Disease resistant library

C&I Issue 3, 2019

A new method to rapidly recruit disease resistance genes from wild plants and transfer them into domestic crops has been developed by an international team led by John Innes Centre researchers. They claim it will speed up the fight against pathogens that threaten food crops worldwide.

Wild relatives of any plant species possess an important repertoire of new genes that can be bred into current commercial varieties to aid disease resistance. However, identifying and transferring these genes from wild species is a time consuming and expensive process, and in some cases may not be possible due to sexual incompatibility.

The new technique called AgRenSeq or speed-cloning enables researchers to search a genetic ‘library’ of resistance genes discovered in wild relatives of modern crops so they can rapidly identify sequences associated with disease-fighting capability. From there, researchers can use laboratory techniques to clone the genes and introduce them into elite varieties of domestic crops to protect them against pathogens and pests such as rusts, powdery mildew and Hessian fly.

By making crops more disease resistant, AgRenSeq will help to improve yields and reduce the use of pesticides, says Brande Wulff, JIC project leader. ‘We have found a way to scan the genome of a wild relative of a crop plant and pick out the resistance genes we need; and we can do it in record time. This used to be a process that took ten or 15 years and was like searching for a needle in a haystack. Now we can clone these genes in a matter of months and for thousands of pounds instead of millions.’

AgRenSeq has been successfully trialled in a wild relative of wheat. Researchers took months to identify and clone four resistance genes for the stem rust pathogen. This process would usually take a decade. The work prepares the way for the method to be used in protecting many crops with wild relatives, including, soya bean, pea, cotton, maize, potato, wheat, barley, rice, banana and cocoa.

The new method combines high-throughput DNA sequencing with state-of-the-art bioinformatics. ‘AgRenSeq is a game changer in the sense that it does not require any reliance on reference genome sequence or production of single gene lines or mutants thereby saving time by several years,’ comments Rohit Mago of CSIRO Agriculture and Food in Canberra, Australia. ‘The method basically enables screening of a large library of resistance genes in wild relatives in germplasm collections and identifies resistance associated sequences which can then be cloned and introduced as part of gene stacks.’

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