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New Phytol. 2019 Jul;223(2):853-866. doi: 10.1111/nph.15815. Epub 2019 Apr 22.

Abscisic acid is a substrate of the ABC transporter encoded by the durable wheat disease resistance gene Lr34.

Author information

1
Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland.
2
Biological and Environmental Science & Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
3
Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.
4
SIB Swiss Institute of Bioinformatics, University of Zurich, Zurich, Switzerland.
5
Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland/OT, Gatersleben, Germany.

Abstract

The wheat Lr34res allele, coding for an ATP-binding cassette transporter, confers durable resistance against multiple fungal pathogens. The Lr34sus allele, differing from Lr34res by two critical nucleotide polymorphisms, is found in susceptible wheat cultivars. Lr34res is functionally transferrable as a transgene into all major cereals, including rice, barley, maize, and sorghum. Here, we used transcriptomics, physiology, genetics, and in vitro and in vivo transport assays to study the molecular function of Lr34. We report that Lr34res results in a constitutive induction of transcripts reminiscent of an abscisic acid (ABA)-regulated response in transgenic rice. Lr34-expressing rice was altered in biological processes that are controlled by this phytohormone, including dehydration tolerance, transpiration and seedling growth. In planta seedling and in vitro yeast accumulation assays revealed that both LR34res and LR34sus act as ABA transporters. However, whereas the LR34res protein was detected in planta the LR34sus version was not, suggesting a post-transcriptional regulatory mechanism. Our results identify ABA as a substrate of the LR34 ABC transporter. We conclude that LR34res-mediated ABA redistribution has a major effect on the transcriptional response and physiology of Lr34res-expressing plants and that ABA is a candidate molecule that contributes to Lr34res-mediated disease resistance.

KEYWORDS:

LR34 ABC transporter; abscisic acid (ABA); cereal crops; durable disease resistance; fungal pathogen

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