Screening for Resistant in Bread Wheat Irrigated Cultivars to Cereal Cyst Nematode Heterodera filipjevi

Wheat Triticum aestivum L., is one of the most important and strategic crops in the world. Bread wheat (2n = 6x = 42), belonging to the family Poaceae, which is considered the most diverse and important family of the plant kingdom, produces large edible grains and provides about one-half of humans’ food calories(Wang et al., 2017). A number of pests and diseases attack wheat, out of which nematodes have been considered universally as one of the important microscopic organisms (ref). The Cereal Cyst Nematodes (CCN: Heterodera spp.) have a global distribution and cause significant economic yield losses in many countries of the world (Pariyar et al., 2016). It is known as the first and most important cereal crop in the world and widely consumed by 75 % of world populations (Drikvand et al., 2013).Cereal cyst nematode Heterodera filipjevi has wider distribution, than other species in cereal fields in Iran. In this study, the reaction of 30 wheat cultivars against cyst nematode were evaluated in statistical design in greenhouse and the field. These cultivars planted in growing seasons (2015/2016) in a H. filipjevi-infested field in Agricultural Research Station, Central Kabotrabad area of Isfahan (30°42′ and 34°30′ N latitude and 49°36′ and 55°32′ E longitude), in a completely randomized block design, with three replications, each of which in a four rows of three meter length and 20cm distance.The cereal cyst species were identified based on morphological, morphometric features and molecular characters. The number of cysts, second stage juveniles and eggs were analyzed. Also, reproductive factor and percentage reduction and or increase in cereal cyst nematode population in each treatment were calculated into its initial population. Statistical and clustered analysis data were carried out on by Duncan's multiple range test (DMRT), SAS and SPSS statistical softwares, respectively. The results showed that, in the greenhouse, the lowest brown cyst was in Behrang cultivar with an average of 15 cysts and then Bam cultivar with an average of 15.25 in 200 cc of soil.The lowest number of CCN eggs and second stage juveniles and reproductive factor were of Pyshtaz cultivar with the average of 0.49 per gram of soil. The, cultivars were classified into three ranges of resistant, tolerant and susceptible. In field conditions, the lowest brown cyst was of Bam cultivar with 113.33 per 200 cc of soil. Whereas the lowest numbers of CCN eggs and second stage juveniles and reproductive factors were in Parsi cultivar with 0.69 per gram of soil, fallowed by Aflak cultivar with 1.69 in two different statistically groups. Also, cluster analysis classified the cultivars into three different categories, which also showed remarkable similarities to Duncan's test results. Currently, the resistant and tolerant wheat cultivars to cyst nematode is widely used in many European countries such as the UK, Denmark, France, Sweden and Australia. Row. Therefore, identifying and recognizing resistant genes in the cultivars under study provides a way for the production of resistant transgenic commercial wheat varieties. From our results, we confirmed that wheat accessions Behrang and Bam possess resistance and can subsequently be crossed with high yielding cultivars improving their genetic resistance to CCNs. There is a deal of potential for this study to develop new resistant varieties to H. filipjevi which will have a great value to the agriculture sector in Iran. These resistant cultivars can be used in crop nematode management program and tracking and transferring resistance genes to desirable crop cultivars. Also, in addition to number of cysts, the number of larvae took into screening programs for better susceptibility assessment justifications. It is suggested that Marker-assisted selection will further improve the development of resistant cultivars. Isolation of candidate genes associated with specific markers will greatly facilitate this process. Finding new sources of resistance would be very much demanded to control the different populations especially in areas, where a mixture of Heterodera species occurs. Therefore, wheat origin countries including Iran, Iraq, Syrian and Turkey obtained wild wheat relatives, which is to be screened to the main Heterodera species. Taking advantage of these sources of resistance is necessary to know the reaction of genotypes against CCN species for new resistant gene/s in Iran.