Initiation of a wheat pre-breeding effort aimed at yield improvement using male-sterility marker assisted recurrent selection

Ngcamphalala, Wandile (2018-12)

Thesis (MA)--Stellenbosch University, 2018

Thesis

ENGLISH ABSTRACT: Continous decline in South Africa’s wheat production over the past few decades has lead to a corresponding rise in reliance on wheat imports to satisfy the local consumption needs. Wheat breeders need to work faster to contribute towards increasing profitability and the attractiveness of the commodity. In response to this, a study was undertaken with the aim of identifying and assessing traits that confer yield in wheat whilst investigating the possibility of a technologically-advanced high throughput phenotyping platform for assessing traits. The first objective was to assess traits by conducting a multilocation field yield trial and a detailed study of yield attributing traits in a controlled environment. The second objective was to initiate a male sterility marker assisted recurrent selection (MS-MARS) population based on the use of wheat quality markers as well as resistance gene markers to wheat rusts and Fusarium head blight while adding high-yield traits via single seed descent breeding. Thirdly, a pilot study was conducted to test if a high-throughput phenotyping platform, based on remote sensing imagery and Remotely Piloted Aircraft Systems (RPAS) technology could be established for automated data collection of agronomic traits. Results of the yield trial showed highly significant (p=0.0000) differences between the three localities where the trial was planted as a result of drought conditions in the season. The top ten yielding entries across the three localities did not yield significantly different from each other (LSD (5%) 1.17 t/ha) and from this set, five entries were selected for the trait study. The top two entries overall were also the best two entries at the locality that was badly affected by drought, indicating yield stability. Grain yield was positively correlated (r>0.75) to biomass, grain number/spike, as well as tiller number and these correlations were highly significant (p<0.0001). The male sterility gene was found to be stable in the population by segregating in the expected 1:1 (sterile: fertile) ratio in the multiple cycles that were conducted. Rust resistance gene frequencies were also successfully maintained during crosses, with no significant differences between cycles (chi-square test, α=5%). Out of the ninety genotypes used in the field trial, forty-four were identified as crossing parents to contribute high-yield alleles in the population, with additional Fusarium resistance gene donor lines. In the resulting progeny of the cross, the Fhb1 gene was found to have been successfully transferred to 10% of the plants. Correlations from the RPAS phenotyping study were not satisfactory, but they were promising enough to warrant further investigation towards establishing a high throughput phenotyping platform.

AFRIKAANSE OPSOMMING: Voortdurende afname in Suid-Afrikaanse koringproduksie oor die afgelope paar dekades het gelei tot ‘n korresponderende toename in die afhanklikheid van koringinvoere ten einde plaaslike verbruikers behoftes te kan bevredig. Koringtelers het dus nodig om vinnger te werk ten einde by te dra tot winsgewendheid en aanloklikheid van die kommiditeit. In respons is ‘n studie onderneem wat ten doel het om eienskappe te indentifiseer en assesseer wat opbrengs in koring tot gevolg het terwyl daar ook gekyk word na gevorderde tegnologie vir ‘n hoë deurset fenotiperingsplatvorm. Die eerste doelwit van die studie was om eienskappe te assesseer deur multilokaliteitsproewe te doen asook ‘n gedetaileerde studie in ‘n beheerde-omgewing. Die tweede doelwit was om ‘n manlike steriliteits gefassiliteerde merker bemiddelde herhalende seleksie populasie gebaseer op die gebruik van koring kwaliteitsmerkers sowel as weerstandsgene vir koringroes en Fusarium te inisieer. Terwyl hoë-opbrengs eienskappe deur enkelpitnageslagteling aangespreek is. Derdens is ‘n ondersoek aangepak om te bepaal of ‘n hoë deurset fenotiperingsplatvorm gebaseer op afstandswaarneming en hommeltuig tegnologie gevestig kon word vir outomatiese data kolleksie van agronomiese kenmerke. Die resultate van die opbrengsproef het statisties betekenisvolle verskille (p=0.0000) uitgewys tusen die drie lokaliteit waar die proef geplant was as gevolg van droogte kondisies tydens die seisoen. Die tien beste inskrywings vir opbrengs oor die drie lokaliteite het nie statisties betekenisvol verskil nie (KBV (5%) 1.17 t/ha) en vanuit die is vyf inskrywings geselekteer vir die verdere bestudering van kenmerke gekoppel aan opbrengs. Die twee beste inskrywings oor al die lokaliteite was ook die beste in die droogste lokaliteit wat opbrengs stabiliteit aandui. Graanopbrengs was positief gekorreleer (r>0.75) met biomassa, korrels/aar, getal are en die korrelasie was boonop almal statisties betekenisvol (p<0.0001). Die manlike-steriliteitsgeen was bevind as stabiel in die segregerende populasie en het voldoen aan die 1:1 (sterile:vrugbaar) ratio oor ‘n aantal siklusse heen. Die roesweerstandsgeen frekwensies was ook suksesvol behou met geen statisties betekenisvol verskille oor siklusse Chi-kwadraattoets, α=5%). Uit die negentig genotipes gebruik in die veldproef is vier-en-veertig geidentifiseer as kruisingsouers wat hoë opbrengs allele sowel as addisionele Fusarium weerstandsgene kan bydra. In die nageslag van die kruising is die Fhb1- geen suksesvol oorgedra in 10% van die plante. Korrelasies van die hommeltuig fenotiperingstudie was nie bevredigend nie, maar was des nie teenstaande nie goed genoeg om verdere oorweging te regverdig.

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