S-allele frequency and genetic diversity of Malus orientalis Uglitzk along an altitudinal gradient in the Hyrcanian forest

Hamed Yousefzadeh,Rasta Rajaei,Gregor Kozlowski,Bjarne Larsen,Hamid Bina

doi:10.5424/fs/2020292-15846

Hamed Yousefzadeh, Rasta Rajaei + Show 3 more

Open Access

https://doi.org/10.5424/fs/2020292-15846

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Abstract

Aim of study: The Caucasian apple (Malus orientalis Uglitzk.) is distributed throughout the Hyrcanian forest. Self-incompatibility (SI) is one of the most important plant strategies to prevent self-fertilization, but the genetic basis of this system has never been studied in Caucasian apple. Investigating the genetic diversity of Caucasian apple along an elevation gradient is the second aim of this study.Area of study: Three populations of Caucasian apple along an altitudinal gradient in northern Iran were studied.Materials and methods: Here, we evaluated the S-allele frequency and genetic diversity of three populations of Malus orientalis using SSR markers.Main results: In total, 18 S-alleles were identified in three populations, and a positive trend was detected between S-allele frequency and altitude, which is consistent with the positive correlation with genetic diversity. Overall, the genetic differentiation among populations was high, and four distinct groups were determined among three altitudinal populations.Research highlights: Despite the small number of individuals and low genetic diversity of the populations, the S-allele frequency of Caucasian apple in Hyrcanian forests is high, and these resources have potential use in apple breeding programs.Keywords: Malus orientalis; S-RNase alleles; Genetic diversity; Mate availability; Conservation strategy; Hyrcanian forest.

Highlights

IntroductionIf the pistil is pollinated with pollen with a matching S-allele, pollen tube growth into the style is blocked, preventing fertilization from occurring (Hoebee et al, 2011; Matsumoto, 2014)
Apple maintains a gametophytic self-incompatibility (GSI) system that is controlled by a single multi allelic locus (S-locus) (Kobel, 1939; De Nettancourt, 2013).Here, if the pistil is pollinated with pollen with a matching S-allele, pollen tube growth into the style is blocked, preventing fertilization from occurring (Hoebee et al, 2011; Matsumoto, 2014)
Main results: In total, 18 S-alleles were identified in three populations, and a positive trend was detected between S-allele frequency and altitude, which is consistent with the positive correlation with genetic diversity

Summary

Introduction

If the pistil is pollinated with pollen with a matching S-allele, pollen tube growth into the style is blocked, preventing fertilization from occurring (Hoebee et al, 2011; Matsumoto, 2014). In cases where cross-pollination involves a pistil and pollen with different S-alleles, pollen tube growth is not blocked by the GSI system, allowing pollen tube growth. M. orientalis is one the fourth crabapple species which are considered to be the closest relatives of Malus domestica L., with which they are fully interfertile (Zohary & Hopf, 2000). This tree is distributed throughout the Hyrcanian forest, from the Arasbaran (northwest) and Zagroasian forest (west of Iran). Caucasian apple is usually dispersed as single trees or populations in its natural habitat, where it can reach approximately 10 meters in height and a maximum age of 80-90 years

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