Enhanced waterlogging tolerance in barley by manipulation of expression of the N‐end rule pathway E3 ligase PROTEOLYSIS 6

• Published in: Plant biotechnology journal Vol. 14; no. 1; pp. 40 - 50
• Main Authors: Mendiondo, Guillermina M., Gibbs, Daniel J., Szurman‐Zubrzycka, Miriam, Korn, Arnd, Marquez, Julietta, Szarejko, Iwona, Maluszynski, Miroslaw, King, John, Axcell, Barry, Smart, Katherine, Corbineau, Francoise, Holdsworth, Michael J.
• Format: Journal Article
• Language: English
• Published: 01-01-2016
• ISSN: 1467-7644; 1467-7652
• DOI: 10.1111/pbi.12334

Summary
Increased tolerance of crops to low oxygen (hypoxia) during flooding is a key target for food security. In
Arabidopsis thaliana
(L.) Heynh., the N‐end rule pathway of targeted proteolysis controls plant responses to hypoxia by regulating the stability of group
VII
ethylene response factor (
ERFVII
) transcription factors, controlled by the oxidation status of amino terminal (Nt)‐cysteine (Cys). Here, we show that the barley (
Hordeum vulgare
L.)
ERFVII BERF
1 is a substrate of the N‐end rule pathway
in vitro
. Furthermore, we show that Nt‐Cys acts as a sensor for hypoxia
in vivo
, as the stability of the oxygen‐sensor reporter protein
MCGGAIL
‐
GUS
increased in waterlogged transgenic plants. Transgenic
RNA
i barley plants, with reduced expression of the N‐end rule pathway N‐recognin E3 ligase
PROTEOLYSIS
6 (Hv
PRT
6), showed increased expression of hypoxia‐associated genes and altered seed germination phenotypes. In addition, in response to waterlogging, transgenic plants showed sustained biomass, enhanced yield, retention of chlorophyll, and enhanced induction of hypoxia‐related genes.
Hv
PRT
6
RNA
i plants also showed reduced chlorophyll degradation in response to continued darkness, often associated with waterlogged conditions. Barley Targeting Induced Local Lesions IN Genomes (
TILLING
) lines, containing mutant alleles of
Hv
PRT
6
, also showed increased expression of hypoxia‐related genes and phenotypes similar to
RNA
i lines. We conclude that the N‐end rule pathway represents an important target for plant breeding to enhance tolerance to waterlogging in barley and other cereals.