Upotreba molekularnih markera u detekciji gena otpornosti Plarg na plamenjaču kod suncokreta

Abstract

Plamenjače suncokreta je bolest koja može da izazove značajno smanjenje prinosa. Šteta prouzrokovana ovim patogenom može da se kontroliše uzgajanjem otpornih hibrida suncokreta. Gen otpornosti Plarg unet je u gajeni suncokret iz divljeg srodnika H. argophillus i obezbeđuje otpornost na sve do sada identifikovane rase plamenjače. Kako bi se proces unošenja gena otpornosti u različite linije ubrzao i učinio pouzdanijim, potrebno je identifikovati molekularne markere blisko vezane za gen otpornosti. Od posebnog interesa su kodominantni markeri, koji mogu da naprave razliku između homozigotno i heterozigotno otpornih biljaka. Cilj ovog rada bio je identifikacija molekularnih markera blisko vezanih za gen Plarg koji će moći da se koriste za marker asistiranu selekciju (MAS). U radu je korišćena mapirajuća populacija koja se sastojala od 103 F2 biljke dobijene iz ukrštanja RHA 419 x RHA-N-49. Molekularne analize pokazale su da se gen Plarg nalazi na LG1 genetičke mape suncokreta. Identifikovan je novi kosegregirajući SSR marker ORS675, dok je kosegregacija markera ORS716 i ORS662 sa Plarg potvrđena. Veza markera i gena potvrđena je na dodatne 22 linije sa genom Plarg. Testiranje linija HA-R4 (Pl14 i Pl16) i HA-R5 (Pl13) markerima ORS662, ORS716 i ORS675 pokazalo je da se gen Plarg nalazi odvojeno od drugih do sada identifikovanih gena sa LG1. Nakon validacije, primena markera ORS675 i ORS716 u selekciji je testirana na dve različite BC1 populacije. Markeri su se pokazali korisnim kako u molekularnom oplemenjivanju tako i za analizu genetičke čistoće linija suncokreta. Može se zaključiti da se molekularni markeri iz ove studije blisko vezani za gen Plarg mogu koristiti za MAS, i s toga se upotrebljavati u selekcionim programima kako bi se olakšao unos gena otpornosti u različite linije suncokreta.

Downy mildew is a common sunflower disease that can cause significant yield reduction. The damage caused by the pathogen can be controlled by growing sunflower varieties resistant to this disease. Resistance gene Plarg was introduced into cultivated sunflower from the wild species H. argophyllus and it provides resistance against all known downy mildew races. Molecular markers can facilitate and accelerate the process of transfer of resistance gene into commercial sunflower lines. Co-dominant markers are particulary useful, since they can discriminate between homozygous and heterozygous resistant plants. The aim of this study was to identify molecular markers closely linked to gene Plarg that will be used in marker assisted selection (MAS). A mapping population of 103 F2 progeny from the cross RHA 419 x RHA-N-49 was used. Molecular analyses indicated that the gene Plarg is located on LG1 of the genetical map of sunflower. A new co-segregating simple sequence repeat (SSR) marker ORS675 was identified and the co-segregation of markers ORS716 and ORS662 with Plarg gene was confirmed. The markers were validated on twenty two resistant inbred lines (RHA 443, RHA 464 and RH 1-20). Results obtained on lines HA-R4 (Pl14 i Pl16) and HA-R5 (Pl13) with markers ORS662, ORS716 i ORS675 showed that Plarg is a resistance locus diffrent from other resistance genes mapped on LG1. Application of the markers ORS675 and ORS716 in marker assisted selection was tested on two different BC1 populations. Markers were found to be useful both for molecular breeding and genetic purity analyses. The closely linked molecular markers from this study will facilitate transfer of the resistance gene into different sunflower lines.