Precision engineering for plant resilience: MYB-driven tissue-specific deposition of essential plant biopolymers

Environmental stressors such as nutritional imbalances, severe temperature, drought, and salinity are detrimental to plant growth. As a major strategy for adaptation to environmental stressors, plants have evolved extracellular barriers as part of their cell walls made of aliphatic biopolymers, cutin and suberin, along with their associated waxes. Cutin and cuticular waxes form the cuticle that covers the outer surfaces of leaves, fruits, and flowers. Suberin, on the other hand, is present in the extracellular space of inner tissues, such as endodermis, periderm, and exodermis, as well as the seed coat. Both cutin and suberin act as barriers, preventing water loss and nutrient leakage while also shielding the plant from pathogens. Despite decades of studies on these biopolymers, many essential aspects of their biosynthesis and assembly remain unclear. Among these is our understanding of the assembly of cuticle and suberin monomers in the extracellular space, as well as the control of the polymerising machinery both developmentally and environmentally. A few members of the GDSL-esterases/lipases (GELP) family have been shown to be involved in the polymerisation of tomato fruit cuticle and Arabidopsis thaliana root suberin. Intriguingly, another subset of GELPs has been shown to be able to degrade cutin or suberin, implying a complex mechanism that plants have evolved to modulate the dynamics of these polymers. On a regulatory level, several MYB transcription factors have been shown to be important in controlling the developmental and tissue-specific responses of suberin and cutin. The proposed research aims at uncovering the mechanisms of MYB-directed and GELP-mediated cuticle and suberin assembly and plasticity during growth and adaptation. Importantly, as part of our proposed work, we intend to use MYBs to manipulate suberin and cutin deposition at the tissue level to create new crop resilience strategies to environmental stressors including drought and salinity.