University of Milan: “Timing is determinant when applying different types of biostimulants to combat heat stress”
This is one of the key results extracted from the transcriptomic study conducted by the Department of Agriculture & Environmental Sciences at the University of Milan and Agricola 2000, in a joint project with Tradecorp.
Transcriptomics is the study of RNA, which among other functions is to act as the messenger from DNA, and carry the instructions for amino acid and protein synthesis in the plant.
The research, whose preliminary results were presented by Professor Antonio Ferrante, from the Dept. of Agricultural & Environmental Sciences, Univ. of Milan, at the 4th Biostimulant World Congress in Barcelona, draws exciting conclusions on how certain biostimulants can affect plant reactions to abiotic stresses right down to gene level. However, these biostimulants do so in different ways and by affecting different genes. Thus, applying certain types of biostimulants at precise times, taking advantage of their specific modes of action, will ensure maximum effect on the plant and, as a result, a more profitable application.
“The research aimed to better understand how the growth of the model research plant, Arabidopsis thaliana, was affected when it was exposed to high temperatures and how these negative effects were mitigated by the use of biostimulants with different modes of action”, explained Prof. Ferrante. With this purpose, the study combined phenotypical methods that observe measurable changes in plant growth and plant cell structure due to heat stress, as well utilising advanced techniques, such as transcriptomic analysis of genetic functions and metabolitic analysis.
- Fig 1. Autofluorescence of plant cells, with Control Cells (A) on the top autofluorescing brightly indicating they had been affected by the heat stress. On the bottom (B) the same heat stress was applied. However, Phylgreen was applied before the stress. The lack of autofluorescence in B indicates the cells did not suffer the same intensity of heat stress damage or accumulation of secondary metabolites that result from stress damage, due to the correct application timing and dose of the biostimulant.
A comprehensive project to understand different types of abiotic stress
Different abiotic stresses cause different reactions within plants1. The current research is part of a larger Tradecorp project to better understand the specific reactions of plants to different abiotic stresses. The research with the University of Milan was built on previous pan European results from collaborative studies with Queens University Belfast2 and Landlab in Italy, among others. These previous studies had helped identify optimum application timing for each product and the mode of action for drought and salinity abiotic stresses.
Tradecorp decided to study heat stress with the University of Milan due to the serious agronomic problems that it causes, such as reduced yield, reduced quality and physical damage, all of which lead to saleable yield losses. “Heat stress and its management have always been a factor in agricultural production, but in the past 20 years, heat gained an increasing importance due to the ongoing effects of climate breakdown”, explains José Nolasco, Strategy and Innovation Director at Tradecorp.
Several well-known Tradecorp biostimulants were studied including Phylgreen and Delfan ranges. The Phylgreen range products are composed of fresh extracts of Ascophyllum nodosum, obtained using the exclusive Gentle Extraction process at Tradecorp’s facility in Ireland, while Delfan range is composed of high quality L-a Free Amino Acids.
The results will help determine whether the application timings of products for generalised abiotic stress are the same, or different, when a single known type of abiotic stress event is happening – such as heat stress.
The importance of timing when applying biostimulants
Timing is key when applying biostimulants because they activate certain genes in plants that help them overcome abiotic stress. For example, when a preventive biostimulant is applied at the optimal time before the stress occurs, the genes that help to reduce the negative stress chemicals in the plant are expressed or their activation intensity is amplified. This results in a strong stress prevention or reduction effect, making the plant better able to resist the abiotic stress event, which helps protect potential yield and grower profitability.
However, this gene activation or amplification triggered by the biostimulant is only temporary. Therefore, if the same preventive biostimulant is applied at the non-optimal time or, for example too far in advance of an abiotic stress event, the stress prevention effect is reduced. Even if the plant metabolism or genes are activated to resist the stress, if the stress does not occur in a specific amount of time, the plant goes back to the initial stage to save wasting energy. When the stress finally occurs, the genes are not fully active and the plant is not able to react as efficiently as a correctly timed biostimulant application. The result is some inevitable loss of potential yield.
The conventional and transcriptomic analysis proved conclusively that both Phylgreen and Delfan family products interact with plants at gene level but do so in very different ways.
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Levitt, J. (ed) (1980) Responses of Plants to Environmental Stress, Volume 1: Chilling, Freezing, and High Temperature Stresses, Academic Press, New York
Fleming Thomas R. et al. (2019) Biostimulants enhance growth and drought tolerance in Arabidopsis thaliana and exhibit chemical priming action. Annals of Applied Biology