Pests, diseases, and aridity have shaped the genome of Corymbia citriodora

Adam Healey ,Jeremy Schmutz ,Jerry Jenkins ,Dário Grattapaglia ,Kerrie Barry ,Orzenil B Silva‐Junior ,René E Vaillancourt ,Jakob B Butler ,Brad M Potts ,Jane Grimwood ,Mervyn Shepherd ,Hope Hundley ,Abdul Baten ,John T Lovell ,David J Lee ,Graham J King ,Blake A Simmons ,Jules S Freeman ,Agnelo Furtado ,Shengqiang Shu ,Avinash Sreedasyam ,Robert J Henry

doi:10.1038/s42003-021-02009-0

Abstract

Corymbia citriodora is a member of the predominantly Southern Hemisphere Myrtaceae family, which includes the eucalypts (Eucalyptus, Corymbia and Angophora; ~800 species). Corymbia is grown for timber, pulp and paper, and essential oils in Australia, South Africa, Asia, and Brazil, maintaining a high-growth rate under marginal conditions due to drought, poor-quality soil, and biotic stresses. To dissect the genetic basis of these desirable traits, we sequenced and assembled the 408 Mb genome of Corymbia citriodora, anchored into eleven chromosomes. Comparative analysis with Eucalyptus grandis reveals high synteny, although the two diverged approximately 60 million years ago and have different genome sizes (408 vs 641 Mb), with few large intra-chromosomal rearrangements. C. citriodora shares an ancient whole-genome duplication event with E. grandis but has undergone tandem gene family expansions related to terpene biosynthesis, innate pathogen resistance, and leaf wax formation, enabling their successful adaptation to biotic/abiotic stresses and arid conditions of the Australian continent.

Highlights

Corymbia citriodora is a member of the predominantly Southern Hemisphere Myrtaceae family, which includes the eucalypts (Eucalyptus, Corymbia and Angophora; ~800 species)
Corymbia citriodora subsp. variegata genotype CCV2-018 was selected for reference sequencing due to its wide use as a parent in the spotted gum breeding program of the Queensland Department of Agriculture and Fisheries, and its use for the generation of interspecific hybrids for investigating pulp and bioenergy production[34]
The generation of a high-quality de novo sequenced genome for Corymbia citriodora subsp. variegata has provided the opportunity to understand how evolutionary history has contributed to genome evolution within the Myrtaceae, an important and diverse group of angiosperms that have radiated across the Southern Hemisphere

Summary

Introduction

Corymbia citriodora is a member of the predominantly Southern Hemisphere Myrtaceae family, which includes the eucalypts (Eucalyptus, Corymbia and Angophora; ~800 species). Eucalyptus grandis was the second forest tree genome to be assembled[13], there has been little progress in unravelling key aspects of genome organization and evolution within the predominantly Southern Hemisphere family. The Myrtaceae is a diverse, ecologically and economically important plant lineage (~5,700 species; 132 genera14) that includes tree species such as clove (Syzygium), guava (Psidium), tea-trees (Melaleuca and Leptospermum) and mangroves (Osbornia)[15] It includes the globally grown eucalypts, which are endemic to Australia and islands to its north[16].

Methods

Results

Conclusion