Scanning electron microscopy reveals deleterious effects of Moringa oleifera seed exuded proteins on root-knot nematode Meloidogyne incognita eggs.

Plant seeds can exudate active molecules with inhibitory effects against several soil pathogens, including nematodes. This study aimed to characterize and evaluate the nematicidal properties against Meloidogyne incognita of exuded proteins from Moringa oleifera seeds. M. oleifera seeds were soaked in distilled water, and exudates were harvested and analyzed for the presence of defense proteins and anthelmintic activity. Enzymatic assays revealed the existence of PR-proteins such as beta-1,3-glucanases (0.18 +/- 0.003 nkatal mg(-1) of protein), chitinases (0.22 +/- 0.004 nkatalmg(-1) of protein), proteases (261.30 +/- 6.405 AU mg(-1) of proteinmin(-1)), serine (190.30 +/- 5.574 IA mg(-1) of protein) and cysteine (231.70 +/- 0.923 IA mg(-1) of protein), protease inhibitors. The exuded proteins presented ovicidal activity and caused 100% mortality of second-stage juveniles (J2s). Scanning electronmicroscopy (SEM) revealed deleterious effects onM. incognita eggs, such as invaginations, cracks, scratched surface, and loss of internal content. These findings confirmthe presence of anthelmintic proteins inM. oleifera seed exudate, possibly involved in plant defense during seed germination. Besides this, the exuded proteins exhibited strong biotechnological potential for use in the biocontrol of M. incognita infections, which are responsible for millions of dollars in staple crop losses every year. (C) 2019 Elsevier B.V. All rights reserved.