1. UNITO: strigolactone-like molecules to improve nutrient use efficiency, as an innovative technology to reduce the need for conventional fertilization in tomato

Short Description of the Technology

To improve nutrient utilization efficiency in a crop plant (tomato), the University of Turin (UNITO) is testing a technology (no. 15 in the ECONUTRI GA) based on hormone-like bioactive molecules and plant extracts. This is part of WP3, which focuses on deploying novel solutions to reduce surface and groundwater pollution caused by leaching and runoff of nitrate and phosphate. The UNITO innovation proposal is a nature-based solution leveraging the published stress-mitigating effects of smoke water to improve nutrient use efficiency, lower the detrimental effects of nutrient deprivation on plant growth and reduce environmental pollution caused by over-fertilization in an environmentally friendly and sustainable way. Smoke water is a traditional fertilizer and biostimulant in Australian agriculture (see for example https://greenmanchar.com.au/products/wood-vinegar-puresmokewater), but more information is needed to make the claims more precise and substantiated, especially re. nutrient adsorption. As one of the active ingredients in smoke water is karrikins, which are hormone-like bioactive molecules, trials with pure synthetic substance (KAR1) are carried out in parallel.

In the ECONUTRI innovation action, UNITO is growing tomato seedlings in hydroponic systems under controlled conditions, and leaf treatment with KAR1 or smoke water is followed by assessment of nutrient utilization efficiency under different nutrient regimes, as compared to mock-treated controls. Field trials are planned, which could in principle allow us to bring the innovation to TRL6. The ECONUTRI output will include support or disproval of the potential for agricultural application of these molecules, treatment protocols under various conditions, and insights on the mechanisms underlying their effects.

Innovative Features

UNITO aims to see whether the claim for smoke water to improve nutrient adsorption in tomato is substantiated (thus leading to claim and purpose expansion), and to gain insights into its mechanisms of action while doing so.

Type of Contribution

UNITO is testing the claim that smoke water and its best-known bioactive ingredient are beneficial to nutrient absorption and nutrient use efficiency in a commercial crop, with a focus on N use efficiency.

Benefits

If the effect is confirmed, foliar spraying with smoke water may offer the advantage of reducing inputs and environmental pollution from fertilizer application, thus helping to keep agriculture sustainable despite sub-optimal environmental conditions. Gaining more knowledge on its mechanism of action would help to substantiate, or disprove, claims made by commercial producers, leading to a more science- and nature-based, efficient agriculture.

2. AUA: small RNAs that suppress the negative factors for P use efficiency, as an innovative technology to reduce P fertilization.

Short Description of the Technology

To improve phosphorus utilization efficiency (PUE) in tomato, the Agricultural University of Athens (AUA) is testing a technology (no. 15 in the ECONUTRI GA), that is based on silencing the expression of negative factors for improving the PUE. This research effort is part of WP3, which focuses on deploying novel solutions to reduce surface and groundwater pollution caused by leaching and runoff of nitrate and phosphate. The AUA’s approach is a nature-based solution, lowering the expression of genes in tomato via a well-known technology, namely Virus-Induced Gene Silencing (VIGS). AUA’s approach will improve the PUE in tomato, lower the detrimental effects of nutrient deprivation on plant growth and reduce environmental pollution caused by over-fertilization in an environmentally friendly and sustainable way.

The negative factors affecting the PUE have been identified. Our working hypothesis is that by reducing their gene expression an improvement of PUE will be made. We optimized the VIGS protocol for tomato using the PDS gene, we have made the constructs for silencing the genes:

• SPX1: P-sensor that blocks the binding of PHR1 transcription factor to DNA.

• SPX4: P-sensor that blocks the translocation of PHR1 from the cytoplasm to the nucleus.

• WRKY6: repressor of PHT1 and PHO1 transcription.

• PHO2: promotes the degradation of the PHO1 efflux P transporter.

In the ECONUTRI innovation action, AUA is growing tomato seedlings in soil or in perlite with various concentrations of PO₄^3- (different nutrient regimes) under controlled conditions in a growth chamber, and the developed VIGS constructs will be applied onto the plants followed by the assessment of P concentration in tomato plants, as compared to mock-treated controls. In addition, phenotypic observations (height, wet and dry biomass) relative to control plants will be performed, allowing us to bring the innovation to TRL5. The ECONUTRI output will include the comparison of the treatments employed of the above-mentioned genes involved in PUE.

Innovative Features

AUA aims to conclude which of the four negative factors/genes, influencing PUE, will have a substantial improvement in tomato growth upon its silencing through VIGS.

Type of Contribution

AUA is testing the hypothesis that reducing the expression of four negative factors for PUE by VIGS will improve tomato’s (a commercial crop) growth.

Benefits

If the improvement of PUE is achieved by gene silencing of the four negative factors, then stable reduction techniques could be suggested to generate tomato varieties with improved PUE, which would benefit the farmers, the environment and the consumers.