Just as humans and animals are susceptible to stress and disease, so, too, are plants. In fact, because plants cannot self-regulate their stress responses like members of the animal kingdom, stress reactions can be lethal for plants. For humans producing crops for food, a high plant stress response creates increased plant waste and lowers food production rates.
Until recently, little was known about plants’ stress responses. Fortunately, scientists have recently made strides in discovering how this process works on a molecular level. This clarity may help pinpoint when plants can withstand stress such as cold temperatures, drought, and high salt levels in soil.
The SUMO Protein
In plants and other organisms, SUMO proteins attach to other proteins. This process alters the protein’s function. Protein modification can assist in increasing protein stability, and can mark which proteins are ready for transport.
Scientists understand that a plant’s vitality and resistance to the stress response seem to hinge on a single post-translational modification in the SUMO protein. This process is called SUMOylation. The modification of the protein helps decrease its stress response and increase its chances of survival.
A Unique Type of PHD
SUMOylation, experts are finding, seems to rely on one zinc finger within the SUMO E3 ligase (SIZ1). When plants do not have this zinc finger, also known as PHD, or it is stunted in some way, it appears that the plant has a more delicate stress response. This means that the plant will not grow as tall, and will likely be more prone to damage due to stress. Thus, PHD is key to ensuring that SUMOylation is effective and serves to fortify the plant’s ability to withstand stress.
Scientists have understood the importance of SIZ1 for years, particularly how important the post-translational modification is to a plant’s hardiness and overall ability to thrive. However, what has only recently been discovered is that the SIZ1 translation relies on PHD. This zinc finger makes the modification more effective, creating a more stable and reliable protein chain. This, in turn, helps to ensure that plants are healthy and hardy.
PHD And SUMO/SIZ1 Together
Because SUMO/SIZ1 has been known to be involved in the stress response of plants, it is significant that we now understand the role that PHD plays. In experiments where the PHD zinc finger was eliminated, plants experienced the stresses of growth retardation and drought intolerance long after actual conditions improved. In addition, researchers now believe PHD is responsible for tri-methylated histone gathering in the cell’s stress-response region, which may allow gene suppression.
Real Life Implications
This discovery has the potential to have wide-reaching effects on many people. With a deeper understanding of plant hardiness, scientists can predict when a plant will survive harsh situations such as cold, drought, and salt. With this information, growers in areas with extreme weather, climate change effects, and other less than ideal growing conditions may be able to successfully produce plants that are resistant to stress.
https://www.eurekalert.org/news-releases/536833 (from Feb 2020)