Strains of cotton with ‘exotic’ genetic material could help improve yields, while also increasing fibre quality.
Tiffany Hionas
One of the primary challenges for cotton breeders is maintaining or increasing yield potential while improving cotton fibre quality. Producing high quality fibre and high yield plays an important role for international trade, with the global cotton market estimated to be worth more than $12bn.
To overcome the yield vs quality challenge – as the yield improves, the fibre quality decreases – a University of Georgia, US, team studied the genetics of hybrid ‘Sealand’ cultivars which were developed by breeding two different species of cotton.
The Sealand cultivars are a hybrid of Upland cotton, also known as ‘Pima’, which has a higher yielding but lower fibre quality than Sea Island cotton, which is known for its long, strong and fine fibres.
As they are a different species, the genetic barriers between them can cause genetic abnormalities during and after breeding. However, breeders at the USDA have successfully bred Upland and Sea Island cotton species, but the genetic makeup of this hybrid has been largely unknown until recently.
Using genetic maps, the researchers have been able to identify which part of the genome controls fibre quality, subsequently proving the superior fibre quality of Sealand cotton, which has been inherited from the Sea Island cotton crop.
Selecting specific traits in the past has led to the loss of potential useful traits, but there are benefits of combining Pima and Upland genetics. In addition to creating strong fibre quality, selective breeding can produce cotton that is drought tolerant and disease resistant.
Molecular markers in Pima cotton make it easier for breeders to track genetic segments through generations, so cotton breeders can use the genetic tools to look for sections of the genome which are connected to traits, such as strong fibre quality, in order to breed new cultivars.
Ongoing research is being carried out on a subset of genetic segments from Pima cotton. ‘We want to confirm their desirable effects across a more diverse set of varieties,’ said Peng Chee, a researcher at the university. ‘Then they will be more useful in cotton breeding programs across the cotton belt.’
DOI: 10.2135/cropsci2018.12.0745
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