Improve crop yields and quality under changing environmental conditions through Europe-Japan STI cooperation

The experimental conditions of rice response to VCs emitted by A. alternata under elevated CO2 and temperature conditions were set up at Niigata University (Japan). VCs clearly increased the rice biomass, tiller and panicle numbers, plant height, and grain length and width compared to the control plants. Under climate change, the rice growth and grain size were promoted, while symptoms of senescence and reduction in grain thickness were observed in non-treated (-VCs) plants. SEM analyses of the starch grain cross-section of rice seeds from VC-untreated plants showed the appearance of chalkiness (one of the key factors determining rice quality and price) under high temperature and elevated CO2, while this critical appearance was suppressed by the volatile compounds practice. VCs improved grain quality by decreasing the chalky grain and/or white core grains ratio under normal and climate change conditions. The analysis of gene expression by transcriptomic showed that several genes involved in various biological processes (e.g. carbohydrate metabolism, protein phosphorylation, cell death, cellular component, purine ribonucleoside triphosphate binding, phosphotransferase activity, and ATP binding) were down-regulated by climate change scenario. Fungal VCs promoted global changes in gene expression. Further analysis of metabolites, proteins, and ions analyses are on-going.

Further, the involvement of R&D company (IDEN Biotechnology) -with wide experience in developing genetically engineered crops and biostimulants- supplied exudates from liquid A. alternata cultures to conduct the studies on the tomato cultivars under climate change–induced droughts. Plants cultured under “severe” irrigation conditions were smaller and developed typical drought symptoms. This response was partly reverted by irrigation with A. alternata exudate. Yields of plants cultured under “moderate” and “severe” irrigation conditions were weaker than those of well-watered plants. Fungal exudates enhanced yields of plants cultured under “moderate” drought stress conditions. Without exudate treatment, fruit texture was comparable in the three irrigation regimes. Functional compounds (antioxidants, amino acid, soluble sugars) in fruits of plants cultured under the two drought stress conditions were higher than in fruits of well-watered plants. Depending on the amount of exudate, a general decrease in metabolic activity occurs in control or in moderate drought conditions. In contrast, fungal exudates strongly improved the metabolic activity in severe drought conditions as reflected by an increase of almost all metabolites involved in primary and amino acid metabolisms. The later might be used to produce secondary metabolites such as anthocyanins that in turn enhance the tolerance capacity of the plants against specific environmental adversities such as drought. Thus, fungal exudate application at specific developmental stages positively influences the overall metabolism and most likely also the growth capacity of tomato plants towards drought. The outcomes obtained in terms of yield and quality are potentially extrapolated to other rice and tomato cultivars and to other vegetables and row crops of agronomic interest to alleviate hunger and under-nutrition in the context of adaptation to climate change. At long term, these results are helping the development of adaptive plant involved in their response to the variety of environmental conditions.