Identification of Ethylene Responsive miRNAs and Their Targets from Newly Harvested Banana Fruits Using High-Throughput Sequencing

The
roles of microRNAs (miRNAs) related to ethylene response in
banana fruits remain unknown because many miRNAs are differentially
expressed as the fruit ripens, making the identification of ethylene-responsive
miRNAs difficult. Using newly harvested banana fruits (within 5 h
after harvest) as material, we found that these fruit did not ripen
when treated with 5 μL/L of ethylene for 12 h at 22 °C.
Two miRNA libraries were generated from newly harvested banana fruits
with and without ethylene treatment and sequenced. In total, 128 known
miRNAs belonging to 42 miRNA families were obtained, and 12 novel
miRNAs were identified. Among them, 22 were differentially expressed
in response to ethylene treatment, among which 6 known miRNAs and
their putative targets were validated using qRT-PCR. These putative
targets encoded proteins including GATA, ARF, DLC, and AGO, etc. KEGG
and GO analyses showed that miRNAs differentially expressed in response
to ethylene mainly function in the molecular and biological processes.