LMA Screening: Delivering and improving an essential service to Australian wheat breeders

Overview

Late Maturity α-Amylase (LMA) is a serious defect in milling wheat varieties, and all new breeding lines must be submitted to the national LMA screen which APPN operates. In parallel to running the commercial screen, APPN, in collaboration with a range of partners, carried out research to improve the LMA screening process.

Why

Previous screening protocols were considered low-throughout, labour intensive and costly. The GRDC-funded research sought to streamline screening protocols.

Outcomes

Based on project results, overall labour and time requirements were greatly reduced for a single screen. Due to these improved time and labour requirements, the screening capacity of APPN has also doubled.

Impact

The research to improve LMA screening protocols means lower cost and higher throughput screening can now be offered, and breeders can remove LMA-sensitive lines sooner from their breeding programs.

Improved screening protocols will also continue to mitigate the negative impact of wheat deliveries failing Falling Number tests (due to the presence of LMA) on farm profitability.

Late Maturity α-Amylase (LMA) is a serious defect in milling wheat varieties that can potentially reduce grain marketability. Australian wheat breeders are required to submit all new varieties to a lengthy and costly screening program (mandated by Grains Australia) to ensure their breeding lines do not carry this defect.  

As LMA screening can be a significant bottleneck in breeding programs, the Australian Plant Phenomics Network (APPN) Node at the University of Adelaide collaborated with the South Australian Research & Development Institute (SARDI), Australian Grain Technologies (AGT) and Statistics for the Australian Grains Industry (SAGI) at the University of Wollongong to improve LMA screening protocols through a Grains Research and Development Corporation (GRDC) investment.

A range of recommendations from this project are already being implemented, delivering immediate impact across the wheat sector.

Wheat is Australia’s most important crop, spanning a planted area of 10.5 million ha, and accounting for over 10% of the total value of Australia’s agricultural production in 2023-24. While wheat plays an essential role in Australia’s food security, it also has an important role in our export markets. An average of 78% of wheat production was exported from 2021-2024, and Australian wheat has a global reputation for being a high quality and in-demand product. 

LMA is a genetic defect in wheat that results in the accumulation of the enzyme α-amylase during late grain development. Activity of α-amylase causes starch breakdown in harvest-ready wheat, reducing both the quality and marketability of the grain.

If grain fails a Falling Number test (a measure of starch breakdown) its milling class can be downgraded. This downgrade is generally significant, having a large impact on grain pricing and leading to reduced farm income. Therefore, wheat breeders must submit new lines for mandated LMA screening before commercial release, to reduce the risk of LMA-sensitive varieties entering the market. 

'The University of Adelaide node of APPN has been operating the national LMA screen, in collaboration with SARDI and SAGI (now AAGI), in recent times, taking over from a previous University of Adelaide group led by Adjunct Associate Professor Daryl Mares.

The mandated LMA screening is important, as LMA expression has direct economic implications for Australian wheat growers. However, previous screening protocols were considered low-throughput, labour intensive and costly. The previous LMA screen involved growing wheat in a temperature-controlled greenhouse, monitoring its phenology and then applying a ‘cool-shock’ treatment to detached tillers at a specific growth stage to trigger LMA expression. 

At maturity, the grain was harvested and submitted to the testing laboratory, where it was milled and tested by ELISA (enzyme linked immunosorbent assay) to assess levels of α-amylase. This process was repeated over two screens conducted each summer and winter, with breeders receiving the results after approximately 16 months. 

The GRDC-funded research sought to streamline the greenhouse phase and optimise the laboratory testing phase to ensure quicker, more affordable and more reliable screening

Based on project results, the cool-shock component of the screen was removed, the amount of greenhouse replication was increased, ELISA testing replication was reduced and genetic marker data included. This meant overall labour and time requirements were greatly reduced through less manual handling of plant material and screenings carried out in a single season rather than two, all without compromising screen reliability.

Due to the changes in time and labour requirements, screening capacity was increased from 700 lines per year to 1,400 lines per year. 

Following recommendations made to Grains Australia, the University of Adelaide APPN node, SARDI and AAGI have implemented the new screening methodology as part of an ongoing trial prior to the changes being fully accepted and adopted. 

Having already been implemented as part of an ongoing trial, this project is delivering immediate impact across the wheat sector. 

As all new wheat varieties are required to undergo the mandated LMA screening, the outcomes of these investigations influence every level of the value chain—from breeders to growers and end-users. A recent ex-post analysis of GRDC’s LMA investment found that for every dollar invested in this project, more than $6.30 was returned,^ demonstrating a strong return on investment.

^ Marsden Jacob Associates for the Grains Research and Development Corporation (2024), Ex-post analysis of LMA Program. Figure reported for LMA project A. 
* Kingwell, R., and Carter, C. (2014). Economic issues surrounding wheat quality assurance: the case of late maturing alpha-amylase policy in Australia. Aust. Agribus. Rev. 2:14. Referencing APW grade down to GP or FED1 grade.

Direct impacts of the project include: 

1. Lower cost and higher throughput screening. By reducing the time and labour required to carry out screening in APPN’s greenhouses, the overall cost to screen a single line for a breeder can be reduced. In addition, screening throughput has been doubled, allowing breeders to submit more lines each year.
2. Earlier identification of LMA-sensitive lines. As the outcome of screening can be made available up to 6-9 months earlier, breeders can remove LMA-sensitive lines sooner, potentially mitigating up to $16 million in costs to the wheat industry by 2030.^
3. Improved genetic gain. By doubling screening capacity, overall genetic gain for grain yield and other traits can be improved as a greater number of lines can be screened in a shorter period of time.
4. Reduced risk of loss for farmers. Improved screening protocols will continue to mitigate the negative impact that wheat deliveries failing Falling Number tests (due to the presence of LMA) have on farm profitability. Previous estimates indicate a potential $50/t penalty if grain is downgraded from premium wheat classes to feed grade.* For some farms this could mean hundreds of thousands of dollars in lost income in a single season. 

Investigations to improve screening protocols was a collaborative project funded by the GRDC and led by APPN’s University of Adelaide node, in collaboration with SARDI, AGT, and the University of Wollongong (SAGI). 

As part of the project, APPN provided essential infrastructure including controlled environment rooms and greenhouses for precise control of climatic conditions necessary for the screen, as well as expertise in plant growth requirements and large-scale screenings.

Parallel screens were conducted in the greenhouses and growth rooms at AGT. The Molecular Diagnostic team at SARDI delivered ELISA based LMA testing as part of the project. Data analysis and biometry was provided by the University of Wollongong.

Photos courtesy of the University of Adelaide.