Peridermal fruit skin formation in Actinidia sp. (kiwifruit) is associated with genetic loci controlling russeting and cuticle formation

Nikolai Macnee,Jibran Tahir,Sean M Bulley,Elena Hilario,Ian C Hallett,David Chagné,Robert J Schaffer,Alastair Currie,Ria Rebstock,Ben Warren

doi:10.1186/s12870-021-03025-2

Nikolai Macnee, Jibran Tahir + Show 8 more

Open Access

https://doi.org/10.1186/s12870-021-03025-2

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Abstract

BackgroundThe skin (exocarp) of fleshy fruit is hugely diverse across species. Most fruit types have a live epidermal skin covered by a layer of cuticle made up of cutin while a few create an outermost layer of dead cells (peridermal layer).ResultsIn this study we undertook crosses between epidermal and peridermal skinned kiwifruit, and showed that epidermal skin is a semi-dominant trait. Furthermore, backcrossing these epidermal skinned hybrids to a peridermal skinned fruit created a diverse range of phenotypes ranging from epidermal skinned fruit, through fruit with varying degrees of patches of periderm (russeting), to fruit with a complete periderm. Quantitative trait locus (QTL) analysis of this population suggested that periderm formation was associated with four loci. These QTLs were aligned either to ones associated with russet formation on chromosome 19 and 24, or cuticle integrity and coverage located on chromosomes 3, 11 and 24.ConclusionFrom the segregation of skin type and QTL analysis, it appears that skin development in kiwifruit is controlled by two competing factors, cuticle strength and propensity to russet. A strong cuticle will inhibit russeting while a strong propensity to russet can create a continuous dead skinned periderm.

Highlights

The skin of fleshy fruit is hugely diverse across species
Inheritance of skin types To assess the inheritance of skin types in kiwifruit, a tetraploid A. melanandra (ME) male was used for an interspecific cross to a tetraploid A. chinensis (CK) female
The MECK x Actinidia chinensis (CK) backcross progeny demonstrated a range of intermediate skin types (Fig. 2), varying from having an epidermis covered in a thick cuticle to a densely layered peridermal exocarp

Summary

Introduction

The skin (exocarp) of fleshy fruit is hugely diverse across species. Most fruit types have a live epidermal skin covered by a layer of cuticle made up of cutin while a few create an outermost layer of dead cells (peridermal layer). The morphology of exocarp types is diverse between fruit species, ranging in color, composition and structure. There are a number of fruits that have closely related species that show both epidermal and peridermal skin types including Actinidia sp. Studies in these species have shown periderm formation (russeting) is controlled by both genetics and environment. The skin of a Japanese pear (Pyrus pyrifolia ‘Nakai’) can be russeted with a characteristic

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