Ground-truthing field expression and value of new flowering- time genes in lupins for Western Australia.

Overall Objective

The aim of this project is to determine the potential value of new genes for flowering time in narrow- leafed lupin in WA farming systems. We will measure the range of flowering times generated by these new genes in a range of environments in WA, and assess the potential of each gene to improve lupin yield.

We also aim to develop genomic markers for these genes so that lupin breeders will be able to easily transfer the genes to future lupin varieties.

Project Synopsis

Narrow-leafed lupin has been a valued component of crop rotations in Australian farming systems since the 1960’s. Over the past two decades, however, narrow-leafed lupin production has been decreasing as more competitive break crops (including canola and chickpea) gain favour. The transition away from lupins is particularly noticeable in WA, where land allocations for this crop have been contracting at an average rate of 43,500 ha per year since peak production in 1999/2000 (ABARE 2000 & 2018). Genetic improvement of crop adaptation traits and yield is necessary to address this decline.

Flowering time is one of the most important traits for adaptation of crops to diverse agricultural environments.

Australian lupin breeders have heavily relied on a single gene, known as Ku, to adapt lupin crops to southern Australia for the past 50 years. Ku achieves this by ensuring crops consistently flower early because they do not require vernalization (cold temperatures which stimulate flowering). Recent genomic research by Dr Candy Taylor at The University of Western Australia (UWA) revealed that Ku is a mutation of the LanFTc1 flowering time gene, and identified two other new mutations (referred to as LanFTc1-Jul and LanFTc1-P22660) that may potentially enhance crop adaptation and production.

The aims of this COGGO project at UWA were to (i) determine the potential effect of these new LanFTc1 gene variations on narrow-leafed lupin flowering time adaption in WA field environments and (ii) design a molecular marker to assist efficient adoption of these genes in future lupin varieties.

We evaluated the two new LanFTc1 flowering time genes in representative high- and mid-rainfall environments at UWA Shenton Park Field Station (369 mm sowing to flowering) in 2019 and Mumberkine (137 mm sowing to flowering) in 2020. The two new LanFTc1 genes were characterized in Krasnolistny (a European variety with LanFTc1-Jul) and P22660 (a wild lupin with LanFTc1-P22660), in addition to the F2, F3 and F4 progeny derived from crosses between these two lupins with local varieties Tanjil (LanFTc1-Ku, early flowering) and Geebung (LanFTc1-ku, late flowering). There was little evidence of flowering time variation in F2 and F3 progeny in the Krasnolistny x Tanjil population, which suggests that LanFTc1-Jul behaves similarly to LanFTc1-Ku in terms of producing early, vernalization-insensitive flowering times. Therefore, new European varieties with LanFTc1-Jul may be used as parents in Australian lupin breeding programs to introduce desirable traits without disrupting the early flowering phenotype. However, substantial diversity of mid-season flowering times was observed in the progeny of P22660, which consistently flowered about 12 days later than Tanjil and 12 days earlier than Geebung. This delay in flowering time associated with LanFTc1-P22660 is estimated to increase average annual grain yields by 13% to 16% (390 to 480 kg/ha) in high-rainfall environments in southern Australia according to recent modelling (Chen et al. 2017).

The mid-season flowering time of LanFTc1-P22660 would potentially also capture a yield benefit from early sowing, which is becoming a more prominent agronomic practice to accommodate the growing scale of WA farming systems and take advantage of increasingly frequent summer/autumn rainfall events. Both new genes will therefore help breeders to now develop future lupin varieties with greater adaptation to a range of environments in southern Australia.

A new “multiplex” molecular marker was successfully designed to identify all possible combinations of the four of the LanFTc1 gene variations within a single reaction. The molecular marker was designed by Dr Taylor and test conditions developed by UWA MSc student Mr Julian van der Zanden. The molecular marker was able to reliably identify homozygous (i.e. contain only one gene) and heterozygous (i.e. contain two genes) plants in the F2, F3 and F4 progeny. In addition, it enabled detection of rare cross-pollination events in 2019, which caused unexpected segregation of genotypes and flowering times among F4 siblings in 2020. The new multiplex marker will enable the LanFTc1-Jul and LanFTc1-P22660 genes to be efficiently incorporated during breeding and fast track the development of new valuable narrow-leafed lupin varieties that are better adapted to targeted environments.