Seminar “Simulating the root ecosystem to optimize plant response to heat stress”

Seminars “Simulating the root ecosystem to optimize plant response to heat stress”. Delivered by Juan Carlos del Pozo, Research Professor at the Center for Plant Biotechnology and Genomics, Polytechnic University of Madrid – Spanish National Research Council. For November 29, 2024, at 12:00 in the Assembly Hall of the Institute of Bioengineering Campus of Elche of the Miguel Hernández University (UMH).

Climate change is causing an increase in extreme heat events, which negatively affect plant development and productivity. Excessive heat severely inhibits cell division in the root meristem, compromising root growth, while promoting cell division in the quiescent center to maintain stem cell niches. As a consequence, this negative effect of high temperatures on root development leads to a reduction in the growth of the aerial part of the plant. It should be noted that most existing experiments studying plant adaptation to heat stress use uniformly high temperatures for both the aerial part and roots of plants. However, this approach does not fully simulate natural field conditions, where roots grow a decreasing temperature gradient in the soil.

To address this problem in the laboratory, we developed the TGRooZ device, which generates a controlled temperature gradient for in vitro and greenhouse assays. Our results demonstrate that roots grown in TGRooZ efficiently maintain their functionality even under high temperature conditions, maintaining, even enhancing, aerial shoot growth through auxin-dependent mechanisms. Importantly, gene expression and rhizosphere microbial composition in roots grown in TGRooZ are less affected compared to roots exposed to uniformly high temperatures. Finally, when heat is combined with other stresses (such as heat and phosphorus deficiency), plants experience severe nutritional imbalances, affecting molecular responses at the transcriptomic level and hormone levels. We have also analyzed the changes induced by these stresses in DNA methylation and induction of miRNAs, finding clear differences when the stresses were applied individually or combined. In summary, our data suggest that in heat stress trials it is essential to use systems that keep the root system protected from excessive heat and in darkness, getting as close as possible to natural conditions. This will allow us to generate more reliable and relevant data and knowledge of how plants respond to high temperatures combined with other stresses.