Abstract
AbstractCotton bunchy top (CBT) is an aphid transmitted Polerovirus disease and a significant threat to the Australian cotton industry. Symptoms include stunted plant growth, and leaves often display pale green angular patterns at the leaf margins and dark green centers with a leathery texture. Resistance to CBT was evaluated in 206 F2 plants and 76 F2:3 families derived from the resistant cultivar ‘Delta Opal’ crossed to the susceptible cultivar ‘Sicot 70’, and in 25 other cultivars the majority susceptible to CBT. CBT resistance in ‘Delta Opal’ was shown to be controlled by a single dominant locus designated Cbt. A combination of AFLP and single nucleotide polymorphism markers located Cbt on chromosome A10, close to the mapped resistance locus in ‘Delta Opal’ to another Polerovirus disease of cotton; cotton blue disease. The markers identified flanking CBT resistance will provide useful tools for breeders for marker-assisted selection to alleviate the impact of this disease on cotton production.
Highlights
Cotton bunchy top (CBT) was first observed in Australian cotton fields in 1998–99 where it caused significant economic losses (Reddall et al 2004)
A population consisting of 206 F2 lines from the cross between Delta Opal and Sicot70 and eight replicates of a CBT susceptible (‘Sicot 70’) and resistant (CS 9 180) lines were tested for CBT resistance
If the CBT resistance in ‘Delta Opal’ is controlled by one single dominant gene, heterozygotes to homozygous resistant families should be identified at a 2:1 ratio in these F3 families
Summary
Cotton bunchy top (CBT) was first observed in Australian cotton fields in 1998–99 where it caused significant economic losses (Reddall et al 2004). Symptoms include reductions in plant height, leaf surface area, petiole and internode length (Ali et al 2007; Reddall et al 2004) resulting in significant loss of fiber yield. The causal agent of CBT was recently identified as the cotton bunchy top virus (CBTV) belonging to the genus Polerovirus of the family Luteoviridae (Ellis et al 2013). Viruses of the Polerovirus genus are aphid transmitted and contain non-enveloped single stranded positive-sense RNA genomes that contain six open reading frames (ORF0 to ORF5) (Mayo and ZieglerGraff 1996)
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