Showing papers on "Heterodera avenae published in 2007"
TL;DR: The objective of this work was to pyramid the two CCN resistance genes in a wheat background through marker-assisted selection, and illustrates the utilization of molecular markers in breeding for host resistance.
Abstract: The cereal cyst nematode (CCN) Heterodera avenae, is a significant pathogen of wheat. The wild grass Aegilops variabilis Accession No.1 has been found to be resistant to pathotypes of CCN; at least two genes transferred to wheat, designated as CreX and CreY, are involved in the resistance response. The CreY gene may be the same as Rkn-mn1, which confers resistance to root knot nematode (RKN) Meloidogyne naasi. The objective of this work was to pyramid the two CCN resistance genes in a wheat background through marker-assisted selection. As a first step, molecular markers flanking CreX were identified. The completely linked RAPD marker of Rkn-mn1 (CreY), OpY16-1065, previously obtained, was converted into a SCAR. All these dominant markers were used to incorporate in the same genotype the two Ae. variabilis chromosome segments carrying the two genes for resistance. CCN bioassays with the Ha12 pathotype showed that the level of resistance of the pyramided line was significantly higher than that of CreX and CreY single introgression lines, but lower than that of Ae. variabilis. This study thus illustrates the utilization of molecular markers in breeding for host resistance.
115 citations
Journal Article•
TL;DR: A new joint intiative was established between CIMMYT International, the Turkish Ministry of Agriculture and Ukurova University in Adana to understand the distribution of cereal nematodes on wheat and assess the economic importance and improve the understanding of the population dynamics.
Abstract: The Cereal Cyst Nematodes (CCNs) are a group of several closely related species which have been documented to cause economic yield loss on rainfed wheat production systems in several part of the world including North Africa, West Asia, China, India, Australia, America and several countries in Europe. The most commonly reported species is Heterodera avenae, however there are at least two other species H. filipjevi and H. latipons are implicated. It is well appreciated that plants under water and nutrient stress suffer greater yield loss. Control of CCNs requires maintaining nematode populations below economic thresholds. Chemicals are not environmentally sustainable or economic and the major emphasis on control has been with host genetic resistance applied with other integrated pest managent options. Unfortunately due to the number of species and pathotype variation genetic control of Cereal Cyst Nematode with plant resistance is complex. Turkey is one of the top ten wheat producers in the world and has identified these nematode as a major biotic constraint in their rainfed wheat systems. In 2001 a new joint intiative was established between CIMMYT International, the Turkish Ministry of Agriculture and (Ukurova University in Adana to understand i) the distribution of cereal nematodes on wheat; ii) assess the economic importance and improve our understanding of the population dynamics iii) culture, screen and assess known sources of resistance and identify new sources to both groups of nematodes; iv) integrate new sources of resistance into bread wheat cultivars for Turkey and International germplasm using conventional and molecular tools; v) investigate other integrated control options such as rotation and different wheat management strategies and finally vi) capacity build scientists to work in this important area. Some highlights of this work will be presented and the newly formed ICCNI - International Cereal Cyst Nematode Initative introduced.
43 citations
TL;DR: The phosphite treatment did not prevent M. marylandi juveniles from penetrating wheat roots or inducing giant cells, however, phosphite inhibited giant cell development: 14 days after inoculation, the giant cells in the phosphite-treated wheat were almost completely vacuolated, whereas those in untreated wheat contained dense cytoplasm.
Abstract: Phosphonic acid (H3PO3) solutions were applied to wheat or to bristle oat as soil drenches before inoculation with juveniles of the sedentary, endoparasitic nematodes Heterodera avenae or Meloidogyne marylandi. All the solutions, which were pH adjusted and added at levels as low as 0.63 mg of phosphite (HPO32-) per plant, reduced the numbers of H. avenae females and M. marylandi egg masses. Phosphate (PO43-), applied as potassium phosphate at the same concentrations, did not reduce the number of female nematodes on the wheat. Addition of phosphate to the phosphite solutions did not change the inhibitory effect of phosphite on H. avenae, but it reduced phosphite's effect on M. marylandi. Phosphite also reduced the number of H. avenae females when applied as many as 20 days after addition of nematodes. The phosphite treatment did not prevent M. marylandi juveniles from penetrating wheat roots or inducing giant cells. However, phosphite inhibited giant cell development: 14 days after inoculation, th...
29 citations
Journal Article•
TL;DR: Five species of cyst-forming nematodes belonging to the Heterodera avenae group were identified from cereal fields and grasslands in Iran and their relationship with similar species is discussed.
Abstract: Five species of cyst-forming nematodes belonging to the Heterodera avenae group were identified from cereal fields and grasslands in Iran Morphological and morphometric characters of H avenae, H filipjevi and a still unidentified species from the H avenae complex and of H latipons and H hordecalis from the H latipons complex are presented and their relationship with similar species is discussed Heterodera filipjevi and H latipons are the dominant species in cereal fields; H avenae was found in wheat fields in only one region in the west of the country Heterodera hordecalis was recovered from a few wheat fields and around grasses in western Iran, and Heterodera sp from grasslands at several sites in northern and western regions of the country
21 citations
TL;DR: The phylogenetic trees of ITS region, MAPK gene fragments and their combination revealed that there was genetic variability among species and isolates, but there was no apparent relationship between the genetic variability and their host or geographic origin.
16 citations
TL;DR: The potential usefulness of Ha2S18 in large scale marker assisted selection schemes has been evaluated in a broad genetic background and is an important complement to the bioassay and to other linked DNA-markers for this trait.
Abstract: Cereal cyst nematodes (Heterodera avenae Woll.) are economically damaging barley parasites in most cereal growing areas of the world and the development of resistant cultivars is the best measure against the pathogen. An ISSR (inter-simple sequence repeat) marker identified as closely linked with the H. avenae race 1 and 2 resistance gene (Ha2) has been converted into a codominant sequence characterized amplified region marker (Ha2S18) and mapped in barley 'SW Buddy' x 'SW Cecilia' DH population at 4.3 cM from the Ha2 locus on the long arm of chromosome 2H. The potential usefulness of Ha2S18 in large scale marker assisted selection schemes has been evaluated in a broad genetic background and is an important complement to the bioassay and to other linked DNA-markers for this trait.
10 citations
Journal Article•
5 citations
01 Jan 2007
TL;DR: Al-Hazmi et al. as mentioned in this paper found white females and cysts of H. avenae on the roots of the Italian rye grass, Lolium multiflorum Lam., (known in Saudi Arabia as Multimo grass and cultivated as a fodder crop), and wild or foxtail barley, Hordeum murinum L., (a tufted annual grass that appears widely in winter).
Abstract: Cereal cyst nematode, Heterodera avenae Wollenweber, 1924, is the most important pest limiting the productivity of wheat and barley in Saudi Arabia (Al-Hazmi et al ., 1999; Ibrahim et al ., 1999). Until now, the nematode has not been recorded on any other host plants except for wheat and barley in Saudi Arabia. However, during a routing study of wheat fields in the Hail region, white females and cysts of H. avenae were found on the roots of the Italian rye grass, Lolium multiflorum Lam., (known in Saudi Arabia as Multimo grass and cultivated as a fodder crop), and wild or foxtail barley, Hordeum murinum L., (a tufted annual grass that appears widely in winter) which appeared as new host records in Saudi Arabia. The detected nematode was initially identified as H. avenae using the keys of Mulvey & Golden (1983) and Golden (1986). Identification was then reconfirmed by morphological and morphometric studies based on cyst vulvar cone structures and measurements, as well as morphometric features of second stage juveniles (J 2), males and gravid females.
1 citations
01 Jan 2007
TL;DR: The conclusion drawn was that farmers with spotwise appearing growth depressions should watch them closely for nematode infestation to take regulation measures as early as possible.
Abstract: Evaluating the problem of spotwise appearing cereal growth depressions 23 fields of 10 organic managed farms were investigated. Potential causes were soil nutrients and other chemical and physical soil properties as well as high abundance of the plant parasitic nematodes Heterodera avenae and Pratylenchus-, Tylenchorhynchus and Trichodorus species. In two on-farm field experiments different catch crops and a black fallow treatment caused a decrease of Pratylenchus and Tylenchorhynchus species. However, the yields of the following spring wheat were low, possibly due to H. avenae infestation. Fertilization with compost and potassium had no effect but the H. avenae resistant variety Isotta produced much higher yields. The conclusion drawn was that farmers with spotwise appearing growth depressions should watch them closely for nematode infestation to take regulation measures as early as possible.
1 citations