Metabolome Integrated Analysis of High-Temperature Response in Pinus radiata

Abstract

The integrative omics approach is crucial to identify the molecular mechanisms underlying high-temperature response in non-model species. Based on future scenarios of heat increase, Pinus radiata plants were exposed to a temperature of 40°C for a period of 5 days, including recovered plants (30 days after last exposure to 40°C) in the analysis. The analysis of the metabolome using complementary mass spectrometry techniques (GC-MS and LC-Orbitrap-MS) allowed the reliable quantification of 2,287 metabolites. The analysis of identified metabolites and highlighter metabolic pathways across heat time exposure reveal the dynamism of the metabolome in relation to high-temperature response in P. radiata, identifying the existence of a turning point (on day 3) at which P. radiata plants changed from an initial stress response program (shorter-term response) to an acclimation one (longer-term response). Furthermore, the integration of metabolome and physiological measurements, which cover from the photosynthetic state to hormonal profile, suggests a complex metabolic pathway interaction network related to heat-stress response. Cytokinins (CKs), fatty acid metabolism and flavonoid and terpenoid biosynthesis were revealed as the most important pathways involved in heat-stress response in P. radiata, with zeatin riboside (ZR) and isopentenyl adenosine (iPA) as the key hormones coordinating these multiple and complex interactions. On the other hand, the integrative approach allowed elucidation of crucial metabolic mechanisms involved in heat response in P. radiata, as well as the identification of thermotolerance metabolic biomarkers (L-phenylalanine, hexadecanoic acid, and dihydromyricetin), crucial metabolites which can reschedule the metabolic strategy to adapt to high temperature.

Experimental Design and Sample Preparation in Forest Tree Metabolomics

“…In addition to the direct economic benefits provided by tree species, i.e., timber and non-timber products, gaming and tourism, forests have an immensurable ecological value, being the major determinants for water, oxygen, carbon, and energy balance and can be seen as a major opportunity to mitigate climate change effects [12], i.e., continued drought, increased soil and water salinization and acidification, and intensification of extreme temperatures [13]. In forest tree metabolomics research, most biological questions are indeed related to the responses towards the acclimation and adaptation to a permanently changing environment [14][15][16][17][18][19][20][21][22][23][24][25][26] as well as to the identification of potentially active components in tree species of pharmacological, agricultural, environmental, or industrial importance [27][28][29][30][31][32][33].…”

“…In forest tree research, LC-MS instruments have also been used for untargeted secondary metabolite profiling and phytohormone quantification studies. The focus of these studies was related with abiotic stress responses [19][20][21][22][23][24]67,88,89]; and to a smaller extent to biotic stress responses [90,91] and plant growth and developmental processes [77,92,93].…”

“…In these cases, the chloroform:methanol:water two-phase solvent system is used, and the polar phase is evaporated to dryness and used for both GC-MS (after derivatization) and LC-MS metabolite profiling (after reconstitution in methanol:water) [21,77,88,89]. To take full advantage of the chloroform:methanol:water two-phase solvent system, the non-polar metabolites (lipophilic fraction) are analyzed by GC-MS after derivatization, for example, with tertmethyl-butyl-ether (MTBE) and trimethylsulfoniumhydroxide (TMSH) [23,92].…”

Mecanismos de respuesta al estrés abiótico: hacia una perspectiva de las especies forestales

“…Las HSP fueron identificadas en condiciones de estrés por calor, pero actualmente se sabe que participan en la respuesta al estrés biótico (Yu et al, 2016), así como al frío, deshidratación, luz UV, salinidad, metales pesados, y daño mecánico (Swindell et al, 2007). Además de las HSP, hay otros grupos de compuestos que intervienen en la respuesta al choque térmico de origen muy diverso, como las citocininas, ácidos grasos, terpenoides y flavonoides que son las rutas metabólicas de mayor influencia en la respuesta a las temperaturas elevadas en Pinus radiata (Escandón et al, 2018); así como giberelinas, etileno y brasinosteroides (Clarke et al, 2009;Zhang y Wang, 2011;Dubois et al, 2018).…”

The mechanisms underlying seasonal timing of breeding : a multi-level approach using bi-directional genomic selection on timing of egg-laying

“…Layer chicks also showed decreased body weight gain under increased temperatures, which is detrimental for poultry health (Tomonaga et al 2018). A study in Pinus radiata plants found crucial metabolites which can reschedule the metabolic strategy to adapt to high temperature (Escandón et al 2018). Assessing avian metabolomics under different temperatures and even food regimes could therefore provide novel insights into biochemical pathways underlying timing of breeding (in response to climate change).…”