BackgroundDicer-like proteins (DCLs) are essential players in RNA-silencing mechanisms, acting in gene regulation via miRNAs and in antiviral protection in plants and have also been associated to other biotic and abiotic stresses. To the best of our knowledge, despite being identified in some crops, cotton DCLs haven’t been characterized until now. In this work, we characterized the DCLs of three cotton species and analyzed their expression profiles during biotic stress.ResultsAs main results, 11 DCLs in the allotetraploid cotton Gossypium hirsutum, 7 and 6 in the diploid G. arboreum and G. raimondii, were identified, respectively. Among some DCLs duplications observed in these genomes, the presence of an extra DCL3 in the three cotton species were detected, which haven’t been found in others eudicots. All the DCL types identified by in silico analysis in the allotetraploid cotton genome were able to generate transcripts, as observed by gene expression analysis in distinct tissues. Based on the importance of DCLs for plant defense against virus, responses of cotton DCLs to virus infection and/or herbivore attack using two commercial cotton cultivars (cv.), one susceptible (FM966) and another resistant (DO) to polerovirus CLRDV infection, were analyzed. Both cvs. Responded differently to virus infection. At the inoculation site, the resistant cv. showed strong induction of DCL2a and b, while the susceptible cv. showed a down-regulation of these genes, wherever DCL4 expression was highly induced. A time course of DCL expression in aerial parts far from inoculation site along infection showed that DCL2b and DCL4 were repressed 24 h after infection in the susceptible cotton. As CLRDV is aphid-transmitted, herbivore attack was also checked. Opposite expression pattern of DCL2a and b and DCL4 was observed for R and S cottons, showing that aphid feeding alone may induce DCL modulation.ConclusionsAlmost all the DCLs of the allotetraploide G. hirsutum cotton were found in their relative diploids. Duplications of DCL2 and DCL3 were found in the three species. All four classes of DCL responded to aphid attack and virus infection in G. hirsutum. DCLs initial responses against the virus itself and/or herbivore attack may be contributing towards virus resistance.

Background Dicer-like proteins (DCLs) are fundamental players in RNA-silencing mechanisms acting in gene regulation via miRNAs and in antiviral protection in plants, in addition to being related to other biotic and abiotic stresses. Despite be identified in some crops, cotton DCLs weren't characterized until now. Here we characterize the DCLs of three cotton species and analyzed their expression profiles during biotic stress. Results We identified 11 DCLs in the allotetraploid cotton Gossypium hirsutum and 7 and 6 in the diploid G. arboreum and G. raimondii, respectively. Among some DCL duplication observed in these genomes, we observe the presence of an extra DCL3 in the three cotton species, not found in others eudicots until now. All the DCL types identified by in silico analysis in the allotetraploid cotton genome were able to generate transcripts, as observed by gene expression analysis in distinct tissues. Based on the importance of DCLs for plant virus defense, responses of cotton DCLs to virus infection and/or herbivore attack using two commercial cotton cultivars (cv.), one susceptible (Fibermax 966) and another resistant (Delta Opal) to polerovirus CLRDV infection were analyzed. Both cvs. responded differently to virus infection. At the initial stages, 24dpi, the resistant cv. showed strong induction of DCL2a and b, while the susceptible cv. showed a down-regulation of these genes, wherever DCL4 expression was highly induced. Herbivore attack did not induce contrasting profiles between cotton DCLs transcripts in either cotton cv. Conclusions The allotetraploide cotton G. hirsutum has almost all DCLs found in their diploid relative and duplication of DCL2 and DCL3 were found in the three species. All the four classes of DCL respond to aphid attack and virus infection in G. hirsutum, however, remarkable differences in DCL initial responses against the virus itself may be responsible for the virus susceptible and/or resistant phenotype of the contrasting cotton cv. studied.

Background Dicer-like proteins (DCLs) are fundamental players in RNA-silencing mechanisms acting in gene regulation via miRNAs and in antiviral protection in plants, in addition to being related to other biotic and abiotic stresses. Despite be identified in some crops, cotton DCLs weren't characterized until now. Here we characterize the DCLs of three cotton species and analyzed their expression profiles during biotic stress. Results We identified 11 DCLs in the allotetraploid cotton Gossypium hirsutum and 7 and 6 in the diploid G. arboreum and G. raimondii, respectively. Among some DCL duplication observed in these genomes, we observe the presence of an extra DCL3 in the three cotton species, not found in others eudicots until now. All the DCL types identified by in silico analysis in the allotetraploid cotton genome were able to generate transcripts, as observed by gene expression analysis in distinct tissues. Based on the importance of DCLs for plant virus defense, responses of cotton DCLs to virus infection and/or herbivore attack using two commercial cotton cultivars (cv.), one susceptible (Fibermax 966) and another resistant (Delta Opal) to polerovirus CLRDV infection were analyzed. Both cvs. responded differently to virus infection. At the initial stages, 24dpi, the resistant cv. showed strong induction of DCL2a and b, while the susceptible cv. showed a down-regulation of these genes, wherever DCL4 expression was highly induced. Herbivore attack did not induce contrasting profiles between cotton DCLs transcripts in either cotton cv. Conclusions The allotetraploide cotton G. hirsutum has almost all DCLs found in their diploid relative and duplication of DCL2 and DCL3 were found in the three species. All the four classes of DCL respond to aphid attack and virus infection in G. hirsutum, however, remarkable differences in DCL initial responses against the virus itself may be responsible for the virus susceptible and/or resistant phenotype of the contrasting cotton cv. studied.