Resistance of wheat, barley and oat to Heterodera avenae in the Pacific Northwest, USA

Abstract

The cereal cyst nematode, Heterodera avenae, occurs in at least seven western states of the USA and reduces grain yield in localised regions and in selected crop management systems. Virulence phenotypes for H. avenae populations in North America have not been reported. Nine individual assays in six experiments were conducted to determine the reactions of barley, oat and wheat cultivars to five H. avenae populations in the Pacific Northwest (PNW) states of Idaho, Oregon and Washington. Three populations were evaluated for virulence to 23 entries of the 'International Test Assortment for Defining Cereal Cyst Nematode Pathotypes', plus selected local cultivars and entries representing a greater diversity of resistance genes. The virulence phenotype(s) for populations of H. avenae in the PNW did not correspond to any of the 11 pathotypes defined by the Test Assortment. Five PNW populations exhibited affinities with Group 2 but were not defined by pathotypes Ha12 and Ha22. Reproduction was prevented or greatly inhibited by barley carrying the Rha3 resistance gene and by most carriers of Rha2 resistance, and by selected oat cultivars with multigenic resistance. Wheat cultivars carrying the Cre1 resistance gene were highly effective in suppressing H. avenae reproduction. Current PNW wheat cultivars do not carry the Cre1 resistance gene. Crosses between Ouyen, an Australian bread wheat with Cre1 resistance, and several PNW wheat cultivars were resistant. The CreR gene also prevented H. avenae reproduction in the trial where it was tested. Intermediate levels of reproduction occurred on wheat cultivars carrying the Cre5, Cre7 and Cre8 resistance genes, each of which was considered useful for pyramiding into cultivars with Cre1 resistance. This research identified genetic resources of value in PNW cereal crop breeding programmes.

Genetic variation of bread wheat accessions in response to the cereal cyst nematode, Heterodera filipjevi

“…Incorporating resistance genes into wheat cultivars and breeding resistant lines is considered the most cost-effective control measure for reducing nematode populations (Dababat et al, 2015). Resistance is also environmentally friendly and achievable with the collaboration of research groups around the world (Smiley et al, 2011;Smiley & Marshall, 2016). Developing high yielding cultivars with tolerance to abiotic and biotic stresses is one of the main challenges in Iran due to limited information about CCN.…”

DNA barcoding, phylogeny and phylogeography of the cyst nematode species of the Avenae group from the genus Heterodera (Tylenchida: Heteroderidae)

“…Patho-type identification of some populations from these geographical regions remains uncertain. For example, five Pacific Northwest CCN populations exhibited affinities with Group 2, but were not defined as Ha12 and Ha22 pathotypes (Smiley et al, 2011). According to our results, several Pacific Northwest CCN populations contain unique COI haplotypes (haplotypes HavA7 and HavA8) on peripheral positions in the COI network.…”

“…The pathotypes are characterised based on the International Cereal Cyst Nematode Test Assortments consisting of several barley, oat and wheat lines -the so-called differentials. The Test Assortments was initially proposed by Andersen & Andersen (1982) and later improved by several authors (Rivoal & Cook, 1993;Cook & Rivoal, 1998;Cook & Noel, 2002;Smiley et al, 2011;Cui et al, 2015). Presently, three pathotypes groups have been identified: Group 1 contains nine pathotypes (Ha11-Ha91); Group 2 -two pathotypes (Ha12, Ha22); and Group 3 -four pathotypes (Ha13-Ha43).…”

“…Pathotypes of Groups 1 and 2 are the most numerous and widely distributed in Europe, North Africa, America and Asia (Andersen & Andersen, 1982;Mor et al, 1992;Valocká et al, 1994;Al-Hazmi et al, 2001;Mokabli et al, 2002;Smiley et al, 2011;Haddadi et al, 2013;Singh & Kaur, 2015) and mainly belong to both haplotype groups of H. avenae or H. sturhani. Patho-type identification of some populations from these geographical regions remains uncertain.…”

Age structure of populations of the cyst nematode Heterodera Filipjevi (Heteroderidae: Nematoda) on different wheat and barley varieties

“…Moreover, the symptom sofin vaded plants are often attributed to local unevenness of the depth of the soil horizon, the soil structure, the water balance or other soil pathogens (e.g. barley yellowdwarfvirus -BYDV) (Smiley et al, 2011). Leaf symptom sarequite similar to those caused by Rhizoctonia.…”