Connecting proline metabolism and signaling pathways in plant senescence

Abstract

The amino acid proline has a unique biological role in stress adaptation. Proline metabolism is manipulated under stress by multiple and complex regulatory pathways and can profoundly influence cell death and survival in microorganisms, plants, and animals. Though the effects of proline are mediated by diverse signaling pathways, a common theme appears to be the generation of reactive oxygen species (ROS) due to proline oxidation being coupled to the respiratory electron transport chain. Considerable research has been devoted to understand how plants exploit proline metabolism in response to abiotic and biotic stress. Here, we review potential mechanisms by which proline metabolism influences plant senescence, namely in the petal and leaf. Recent studies of petal senescence suggest proline content is manipulated to meet energy demands of senescing cells. In the flower and leaf, proline metabolism may influence ROS signaling pathways that delay senescence progression. Future studies focusing on the mechanisms by which proline metabolic shifts occur during senescence may lead to novel methods to rescue crops under stress and to preserve post-harvest agricultural products.

Proline coordination with fatty acid synthesis and redox metabolism of chloroplast and mitochondria

“…The hypothesis that Pro metabolism is regulated by redox or metabolic factors as well as abiotic stress has been proposed and discussed in several places (Szabados and Savouré, 2010;Verslues and Sharma, 2010;Sharma et al, 2011;Servet et al, 2012;Liang et al, 2013;Ben Rejeb et al, 2014;Giberti et al, 2014;Zhang and Becker, 2015), but experimental data to support such hypotheses are limited. The PDH1 pro :LUC2 mutant screen has revealed an unexpected coordination of Pro and lipid metabolism, with altered cellular redox status being one of the factors allowing the coordinated regulation of these pathways.…”

Expression of an arctic chickweed dehydrin, CarDHN, enhances tolerance to abiotic stress in tobacco plants

“…6f). It is well known that proline metabolism is a complex process influenced by multiple factors, stress condition being one of the signals to up regulate proline biosynthesis and accumulation (Zhang and Becker 2015). In our case, one could speculate that the CarDHN-expressing plants may perceive the salt irrigation not as stressful as did the wild type plants, therefore without provoking the same degree of proline elevation as the wild type.…”

FITNESS, a CCT domain‐containing protein, deregulates reactive oxygen species levels and leads to fine‐tuning trade‐offs between reproductive success and defence responses in Arabidopsis

“…Pro has a unique role in stress adaptation. Multiple and complex regulatory pathways can alter Pro metabolism under stress (L. Zhang & Becker, ), and its metabolism has been proposed as a helper in keeping the NADPH/NADP + balance and GSH levels (Liang, Zhang, Natarajan, & Becker, ). Taking into account that Pro can act as a potent nonenzymatic antioxidant (Rejeb et al, ), its accumulation along with ROS rise in FITNESS ox lines may contribute to partially alleviate the oxidative damage in these plants.…”