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Submitted to: International Journal of Current Biotechnology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/30/2013 Publication Date: 12/31/2013 Citation: Youssef, R.M., Matthews, B.F. 2013. Expression of Arabidopsis genes AtNPR1 and AtTGA2 in transgenic soybean roots of composite plants confers resistance to root-knot nematode (Meloidogyne incognita). International Journal of Current Biotechnology. 1(10):15-25. Interpretive Summary: Root-knot nematodes (RKN) are among the most destructive plant parasitic nematodes, infecting almost all cultivated plants and resulting in yield losses of billions of dollars annually Currently grown soybean varieties are not resistant to all field populations of RKN. We genetically engineered soybean roots with tow genes, NPR1 and TGA2 from another plant, Arabidposis. We overexpressed NPR1 and TGA2, independently in soybean roots, then inoculated the roots with RKN. The NPR1 gene reduced the number of galls formed by RKN by 82%, while overexpression of TGA2 reduced the number of galls by 79%. Our results transfer knowledge of these genes gained from the model system, Arabidopsis, to soybean. Furthermore, our results provide insights into the defense response of soybean to RKN, and how RKN may be controlled through genetic engineering. Technical Abstract: Root-knot nematodes (RKN; Meloidogyne spp.) are among the most destructive of the plant parasitic nematodes, infecting almost all cultivated plants and resulting in yield losses of billions of dollars annually. NPR1 (nonexpresser of pathogenesis related genes 1, AtNPR1) plays a positive role in the salicylic acid (SA) signaling pathway that controls systemic acquired resistance (SAR), and it is also involved in cross-talk with the jasmonic acid (JA) pathway. TGA transcription factors in Arabidopsis thaliana have been shown to interact with NPR1.We overexpressed the A. thaliana genes AtNPR1 and AtTGA2 separately in transgenic soybean (Glycine max) roots of composite plants and inoculated the roots with the RKN M. incognita. The number of RKN galls counted 35 days after inoculation in NPR1- and TGA2-transformed roots were 82 and 79 percent fewer than in control roots. This inhibition of RKN maturation was associated with constitutive changes in expression of the defense-related soybean genes ERF1, encoding ethylene response factor 1; chiB1, encoding a basic chitinase protein; and PR5, encoding an osmotin-like protein, demonstrating the cross talk between SA and Jasmonic acid (JA)/Ethylene (ET)in plant resistance against pathogens. |
