Enzyme-Based Biostimulants Influence Physiological and Biochemical Responses of Lactuca sativa L.

Biostimulants (BSs) are natural materials (i.e., organic or inorganic compounds, and/ormicroorganisms) having beneficial effects on plant growth and productivity, and able to improveresilience/tolerance to biotic and abiotic stresses. Therefore, they represent an innovative alternativeto the phyto- and agrochemicals, being environmentally friendly and a valuable tool to cope withextreme climate conditions. The objective of this study was to investigate the effects of severalbiomolecules (i.e., Xylanase, ?-Glucosidase, Chitinase, and Tramesan), alone or in combinations,on lettuce plant growth and quality. With this aim, the influence of these biomolecules on biomass,pigment content, and antioxidant properties in treated plants were investigated. Our results showedthat Xylanase and, to a lesser extent, ?-Glucosidase, have potentially biostimulant activity for lettucecultivation, positively influencing carotenoids, total polyphenols, and ascorbic acid contents; similareffects were found with respect to antioxidative properties. Furthermore, the effect of the morepromising molecules (Xylanase and ?-Glucosidase) was also evaluated in kiwifruit cultured cellsto test their putative role as sustainable input for plant cell biofactories. The absence of phytotoxiceffects of both molecules at low doses (0.1 and 0.01 ?M), and the significantly enhanced cell biomassgrowth, indicates a positive impact on kiwifruit cells.