Priming with Vitamin U Enhances Cold Tolerance of Lettuce (Lactuca sativa L.)

Abstract

Priming may be an efficient pre-treatment of plants in order to enhance their ability to cope with unfavourable growth conditions, and to improve defensive metabolism through elevated levels of protective substances which may also act as health-promoting agents upon human consumption. The aim of this work was to evaluate the beneficial influence of priming with the naturally occurring, but scarcely known vitamin U (S-methylmethionine) on cold stress tolerance of lettuce (the frequently grown ‘May King’ cultivar). Effects on germination, photosynthetic efficiency, as well as on health-promoting carotenoid and vitamin C contents were investigated. Photosynthetic capacity, strongly related to productivity, was evaluated with parameters of induced chlorophyll fluorescence and of leaf gas exchange through stomata, using plants grown in hydroponic cultures. Priming with vitamin U significantly compensated for the delaying effect of low temperature (5 °C) on seed germination, as well as for inhibition of light-converting photochemical reactions and of carbon dioxide assimilation by cold stress. Use of vitamin U to prime lettuce plantlets for low temperature stress resulted in an elevated content of carotenoid pigments and of vitamin C in leaves, which improve the quality of consumed lettuce with respect to the health-promoting capacity. This beneficial influence of vitamin U was not proportional with its concentration (2 mM had no stronger effects than 0.25 mM), so small amounts of this substance were sufficient for a sustained efficiency in promoting hardening against chilling temperatures. This is the first report on priming of lettuce for cold tolerance by using S-methylmethionine (vitamin U), with a possible application in improvement of crop quality and productivity.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Exogenous S-Methylmethionine Alleviates Salinity Stress by Modulation of Physiological Processes in Canola (Brassica napus)

“…This may be a simple and effective way to overcome the negative impacts of high soil salinity on germination and on the vigor of new plantlets (Tabasssum et al 2017). Similar results were reported for lettuce seeds, in which cold tolerance during germination and seedling establishment was enhanced with pre-treatment using 0.25 mM and 2.0 mM SMM (Fodorpataki et al 2019). Seed priming was also achieved with a sequential pre-treatment with triacontanol and ascorbate, resulting in improved germination index and reduced germination time of wheat grains exposed to salt stress (Mahboob et al 2019).…”

“…Previous studies demonstrated that addition of micromolar or millimolar concentrations of SMM to the nutrient solution contributed to the tolerance of hypoxia, of mosaic virus infection, of heavy metal toxicity and of low temperature in certain crop species (Paldi et al 2014). Its utility as a priming agent was reported only in lettuce plants exposed to cold stress and to high salinity, where it also increased the healthpromoting properties of fresh leaves (Fodorpataki et al 2016(Fodorpataki et al , 2019. All these studies lead to the idea that exogenous supplementation of SMM may promote plants' growth and development under environmental stress conditions.…”

Pure Organic Active Compounds Against Abiotic Stress: A Biostimulant Overview

“…A scarcely studied vitamin is S-methylmethionine (vitamin U). It is produced by all angiosperms, since it is involved in their sulphur metabolism ( Ludmerszki et al, 2014 ; Fodorpataki et al, 2019 ). In fact, its role in the biosynthesis of sulfopropionates (osmoprotectants) and polyamines is valuable for plant resistance ( Ludmerszki et al, 2014 ).…”

“…It was highly effective in protecting maize against cold stress, by stimulating the phenylpropanoid pathway, increasing the content of phenol derivatives and anthocyanins, and protecting the photosynthetic apparatus ( Páldi et al, 2014 ). Priming lettuce with this vitamin resulted in a greater tolerance to cold, improving its germination, photosynthetic efficiency, and content of carotenoids and vitamin C ( Fodorpataki et al, 2019 ).…”

A Beginner’s Guide to Osmoprotection by Biostimulants

“…Another compound from this family is S-methylmethionine (vitamin U), produced by all angiosperms. Treating plants with it to enhance cold tolerance has been studied [ 101 , 102 ], but to date its application against salt or drought stress has not been.…”