Submitted to: Biochemica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/22/2004
Publication Date: 12/1/2004
Citation: Callahan, F.E., Zhang, X., Ma, D., Jenkins, J.N., Hayes, R.W., Tucker, M.L. 2004. Comparison of MIC-3 protein accummlation in response to root-knot nematode infection in cotton lines displaying a range of resistance levels. Journal of Cotton Science. 8:186-190. Interpretive Summary: Nematode pathogenesis is suspected to be a major limiting factor to yield in cotton. Host plant resistance in cotton breeding programs has long been a desirable goal for control of nematode pathogens such as root-knot nematode (RKN), Meloidogyne incognita; however, for both economical and practical reasons, currently available resistant (R) breeding lines of cotton have not been developed into commercial cultivars by industry. For genetic engineering technologies to aid in more rapid development of nematode resistant cultivars, it has been necessary to elucidate the molecular interaction between nematodes and the plant root cell with regard to factors/signals that allow feeding site formation as well as resistance mechanisms that restrict or prevent development and reproduction of nematodes. The work conducted in this study correlates expression of a specific cotton root protein, MIC-3, with the resistance response to RKN in a large group of breeding lines and cultivars, which display a range of resistance levels. Measurements of expression levels of the protein in such a study was made possible by the development of an antibody probe with specificity to the MIC (14 kDa) protein. Similarities of the MIC-3 gene to new cotton sequences present in public gene databases suggest an additional correlation to fungal (Fusarium wilt) resistance.
Technical Abstract: We previously cloned and sequenced a full-length cDNA, MIC-3 (Meloidogyne Induced Cotton protein), corresponding to a 14 kDa protein whose expression is induced in a root-knot nematode (RKN) resistant (R) cotton breeding line following nematode infection. In this study, we developed a polyclonal antibody to the MIC-3 protein through transformation and over-expression of a MIC-3 fusion protein in an E. coli system. The antibody was then used as a probe to further verify the relationship between the MIC-3 cDNA and the 14 kDa protein and subsequently to assess expression levels of the 14 kDa (MIC) protein in a larger group of RKN resistant breeding lines and susceptible cultivars of cotton. The MIC antisera recognized the 14 kDa protein and revealed higher expression of the protein in all R inoculated lines (M-92, M-315, M-272, M-155, M-331, M-120, M-240, NemX) as compared to S inoculated lines(M8, DPL 61, DES 119, Suregrow 125, DP 90, DP 50, La887); labeling was not detectable in non-inoculated controls. Dissection and immunoblot analysis of proteins from galled versus symptomless regions of individual roots of resistant M315 further substantiated previous work suggesting that induction of the 14 kDa protein is in the vicinity of the developing feeding site of the nematode. Recent submissions to the cotton EST database represent the first entries with significant homology to the MIC-3 cDNA and support the notion that the MIC genes comprise a large multi-gene family, but surprisingly, suggest that a fungal pathogen (Fusarium oxysporum) may also induce expression of the MIC proteins.