AUTHOR=Mphahlele Makobatjatji M. , Isik Fikret , Hodge Gary R. , Myburg Alexander A. 

TITLE=Genomic Breeding for Diameter Growth and Tolerance to Leptocybe Gall Wasp and Botryosphaeria/Teratosphaeria Fungal Disease Complex in Eucalyptus grandis

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.638969

DOI=10.3389/fpls.2021.638969

ISSN=1664-462X

ABSTRACT=<p><italic>Eucalyptus grandis</italic> is one of the most important species for hardwood plantation forestry around the world. At present, its commercial deployment is in decline because of pests and pathogens such as <italic>Leptocybe invasa</italic> gall wasp (<italic>Lepto</italic>), and often co-occurring fungal stem diseases such as <italic>Botryosphaeria dothidea</italic> and <italic>Teratosphaeria zuluensis</italic> (<italic>BotryoTera</italic>). This study analyzed <italic>Lepto</italic>, <italic>BotryoTera</italic>, and stem diameter growth in an <italic>E. grandis</italic> multi-environmental, genetic trial. The study was established in three subtropical environments. Diameter growth and <italic>BotryoTera</italic> incidence scores were assessed on 3,334 trees, and <italic>Lepto</italic> incidence was assessed on 4,463 trees from 95 half-sib families. Using the <italic>Eucalyptus</italic> EUChip60K SNP chip, a subset of 964 trees from 93 half-sib families were genotyped with 14,347 informative SNP markers. We employed single-step genomic BLUP (ssGBLUP) to estimate genetic parameters in the genetic trial. Diameter and <italic>Lepto</italic> tolerance showed a positive genetic correlation (0.78), while <italic>BotryoTera</italic> tolerance had a negative genetic correlation with diameter growth (−0.38). The expected genetic gains for diameter growth and <italic>Lepto</italic> and <italic>BotryoTera</italic> tolerance were 12.4, 10, and −3.4%, respectively. We propose a genomic selection breeding strategy for <italic>E. grandis</italic> that addresses some of the present population structure problems.</p>