Bioactive natural compounds

Garlic (Allium sativum L., family Amaryllidaceae) plants are usually used because of bioactive compounds in their leaves and bulbs. Compounds extracted from this plant are often able to protect against some diseases. There is not enough information about infusions garlic extracts that can be used for plant pathogen control. Creating effective biologicals to protect plants against various diseases is an urgent task to improve crop yields. In this work, the bioactive compounds possessing activity against some phytopathogens were isolated from garlic plant bulbs Allium sativum L. A complex of lectin-allinase and peptide with molecular weight of 4392 Da was obtained from A. sativum bulbs. This complex described in literature before is consisted of allinase enzyme (molecular weight 54 kDa) and mannose-specific garlic lectin (ASA) with molecular weight of 6.4 kDa, and is formed when the bulb tissues are ground. Since, to our knowledge, no data on the biological action of this complex were reported before, we studied its activity against the pathogen of rice blast Magnaporthe grisea. This study showed that the lectin-allinaza complex had no suppressive effect on the pathogen spore germination (spore germination both in control and under treatment was at the 80-90 % level), but reduced the number of necrosis on treated leaves of rice (the percentage of uninfected leaves increased from 15 % in control to 75 %). Thus, the complex did not affect M. grisea directly, but protected plants upon their infection by this pathogenic fungus. These findings suggest that lectinallinaza complex isolated from garlic bulbs is able to induce resistance to M. grisea, probably by activation of plant defense responses. The ability of obtained peptide not described in literature before to inhibit action of B. sorokiniana, the causative agent of Helminthosporium root rot and barley leaf blotch, at concentration corresponding to 10-11 mg protein/ml, was shown on wheat and barley leaves. Since the peptide 4392 Da did not inhibit the growth of B. sorokiniana colonies in vitro, it can be assumed that the peptide is capable of activating the protective functions of the plant during the pathogen infection. When evaluating the effect of the peptide 4392 Da on seed germination and growth stimulation in peas, cucumber, mustard, sunflower and garlic, the germination of garlic seeds increased by 13.6 % (р < 0.01), while 65.5 % (р < 0.01) increase in the length of its stems and a four-fold increase of the root length were observed, but the peptide had no effect on seeds and sprouts of the other crops tested. Thus, the resulting substances do not possess phytotoxicity, and due to its high activity at low concentrations show very low discharge at its application. Moreover, by virtue of its origin they are absolutely harmless for humans and animals and are environmentally safe technology of plant protection, which is especially important in modern agriculture.