Morphological and chemical diversity in the Type IV glandular trichomes of Solananeae (S. sisymbrifolium and N. glauca) as germplasm resources for agricultural and food uses

Abstract

Morphological variation in type IV trichomes in Ss and Ng was studied through SEM. The differences can be related to chemical differences in the excreted sugar esters. Ng trichomes exude two fractions, one of glucose tri-esters and the other one of sucrose tetra-esters, in a 3:7 ratio. The main acid found forming these esthers, is 3-methylvalerianic acid, in consonance to those secreted by other Solanaceae. Esters from Ss are novel structures, which can also be separated into three fractions, two of arabinoxylans, and the other one of arabinose, all glycosilated with β-hydroxipalmitic acid and sterified with the C₁₂-C₁₆ acids. All five fractions have antifungic activity at μg/cm² concentrations, both against common and mycotoxigenic fungi, such as A. niger, A. flavus, P. chrysogenum y P. expansum. A. flavus does not grow in the presence of the SE of Ss and is not insensible to those from Ng, but these last are more effective in the inhibition of P. expansum, the other mycotoxigenic fungi studied. The differential antifungal activity observed gives the plant protection against a wide spectrum of fungi, resulting in a better adaptation to the environment. Both plants are common weeds, with the potential of contributing to germplams lines in the improvement programmes of crops such as L. esculentum, and their extracts can be used as natural fungicides to protect crops and plantations.