Inheritance of Yield Components and Morphological Traits in Avocado cv. Hass From “Criollo” “Elite Trees” via Half-Sib Seedling Rootstocks

Abstract

Grafting induces precocity and maintains clonal integrity in fruit tree crops. However, the complex rootstock × scion interaction often precludes understanding how the tree phenotype is shaped, limiting the potential to select optimum rootstocks. Therefore, it is necessary to assess (1) how seedling progenies inherit trait variation from elite ‘plus trees’, and (2) whether such family superiority may be transferred after grafting to the clonal scion. To bridge this gap, we quantified additive genetic parameters (i.e., narrow sense heritability—h2, and genetic-estimated breeding values—GEBVs) across landraces, “criollo”, “plus trees” of the super-food fruit tree crop avocado (Persea americanaMill.), and their open-pollinated (OP) half-sib seedling families. Specifically, we used a genomic best linear unbiased prediction (G-BLUP) model to merge phenotypic characterization of 17 morpho-agronomic traits with genetic screening of 13 highly polymorphic SSR markers in a diverse panel of 104 avocado “criollo” “plus trees.” Estimated additive genetic parameters were validated at a 5-year-old common garden trial (i.e., provenance test), in which 22 OP half-sib seedlings from 82 elite “plus trees” served as rootstocks for the cv. Hass clone. Heritability (h2) scores in the “criollo” “plus trees” ranged from 0.28 to 0.51. The highesth2values were observed for ribbed petiole and adaxial veins with 0.47 (CI 95%0.2–0.8) and 0.51 (CI 0.2–0.8), respectively. Theh2scores for the agronomic traits ranged from 0.34 (CI 0.2–0.6) to 0.39 (CI 0.2–0.6) for seed weight, fruit weight, and total volume, respectively. When inspecting yield variation across 5-year-old grafted avocado cv. Hass trees with elite OP half-sib seedling rootstocks, the traits total number of fruits and fruits’ weight, respectively, exhibitedh2scores of 0.36 (± 0.23) and 0.11 (± 0.09). Our results indicate that elite “criollo” “plus trees” may serve as promissory donors of seedling rootstocks for avocado cv. Hass orchards due to the inheritance of their outstanding trait values. This reinforces the feasibility to leverage natural variation from “plus trees”viaOP half-sib seedling rootstock families. By jointly estimating half-sib family effects and rootstock-mediated heritability, this study promises boosting seedling rootstock breeding programs, while better discerning the consequences of grafting in fruit tree crops.

The Inheritance Pattern of Key Desirable Agronomic and Fruit Quality Traits in Elite Red Papaya Genotypes

“…The heritability of agronomic and fruit quality traits was calculated widely for fruit crops, including apple (Malus pomila) [11], citrus (Citrus spp.) [12], and avocado (Persea americana) [13]. High heritability (>80%) was previously reported in papaya for tree height [14], soluble solid contents [15], and fruit weight, length, and width [16].…”

“…Similarly, major environmental influences were previously demonstrated to affect the expression of fruit size (length and width), fruit weight, and soluble solid contents ( • Brix) in apple (Malus pomila) [11], citrus (Citrus spp.) [12], and avocado (Persea americana) [13].…”

Genetic modulation of Valencia sweet orange field performance by 50 rootstocks under huanglongbing-endemic conditions

“…An additional benefit of incorporating genetic information to partition genetic components of rootstock-mediated traits is that genome-wide information will capture shared ancestry not reflected in the pedigree. While the integration of genetic information (either based on pedigree or genetic variation) with phenotypic data using mixed models is a common practice for 1) dissecting genetic components of quantitative traits and 2) predicting additive genetic values (EBVs), including for tree crop species ( Martínez-García et al., 2017 ; Fernández-Paz et al., 2021 ; Cañas-Gutiérrez et al., 2022 ), this is an early application for dissecting genetic control of rootstock-mediated effects. Such studies in citrus have focused on scion-related traits, including implementation of genomic selection for fruit quality ( Gois et al., 2016 ; Imai et al., 2016 ; Minamikawa et al., 2017 ; Imai et al., 2019 ).…”

Graft compatibility effects on cv. Hass avocado fruit growth

“…The selection of a suitable rootstock is rarely based on the scion's genotype and the environment or agro-climatic zone in which the grafted tree will be cultivated. In other words, due to a triple rootstock/scion/environment interaction, rootstock selection from "criollo" seedling genotypes is challenging (Cañas-Gutiérrez et al, 2022). The genetic origin of the creole materials used in Colombia as rootstocks is unclear.…”