Varieties that offer a range of sowing and maturity times can strongly affect yield by helping to make the best use of stored soil moisture and avoid heat, drought, disease and frost stresses. While such changes to the phenology of cereals are well underway, a project at the University of Tasmania is creating equivalent genetic potential for pulses, starting with chickpeas and lentils.

Efforts to exploit diversity in phenology traits in legumes is underway with a starting focus on chickpea and lentil. Photo: Jacqueline Vander Schoor

Led by Associate Professor Jim Weller, genes are being identified that play major roles adapting legumes to different global environments by virtue of changing the timing of key events in the plant growth cycle (or its phenology). The genetic work is the product of GRDC investment and it aims to create a spectrum of early to late-maturing phenologies for use by Australian pulse breeders.

Associate Professor Weller says the project got underway in 2019 with the assembly of a reference panel of legume cultivars (chickpea and lentil) that represent global phenological diversity. Data about this germplasm – along with information about its environmental adaptations – was used to infer the most-relevant genetic diversity for use in Australia.

The selected germplasm was further screened in Hobart within a specialised glasshouse. Here, plants can be tested for their response to changes in day length using an automated system that moves plants in and out of natural light.

Associate Professor Weller explains: “One of the most important factors in specifying major phenology differences is the plant’s response to changes in day length. We used observation about this response to define a panel of about 300 cultivars that best capture global variation in phenology.”

Crosses were then made with the most contrasting lines – those that flower and mature earliest under short day lengths crossed with very-late-flowering lines requiring the longest day lengths. The crosses cause fragments of DNA to recombine in novel and contrasting combinations that can be locked in through inbreeding. Those chromosome fragments that contain genes responsible for the contrasting phenologies can then be readily detected and selected using DNA markers.

“We have had a lot of success identifying small regions of the chromosomes that control phenology traits,” Associate Professor Weller says. “In all, we found that half a dozen major genes are needed to go from very late to super early growth patterns in both of these species. Among these, we have identified two major genes that contribute to earlier phenologies and we are on track to identify a few more.”

The DNA markers for this genetic diversity can ultimately be used by breeders to shift phenology to better suit different environments as needed.

With the project only about halfway to completion, work continues to drill down and characterise the major genes that influence the timing of key plant growth events. The team are also turning their attention to understanding which genes are important in current Australian varieties, and which might be useful in the future.

The goal ultimately is to expand the range over which pulses can be grown so that more regions can benefit from the ability of pulse crops to improve soil fertility, reduce fertiliser expenses and diversify rotations. The genetic resources under development in Tasmania are especially important given the rising importance of legumes to both on-farm sustainability and profitability.

For example, chickpeas were only grown for the first time commercially in Australia in the early 1970s yet, by 2021, the export value of Australian chickpeas was nearly US$461 million. This pulse crop is now vitally important in northern farming systems and growing in importance in southern and western systems.

“The project has clarified what is possible in terms of better adapting pulse crops to the breadth of Australian cropping regions,” Associate Professor Weller says.

“While we view breeders as our end-users, we will soon start to communicate our findings more broadly so that growers can conceptualise how crops with different phenologies could impact on year-to-year decisions about what to sow and when to sow it.”

For this project, the University of Tasmania team is working within an international collaboration with researchers in Canada, the US, Spain, France and China. Besides chickpeas and lentils, work is also underway on field peas, common beans and soybeans. The collaboration provides access to valuable new genomic resources and a wealth of field trial data from across the world’s major pulse-growing regions, including from the Crop Development Centre at the University of Saskatchewan, the US Department of Agriculture, the Chinese Academy of Sciences and the French National Institute for Agricultural Research (INRA).

Key advances have also been made within the broader international collaboration. Included are the identification of major genes that control winter/spring flowering differences in field peas and the genetic variant in Precoz lentils that confers early flowering, a trait that drove up productivity in many short-season production environments globally.

More information: Jim Weller, jim.weller@utas.edu.au