Abstract
Fusarium crown rot (FCR), caused by various Fusarium species, is a destructive disease of cereal crops in semiarid regions worldwide. As part of our contribution to the development of Fusarium resistant cultivars, we identified several novel sources of resistance by systematically assessing barley genotypes representing different geographical origins and plant types. One of these sources of resistance was investigated in this study by generating and analysing two populations of recombinant inbred lines. A major locus conferring FCR resistance, designated as Qcrs.cpi-4H, was detected in one of the populations (mapping population) and the effects of the QTL was confirmed in the other population. The QTL was mapped to the distal end of chromosome arm 4HL and it is effective against both of the Fusarium isolates tested, one F. pseudograminearum and the other F. graminearum. The QTL explains up to 45.3% of the phenotypic variance. As distinct from an earlier report which demonstrated co-locations of loci conferring FCR resistance and plant height in barley, a correlation between these two traits was not detected in the mapping population. However, as observed in a screen of random genotypes, an association between FCR resistance and plant growth rate was detected and a QTL controlling the latter was detected near the Qcrs.cpi-4H locus in the mapping population. Existing data indicate that, although growth rate may affect FCR resistance, different genes at this locus are likely involved in controlling these two traits.
Highlights
Fusarium crown rot (FCR) is a chronic and severe disease of cereals in many parts of the semiarid regions of the world [1]
Drastic differences in FCR resistance were detected between the commercial cultivar Baudin and the source of resistance AWCS276 using either the F. graminearum or the F. pseudograminearum isolate analysed (Figure 1)
Differences in FCR resistnace between the best lines from the two controlled environment facilities (CEF) trials with the use of the F. pseudograminearum isolate and the resistant parent were more than 50% (Table 1)
Summary
Fusarium crown rot (FCR) is a chronic and severe disease of cereals in many parts of the semiarid regions of the world [1]. Various practices have been assessed for their effectiveness in managing levels of FCR These include crop rotation and stubble burning to reduce inoculum load [7,8]. These practices have apparently not been very effective as the incidence of FCR has increased in Australia as well as in many other cereal growing regions worldwide in recent years, most likely due to the high intensity of cereals in cropping systems combined with the wider adoption of minimum tillage for moisture conservation as FCR pathogens are carried over in residues [1,3,9]. Growing resistant barley cultivars could reduce yield loss of the barley crop itself and yield loss in barley or other cereal crops in the following years by reducing the inoculum load
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