The pulse of the tree is under genetic control: eucalyptus as a case study

Area of Science:

• Plant physiology
• Forest genetics
• Environmental science

Background:

• Diurnal stem radius fluctuations (dSRF) analyze tree responses to environmental conditions, particularly water relations.
• The genetic basis and environmental interactions of dSRF remain largely uninvestigated.

Purpose of the Study:

• To characterize the genetic and environmental factors influencing dSRF in Eucalyptus.
• To differentiate the determinants of hydraulic capacitance (daily amplitude of shrinkage, DA) and net growth (change in maximum radius, ΔR).

Main Methods:

• Monitoring dSRF in 210 Eucalyptus trees over two years.
• Analyzing DA and ΔR in relation to atmospheric and soil water variables.
• Identifying quantitative trait loci (QTL) for DA and ΔR.

Main Results:

• DA correlated positively with atmospheric water demand; ΔR correlated with soil water content.
• Heritability for DA and ΔR was low to moderate and time/environment-dependent.
• 686 and 384 daily QTL were identified for DA and ΔR, respectively, with 27 major genomic regions.

Conclusions:

• Environmentally induced dSRF in trees is genetically controlled.
• Daily water-related responses integrated over time influence the genetic architecture of mature tree traits.