Strategies to breed sterile leucaena for Western Australia

Daniel Real,Clinton Revell,Marieclaire Castello,Chengdao Li,Saipriyaa Vasan,Sam Crouch,Sue Broughton,Yong Han,C Donovan Bailey,Alexander Abair

doi:10.17138/tgft(7)80-86

Abstract

Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Strategies to breed sterile leucaena for Western Australia include plant breeding and biotechnology tools to generate sterile lines at both the tetraploid and triploid ploidy levels. For tetraploids, the main target species is the commercial Leucaena leucocephala, that is well known for its potential as a high-quality, productive and persistent forage. Gene editing technologies (CRISPR) will be utilized to edit out flowering genes and develop a non-flowering L. leucocephala. For triploids, the strategy is to cross tetraploid species (L. leucocephala and/or L. diversifolia) with diploid species to generate sterile triploid hybrids. The diploid parents will include species that have good forage attributes such as L. collinsii, L. macrophylla, L. shannonii and L. pulverulenta. Several of these triploid crosses have already been created by the Department of Primary Industries and Regional Development (Perth, Western Australia) and will be evaluated in the Kimberley and Pilbara regions of Western Australia for their agronomic performance and sterility. Vegetative propagation will be required for the tetraploid gene-edited non-flowering L. leucocephala. Triploids can either be vegetatively propagated, once generated, or generated via a seed production nursery.

Highlights

The genus Leucaena contains 24 species (Govindarajulu et al 2011a), but only one species, L. leucocephala, has a pantropical distribution
In the last 60 years, L. leucocephala has been the target of modern breeding techniques in USA, Australia and Colombia and several cultivars are commercially available, such as Cunningham, Tarramba, Wondergraze and Redlands (Cook et al 2005; IP Australia 2018)
Leucaena leucocephala is highly valued as a multipurpose tree for wood and forage production

Summary

Introduction

The genus Leucaena contains 24 species (Govindarajulu et al 2011a), but only one species, L. leucocephala, has a pantropical distribution. In the last 60 years, L. leucocephala has been the target of modern breeding techniques in USA, Australia and Colombia and several cultivars are commercially available, such as Cunningham (released in 1976), Tarramba (released in 1997), Wondergraze (released in 2010) and Redlands (released in 2017) (Cook et al 2005; IP Australia 2018). Leucaena leucocephala is highly valued as a multipurpose tree for wood and forage production. In the major leucaena-growing area of Australia (central and southeast Queensland), about 130,000 ha of L. leucocephala has been planted for forage production in single or twin rows with inter-row spacings of 6‒12 m with tropical grasses in the inter-rows (Beutel et al 2018). Bowen et al (2018) suggest that a L. leucocephala-grass mixture is the most productive forage option for beef production in Queensland

Objectives

Conclusion