Optical study of laser biospeckle activity in leaves of Jatropha curcas L.: a non-invasive and indirect assessment of foliar endophyte colonization

Currently, the detection of endophytic fungi is mostly determined by invasive methods, including direct isolation of fungal organisms from plant tissue in growth media, molecular detection of endophytic fungi DNA from plant material by PCR, or evaluation using microscopy techniques. In this work, we explore the potential of laser biospeckle activity (LBSA) for the detection of endophytic colonization of leaves of a promising energy crop, Jatropha curcas L. We compared the laser biospeckle activity of endophyte infected and uninfected J. curcas leaves. The differences between blade and veins (including midrib) of the studied leaves were validated and growth parameters of the studied plants were also analyzed using the normalized weighted generalized differences coefficient (nWGD), which characterizes a particular laser bioactivity behavior. The obtained results showed a relationship between the endophytic burden of leaves and the LBSA, suggesting that LBSA is a useful tool to indirectly detect endophytic colonization in situ. Also, the increased water movements inside leaves promoted by endophytic colonization could be explained by the obtained data.