The Wheat Lr67 Gene from the Sugar Transport Protein 13 Family Confers Multipathogen Resistance in Barley1[OPEN]

• Published in: Plant physiology (Bethesda) 2018-10, Vol.179 (4), p.1285-1297
• Main Authors: Milne, Ricky J., Dibley, Katherine E., Schnippenkoetter, Wendelin, Mascher, Martin, Lui, Andy C.W., Wang, Lanxiang, Lo, Clive, Ashton, Anthony R., Ryan, Peter R., Lagudah, Evans S.
• Format: Article
• Language: English
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.18.00945

The Lr67res multipathogen resistance gene from wheat confers resistance to barley-specific pathogens when transformed into barley. Fungal pathogens are a major constraint to global crop production; hence, plant genes encoding pathogen resistance are important tools for combating disease. A few resistance genes identified to date provide partial, durable resistance to multiple pathogens and the wheat ( Triticum aestivum ) Lr67 hexose transporter variant (Lr67res) fits into this category. Two amino acids differ between the wild-type and resistant alleles – G144R and V387L. Exome sequence data from 267 barley ( Hordeum vulgare ) landraces and wild accessions was screened and neither of the Lr67res mutations was detected. The barley ortholog of Lr67, HvSTP13, was functionally characterized in yeast as a high affinity hexose transporter. The G144R mutation was introduced into HvSTP13 and abolished Glc uptake, whereas the V387L mutation reduced Glc uptake by ∼ 50%. Glc transport by HvSTP13 heterologously expressed in yeast was reduced when coexpressed with Lr67res . Stable transgenic Lr67res barley lines exhibited seedling resistance to the barley-specific pathogens Puccinia hordei and Blumeria graminis f. sp. hordei , which cause leaf rust and powdery mildew, respectively. Barley plants expressing Lr67res exhibited early senescence and higher pathogenesis-related ( PR ) gene expression. Unlike previous observations implicating flavonoids in the resistance of transgenic sorghum ( Sorghum bicolor ) expressing Lr34res , another wheat multipathogen resistance gene, barley flavonoids are unlikely to have a role in Lr67res-mediated resistance. Similar to observations made in yeast, Lr67res reduced Glc uptake in planta . These results confirm that the pathway by which Lr67res confers resistance to fungal pathogens is conserved between wheat and barley.