G. STEFANOVA1, V. VASSILEVA2 and M. VLAHOVA1
1 AgroBioInstitute, BG – 1164 Sofia, Bulgaria
2 Bulgarian Academy of Sciences, Institute of Plant Physiology and Genetics, BG - 1113 Sofia, Bulgaria
STEFANOVA, G., V. VASSILEVA and M. VLAHOVA, 2013. Human lactoferrin changes leaf morphology and pathogen resistance of Medicago sativa L. Bulg. J. Agric. Sci., 19: 701-708
Human lactoferrin (hLf) is an iron-binding glycoprotein having antimicrobial activity, which is known to be involved in iron absorption and cell growth and proliferation. This study aimed investigation of the effect of hLf expression on leaf epidermal cell morphology of transgenic alfalfa plants (Medicago sativa L.), which exhibited enhanced resistance to bacterial pathogens. Leaf epidermal parameters were measured and a clear tendency of increasing size and decreasing number of pavement cells was found, which seemed to be related to hLf-cell cycle inhibition and compensatory cell enlargement. Furthermore, stomatal density was lower on both leaf surfaces of transgenic plants, probably due to Lf-induced inhibition of stomatal development as well. In addition, transgenic plants exhibited some characteristics, such as significant elongation of leaf epidermal cells, reduction in overall leaf size, and occasionally visible reduction of leaf chlorophyll content, which are usually related to a condition of iron deficiency, and in our case might due to iron chelation properties of hLf. Based on our observations, we assume that hLf expression changed leaf morphology, which partially contributed to the improved pathogen resistance of alfalfa in addition to the direct antimicrobial effect of the recombinant protein.