January 15-19, 2011
Town & Country Convention Center
San Diego, CA
Sampurna Sattar , Ramanjulu Sunkar , Gary A. Thompson
Aphis gossypii resistance in Cucumis melo has been attributed to the presence of Vat, a single dominant gene belonging to the NBS-LRR family of resistance genes. Previous data showed that significant transcriptional reprogramming occurs in Vat+ plants during aphid infestations. Based on these observations, it was hypothesized that miRNAs are involved in fine tuning these gene responses. Small RNA libraries were constructed from bulked leaf tissues of a Vat+ melon line following early (2, 4 and 6 h) and late (8, 10, and 12 h) aphid infestations. A non-infested control library was used to study the basal level of miRNA expression in the Vat+ melon line. Illumina sequencing of the libraries revealed that conserved miRNAs were differentially expressed in the early and late time periods of aphid infestations. Expression of most of the conserved miRNAs peaked at the early stages of aphid infestation, but returned near the basal levels of expression during the later stages. Northern blots of the conserved miRNAs confirmed the trends observed with the library data. These data indicate that miRNAs influence the expression levels of a significant number of genes during the early stages of aphid herbivory. The melon genes targeted by these miRNA were confirmed by RACE, and their expression patterns evaluated by qRT-PCR experiments.