Identification of microRNAs in the green and red sectors of Amaranthus tricolor L. leaves based on Illumina sequencing data

Betalains are abundant in amaranth plants. Additionally, the betalain molecular structure and metabolic pathway differ from those of betanin in beet plants. To date, only a few studies have examined the regulatory roles of miRNAs in betalain biosynthesis in plants. Thus, we constructed small RNA libraries for the red and green sectors of amaranth leaves to identify miRNAs associated with betalain biosynthesis. We identified 198 known and 41 novel miRNAs. Moreover, 216 miRNAs were distributed in 44 miRNA families, including miR156, miR159, miR160, miR166, miR172, miR319, miR167, miR396, and miR398. An analysis of all unigene sequences in an amaranth transcriptome database resulted in the detection of 493 target genes for the 239 screened miRNAs. The targets included SPL2, ARF18, ARF6, and NAC. A quantitative real-time polymerase chain reaction validation of 20 miRNAs and nine target genes revealed expression-level differences between the red and green sectors of amaranth leaves. This study involved the application of an Illumina sequencing platform to identify miRNAs regulating betalain metabolism in amaranth plants. The data presented herein may provide insights into the molecular mechanisms underlying the regulation of betalain biosynthesis in amaranth and other plant species.