The use of amplified fragment length polymorphism (AFLP) and morphological data to determine heterotic groups in sunflower (Helianthus annuus)

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Date
2002-05
Authors
Van Deventer, Janine
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University of the Free State
Abstract
English: Breeders would like to predict the outcome of crosses, before producing and testing lines derived from them in field trials. One way to ensure this is by finding a correlation between the genetic distances of inbreds and the amount of heterosis obtained by such a hybrid. The aim of this study was to determine the genetic distances between 12 sunflower inbred lines with the use of the AFLP technique and to correlate these results with the amount of heterosis obtained in F1-hybrids. Twelve inbred lines, consisting of six females (lines) and six males (testers), was planted in a glasshouse at the University of the Free State (UFS) in Bloemfontein, South Africa. Two experiments were done on these parental lines. Young leaves were collected from each line. DNA was extracted from the leaves and AFLP analysis was performed on the DNA. Six different primer combinations were used, namely: Mse-Cn + Eco-ACA; Mse-CAG + Eco- ACA; Mse-CTC + Eco-ACA; Mse-Cn + Eco-AAC; Mse-CAG + Eco-AAC and Mse-CTC + Eco-AAC. The objective was to determine the genetic distances of the 12 lines with the use of the AFLP technique and different primer combinations. These results would then be used to identify heterotic groups in a hybrid breeding program. The genetic similarities were lower overall for CMS (A) x restorer (R) crosses than for AxA or RxR. This was confirmed by Hongtrakul et a/ (1997). Msecn + Eco-ACA, Mse-CAG + Eco-ACA and Mse-CTC + Eco-AAC identified the highest amount of dissimilarity between female lines 1A and 4A. The highest amount of dissimilarity between male lines 14R and 16R were identified by Mse-CTC + Eeo-ACA and Mse-CTC + Ecc-AAC. According to Hongtrakul et al (1997), the cluster analysis separated lines into two groups, one for A-lines (females) and another for R-lines (males). This was also found in this study. These groupings illustrate the breeding history and basic heterotic pattern of sunflower. In the second experiment, all six testers were individually crossed with each line to produce F1 hybrid seed. Thirty six crosses were made and sufficient seed was generated, except from the cross between parental lines 4A and 16R that resulted in a sterile hybrid with no seed. Therefore, 4Ax16R was replaced with a standard, HV3037. The 36 F1 hybrids were planted according to a randomized complete block design with three replications. The plant height, flowering date, head diameter, 1000-seed weight, yield and oil percentage of each hybrid was determined with the Line x Tester analysis. The aim was to determine the combining ability of the inbred lines, to determine if there are genetic correlations between the different characteristics and to determine the expression of heterosis for the different characteristics. Hybrid 6Ax13R had the latest flowering date and the highest yield. The F1 hybrid that had the highest head diameter and highest oil percentage was 1Ax12R. Some crosses performed equally or better than their best parents indicating the presence of heterotic effects. If yield is the most important selection criteria, the hybrid 6Ax13R would perform the best in a breeding . program as it ranked the highest. Line 1A could be used to improve head diameter, 1000-seed weight, yield and oil percentage, as it had the highest or second highest GCA effects for these characteristics. The tester 13R could also be used to increase plantheight and yield. To increase flowering date and 1000-seedweight, one can use 16R. F1 hybrid 3Ax15R was the only hybrid that had positive SCA effects for all the characteristics measured. The hybrid 4Ax14R was the best specific combiner for 1000-seed weight and yield, while 1Ax11R had the highest positive effects for oil percentage. According to the GCA:SCA ratio the SCA was greater, indicating non-additive gene action. This was found in the studies of Merinkovic (1993) who concluded that non-additive gene effects controlled yield. Putt (1966) also found that non-additive gene effects controlled the inheritance of flowering date, head diameter and 1000-seed weight. Correlations of interest were that when selecting for increased plant height one would increase the head diameter, 1000-seed weight and yield, but it would however, result in a decrease in the oil percentage. By increasing the flowering date, one would increase the oil percentage, but reduce the head diameter. Doddamani et al (1997) also found that head diameter, 1000-seed weight and plant height had a significant positive correlation with yield. They also found that flowering date had a negative correlation with yield. The results of this study thus confirm their results. Flowering date had the highest broad-sense heritability, followed by 1000- seed weight and plant height. Oil percentage had the highest narrow-sense heritability, followed by 1000-seed weight and flowering date. The hybrid with the highest MP and HP heterosis for yield was 6Ax13R. Hybrid 1Ax12R had the highest MP heterosis while 5Ax12R the highest HP heterosis for oil percentage. The three hybrids that expressed the highest heterosis overall, were 1Ax12R, 1Ax13R and 6Ax13R. Seetharam et al (1977) observed a significant positive heterosis for flowering date, plant height, head diameter, oil percentage and yield. According to Schuster (1964), heterosis for yield for the hybrids was up to 70% better than that of the parents. Half the hybrids showed heterosis for plant height (47% better) and heterosis for head diameter was 60%. Popov and Lazarov (1963) as well as Shuravina (1972) found that only a few hybrids exceeded the parents for oil percentage (heterosis of 4.8%). Above is all similar to the results found in this study. Correlations between genetic distance, heterosis, and hybrid performance for yield in sunflower were estimated. Genetic distances from AFLP fingerprints were correlated with the amount of heterosis found in F1 hybrids. Mse-CTT + Eco-ACA had the highest correlation with the amount of heterosis in the F1 generation. It can therefore be recommended that this primer combination can be used to identify heterosis for flowering date, head diameter, yield and oil percentage in hybrids. Therefore, it is possible to correlate the genetic distances found with AFLP data with the amount of heterosis that can be expected in F1 hybrids. This makes it possible to screen thousands of inbred lines and shorten the hybrid breeding program. The number of crosses, trails and amount of labor will decrease and will result in a lower farm price for hybrid seeds.
Afrikaans: Telers verkies om die resultate van kruisings te kan voorspel voordat die toets en produksie van basters op die lande, plaasvind. Een manier om dit te doen is om 'n korrelasie tussen die genetiese afstande van die ingeteelde lyne en die hoeveelheid heterose in 'n baster, te bepaal. Die doel van hierdie studie was om die genetiese afstande te bepaal tussen 12 sonneblom ingeteelde lyne met die gebruik van die AFLP tegniek en om hierdie resultate te korreleer met die hoeveelheid heterose gevind in F1 basters. Twaalf ingeteelde lyne, bestaande uit ses vroulike (lyne) en ses manlike (toetsers) lyne, is geplant in 'n glashuis by die Universiteit van die Vrystaat in Bloemfontein, Suid-Afrika. Twee eksperimente is gedoen op hierdie ouer lyne. Jong blare van elke lyn is versamel. Die DNA is ge-ekstraheer vanaf die blare en AFLP analises is uitgevoer op die DNA. Ses verskillende primer kombinasies is gebruik, naamlik: Mse-CTT + Eeo-ACA; Mse-CAG + Eeo-ACA; Mse-CTC + Eeo-ACA; Mse-CTT + Eeo-AAC; Mse-CAG + Eeo-AAC en Mse- CTC + Eeo-AAC. Die doelwit was om die genetiese afstande te bepaal van die 12 lyne met die gebruik van die AFLP tegniek en verskillende primer kombinasies. Hierdie resultate sou dan gebruik word om heterotiese groepe in 'n baster teelprogram, te identifiseer. Die genetiese ooreenkomste was oor die algemeen laer vir CMS (A) x hersteller (R) kruisings as vir AxA of RxR. Dit is bevestig deur Hongtrakul et al (1997). Mse-CTT + Eeo-ACA, Mse-CAG + Eeo-ACA en Mse-CTC + Eeo- AAC het almal dieselfde mees onverwante vroulike lyne (1A en 4A) geïdentifiseer. Dieselfde mees onverwante manlike lyne (14R en 16R) is deur Mse-CTC + Eeo-ACA en Mse-CTC + Eeo-AAC geïdentifiseer. Volgens Hongtrakul et al (1997), verdeel die dendrogram analise die lyne in twee groepe, een vir A-lyne (vroulik) en 'n ander vir R-Iyne (manlik). Dit is ook in die studie gevind. Hierdie groeperings illustreer die teelgeskiedenis en basiese heterotiese patroon van sonneblom. In die tweede eksperiment, is al ses toetsers individueel gekruis met elke lyn om F1 bastersaad te produseer. Ses en dertig kruisings is gemaak en voldoende saad is gegenereer, behalwe vanaf die kruising tussen ouerlyne 4A en 16R wat 'n steriele baster met geen saad gevorm het. Daarom is 4Ax16R vervang met 'n standaard, HV3037. Die 36 F1 basters is geplant volgens 'n gerandomiseerde volledige blokontwerp met drie replikasies. Die planthoogte, blomdatum, kopdeursnee, 1DOO-saadmassa, opbrengs en olie persentasie van die basters is bepaal met die Lyn x Toetser analise. Die doelwitte was om die kombineervermoë van die ingeteelde lyne te bepaal, om te sien of daar genetiese korrelasies tussen die verskillende eienskappe is en om die uitdrukking van heterose vir die verskillende eienskappe te bepaal. Baster 6Ax13R het die langste blomdatum en die hoogste opbrengs gegee. Die F1 baster met die grootste kopdeursnee en hoogste olie persentasie was 1Ax12R. Sommige kruisings het dieselfde of beter as hul beste ouers gepresteer, wat dui op die teenwoordigheid van heterotiese effekte. As opbrengs die belangrikste seleksie kriteria is, sal die baster 6Ax13R die beste presteer in 'n teelprogram aangesien dit die hoogste opbrengs gehad het. Lyn 1A kan gebruik word om kopdeursnee, 1DOO-saadmassa, opbrengs en olie persentasie te verbeter, aangesien dit die hoogste of tweede hoogste GCA effekte gehad het vir hierdie eienskappe. Die toetster 13R kan ook gebruik word om planthoogte en opbrengs te verbeter. Om blomdatum en 1000-saad massa te verbeter, kan 16R gebruik word. Die F1 baster 3Ax15R was die enigste baster wat positiewe SCA effekte vir al die eienskappe gehad het. Die baster 4Ax14R was die beste spesifieke kombineerder vir 1DOO-saadmassa en opbrengs, terwyl 1Ax11R die hoogste positiewe effekte vir olie persentasie gehad het. Volgens die GCA:SCA verhouding was SCA groter, wat dui op nie-additiewe geenaksie. Merinkovic (1993) het ook tot die gevolgtrekking gekom dat nie additiewe geen effekte die oorerwing van blomdatum, kopdeursnee en 1000- saad massa beheer. Korrelasies van belang was dat wanneer daar geselekteer word vir hoër planthoogte, die kopdeursnee, 1000-saad massa en opbrengs sal toeneem, alhoewel dit 'n afname in die olie persentasie tot gevolg sal hê. Deur die blomdatum te verhoog, sal die olie persentasie toeneem, maar kopdeursnee sal afneem. Doddamani et al (1997) het ook gevind dat die kopdeursnee, 1000-saadmassa en planthoogte 'n betekenisvolle positiewe korrelasie met opbrengs gehad het. Hulle het ook gevind dat die blomdatum 'n negatiewe korrelasie met opbrengs gehad het. Die resultate van hierdie studie bevestig dus hulle gevolgtrekking. Blomdatum het die hoogste breë sin oorerflikheid gehad, gevolg deur 1000- saad massa en planthoogte. Olie persentasie, gevolg deur 1000-saad massa en blomdatum het die hoogste nou sin oorerflikheid gehad. Die baster met die hoogste MP en HP heterose vir opbrengs was 6Ax13R. Baster 1Ax12R het die hoogste MP heterose, terwyl 5Ax12R die hoogste HP heterose vir olie persentasie gehad het. Die drie basters wat oor die algemeen die hoogste heterose gehad het, was 1Ax12R, 1Ax13R en 6Ax13R. Seetharam et al (1977) het In betekenisvolle positiewe heterose vir blomdatum, planthoogte, kopdeursnee, olie persentasie en opbrengs waargeneem. Volgens Schuster (1964) was heterose vir opbrengs vir die basters tot 70% beter as die van die ouers. Die helfte van die basters het heterose vir planthoogte (47% beter) gehad en heterose vir kopdeursnee was 60%. Popoven Lazarov (1963), so wel as Shuravina (1972) het gevind dat net enkele basters die ouers met olie persentasie oorskry (heterose van 4.8%). Bogenoemde is alles in ooreenstemming met die resultate van hierdie tesis. Korrelasies tussen genetiese afstand, heterose en baster prestasie vir opbrengs in sonneblom is bepaal. Genetiese afstande vanaf AFLP vinger- afdrukke was gekorreleer met die hoeveelheid heterose gevind in die F1 basters. Mse-CTT + Eeo-ACA het die hoogste korrelasies met die hoeveelheid heterose in die F1 generasie gehad. Dit kan dus aanbeveel word dat hierdie primer kombinasies gebruik kan word om heterose te identifiseer vir blomdatum, kopdeursnee, opbrengs en olie persentasie in basters. Dit is dus moontlik om die genetiese afstande gevind met die AFLP data, te korreleer met die hoeveelheid heterose wat verwag kan word in F1 basters. Dit maak dit moontlik om duisende ingeteelde lyne te evalueer en kan dus die baster teelprogram verkort. Die aantal kruisings, proewe en hoeveelheid arbeid nodig, sal afneem en dit kan 'n laer prys vir die boere vir bastersaad tot gevolg hê
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Heterosis, Sunflowers -- Genetics, Genetic markers, Dissertation (M.Sc.Agric. (Plant Sciences (Plant Breeding))--University of the Free State, 2002
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