Genotypic Population Structure of Ascochyta Pinodes and Phoma Pinodella in Poland
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Helena Furga³-Wêgrzycka, Micha³ Wêgrzycki Genotypic pop u la tion struc ture of Ascochyta pinodes and Phoma pinodella in Po land Ed ward Arseniuk PLANT BREEDING AND SEED SCIENCE Volume 59 2009 DOI:10.2478/v10129-009-0003-9 Hel ena Furga³-Wêgrzycka, Micha³ Wêgrzycki Uni ver sity of Warmia and Mazury in Olsztyn, Faculty of Med i cine e-mail: [email protected] GENOTYPIC POPULATION STRUCTURE OF ASCOCHYTA PINODES AND PHOMA PINODELLA IN POLAND ABSTRACT The genotypic pop u la tions struc ture of Ascochyta pinodes and Phoma pinodella was de term ined across a hi er ar chy of spa tial and tem po ral scale by us ing veg e ta tive in com pat i bil ity sys tem as phenotypic ge netic marker. Com po nents of ge netic vari a tion within and be tween pop u la tions in cluded the fol low ing val ues: in di- ces of diver sity H’, rich ness (g), in dices of evenness E1, E2 and E5, spatio-tem po ral analy sis of genotypic vari - a tion (HT and HS val ues), pairwise com par i sons of ge no type di ver sity, dis tri bu tion of VCGs across spatio-tem po ral scale (GST value) and anal ysis of vari ance cal cu lated on VCGs ge no type fre quen cies within pop u lations. It has been found that genotypic popu lations structure of Ascochyta pinodes and Phoma pinodella be long to mixed pop u la tion struc ture clonal and re com bin ing. Three re gional pop u la tions of Ascochyta pinodes and Phoma pinodella differe d signif i cantl y in both of VCGs ge no type frequen cies and their distri bu tion on a spatio-tem po ral scale indi cat ing on the low or mod erate de gree of geno type migra tion betwee n regions of Poland. Keywords: Mycosphaerella (Didymella) pinodes anamorph Ascochyta pinodes, Phoma pinodella (teleomorph Didymella), genotypic pop u la tion struc ture, com po nents the ge netic vari a tion of pop u la tion, VCG fre quency, spa tial and tempo ral VCG diversity INTRODUCTION Ascochyta blight of pea is caused prim arily by Ascochyta pinodes (Berk et Blox) Jones teleomorph Mycosphaerella pinodes (Berk et Blox) Vesterg = Didymella pinodes, Pertrak and Phoma medicaginis var pinodella (Jones) Boerema = A.pinodella Jones (teleomorph Didymella). This dis ease pro- vides a good ex am ple of the diffi cul ties in seed infec tions con trolling and ep i dem ics of Ascochyta blight causes by patho gens that are highly host-specific and are capa ble of causing seri ous dam age in a con duc tive en - vi ronm ent. Since the area of pea has system ati cally in creased in some coun - tries of the world, Ascochyta blight of pea has becom e one of the most im portant dis eases in pea produc tion. Except of di rect yield losses, Communicated by Ed ward Arseniuk 22 Hel ena Furga³-Wêgrzycka, Micha³ Wêgrzycki Ascochyta blight of pea reduces of seeds quality and seeds are often con - tam i nated by myco toxins. In Poland there have not been ob tained pea cultivars of high re sistance to A.pinodes and P.pinodella de spite con sid er able ef forts in breed ing for dis- ease re sis tance. Little knowl edge of ge netic pop u la tion struc ture of A.pinodes and P.pinodella as well as of the host resis tance mainly due to the quan ti ta tive na ture of both of them make prob lems in plant breed ing for dis- ease re sis tance. There is also not enough in form a tion about the source of resis tance and the pop u la tion bi ol ogy of A.pinodes and P.pinodella at mo lecu lar level. An - other lim i ta tion is due to lack or little knowledge about gene flow and geno - types mi gra tion within and be tween Pol ish, Eu ro pean or trans con ti nen tal pop u la tions of A.pinodes and P.pinodella and on the phylo gen etic rela tion - ship be tween geo graph i cally dis tant pop u la tions. Nev er the less over the last de cade pea breeders have concerned their works regard ing the resis tance of lequminose spe cies to some pathogens and viruses . Although the number of studies on fungal spe cies has increased last years, the most com prehen sive work was focused on quan ti ta tive resis tance pea to F.oxysporum f.sp. pisi, F.solani f.sp. pisi, Aphanomyces euteiches and A.pinodes. Sim i lar re searches have con ducted re gard ing the re sis tance chick pea to F.oxysporum f.sp. ciceris and Ascochyta rabiei, faba-bean to A.fabae and lentis to A.lentis. Substan tial progress in the field of under - standing the quan ti ta tive resis tance of pea, chickpea, faba-been and lentis to patho gens has been made (McPhee et al. 2006, Muehlbauer and Chen 2006, Cubero et al. 2005, Ford et al. 1999, Prioul et al. 2004, Taylor and Ford 2006, Baranger et al. 2006, Tivoli et al. 2006, Fondevilla et al. 2006). Ge netic anal y sis of A.pinodes pop u lation was hindered for a long time due to the in abil ity to perform ge netic crosses regard ing the homothallic mating system of this fungus. Sim i larly still is im pos sible to make the con - ven tional ge netic sexual crossing and ob tain pseudothecia regard ing the heterothallic species of Ascochyta (Didymella) pisi and Phoma (Didymella) pinodella due to lack of mat ing type test ers and sensi tive mo lec u lar mark- ers. More de tailed anal y ses on pop u la tion ge net ics of A.pisi, A.pinodes and P.pinodella have begun since 1997 when mo lecu lar markers for the first time were used (Bouznad et al. 1995, 1996, Barve et al. 2003, Faris-Mokaiesh et al. 1996, Fatehi and Bridge 1998, Fatehi 2000, Fatehi et al. 2003, Onfroy et al. 1999, Tohamy and Mohamed 1998, Lubeck et al. 1998, Armstrong et al. 2001, Peever et al. 2002, 2004, Fondevilla et al. 2006, Zhang et al. 2003, 2006). At pres ent us ing of mo lec u lar mark ers is giv ing dif fer ent ap proaches of ge netic di ver sity ex am in ing within pop u la tions of A.pinodes and P.pinodella by possi bil ity of insight into the repro duc tive strategy and pop- u la tion ge net ics. In the ory, the com par i son the di ver sity of RAPDs or AFLP-PCR-finger prints haplotype patterns within and be tween popu la- Genotypic popu lation structure of Ascochyta pinodes and Phoma pinodella in Poland 23 tions is a way to ana lyze ge netic pop u la tion structure of heterothallic P.pinodella (Didymella), A.pisi (Didymella) and in less extence of homothallic Mycosphaerella (Didymella) pinodes . Looking for the num ber of single and rare geno types in pop u la tions is a second one to es ti mate ge - netic pop u la tion structure. The find ing of a few dom i nant ge no types within a lo cal pop u la tion is the com pel ling ev i dence for clonal pop u la tion struc- ture and asex ual repro duc tion. On the contrary, the finding that most iso- lates of P.pinodella or A.pinodes belong to differ ent geno types can be con cerned as the evi dence for mixed pop u la tion structure, (clonal and re- com bin ing) and for sex ual re pro duc tion un der field con di tions (Milgroom 1995, 1996, Milgroom and Fry 1997, McDon ald 1997, McDon ald and Linde 2002, Zhan et al. 2000). Given the seem ingly asex ual na ture of A.pinodes or sexual homothallic na ture of Mycosphaerella (Didymella) pinodes and heterothallic nature of P.pinodella (Didymella) and their wide dis tribu tion worldwide it would be in terest ing to ex am ine the ex tent of gene and genotypic di versity within and be tween regional pop u lations and the test the null hy poth e sis that A.pinodes and P.pinodella are clonally distrib uted across Poland. Un der stand ing the pop u la tions struc ture of A.pinodes and P.pinodella and their evo lu tion is nec essary for de sign of man age ment practices aimed at lim it ing of the ap pearance and spreadingof the new geno types and more viru lent pathotypes of the pathogens. Knowledge on the ge netic pop u la tion structure and asexual or sexual strate gies of re pro duc tion of A.pinodes and P.pinodella on a lo cal scale gives in sight into the evo lu tion ary processes that shaped the local pop u la - tions in the past and offers insight into the future of evolu tion ary poten tial pop u la tions of these fungi. Knowl edge on the evo lu tion ary po ten tial of A.pinodes and P.pinodella may prove useful to op ti mize the man age ment of resis tance genes, applied of fungi cides, max i mize their useful and min i - mize the losses in effi cacy of these control meth ods.