Small RNA Sequencing Analysis of Germinating Single-bud Seedcane Sett in Sugarcane

Standardized mechanical planting of single-bud seedcane sett can improve planting efficiency and reduce costs in sugarcane production and is a research focus at present. Small RNA (miRNA) is an important regulator of life activities, which regulates many plant physiological processes such as gene expression, growth, development and metabolism. In this study, miRNAs in six germinating bud samples (S, bud of single-bud sett; D1, upper bud of double-bud sett; D2, lower bud of double-bud sett; T1, upper bud of three-bud sett; T2, median bud of three-bud sett; T3, lower bud of three-bud sett) derived from sugarcane variety GT42 were analyzed. As a result, 8,055,449, 19,172,991, 8,163,579, 11,748,126, 13,547,550 and 12,861,743 clean tags were obtained respectively, and their length was ranged from 16 to 35 nt. For different bud samples, S, D1, D2, T1, T2 and T3, 174, 600, 318, 425, 466, and 317 novel miRNAs were identified respectively, and a total of 1797 miRNAs, 28,042 target genes and 53,141 target sites were obtained from them. As compared with D1, D2, T1, T2 and T3, it was found the sample S showed 219, 157, 108, 44 and 41 up-regulated miRNAs, respectively. Plant hormone signal transduction pathway was the unique pathway enriched by KEGG analysis, and the enriched gene number was 67, 48, 54, 44 and 40 in S_VS_D1, S_VS_D2, S_VS_T1, S_VS_T2 and S_VS_T3, respectively. Furthermore, a total of 19 allelic genes were co-enriched. Among them, the most abundant allelic gene was found to be IAA gene, with a total of 32 gene sequences. All the up-regulated genes were involved in eight aspects metabolic regulation in plant hormone information transduction. The results showed that plant hormone information transduction played a dominant role in the single-bud sett germinating process, which might be the main reason for promoting the early germination and growth. These results can be referred for popularization and application of standardized mechanical planting of single-bud sett in sugarcane.