Haplotype- and SNP-Based GWAS for Growth and Wood Quality Traits in Eucalyptus cladocalyx Trees under Arid Conditions.

Camilo E Valenzuela,Sajid Fiaz,Paulina Ballesta,Sunny Ahmar,Parviz Heidari,Freddy Mora-Poblete,Carlos Maldonado

doi:10.3390/plants10010148

Abstract

The agricultural and forestry productivity of Mediterranean ecosystems is strongly threatened by the adverse effects of climate change, including an increase in severe droughts and changes in rainfall distribution. In the present study, we performed a genome-wide association study (GWAS) to identify single-nucleotide polymorphisms (SNPs) and haplotype blocks associated with the growth and wood quality of Eucalyptus cladocalyx, a tree species suitable for low-rainfall sites. The study was conducted in a progeny-provenance trial established in an arid site with Mediterranean patterns located in the southern Atacama Desert, Chile. A total of 87 SNPs and 3 haplotype blocks were significantly associated with the 6 traits under study (tree height, diameter at breast height, slenderness coefficient, first bifurcation height, stem straightness, and pilodyn penetration). In addition, 11 loci were identified as pleiotropic through Bayesian multivariate regression and were mainly associated with wood hardness, height, and diameter. In general, the GWAS revealed associations with genes related to primary metabolism and biosynthesis of cell wall components. Additionally, associations coinciding with stress response genes, such as GEM-related 5 and prohibitin-3, were detected. The findings of this study provide valuable information regarding genetic control of morphological traits related to adaptation to arid environments.

Highlights

Introduction nal affiliationsMediterranean-type ecosystems and their surrounding regions are some of the most vulnerable to climate change, so increases in severe droughts and changes in rainfall distribution expected in the future threaten agricultural and forestry productivity in these regions [1,2,3]
The present study describes and provides annotations of exclusive and pleiotropic candidate genes for growth and wood quality traits of E. cladocalyx
The trees of the species grown in an arid environment in the southern Atacama Desert exhibited an important variation in growth- and wood quality-related traits, which allowed the identification of several genomic regions associated with these traits

Summary

Introduction

Mediterranean-type ecosystems and their surrounding regions are some of the most vulnerable to climate change, so increases in severe droughts and changes in rainfall distribution expected in the future threaten agricultural and forestry productivity in these regions [1,2,3]. The central region of Chile (30–38◦ S; Mediterranean-type climate), for example, has experienced progressive drying since the late 1970s, and this trend is expected to continue, which may lead to a reduction of up to 40% in the mean annual rainfall in the second half of this century [4]. Prolonged drought can cause physiological dysfunction in plants [5], which leads to the loss of natural and productive ecosystems. Plant species that can tolerate environments with low water availability must be studied [7].

Methods

Discussion

Conclusion