Researchers from the Department of Plant Physiology at RPTU Kaiserslautern have achieved a significant breakthrough in understanding how plants, particularly the model plant thale cress (Arabidopsis thaliana), adapt to cold temperatures and frost. The study, led by Ph.D. student Annalisa John, has decoded the cellular mechanisms that enable plants to swiftly adjust to abiotic stress factors like temperature changes. The findings, shedding light on the intricate processes within plant cells, have been published in The Plant Cell.
As sessile organisms, plants exhibit remarkable flexibility in adapting to diverse environmental conditions crucial for their survival. The study focused on the modification of cellular mechanisms, especially those related to lipid bilayers in cell membranes, when exposed to cold temperatures. Cold-induced adjustments are essential to maintain membrane fluidity, a prerequisite for optimal functionality.
According to John, who is the first author of the study, “When exposed to cold, the composition of the lipid bilayers that make up the cell membranes must be modified quickly and efficiently.” This modification is achieved through the synthesis of newly generated lipids, occurring in two cell compartments—the chloroplasts and the endoplasmic reticulum (ER). Fatty acids, the basic building blocks of lipid synthesis, are initially produced in the chloroplasts and then transported to the ER via the Fatty Acid Export 1 (FAX1) protein.
The study delved into the regulation of FAX1 protein abundance in response to cold temperatures. It was previously observed that FAX1 levels significantly decrease in Arabidopsis plants exposed to cold. John’s research revealed that this decrease is a crucial aspect of cold and frost adaptation, controlled by the rhomboid-like protease 11 (RBL11 protease) located in the inner envelope of the chloroplasts.
The study’s significance is underlined by the observation that plant mutants continuously producing high levels of FAX1 exhibited inefficient growth, premature aging, defects in photosynthesis, and the generation of reactive oxygen species. This disrupted the balanced lipid synthesis between chloroplasts and the ER, providing key insights into the importance of controlled FAX1 degradation during cold temperatures.
Professor Dr. Ekkehard Neuhaus, responsible for the Department of Plant Physiology, emphasized the research’s contribution to understanding chloroplast functions in adapting plants to changing environmental conditions. The newfound knowledge holds promise for optimizing the cold tolerance of sensitive crop plants, potentially safeguarding them against sudden temperature drops or frost. The coordinated research program aims to leverage these insights to enhance the resilience of crops facing varying environmental challenges.