Genetic Dissection of Growth and Eco-Physiological Traits Associated with Altitudinal Adaptation in Sakhalin Fir (Abies sachalinensis) Based on QTL Mapping.

Susumu Goto,Haruhiko Taneda,Hiromi Kajiya-Kanegae,Hiroyoshi Iwata,Hideki Mori,Wataru Ishizuka,Masaru Kono,Kentaro Uchiyama

doi:10.3390/genes12081110

Abstract

(1) Background: The genetic basis of local adaptation in conifers remains poorly understood because of limited research evidence and the lack of suitable genetic materials. Sakhalin fir (Abies sachalinensis) is an ideal organism for elucidating the genetic basis of local adaptation because its altitudinal adaptation has been demonstrated, and suitable materials for its linkage mapping are available. (2) Method: We constructed P336 and P236 linkage maps based on 486 and 516 single nucleotide polymorphisms, respectively, that were derived from double digest restriction site-associated DNA sequences. We measured the growth and eco-physiological traits associated with morphology, phenology, and photosynthesis, which are considered important drivers of altitudinal adaptation. (3) Results: The quantitative trait loci (QTLs) for growth traits, phenology, needle morphology, and photosynthetic traits were subsequently detected. Similar to previous studies on conifers, most traits were controlled by multiple QTLs with small or moderate effects. Notably, we detected that one QTL for the crown area might be a type-A response regulator, a nuclear protein responsible for the cytokinin-induced shoot elongation. (4) Conclusion: The QTLs detected in this study include potentially important genomic regions linked to altitudinal adaptation in Sakhalin fir.

Highlights

Local adaptation is an evolutionary process that is considered a home-site advantage, in which a genotype performs best in its native site [1]
The segregated populations were constructed by a control cross between F1 hybrids with two contrasting ecotypes, which might be useful to clarify the genetic basis of altitudinal adaptation in conifers as described in a previous paper [19]
To elucidate the genetic basis of altitudinal adaptation in Sakhalin fir, a QTL analysis with linkage maps was conducted for 15 functional traits potentially associated with altitudinal adaptation

Summary

Introduction

Local adaptation is an evolutionary process that is considered a home-site advantage, in which a genotype performs best in its native site [1]. Plants are directly affected by the local climate, which is one of the most important drivers of adaptation [2]. A pairwise comparison between local and foreign plants revealed that local adaptation was observed in only 45% of the 1032 studied populations [3]. Local adaptation is determined by the balance between gene flow and selection intensity [4]. Forest tree species with extensive gene flow generally exhibit local adaptation at a wide scale [5]. Selection drivers are usually complex because of a combination of climatic factors at distant sites, so the genetic basis of local adaptation in conifers is poorly understood

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