Resistance to the cereal cyst nematode (Heterodera avenae Woll.) transferred from the wild grassAegilops ventricosa to hexaploid wheat by a ?stepping-stone? procedure

Abstract

Transfer of resistance toHeterodera avenae, the cereal cyst nematode (CCN), by a "stepping-stone" procedure from the wild grassAegilops ventricosa to hexaploid wheat has been demonstrated. The number of nematodes per plant was lower, and reached a plateau much earlier, in the resistant introgression line H93-8 (1-2 nematodes per plant) than in the recipient H10-15 wheat (14-16 nematodes per plant). Necrosis (hypersensitive reaction) near the nematode, little cell fusion, and few, often degraded syncytia were observed in infested H93-8 roots, while abundant, well-formed syncytia were present in the susceptible H10-15 wheat. Line H93-8 was highly resistant to the two Spanish populations tested, as well as the four French races (Fr1-Fr4), and the British pathotype Hall, but was susceptible to the Swedish pathotypes HgI and HgIII. Resistance was inherited as though determined by a single quasi-dominant factor in the F2 generations resulting from crosses of H93-8 with H10-15 and with Loros, a resistant wheat carrying the geneCre1 (syn.Ccn1). The resistance gene in H93-8 (Cre2 orCcn2) is not allelic with respect to that in Loros. RFLPs and other markers, together with the cytogenetical evidence, indicate that theCre2 gene has been integrated into a wheat chromosome without affecting its meiotic pairing ability. Introduction ofCre2 by backcrossing into a commercial wheat backgroud increases grain yield when under challenge by the nematode and is not detrimental in the absence of infestation.

A Comparative Analysis of Chromosome Pairing at Metaphase I in Interspecific Hybrids between Durum Wheat <i>(Triticum turgidum </i>L<i>.)</i> and the Most Widespread <i>Aegilops</i> Species

“…Our results further predict that, on average, durum wheat genetic sequences located on the A genome have a much higher chance of being introgressed into wild genomes than those on the B genome. Some of the Aegilops parental species used here are employed as sources of agronomically desirable traits in wheat breeding programs [Delibes et al, 1993;Bai et al, 1995;AghaeeSabarzeh et al, 2002]. In this reverse genetic flow direction, our results allow one to expect that alien genes of interest will be more likely incorporated by homoeologous-recombination based strategies into A genome chromosomes.…”

“…squarrosa [Mena et al, 1993;Zemetra et al, 1998]. This is the most obvious reason for the remarkably high level of MI association in bread wheat hybrids with Ae.…”

“…Ae. ventricosa Tausch is not as widely distributed as the remaining allotetraploid Aegilops species in the study, but it can be highlighted as the most successful donor of agronomic desirable traits for wheat breeding (mainly resistances) among them [Delibes et al, 1993;Friebe et al, 1996;Schneider et al, 2008]. On the other hand, these wild parents represent 5 distinct combinations of the diploid Aegilops genomes present in the allotetraploid species of the genus.…”

Characterization and expression profiling of a novel cereal cyst nematode resistance gene analog in wheat

“…A resistance locus, Cre , has been identified [8,15] and nine genes resistant to CCN (designated Cre1 , 2,3,4,5,6,7,8 , and R ) have been described, in which Cre1 and Cre8 were derived directly from common wheat [16][17][18][19][20][21][22][23][24]. The Cre3 locus, which was derived from Ae.…”

Characterization and selection of hexaploid wheats containing resistance to Heterodera avenae or Mayetiola destructor introgressed from Aegilops: a review

“…Using this approach, resistance genes to the fungi Pseudocercosporella herpotrichoides and Blumeria graminis, to M. destructor, and to H. avenae, have been introduced into wheat chromosomes (Doussinault et al, 1983;Delibes et al, 1987Delibes et al, , 1993Delibes et al, , 1997Mena et al, 1992 (Delibes et al, 1997).…”