Genetic Variation in Drought-Tolerance Traits and Their Relationships to Growth in Pinus radiata D. Don Under Water Stress

Ahmed Ismael; Jianming Xue; Dean Francis Meason; Jaroslav Klápště; Marta Gallart; Yongjun Li; Pierre Bellè; Mireia Gomez-Gallego; Ki-Taurangi Bradford; Emily Telfer; Heidi Dungey

doi:10.3389/fpls.2021.766803

Genetic Variation in Drought-Tolerance Traits and Their Relationships to Growth in Pinus radiata D. Don Under Water Stress

Front Plant Sci. 2022 Jan 4:12:766803. doi: 10.3389/fpls.2021.766803. eCollection 2021.

Authors

Ahmed Ismael^{1

2}, Jianming Xue³, Dean Francis Meason¹, Jaroslav Klápště¹, Marta Gallart⁴, Yongjun Li^{1

5}, Pierre Bellè¹, Mireia Gomez-Gallego^{1

6}, Ki-Taurangi Bradford¹, Emily Telfer¹, Heidi Dungey¹

Affiliations

¹ Scion (New Zealand Forest Research Institute Ltd.), Rotorua, New Zealand.
² Research and Development, Livestock Improvement Corporation, Hamilton, New Zealand.
³ Scion (New Zealand Forest Research Institute Ltd.), Christchurch, New Zealand.
⁴ Centre for Planetary Health and Food Security, Griffith University, Nathan, QLD, Australia.
⁵ Agriculture Victoria, AgriBio Center, Bundoora, VIC, Australia.
⁶ INRAE, IAM, Université de Lorraine, Nancy, France.

Abstract

The selection of drought-tolerant genotypes is globally recognized as an effective strategy to maintain the growth and survival of commercial tree species exposed to future drought periods. New genomic selection tools that reduce the time of progeny trials are required to substitute traditional tree breeding programs. We investigated the genetic variation of water stress tolerance in New Zealand-grown Pinus radiata D. Don using 622 commercially-used genotypes from 63 families. We used quantitative pedigree-based (Genomic Best Linear Unbiased Prediction or ABLUP) and genomic-based (Genomic Best Linear Unbiased Prediction or GBLUP) approaches to examine the heritability estimates associated with water stress tolerance in P. radiata. Tree seedling growth traits, foliar carbon isotope composition (δ¹³C), and dark-adapted chlorophyll fluorescence (Y) were monitored before, during and after 10 months of water stress. Height growth showed a constant and moderate heritability level, while the heritability estimate for diameter growth and δ¹³C decreased with water stress. In contrast, chlorophyll fluorescence exhibited low heritability after 5 and 10 months of water stress. The GBLUP approach provided less breeding value accuracy than ABLUP, however, the relative selection efficiency of GBLUP was greater compared with ABLUP selection techniques. Although there was no significant relationship directly between δ¹³C and Y, the genetic correlations were significant and stronger for GBLUP. The positive genetic correlations between δ¹³C and tree biomass traits under water stress indicated that intraspecific variation in δ¹³C was likely driven by differences in the genotype's photosynthetic capacity. The results show that foliar δ¹³C can predict P. radiata genotype tolerance to water stress using ABLUP and GBLUP approaches and that such approaches can provide a faster screening and selection of drought-tolerant genotypes for forestry breeding programs.

Keywords: Pinus radiata; carbon isotope composition; chlorophyll fluorescence; drought tolerance; genetic correlation; genomic selection; heritability; water stress.