Accumulation Of Signaling Molecules Research Articles

ROS-induced lipid transformations without oxygen participation.

This review presents data showing the possibility of novel pathways to be realized for free-radical transformations of glycerophospholipids and sphingolipids. These transformations include the stages of formation and subsequent decay of carbon- and nitrogen-centered radicals of the starting lipids resulting in the accumulation of signal molecules. The presence of a hydroxyl group in the polar component of lipids is a prerequisite for the implementation of these processes. This enables their structural modification and/or destruction to take place with the accumulation of biologically active products such as phosphatidic acid, ceramides, diacylglycerols and acylamides. Sphingolipids containing a free amino group, when interacting with active species of oxygen or chlorine, form aminyl radicals. These lipid radicals undergo further fragmentation, leading to the accumulation of 2-hexadecenal, which has a broad spectrum of biological activity. The presence of an amide group in the structure of sphingolipids determines the possibility of their photodestruction, which also results in the formation of 2-hexadecenal. In contrast with lipid peroxidation, which is inhibited by reducing agents, free-radical fragmentation reactions of hydroxyl-containing lipids involving carbon-centered radicals are blocked by oxidants.

A systemic response of geophytes is demonstrated by patterns of protein expression and the accumulation of signal molecules in Zantedeschia aethiopica

In geophyte plants, such as Zantedeschia, individual leaves are directly connected to a specialized underground storage organ (rhizome/tuber), raising a question regarding systemic resistance as a mechanism of defense. A systemic response requires a transfer of a signal through the storage organ which has been evolutionary adapted to store food, minerals and moisture for seasonal growth and development. We have characterized the nature of induced defense responses in Zantedeschia aethiopica, a rhizomatous (tuber-like) ornamental plant by the application of local elicitation using two well-known defense elicitors, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and methyl jasmonate (MJ). The system consisted leaves in which local responses were directly induced, and systemically responsive leaves in which defense molecules were detected, demonstrating a transported vascular signal. Using anatomical and biochemical tools and local elicitation with MJ, the systemic nature of the response was verified in adjacent leaves by unique protein expression patterns; similarly polyphenol oxidase (PPO) activity was found to increase systemically in all parts of the locally induced plants, including the rhizome, and adjacent leaves; finally, significant accumulation of defense signal molecules such as salicylic and jasmonic acids was recorded in local and systemic leaves following elicitation with BTH. Anatomical sections through the leaves and the rhizome revealed that to be transferred from one leaf to its neighbor, signal molecules must have been transferred through the storage organ. The collected data strongly support our hypothesis that defense signals may and are transferred through the storage organ in monocot geophytes.