Murdoch University works on pod shattering resistance in lupins

By Shannon Beattie
Updated February 25 2022 - 8:04am, first published December 27 2021 - 11:00pm
Murdoch University researcher Tianhua He.

ACHIEVING maximum pod shattering resistance in narrow-leafed lupins through the identification and combination of the best alleles from two genes, is the aim of a new project from Murdoch University.

Agronomic features of a crop - such as grain yield, seed weights, disease tolerance and pod-shattering resistance - are usually controlled by several genes.

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These genes typically work additively to control a feature.

Usually, there are different versions of a gene within a population and a version of the gene is termed an allele.

Different alleles may have different effects on the agronomic features, so one version of the gene (allele A) has a better effect on the agronomic feature than another version of the gene would have.

Murdoch University researcher Tianhua He said in narrow-leafed lupins, two critical genes control pod-shattering resistance, as in keeping the pod shut and not split after the grains mature.

"There are several different alleles within each gene that each have different levels of controlling pod-shattering resistance," Dr He said.

"Identifying and combining the best allele that has the best control of pod-shattering resistance from the two genes into one variety will achieve better pod-shattering resistance."

Legume seeds, such as narrow-leafed lupins, are typically dispersed by the explosive dehiscence of the pod at fruit maturity and this process is known as pod shattering.

This form of dispersal has been highly successful for wild species and at maturity, wild legumes disperse their seeds through pod shattering.

A reduction in pod shattering is one of the main components of grain legume domestication over thousands of years, however narrow-leafed lupins are a relatively new legume crop with a short domestication history.

Dr He said the capacity for their pods to maintain shut at fruit maturity was not strong enough, particularly under WA's arid and semi-arid growing conditions.

"In practice, lupin plants have to be left in the field for the grain to be dried below a certain level - 14 per cent for CBH Group receival standards," he said.

"Consequently, many lupin grains are lost due to pod splitting pre-harvest and during machinery harvest.

"As a consequence, there would be an average yield loss between 12-15pc if the harvest was delayed after the crop ripened, which is a considerable economic loss for the lupin growers."

The project, which received $99,805 in funding over two years from the Council of Grain Grower Organisations, aims to link the type of allele to their capacity of controlling pod-shattering resistance through genetic analysis of 200 narrow-leafed lupin varieties.

Researchers will sequence the two genes to identify the allele in each of the 200 varieties, measure the level of resisting pod-shattering of each of the varieties and then rank the capacity of control pod-shattering resistance of each type of allele.

Finally, they will cross the varieties carrying the best alleles in each of the two genes to combine the best allele to achieve the best pod-shattering resistance.

Overall, the outcome from the project will be advanced breeding lines with the best pod-shattering resistant genes combined in each material.

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Dr He said the varieties developed from these breeding lines would significantly reduce yield loss due to pod-splitting pre-harvest and during machinery harvest.

"We expect the breeding lines will be further tested and evaluated in wider environments and be developed to commercial narrow-leafed lupin varieties that are available to farmers in WA," he said.

"We expect yield loss due to pod-splitting pre-harvest and during the harvest of these new varieties will be fewer than 50pc of current level yield loss due to poor pod-shattering resistance.

"The estimated benefit of these new varieties to lupin growers would be an extra income of $36-$72 per hectare without additional investment."

Murdoch University expects the new varieties with better pod-shattering resistance to be available to farmers in five years.

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