QTL mapping for resistance to Ceratocystis wilt in Eucalyptus

Abstract

Ceratocystis wilt caused by the fungus Ceratocystis fimbriata, is currently one of the major diseases in commercial plantations of Eucalyptus trees in Brazil. Deployment of resistant genotypes has been the main strategy for effective disease management. The present study aimed at identifying genomic regions underlying the genetic control of resistance to Ceratocystis wilt in Eucalyptus by quantitative trait loci (QTL) mapping in an outbred hybrid progeny derived from a cross between (Eucalyptus dunnii × Eucalyptus grandis) × (Eucalyptus urophylla × Eucalyptus globulus). A segregating population of 127 individuals was phenotyped for resistance to Ceratocystis wilt using controlled inoculation under a completely randomized design with five clonal replicates per individual plant. The phenotypic resistance response followed a continuous variation, enabling us to analyze the trait in a quantitative manner. The population was genotyped with 114 microsatellite markers and 110 were mapped with an average interval of 12.3 cM. Using a sib-pair interval-mapping approach five QTLs were identified for disease resistance, located on linkage groups 1, 3, 5, 8, and 10, and their estimated individual heritability ranged from 0.096 to 0.342. The QTL on linkage group 3 overlaps with other fungal disease-resistance QTLs mapped earlier and is consistent with the annotation of several disease-resistance genes on this chromosome in the E. grandis genome. This is the first study to identify and attempt to quantify the effects of QTLs associated with resistance to Ceratocystis wilt in Eucalyptus.

Regional heritability mapping and genome‐wide association identify loci for complex growth, wood and disease resistance traits in Eucalyptus

“…In a recent bi‐parental mapping study, this same view was corroborated and four additional major effect QTLs were mapped, one again on chromosome 3 at position 57 Mb (Butler et al ., ). Major effect QTLs for resistance to other fungal disease in Eucalyptus have also been reported on chromosome 3 for Mycosphaerella cryptica leaf disease (Freeman et al ., ) and Ceratocystis fimbriata wilt (Rosado et al ., ). The fact that QTLs for fungal disease resistance have been repeatedly reported on chromosome 3 in independent studies clearly points to a major involvement of this chromosome in the pathogen resistance response.…”

Xylem Vessel Diameter Affects the Compartmentalization of the Vascular Pathogen Phaeomoniella chlamydospora in Grapevine

“…However, tolerant plant genotype exhibits little disease symptoms despite pathogen colonization as oppose to susceptible plant genotypes suggesting that tolerant plants have the ability to counteract the effects of virulence factors produced by the wilt pathogens ( Beckman and Roberts, 1995 ). The genetic basis of the resistance can be monogenic or polygenic ( Perchepied et al, 2005 ; Fradin and Thomma, 2006 ; Gowda et al, 2009 ; Ben et al, 2013 ; Rosado et al, 2016 ). Single gene resistance is often complete (i.e., non-host interaction) and pathogen race specific.…”

Genetic control of the operculum and capsule morphology of Eucalyptus globulus

“…Most QTL studies in Eucalyptus to date have focused on traits of economic importance such as growth and wood quality ( Thumma et al , 2010 ; Gion et al , 2011 ; Freeman et al , 2013 ; Resende et al , 2016 ) and resistance to pests and disease ( Alves et al , 2012 ; Zarpelon et al , 2015 ; Rosado et al , 2016 ; Mhoswa et al , 2020 ). However, a few studies have addressed other traits related to physiological and/or ecological functions, such as foliar terpene and cuticular wax composition, heterochrony and drought resistance ( Freeman et al , 2008 ; Hudson et al , 2014 ; Gosney et al , 2016 ; Ammitzboll et al , 2020 ).…”