Biological and Chemical Characterization of Musa paradisiaca Leachate

SIMPLE SUMMARY: There is a growing demand for molecules of natural origin for biocontrol and biostimulation, given the current trend away from synthetic chemicals. Leachates extracted from plantain stems, obtained after the biodegradation of plant material, were characterized to test their potential role as fungicides, plant defense elicitors, and/or plant biostimulants. The plant extracts induced a slight inhibition of fungal growth of an aggressive strain of Colletotrichum gloeosporioides, responsible for anthracnose. Organic compounds such as cinnamic, ellagic, quinic, and fulvic acids and indole alkaloids such as ellipticine, as well as minerals such as potassium, calcium, and phosphorus, may be responsible for the inhibition of fungal growth. Jasmonic, benzoic, and salicylic acids have also been found. These are known to play a role in plant defense and as biostimulants in tomatoes. Indeed, foliar application of banana leachate induced overexpression of the LOXD, PPOD, and Worky70-80 genes, which are involved in phenylpropanoid metabolism, jasmonic acid biosynthesis, and salicylic acid metabolism, respectively. Leachate also activated root growth in tomato seedlings. However, the main effect of leachate was observed in mature plants, where it reduced leaf area and fresh weight, remodeled stem cell wall glycopolymers, and increased proline dehydrogenase gene expression. ABSTRACT: There is a growing demand for molecules of natural origin for biocontrol and biostimulation, given the current trend away from synthetic chemical products. Leachates extracted from plantain stems were obtained after biodegradation of the plant material. To characterize the leachate, quantitative determinations of nitrogen, carbon, phosphorus, and cations (K(+), Ca(2+), Mg(2+), Na(+)), Q2/4, Q2/6, and Q4/6 absorbance ratios, and metabolomic analysis were carried out. The potential role of plantain leachates as fungicide, elicitor of plant defense, and/or plant biostimulant was evaluated by agar well diffusion method, phenotypic, molecular, and imaging approaches. The plant extracts induced a slight inhibition of fungal growth of an aggressive strain of Colletotrichum gloeosporioides, which causes anthracnose. Organic compounds such as cinnamic, ellagic, quinic, and fulvic acids and indole alkaloid such as ellipticine, along with some minerals such as potassium, calcium, and phosphorus, may be responsible for the inhibition of fungal growth. In addition, jasmonic, benzoic, and salicylic acids, which are known to play a role in plant defense and as biostimulants in tomato, were detected in leachate extract. Indeed, foliar application of banana leachate induced overexpression of LOXD, PPOD, and Worky70-80 genes, which are involved in phenylpropanoid metabolism, jasmonic acid biosynthesis, and salicylic acid metabolism, respectively. Leachate also activated root growth in tomato seedlings. However, the main impact of the leachate was observed on mature plants, where it caused a reduction in leaf area and fresh weight, the remodeling of stem cell wall glycopolymers, and an increase in the expression of proline dehydrogenase.