Carmody et al., (2020) Frontiers in Plant Science 11:807
Ascophyllum nodosum Extract Biostimulant Processing and its Impact on Enhancing Heat Stress Tolerance During Tomato Fruit Set
https://www.frontiersin.org/articles/10.3389/fpls.2020.00807/full
Summary
2023 marked the hottest year on record. The surge in global heat events, attributed to the effects of climate change, has become increasingly pervasive in recent years. The heightened occurrence of these unpredictable and intense heat weather incidents presents a substantial hazard to the sustainability of modern agriculture.
Of particular concern is the reproductive stage of crops, a pivotal and vulnerable period for plants, as they transition from vegetative growth to profitable yield for growers. Our team of scientists at Brandon Bioscience have investigated the impact of ANE biostimulants have on enhancing heat stress tolerance mechanisms on tomatoes, focusing specifically on fruit set. Heat stress stands as a prominent impediment to achieving successful fruit set in crops. By enhancing these mechanisms, the severe impact of heat waves can be mitigated, potentially safeguarding food production from future decline.
To assess these mechanisms, our team of researchers devised an experimental framework, replicating conditions of moderate heat stress specific to tomato plants. Subsequently, an analysis was conducted to gauge the impact of heat stress, coupled with the application of ANE, on various aspects including pollen viability, flower count, fruit development, levels of soluble sugars, photosynthetic efficiency, and the expression patterns of heat shock proteins.
We utilized two types of ANEs – a competing cold extract and our proprietary PSIยฎ494 extract – to investigate how processing methods affect the composition and physicochemical properties of the extract and the influence it has on the mode of action of the products. We assessed the molecular mass distribution profiles of the ANEs and found that PSIยฎ494 exhibited a lower molecular mass. Past research has shown that low molecular weight polysaccharides and oligosaccharides from seaweed effectively enhance abiotic stress tolerance in various crop species. Our findings also suggest a connection between the smaller molecular size of carbohydrates in ANEs and improved heat stress resilience in tomato plants during their reproductive stage.
Plants treated with both C129 and PSIยฎ494 exhibited different phenotypical traits including greater pollen viability percentages compared to the untreated group following exposure to heat stress. Notably, the application of PSIยฎ494 led to substantial improvements in flower count, pollen viability, and fruit set, surpassing the effects observed in the untreated stressed control group. Impressively, the implementation of PSIยฎ494 resulted in a remarkable 86% increase in fruit yield compared to plants that did not receive treatment.
At the biochemical level, PSIยฎ494 effectively preserved the levels of soluble sugars (glucose and fructose) within tomatoes, while concurrently enhancing the presence of sucrose in flowers. These outcomes illustrate the capacity of the PSIยฎ494 to counteract the reduction in carbohydrate content and explains the superior effect PSIยฎ494 had on fruit set.
Plants treated with PSIยฎ494 exhibited comparable ฮฆNPQ levels to those observed in unstressed plants, indicating the potential of PSIยฎ494 to sustain photosynthetic efficiency in the face of heat stress conditions.
At the level of gene activity, the application of PSIยฎ494 led to a notable increase in the expression of Heat Shock Proteins (molecular chaperones) when compared to the control group. Specifically, PSIยฎ494 demonstrated a significant upregulation of HSP101.1 and HSP70.9, highlighting its capacity to positively influence specific molecules that contribute to enhanced heat tolerance at the molecular level.
In summary, PSIยฎ494 exhibited a beneficial impact on enhancing heat tolerance mechanisms across various aspects of tomato plants, encompassing their physical traits, metabolic processes, biochemical reactions, and genetic expressions. These findings suggest that PSIยฎ494 holds promise as a potential agronomic tool, offering a means to alleviate the adverse consequences of heat stress, particularly during the critical reproductive stages of plant growth.
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