Toward the Genetic Improvement of Drought Tolerance in Conifers: An Integrated Approach

Abstract

The constant rise in the global temperature and unpredictable shifts in precipitation patterns are two of the main effects of climate change. Therefore, there is an increasing amount of interest in the identification of tree species, provenances and genotypes capable of withstanding more arid conditions and tolerating drought stress. In the present review, we focus our attention on generally more susceptible conifers and describe the different strategies that plants adopt to respond to drought stress. We describe the main approaches taken in studies of conifer adaptations to low water availability, the advantages and limitations of each, and the main results obtained with each of these approaches in the recent years. Then we discuss how the increasing amount of morphological, physiological and genetic data may find practical applications in forest management, and in particular in next-generation breeding programs. Finally, we provide some recommendations for future research. In particular, we suggest extending future studies to a broader selection of species and genera, increasing the number of studies on adult plants, in particular those on gene expression, and distinguishing between the different types of drought stress that a tree can withstand during its life cycle. The integration of data coming from different disciplines and approaches will be a key factor to increasing our knowledge about a trait as complex as drought resistance.

Unravelling the biogeographic determinants of tree growth sensitivity to freeze and drought in Canada's forests

“…Pinus banksiana ) when atmosphere and soil conditions become increasingly dry to save water and maintain their hydraulic integrity (Marchand et al., 2021). Besides the depth of the root system, many other morphological characteristics such as root diameter, branch configuration, needle morphology or xylem architecture can also influence the timing and severity of drought stress in trees (Baldi & La Porta, 2022). From a temporal perspective, in many of the studied species, the detrimental influences of drought occurred the following year.…”

Breeding for growth has resulted in increased tolerance to drought at the cost of genetic diversity in Scots pine

“…Although attempts have been made to incorporate root characteristics as a selection criterion in tree improvement programs (Baldi and La Porta, 2022), the difficulties in assessing root properties has hampered them. In conifers, breeding for drought tolerance have primarily focused on individual traits such as root depth (Cregg and Zhang, 2001; Matías, González-Díaz and Jump, 2014; Kolb et al ., 2016) or general plant growth (De La Mata, Merlo and Zas, 2014; Kerr et al ., 2015), whereas efforts to improve drought tolerance based on root and/or canopy architecture have yet to be made.…”

Tree Genetics: Molecular and Functional Characterization of Genes

“…Indeed, six papers focus on broadleaved trees and four on conifers, including economically relevant species for a plethora of different uses, but also rare/endangered species [3] and ecologically important trees [4,5]. The variety of different species studied by the research papers belonging to this Special Issue perfectly respond to the invitation reported in [2], to extend the research fields in forest genetics to a broader number of species.…”

“…To achieve deeper knowledge on these issues, plant molecular biology approaches leading to genomics descriptions and gene-to-function-centered studies are crucial. Such studies have already disclosed the genetic basis of various useful traits [1,2], but this information has limitedly been utilized in tree improvement and conservation. Indeed, breeding woody perennials is primarily bottlenecked by genomics and reproductive biology features [1], but these limitations can be at least partially solved with high-throughput genomics-assisted selection and phenotyping.…”

“…The review from Baldi and La Porta [2] focuses on the molecular response of conifer adaptations to low water availability, describing the advantages and limitations of the approaches used in this field and the main results obtained in recent years. Furthermore, recommendations for future research are also offered, in particular regarding the study of a broader selection of resilient species and genera.…”