Developing higher protein wheat for Western Australia with superior processing characteristics

Overall Objective

Proteins are one of the most important attributes determining wheat’s end-use quality and marketability. The protein quality is often emphasised more than the protein quantity by miller and bakers to meet their specific purposes. This project aimed to deliver varieties with higher Nitrogen Use Efficiency (NUE) together with higher dough strength and extensibility for improved bread-making quality, which would enable Australian wheat to compete in the premium bread-making markets in South-East Asia against North American wheats.

While NAM genes boost the NUE of a variety, different High Molecular Weight glutenin subunits (HMW-GS) greatly impact the breadmaking quality. It is well recognised that GluD1 d (5+10), GluB1 I (7+8)  and GluB1 i (17+18) positively influence the bread-making properties through better dough strength, and HMW-GS 1Ay provides better dough extensibility. In contrast, GluD1 d (2+12) is associated with poor dough and bread-making quality.

Crosses were made to combine favourable alleles of NUE, dough strength and extensibility, and advanced lines have been selected based on qPCR assays and Maldi-Tof Mass Spectrometer screening combined with yield performance. Two advanced protein variety trials were conducted under this project during the winters of 2021 and 2022 at York.  In both seasons, preliminary yield trials and observation nurseries were grown in addition to advanced variety trials. In addition to the advanced and preliminary yield trials, 960 and 968 new breeding lines have been advanced at Manjimup in the respective summer of seasons of 2021 and 2022. Altogether 275 and 204 advanced lines have been screened through qPCR assays and Maldi-Tof Mass Spectrometer for favourable alleles of the three components discussed above.

Among the 72 lines grown in an advanced variety trial during winter 2021, 18 were identified to possess favourable wild-type NAM-B1 alleles for higher NUE and 20 were identified having 5+10 HMW-GS for better dough strength.  All the four Australian checks contain mutated type NAM-B1 and 2+12 HMW-GS. Seven lines were found to have favourable 1Ay HMW-GS for dough extensibility. None of the lines combined all three favourable alleles of wild type NAM-B1, 5+10 HMW-GS and 1Ay, although six lines combined wild type NAM-B1 with 5+10 HMW-GS and two lines combined 5+10 with 1Ay.

Complete milling and baking tests were undertaken on two different sets of 20 lines; the first set was selected from the advanced variety trials in 2020, and the second set from advanced variety trials in 2021. Similarly, separate sets of 100 lines selected from the preliminary trial and observation nurseries in 2020 and 2021 were tested for NIR protein quality. From the first set, nine lines from five different crosses showed very good overall baking quality. Three lines carried the HMW 5+10 glutenin subunits for strong dough mixing, a key trait we need to improve for the SE Asian bread wheat markets. Similarly, seven lines from the second set showed excellent overall baking quality compared to Emu Rock and Scepter.

Project Synopsis

WA generates about 50% of Australia’s total wheat production with more than 95% of this exported, predominantly to Asia and the Middle East. While yield is the main driver for variety adoption, protein content and quality are the major players in end-use quality and marketability. Australian wheat has a good reputation for noodles in South-East Asia, but cannot compete with North American wheat when it comes to baking due to lower protein content, higher gluten content, greater dough strength and longer extensibility. For a more profitable and sustainable grain industry, we should target the baking industry to capture the premium price on wheat for bread-making in the SE Asian markets by matching (or exceeding) the North American wheats for dough strength and dough extensibility.

Dough extensibility drops rapidly at lower flour protein levels, but light textured WA’s soil cannot support higher protein content, resulting in the high input cost of nitrogen fertiliser for Western Australian wheat producers. Again, under field crop conditions, in general only 14% of applied nitrogen is translated into grain protein (Lopez-Bellido et al, 2005). The NAM-B1 gene in wheat facilitates the remobilisation of nutrients from leaves and stems to the developing grains, and contributes to the higher grain protein. While NAM genes boost the NUE of a variety, different High Molecular Weight glutenin subunits (HMW-GS) like GluD1 d (5+10), GluB1 I (7+8)  and GluB1 i (17+18) give better dough strength, and HMW-GS 1Ay provides better dough extensibility.

This project addressed these three areas of improvement by stacking genes for higher Nitrogen Use Efficiency (NUE), higher dough strength and extensibility for improved bread-making quality to optimise grower returns and ensure the sustainability of our industry.

In this project, 275 of Edstar’s advanced breeding lines and four Australian check varieties have been analysed for the presence of NAM genes. Seventy-six of the 275 lines were found to carry a favourable wild-type NAM-B1 allele, while all the check varieties had the mutated (non-functional) NAM-B1 allele. Amongst 72 selected lines grown in the Protein Advanced Variety trial, the top four protein content lines had the NAM-B1 gene and delivered more than 13% grain protein, as compared to Magenta (12.81%) and Emu rock (12.18%). Sixteen higher NUE lines yielded similar to Mace and Scepter (statistically non-significant difference), resulted in more kilograms of grain protein per hectare compared to the checks. Thirty-six high NUE lines combined HMW-GS subunits Bx5+By10 for strong dough, and 23 lines combined 1Ay HMW-GS subunits for dough extensibility. Significantly, six of the lines carry all three desired alleles together. These lines will need further evaluation for yield performance in advanced trials and for bread-making quality. In addition, a portfolio of advanced lines with different combinations of these three genes has been generated that will be used as a parent pool in the future crossing program.

Milling and baking tests on selected NUE lines led to the identification of 7 lines with higher dough extensibility than Emu Rock, with the same level of dough strength. Two lines, EDGE15W-015-6-4-01 and EDGE15W-027-6-1-02 have been nominated for National Variety Trials 2023 and will be submitted for preliminary classification in October 2023.  Based on NVT performance, once the varieties released from this project materialise, Elders commits to paying an agreed share of the royalty to COGGO.