Phenology of temperate woody perennials is determined by the environment. Long days and warm temperatures promote growth. Day shortening and a drop of temperatures induce dormancy, but once established, growth cannot resume until a minimal requirement of cold hours has been satisfied. Moreover, tree acclimation to seasons involves the activation of adaptative mechanism related to plant stress tolerance. Understanding woody perennials response to the environment will contribute with an efficient vegetative and reproductive tree growth, reduce economic costs in tree management, and improve productivity, adaptation and geographical distribution.

Poplar is regarded as a model temperate tree species in forest genetics, genomics, physiology and phytoremediation. Poplar (Populus spp.) is a genus of fast growing trees with economic importance for biomass production worldwide. We aim to understand fundamental mechanisms determining environmental control of poplar development for engineering the best adapted genetic material to develop plantations. To achieve that, we are investigating the following processes:

PHOTOPERIODISM and LIGHT SIGNALING

Hypothesis: “Periodic genes are the first layer of environmental surveillance that guides plant developmental transitions, growth dynamics, periodic physiology and stress responses”

Our Approach: We investigate the seasonal function and molecular mechanism of periodic genes (diurnal and circadian) in poplar tree model. We apply genetics (CRISPR/Cas9), genomics, temporal reporter genes, molecular and cell biology tools, and computational modeling in collaboration with Dr. K. Wabnik laboratory (CBGP). We focus on poplar homologs to Arabidopsis genes with roles in:

1. Flowering time regulators
2. Circadian clock regulators
3. Light signaling mediators

TERMORESPONSE and DORMANCY REGULATION

Hypothesis: “It is possible to bioengineer or biostimulate seasonal dormancy break and flowering in perennials”

Our Approach: We look for seasonal regulators and metabolites that promote shoot apical meristem growth reactivation. We focus on thermoresponsive genes, proteins, and metabolites obtained through:

1. Transcriptomic and methylome studies
2. Proteomic studies
3. Non targeted metabolomic studies
4. Chemical screening
5. Plant phenological and biostimulation assays in poplar
6. Field trial using fruit trees in collaboration with IBMCP, IVIA and IMIDA.

POPLAR TREES FOR ZEROPOLLUTION

Hypothesis: “Stress related transcription factors can be used to improve poplar heavy metals phytoremediation from polluted soil”

We investigate the phytoremediation potential of poplar by using overexpression and knockout lines of stress-related transcription factors. Through integrated physiological, molecular, and genomic analyses, we study heavy metal uptake, translocation, and accumulation in order to better understand the molecular mechanisms underlying poplar phytoextraction.

Our research aims to identify novel genes and regulatory pathways involved in metal tolerance and accumulation. These findings will be used to design gene-stacking strategies to develop improved poplar genotypes with enhanced phytoremediation efficiency.

This project is developed in collaboration with Dr. Michel Chalot’s laboratory (UMP, France) and with bioremediation experts involved in the Horizon Europe BIOSYSMO project, ensuring strong scientific complementarity and European added value.

UNDERSTANDING SECONDARY VASCULAR AND STOMATAL DEVELOPMENTAL PLASTICITY UNDER SEVERE DROUGHT

Hypothesis: “It is possible to bioengineer drought tolerant poplars by manipulating shoot vascular and stomatal development ”

Our Approach: We are implementing scRNA-Seq to identify unique cell types, states, and responses on a single- cell level of poplar under well irrigated and severe drought conditions. Using snRNA-seq pipeline, we will define complex regulatory networks that change in response to stress, providing a map to uncover critical mechanisms of cell specific drought stress tolerance in trees.  This work is conducted by Dr. Daniel Conde Cesar Nombela Young Investigator Researcher in CBGP (https://www.cbgp.upm.es/index.php/es/informacion-cientifica/vascular-development-in-perennial-plants-and-its-plasticity-to-cope-with-abiotic-stresses).

POPLAR ROOTING

Hypothesis: “Poplar root system development relies on evolutionarily conserved transcriptional and signaling networks that are shared with Arabidopsis thaliana, despite differences in growth habit and life cycle ”

Our Approach: We investigate the environmental regulation of poplar root system development using root clock luciferase reporter lines. By combining real-time imaging with quantitative phenotyping, we analyze how environmental cues shape root developmental dynamics.

We further take advantage of CRISPR-generated mutants of shoot light signaling regulators developed in our laboratory to examine the impact of light quality and intensity on root development and function. These analyses are conducted in close collaboration with Dr. Moreno-Risueño’s laboratory (CBGP), bringing complementary expertise in root developmental biology and the input of environmental cues.