Identification and characterization of circRNAs involved in the regulation of low nitrogen-promoted root growth in hexaploid wheat

BACKGROUND: CircRNAs are widespread in plants and play important roles in response to abiotic stresses. Low nitrogen (LN) promotes the growth of plant root system, allowing it to explore more nitrogen. However, whether circRNAs involved in the response to LN stress and the regulation of LN-promoted root growth in wheat remains unclear. METHODS: Two wheat varieties (LH9 and XN979) with contrasting root phenotypes to LN stress were used as materials to identify circRNAs under control and LN conditions by using high-throughput sequencing technology. RESULTS: Six differentially expressed circRNAs (DECs) involved in the common response to LN stress and 23 DECs involved in the regulation of LN-promoted root growth were successfully identified. GO analysis of the DEC-host genes involved in the regulation of LN-promoted root growth showed that GO terms related to biological regulation, responses to stimuli and signalling were significantly enriched. Moreover, seven DECs were predicted to have miRNA binding sites and may serve as miRNA sponges to capture miRNAs from their target genes. CONCLUSIONS: LN stress altered the expression profiles of circRNAs in wheat. This is the first report of LN stress responsive circRNAs in plants. Our results provided new clues for investigating the functions of circRNAs in response to LN stress and in the regulation of LN-promoted wheat root growth.

Transcriptome library construction in whole plant of Erigeron breviscapus stressed by low nitrogen and its sequencing / 中草药

Objective: To explore the genetic background of Erigeron breviscapus, a very important herb, we used the plantlets under low nitrogen and normal condition cultured in vitro as material to construct the transcriptome library, and to sequence the library via next generation sequencing technique. Methods: Modified guanidinium isothiocyanate-CTAB method was used to isolate the total RNA from low nitrogen and normal condition cultured plantlets. The mRNA was enriched from the total RNA and broken into short fragments, and then the cDNA library was established for RNA-Seq. Results: In total, 35.87 million and 25.82 million raw reads were generated from LD and CK libraries via next generation sequencing, respectively. The overall sequencing outputs were over 6 Gb. Among all of the raw reads, more than 98.37% and 98.67% had Phred-like quality scores at Q20 level (an error probability of 1%), respectively. After filtered to remove low quality reads, the high quality sequencing sequence was used for de novo assembling. Unigenes of 101 and 156 pieces with the average length of 768 bp (N50 1 290 bp) were obtained, and the length of 44 908 pieces (about 44.39%) is more than 500 bp. Among 101 and 156 Unigenes, 59 538 (58.86%) showed the significant BLAST hits in the public databases. Many sequences concerning flavanoids bio-synthesis which included PAL, C4H, CHS, CHI, F3H, F3'H, and ANS were obtained from the experiment. Conclusion: Transcriptome information of E. breviscapus has been better preserved, which provides the foundation for the further analysis in genetic-environment interaction and molecular assistant breeding.