Effective Resistance to Four Fungal Foliar Diseases in Samples of Wild Triticum L. Species from the VIR (N.I. Vavilov All-Russian Institute of Plant Genetic Resources) Collection: View from Vavilov's Concepts of Plant Immunity.

Abstract

To identify new sources of effective resistance to four foliar diseases of wheat, 173 accessions of four wheat species, Triticum boeoticum, T. urartu, T. araraticum, and T. dicoccoides, from the VIR collection were tested at the juvenile and adult growth stages for resistance to leaf rust (Pt = Puccinia triticina), powdery mildew (Bgt = Blumeria graminis tritici), Septoria nodorum blotch (SNB), and dark-brown leaf spot blotch (HLB = Helminthospjrium leaf blotch). The accessions included new additions to the collection, some old samples that had never been tested before, as well as earlier tested samples noted for high levels of juvenile resistance to some fungal diseases. Natural populations of Puccinia triticina and Blumeria graminis f. sp. tritici, mixture of Parastagonospora nodorum and Bipolaris sorokiniana isolates were used to inoculate and to evaluate resistance to Pt, Bgt, SNB, and HLB, respectively. Two samples of T. boeoticum, three of T. urartu, and one of T. araraticum were resistant to leaf rust at both tested stages. Further tests (phytopathological and molecular analyses) excluded Lr9, Lr19, Lr24, Lr41, or Lr47 as single genes controlling resistance; hence, these accessions likely carry new effective leaf rust resistance genes. High level of Bgt resistance was identified in three entries of T. boeoticum, one of T. araraticum, and eleven of T. dicoccoides. All tested accessions were susceptible to HLB and SNB at both tested stages. Accessions identified as resistant are valuable plant material for introgressive hybridization in bread and durum wheat breeding. The results are discussed in the context of N.I. Vavilov's concept of crop origin and diversity, and the laws of plant natural immunity to infectious diseases.