DiVerent quantitative trait loci for Fusarium resistance in wheat ...

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Jun 26, 2008 - in wheat seedlings and adult stage in the Wuhan/Nyubai wheat population ..... Canadian Adaptation Council (CanAdapt) and the enhanced.
Euphytica (2009) 165:453–458 DOI 10.1007/s10681-008-9747-9

DiVerent quantitative trait loci for Fusarium resistance in wheat seedlings and adult stage in the Wuhan/Nyubai wheat population L. Tamburic-Ilincic · D. Somers · G. Fedak · A. Schaafsma

Received: 1 April 2008 / Accepted: 11 June 2008 / Published online: 26 June 2008 © Springer Science+Business Media B.V. 2008

Abstract Fusarium head blight (FHB), caused primarily by Fusarium graminearum (Schwabe), is an important wheat disease. In addition to head blight, F. graminearum also causes Fusarium seedling blight (FSB) and produces the mycotoxin deoxynivalenol (DON) in the grain. The objectives of this study were: (1) to compare the relationship between resistance of wheat lines to F. graminearum in the seedlings and spikes and (2) to determine whether the quantitative trait loci (QTL) for FSB were the same as QTLs for FHB resistance and DON level reported for the same population previously (Somers et al. 2003). There was no relationship between FSB infection and FHB index or DON content across the population. A single QTL on chromosome 5B that controlled FSB resistance was identiWed in the population; the marker WMC75 explained 13.8% of the phenotypic variation for FSB. This value implies that there may be other QTL with minor eVects present, but they were not

detected in the analysis. Such a QTL on chromosome 5B was not reported previously among the QTLs associated with FHB resistance and DON level in this population. However, because of recombination, some lines in the present study have Fusarium resistance for both seedling and head blight simultaneously. For example, DH line HC 450 had the highest level of resistance to FSB and FHB and was among the ten lines with lowest DON content. This line is a good candidate to be used as a parent for future crosses in breeding for Fusarium seedling resistance, together with breeding for head blight resistance. This approach may be eVective in increasing overall plant resistance to Fusarium. Keywords Breeding · Deoxynivalenol · Fusarium graminearum · Microsatellite markers

Introduction L. Tamburic-Ilincic (&) · A. Schaafsma University of Guelph, Ridgetown Campus, Ridgetown, ON, Canada N0P 2C0 e-mail: [email protected] D. Somers Cereal Research Centre, AAFC, Winnipeg, MB, Canada R3T 2M9 G. Fedak Central Experimental Farm, Eastern Cereals and Oilseeds Research Centre, AAFC, Ottawa, ON, Canada K1A 0C6

Fusarium head blight (FHB) is a destructive disease of wheat (Triticum aestivum L.), caused primarily by Fusarium graminearum (Schwabe), the anamorph of Gibberella zeae (Schw.) Petch. F. graminearum also causes fusarium seedling blight (FSB) (Sutton 1982). FSB is a problem mainly in areas where the Fusarium is seedborne and if the crop germinates in hot conditions (Cook 1980; Chongo et al. 2000). DiVerent types of resistance and their polygenic control make breeding for FHB resistance very diYcult. There is a

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need for a fast, reliable, highly productive in vitro selection method in breeding for FHB resistant wheat. The problems most often associated with in vitro screening include repeatability of data obtained using diVerent genotypes and low correlation between laboratory and Weld data. Toxins were used as the selective agents for disease resistance in several studies (Bruins et al. 1993; Lemmens et al. 1994; Ruckenbauer et al. 2001). DON is phytotoxic and induces lesions on wheat leaves, and inhibits the growth of wheat seedlings, coleoptile segments, embryos and calli (Bruins et al. 1993; Wang and Miller 1988). Considerable progress has been made in the past ten years or so in understanding the genetic control of FHB resistance. QTL for type 2 resistance, mainly from Chinese sources such as Sumai3 have been located mainly on chromosomes 3B and 5A (Waldron et al. 1999; Anderson et al. 2001). The main QTL for type 1 resistance, in the cultivar Frontana, has been mapped on chromosome 3A (Steiner et al. 2004). Somers et al. (2003) showed that type 1 resistance, type 2 resistance and resistance to DON accumulation were controlled by diVerent loci in the same population. In that study, the QTL for type 1 resistance were located on chromosomes 3Bc and 4B, for type 2 resistance on 2D and 3BS and resistance to DON accumulation on chromosomes 2D, 3BS and 5A. Wheat with genes pyramided from Sumai 3 (type 2 resistance) and Frontana (type 1 resistance) show improved levels of resistance to FHB and DON accumulation (Tamburic-Ilincic et al. 2006). Initial attempts at marker assisted selection (MAS) using the known QTL were reported to be eVective (Zhou et al. 2003; Yang et al. 2003). Much more detailed MAS studies (McCartney et al. 2007; Wilde et al. 2007) showed that pyramiding of known FHB resistance QTL into elite wheat germplasm was an eVective way of building FHB resistance. MAS could help to track and pyramid Fusarium resistant genes and develop wheat with simultaneous overall crop resistance to Fusarium. However, as suggested by Zhang et al. (2006) those using MAS need to perform a more complete characterization of the lines and correlations among the traits because of a strong possibility of unexpected trait linkages and pleiotropic eVects. The objectives of this study were: (1) to compare the relationship between resistance of wheat lines to F. graminearum in the seedlings and spikes and (2) to determine whether the quantitative trait loci (QTL)

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for FSB were the same as QTLs for FHB resistance and DON level reported for the same population previously (Somers et al. 2003).

Materials and methods In a previous study, as described in Somers et al. (2003), the Wuhan/Maringa doubled haploid (DH) wheat population (ninety one lines) was developed, spray and point-inoculated with F. graminearum at Xowering, evaluated for FHB index and DON content by ELISA method and mapped. The population name was recently corrected to Wuhan £ Nyubai (McCartney et al. 2007). In the present study, the same population was tested for the Fusarium seedling blight (FSB) using an in vitro seedlings test. Seedling assays were conducted individually on slants of Knop agar (Knop, 1860, in Sijmons et al. 1991) medium (1 g KNO3; 0.12 g KCl; 0.25 g KH2PO4; 0.25 g MgSO4 £ H2O; trace FeCl £ 6 H2O; 15 g agar, and 1 l distilled water) in glass tubes in four replications in the laboratory. The experiment was repeated two times. The replications within an experiment were arranged in a randomized complete block design. A mycelium disk (4.0 mm diameter) of the F. graminearum strain (DAOM178148) grown on potato dextrose agar (PDA) medium at room temperature for 1 week, was placed on the Knop agar medium in glass tubes near the bottom of the slant. A single germinated seed was placed 2 cm above the mycelium disk in each tube. Controls were fungus-free. Seedlings were grown under artiWcial light for 14 d, and then evaluated using a scale from 1 to 6 where 1 = no necrosis, healthy seedlings with normal root and shoot development, 2 = seedlings with healthy root, and 20% necrosis on the shoot, 3 = seedlings with healthy root, and 50% necrosis on the shoot, 4 = mycelium covering seed with normal root growth, and shoot growth reduced to 6 cm, 5 = mycelium covered seed, normal root growth, and shoot growth reduced to 3 cm, 6 = mycelium covered seed, roots discolored, and seedling growth stopped. Reisolations of the pathogen were done from infected tissue to conWrm infection by F. graminearum. The QTL analysis was performed with QTL Cartographer (Wang et al. 2004) and the mapping was done with JoinMap V3.0. The LOD peak for the FSB QTL was 3.5, a threshold of 3.0 was used to consider signiWcant QTL.

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Statistical analysis

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Normality and homogeneity of variance for the data was tested using PROC UNIVARIATE test (SAS Institute Inc. 2003). The data for level of FSB infection were normally distributed and not transformed. Correlations of the traits studied were calculated using PROC CORR (SAS Institute Inc. 2003). The level of signiWcance used for statistical analyses was P = 0.05 unless otherwise stated. DH lines were assigned to the classes on basis on their position in the distribution of FSB infection using a scale from 1 to 6 as explained above.

FSB (1-6)

6 5 4 3

2

R = 0.0334

2 1 0 0

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FHB index (%)

Fig. 2 Relationship between FHB index (%) after spray-inoculation in the Weld and FSB (1–6) in ninety one doubled-haploid lines in Wuhan/Nyubai population 7

FSB (1-6)

6

Results Genotypes had a signiWcant eVect on FSB development (Table 1). There was segregation for FSB infection across the population, ranging from 3.0 to 6.0 (Fig. 1). Transgressive segregants were obtained in both directions (Fig. 1). There was no signiWcant correlation between FSB and FHB or DON level. CoeYcient of determination for FSB and FHB index after spray inoculation in the Weld and DON level in the grain are presented in Figs. 2 and 3, respectively. A QTL on chromosome 5B associated with FSB resisTable 1 Analysis of variance for the sources of variation on Fusarium seedling blight (1–6) in Wuhan/Nyubai wheat population after inoculation with Fusarium graminearum Source of variation Replication Genotype

DF

MS

F Value

Pr > F

3

0.73

1.75

0.1588

77

1.01

2.42