CORESTA Meeting, Agronomy/Phytopathology, 2017, Santa Cruz do Sul, AP 55

Genetic and functional analysis of va resistance durability to Potato virus Y in tobacco

JULIO E.(1); MICHEL V.(2); COTUCHEAU J.(1); DORLHAC DE BORNE F.(1); GLAIS L.(3.4); JACQUOT E.(5); DECROOCQ V.(2); CANDRESSE T.(2); GERMAN-RETANA S.(2)
(1) Imperial Tobacco Limited, Leaf Research, La Tour, Bergerac, France; (2) INRA et Université de Bordeaux, UMR 1332 BFP, BP81, Villenave d’Ornon, France; (3) FN3PT/RD3PT, Paris, France; (4) INRA, UMR1349 IGEPP, Le Rheu, France; (5) INRA-Cirad-Supagro Montpellier, UMR BGPI, Montpellier, France

Many recessive resistances against potyviruses are mediated by eukaryotic translation initiation factors (eIF4E). In tobacco, the va resistance gene commonly used to control PVY corresponds to a large (almost 1Mb) deletion affecting a copy of eIF4E (S10760)[1].

We compared the resistance durability conferred by various types of mutations affecting the S10760 gene (large deletions, Frameshift, or EMS nonsense mutations). Thirteen tobacco genotypes were challenged with ten PVY isolates according to their biological and molecular characteristics[2]. The “large deletion” genotypes display the largest resistance spectrum and durability towards the ten PVY isolates, whereas, the “Frameshift” and “EMS nonsense” mutants display the less durable resistance, with rapid and frequent apparition of resistance-breaking PVY isolates.

Upon further investigations, genetic and transcriptomic analyses revealed that resistance durability is strongly influenced by a complex genetic locus which contains two eIF4E copies, one of which is truncated in the most stable genotypes, while the other is differentially expressed between the tested varieties. RNASeq transcriptomic data and Q-PCR experiments demonstrate that the expression level of this second copy, T021658, is positively correlated with resistance durability. This suggests that T021658 might act as a decoy, in a virus-plant non-productive interaction and limiting the ability of PVY to evolve towards resistance-breaking. Taken together these results show that va durability can be explained by redundancy/competition effects in the eIF4E gene family, similar to what was recently shown in tomato[3].

[1] Julio, E., et al., 2014. Plant Molecular Biology Reporter 32 (4), 781-942.
[2] Janzac, B., et al., 2014. Plant Disease 98, 1521-1529.
[3] Gauffier, C., et al., 2016. The Plant Journal 85, 717–729.