Science to prolong the short life of cut flowers
The life of a flower is conditioned by the effects of the photooxidative stress in the growing process of the plant -even during flower opening- according to an article published in the journal Plant Science. This new study, which opens new horizons to design products to prolong the life of flowers of economic interest in agriculture, and is signed by the experts Sergi Munné-Bosch, Paula Muñoz and Míriam Briones, from the Faculty of Biology of the UB.
The life of a flower is conditioned by the effects of the photooxidative stress in the growing process of the plant -even during flower opening- according to an article published in the journal Plant Science. This new study, which opens new horizons to design products to prolong the life of flowers of economic interest in agriculture, and is signed by the experts Sergi Munné-Bosch, Paula Muñoz and Míriam Briones, from the Faculty of Biology of the UB.
In plants, some extreme environmental conditions can cause photooxidative stress, a process that causes synthesis of reactive oxygen species (ROS), photosynthesis inhibition, and in some cases, senescence or cell death. The new study is based on the analysis of photooxidative stress on flowers of the Lilium genus, which gathers more than a hundred species from Japan and with great value in the commercial sector of decorative plants.
How does photooxidative stress impact flower opening?
The study reveals that the effects of oxidative stress condition the life length of the Lilium flower “not only during senescence but even during the flower opening”, highlights Sergi Munné-Bosch, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences and head of the research group ANTIOX of the UB.
Flower petals -leaves that form flowers- are the first floral organs to deteriorate, a process which limits the life of cut flowers. To control the longevity of the flower, most of the studies focused on the process of senescence or cell death in flowers. According to Paula Muñoz, first author of the article and member of the group ANTIOX, “the new study analyses for the first time the process of flower opening as the determining factor of the life of cut flowers. If the opening is late, flowers will get later to the senescence and the life of the flower will be longer”.
The Lilium genus has a green coloring at the initial stages of its development -when the flower is closed- due the presence of chlorophyll. When the flower starts blooming, chlorophylls degrading and photosynthesis is reduced. “At this moment -says Muñoz- there is an increase of photooxidative stress on the flower and the lipid peroxidation speeds up, with the creation of new oxygen reactive species that activate the synthesis of hydroperoxides, Malondialdehyde and jasmonic acid”.
The controlled synthesis of these molecules could help regulating flower opening without affecting its development, the study notes. “The findings could open the path to the design of new treatments in the initial stages of the flower development -before harvest- to prolong the life of the flower, replacing the most traditional treatments (with sugary, antimicrobial and phytohormone products) applied before or after they are sold to customers”, says Sergi Munné-Bosch.
New functions of ROS in plant physiology
Leaves, flowers and fruits respond differently to the effects of photooxidative stress during the cycle of life of the plant. Synthesis of antioxidant molecules -carotenoids, tocopherols, etc.- are some of the detoxifying mechanisms that block ROS and limit its effects on plants. The research group ANTIOX of the UB has recently reviewed the critical moments of ROS species production -maturation of some plant fruits and flowers, etc.- and the functions these compounds can have on plant physiology (Plant Physiology, 2018).
“Leaves are the organs in which photoactive stress mechanisms have been studied in further detail”, says Paula Muñoz. “In the senescence phase, for example, one of the first symptoms is the reduction of the highest efficiency of the photosystem II in the photosynthetic apparatus of chloroplasts (organelles that turn light energy into chemical energy). If defence mechanisms are not effective, ROS compounds can pile up and create a massive degradation of macromolecules by proteolysis and autophagy”.
However, in some cases the production of ROS species occurs in a controlled way, so these compounds could act as chloroplast molecular signals to the regular and cell nucleus (redox signalling) in essential processes for the development of leaves. As part of this study, the authors state that the several oxygen reactive species take part in redox signalling processes in different ways.
Therefore, certain ROS compounds -such as O₂ or hydrogen peroxide (H₂O₂) - that cross the chloroplast membrane and spread easily, take part in metabolic paths to activate or limit the expression of certain regulating genes in the development of the plant, according to the experts of the UB.
From plant physiology labs to the world of business
The study carried out by the research group ANTIOX at the UB has a wide scene of application in several sectors (food, biotechnology, agriculture, etc). In the field of technology transparency, the project to “wake trees up” -carried out in collaboration with the company Biovert and the support of the Bosch i Gimpera Foundation (FBG)- was highlighted among the top experiences university-company in the Innovation Atlas in Catalonia 2016.
This year, they described how the modulation of the signalling route of abscisic acid could help preserving better green leaf foods at an ambient temperature. According to the study (Plant Biotechnlogy Journal, 2018), the design of new agonists and antagonists for abscisic acid -a plant hormone- could help define a strategy to prolong the useful life of products without damaging effects for human health.