Marker-assisted backcross breeding for Fusarium head blight resistance in South African wheat

Loading...
Thumbnail Image
Date
2014-06
Authors
Sydenham, Scott Lloyd
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Free State
Abstract
English: In our modern era with the global population soon to reach the nine billion mark, there are rising concerns about food security. There is a driven need for more sustainable food production. Wheat is considered one of the most important cereal crops grown worldwide. However, wheat production in SA has been declining steadily over the last decade. A shift in SA wheat production has occurred from winter dryland to irrigated spring wheat being planted in a maize-wheat crop rotation system. Wheat production is vulnerable globally and locally due to yield losses and grain damage caused by sporadic FHB disease outbreaks, which are predominantly caused by F. graminearum. Currently the number of FHB resistant wheat cultivars available in SA is limited and not adequate. The aim of this study was to develop FHB resistant lines through backcross breeding and MAS to track the introgression of targeted FHB resistance genes/QTL (Fhb1, Fhb2, Qfhs.ifa-5A QTL and 7A QTL) into the SA wheat cultivar Krokodil. The use of a MABC pre-breeding programme to transfer targeted FHB resistance genes/QTL from FHB resistant donor CM-82036 into the background of SA spring wheat cultivar Krokodil is discussed. F1 individuals from which a BC1F1 generation was developed were validated using SSR marker Gwm493, which is linked to the Fhb1 gene. Marker-assisted foreground selection was done for targeted FHB resistance genes/QTL combined with background selection against unwanted donor alleles. A partial linkage map of targeted chromosomes 3B, 5A, 6B and 7A was generated from a BC1F1 population consisting of 120 individuals. Based on this linkage map GGT profiles were developed for each individual which allowed analysis and comparison of recombination events on these chromosomes. Families containing three and four targeted FHB resistance genes/QTL were identified. These lines were backcrossed to Krokodil to yield a BC2F1 population of 238 individuals. Simultaneously, a phenotypic validation glasshouse trial was done on additional individuals of the BC1F1 population to confirm expression of the targeted FHB resistance genes/QTL. Spray and point inoculation methods were used to evaluate Type I and Type II FHB resistance responses on six selected controls and 130 segregating BC1F1 genotypes. These BC1F1 individuals were genotyped using markers associated with targeted FHB resistance genes/QTL. FHB disease symptoms were expressed as a percentage infection per spike and assessed 4, 7, 10, 14, 18 and 21 dpi. BC1F1 genotypes containing the targeted Fhb1 gene in combination with the Qfhs.ifa-5A QTL contributed additively to overall FHB resistance and the prevention of expected yield loss. Preliminary results indicated that the Fhb1 gene reduced the presence of tombstone kernels. The Fhb1 gene in combination with the Qfhs.ifa-5A QTL were successfully transferred using MAS and validated phenotypically in the background of Krokodil displaying improved FHB resistance levels. Since the primary objective was improvement of FHB resistance, this study successfully identified 44 BC2F1 individuals that contained the FHB resistance gene Fhb1 and/or the Qfhs.ifa-5A QTL. A partial linkage map across all 21 wheat chromosomes was generated by testing 120 polymorphic SSR markers on these 44 individuals. With the aid of GGT profiles the RPGP analysis was done for each BC2F1 individual. Sixteen high value lines that contained Fhb1 and/or the Qfhs.ifa-5A QTL with a minimum RPGP value of 80% were identified and selected for further analysis. Eight elite lines that contained the targeted FHB resistance genes/QTL as well as the potential for good baking quality were selected for further development. Lines identified and recommended from this study can be used to initiate the further development of FHB resistant wheat cultivars in SA.
Afrikaans: Daar is ‘n groeiende besorgdheid oor voedselsekuriteit in ons moderne era waar die wêreldpopulasie binnekort die nege miljard merk gaan bereik. Daar is ‘n dringende behoefte aan verbeterde volhoubare voedselproduksie. Koring word as een van die belangrikste graangewasse wat wêreldwyd verbou word, beskou. Koringproduksie in Suid-Afrika (SA) het egter gedurende die laaste dekade geleidelik begin afneem. SA koringproduksie het vanaf droëland winterverbouing na somerkoring onder besproeiing gekoppel aan ‘n mielie-koring gewasrotasie-sisteem verander. Koringproduksie is wêreldwyd asook plaaslik kwesbaar weens opbrengsverliese en skade aan graan wat deur sporadiese Fusarium aarskroei (FHB) uitbrake, hoofsaaklik weens Fusarium graminearum, veroorsaak word. Die aantal FHB weerstandbiedende kultivars wat tans in SA beskikbaar is, is beperk en nie voldoende nie. Die doel van die studie was om FHB weerstandbiedende lyne te ontwikkel deur van terugkruisteling en merker-ondersteunde seleksie (MAS) om die inbou van die geteikende FHB weerstandsgene/kwantitatiewe eienskapslokusse (QTL; Fhb1, Fhb2, Qfhs.ifa-5A QTL en 7A QTL) in die SA koringkultivar Krokodil te volg, gebruik te maak. Die gebruik van ‘n merker-ondersteunde terugkruisteling vooraf-teelprogram om die geteikende FHB weerstandsgene/QTL vanaf die FHB weerstandsbron CM-82036 na die agtergrond van die SA koringkultivar Krokodil oor te dra, word bespreek. F1 individue wat gebruik is om die BC1F1 generasie te ontwikkel se identiteit is bevestig deur die mikrosatellietmerker Gwm493, gekoppel aan die Fhb1 geen, te gebruik. Merker-ondersteunde voorgrond-seleksie vir die geteikende FHB weerstandsgene/QTL gekombineer met agtergrond-seleksie teen ongewensde skenker allele is gedoen. ‘n Gedeeltelike koppelingskaart van die geteikende 3B, 5A, 6B en 7A chromosome is opgestel deur van 120 individue van die BC1F1 populasie gebruik te maak. Gebaseer op hierdie koppelingskaart is GGT profiele vir elke individu ontwikkel wat die analise en vergelyking van rekombinasie gebeurtenisse op hierdie chromosome moontlik gemaak het. Families wat drie en vier geteikende FHB weerstandsgene/QTL bevat het, is geïdentifiseer. Hierdie lyne is na Krokodil teruggekruis om ‘n BC2F1 populasie bestaande uit 238 individue te ontwikkel. Gelyktydig hiermee is ‘n fenotipiese glashuisproef op addisionele individue van die BC1F1 populasie gedoen om die uitdrukking van die geteikende FHB weerstandsgene/QTL te bevestig. Spuit- en puntinokulasie metodes is gebruik om Tipe I en Tipe II FHB weerstandsreaksies op ses geselekteerde kontroles en 130 segregerende BC1F1 genotipes te evalueer. Hierdie BC1F1 individue is met merkers wat aan die geteikende FHB weerstandsgene/QTL gekoppel is, gegenotipeer. FHB siekte simptome is as ‘n persentasie infeksie per aar uitgedruk en 4, 7, 10, 14, 18 en 21 dae na inokulasie geëvalueer. BC1F1 genotipes wat die geteikende Fhb1 geen in kombinasie met die Qfhs.ifa-5A QTL bevat het, het additief tot die algehele FHB weerstand en in die voorkoming van die verwagte opbrengsverlies, bygedra. Voorlopige resultate het aangetoon dat die Fhb1 geen die teenwoordigheid van Fusarium-beskadigde pitte verminder het. Die Fhb1 geen in kombinasie met die Qfhs.ifa- 5A QTL is suksesvol met behulp van MAS oorgedra en fenotipies in die Krokodilagtergrond wat verbeterde FHB weerstandsvlakke vertoon het, bevestig. Aangesien die hoofdoel die verbetering van FHB weerstand was, was hierdie studie suksesvol in die identifikasie van 44 BC2F1 individue wat die FHB weerstandsgeen Fhb1 en/of die Qfhs.ifa-5A QTL bevat het. ‘n Gedeeltelike koppelingskaart van al 21 koring chromosome is opgestel deur 120 polimorfiese mikrosatelliet merkers op hierdie 44 individue te toets. Die herhalende ouer se genoom persentasie analise is met behulp van GGT vir elke BC2F1 individu gedoen. Sestien hoë gehalte lyne wat Fhb1 en/of Qfhs.ifa- 5A QTL tesame met ‘n minimum herhalende ouer genoom persentasie van 80% bevat het, is geïdentifiseer en geselekteer vir verdere analises. Agt lyne wat die geteikende FHB weerstandsgene/QTL asook die potensiaal vir goeie bakkwaliteit bevat het, is vir verdere ontwikkeling geselekteer. Geïdentifiseerde en aanbevole lyne van hierdie studie kan vir die verdere ontwikkeling van FHB weerstandbiedende koringkultivars in SA gebruik word.
Description
Keywords
CM-82036, Fhb1, Fusarium graminearum, Marker-Assisted Selection (MAS), Qfhs.ifa-5A QTL, Recurrent parent genome percentage (RPGP), Resistance breeding, Simple Sequence Repeats (SSR), Two generation backcrossing programme, Wheat scab, Wheat -- South Africa, Fusarium disease of plants -- South Africa, Fungal diseases of plants, Thesis (Ph.D. (Plant Breeding))--University of the Free State, 2014
Citation