Microrna and Target Gene Responses in Cotton (Gossypium hirsutsum) Elicited By Root-Knot Nematode (Meloidogyne incognita) Infection

MicroRNAs (miRNAs) are an extensive class of small regulatory molecules. Many studies have demonstrated that miRNAs play important roles in almost all biological processes since they regulate gene expression, but no study has been performed on the role of miRNAs in cotton response to the root-knot nematode (RKN, Meloidogyne incognita) infection. M. incognita is one of the most important plant-parasitic nematodes of cotton, and can significantly affect cotton plant growth and development, adversely affecting cotton fiber yield and quality. In this study, we have selected 28 miRNAs and 8 miRNA target genes to investigate the miRNA-target response to RKN infection in cotton roots. Our results show that RKN infection significantly affected the expression of miRNAs and their targeted genes. After 10 days of RKN infection, the changes in miRNA expression ranged from down-regulation by 33% to upregulation by 406%.  Compared with the untreated control, the expression levels of miRNA targets were 46 % to 231% in cotton roots. Such changes in response to infection suggest important gene regulation mechanisms are activated in cotton under RKN infection. Such information could be valuable for future design of anti-nematode infection strategies.