017). Simultaneous silencing of isoamylases ISA1, ISA2 and ISA3 by multi-target RNAi in potato tubers leads to decreased starch content and an early sprouting phenotype. PLoS ONE, 12(7). https://dx.doi.org/10.1371/journal.pone.0181444

MLA:
Ferreira, Stephanus J., et al. "Simultaneous silencing of isoamylases ISA1, ISA2 and ISA3 by multi-target RNAi in potato tubers leads to decreased starch content and an early sprouting phenotype." PLoS ONE 12.7 (2017).

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Last updated on 2018-10-08 at 21:24