Long non-coding RNAs and their potential functions in Ligon-lintless-1 mutant cotton during fiber development

Long non-coding RNAs (LncRNAs) are part of genes, which are not translated into proteins and play a vital role in plant growth and development. Nevertheless, the presence of LncRNAs and how they functions in Ligon-lintless-1 mutant during the early cessation of cotton fiber development are still not well understood. In order to investigate the function of LncRNAs in cotton fiber development, it is necessary and important to identify LncRNAs and their potential roles in fiber cell development. In this work, we identified 18,333 LncRNAs, with the proportion of long intergenic noncoding RNAs (LincRNAs) (91.5%) and anti-sense LncRNAs (8.5%), all transcribed from Ligon-lintless-1 (Li1) and wild-type (WT). Expression differences were detected between Ligon-lintless-1 and wild-type at 0 and 8 DPA (day post anthesis). Pathway analysis and Gene Ontology based on differentially expressed LncRNAs on target genes, indicated fatty acid biosynthesis and fatty acid elongation being integral to lack of fiber in mutant cotton. The result of RNA-seq and RT-qPCR clearly singles out two potential LncRNAs, LNC_001237 and LNC_017085, to be highly down-regulated in the mutant cotton. The two LncRNAs were found to be destabilized or repressed by ghr-miR2950. Both RNA-seq analysis and RT-qPCR results in Ligon-lintless-1 mutant and wild-type may provide strong evidence of LNC_001237, LNC_017085 and ghr-miR2950 being integral molecular elements participating in various pathways of cotton fiber development. The results of this study provide fundamental evidence for the better understanding of LncRNAs regulatory role in the molecular pathways governing cotton fiber development. Further research on designing and transforming LncRNAs will help not only in the understanding of their functions but will also in the improvement of fiber quality.