Assessing the additive and dominance genetic effects of vegetative propagation ability in Eucalyptus—influence of modeling on genetic gain

Abstract

To study the genetic determinism of propagation by cutting, 2,115 individuals of 83 full-sib families of the Eucalyptus urophylla×Eucalyptus grandis hybrid were used as stock plants and propagated by cuttings. Shoot production (PROD) and cutting success (CUT) were measured in two periods corresponding to the dry and rainy seasons. The experiments showed a significant effect of propagation period, suggesting the combined influence of environmental conditions and physiological state of stock plants. Using the linear mixed model (LMM) and the generalized one (GLMM) to take into account the non-normal distribution, the additive and dominance variances were estimated. They were significantly different from zero for PROD and CUT, as was the interaction between genetic effects and periods. The dominance variance was equal or higher than additive variance for both traits (1 < σ 2 D /σ 2 A < 1.5). Broad-and narrow-sense heritabilities change with the model type. For PROD, with LMM, they were moderate (h 2 ss =0.182 and H 2 sl =0.443) but high with GLMM (h 2 ss =0.431 and H 2 sl =0.891). For CUT, the same trend was observed for variances but the genetic control was weaker with heritabilities smaller than 0.3. The selection accuracy (r) was affected by the statistical model, r=0.94 and r=0.42 for PROD using LMM and GLMM, respectively. Genetic correlations between PROD, CUT, and the field growth of clones at 25 months were relatively low. These results are important elements to consider for breeding strategies that target genetic gain for both field growth and cutting success.

Quantitative genetic methods depending on the nature of the phenotypic trait

“…The availability of a wide variety of distributions is relevant for evolutionary biologists, as most evolutionary relevant traits have complex distributions. Such models have been used to study the genetics of various traits, such as dispersal, number of offspring, disease, resistance, and productivity …”

Integrating genome‐wide association mapping of additive and dominance genetic effects to improve genomic prediction accuracy in Eucalyptus

“…In rice, genome‐wide dissection uncovered multiple non‐additive effect loci for yield increase (Li et al., 2016; Zhen et al., 2017), for example, rice heterosis 8 ( RH8 ), a major QTL regulating grain‐yield component traits (Li et al., 2016). In Eucalyptus hybrids, dominance appears to be an important and widespread contributor to many growth‐related traits (Bison et al., 2006; Bouvet & Vigneron, 1995; Volker et al., 2008), and ratios of dominance to additive variances exceeding 1.2 have been estimated for growth in E. grandis × E. urophylla hybrids (Bouvet et al., 2009; Makouanzi et al., 2014; Tan et al., 2017). Such results suggest that there should be ample opportunities to identify SNPs accounting for dominance or over‐dominance effects in Eucalyptus hybrids.…”

Stem Anatomy and Adventitious Root Formation in Cuttings of Angophora, Corymbia and Eucalyptus

“…Productivity of eucalypt plantations has been limited by the low amenability of many species to vegetative propagation. Eucalypts are commonly grown from seed although several breeding programs have incorporated cutting propagation systems to supply superior eucalypt clones for plantations [3][4][5][6][7][8][9]. Vegetative propagation methods have been suitable for some species, such as Eucalyptus grandis and E. camaldulensis, from high-rainfall or riparian habitats, but vegetative propagation has proven difficult for species, such as Corymbia citriodora and E. cloeziana, from lower-rainfall environments [3,[6][7][8][9][10][11].…”