Knock-down the expression of TaH2B-7D using virus-induced gene silencing reduces wheat drought tolerance

BACKGROUND: Drought is a major abiotic stress affecting global wheat (Triticum aestivum L.) production. Exploration of drought-tolerant genes is essential for the genetic improvement of drought tolerance in wheat. Previous studies have shown that some histone encoding genes are involved in plant drought tolerance. However, whether the H2B family genes are involved in drought stress response remains unclear. METHODS: Here, we identified a wheat histone H2B family gene, TaH2B-7D, which was significantly up-regulated under drought stress conditions. Virus-induced gene silencing (VIGS) technology was used to further verify the function of TaH2B-7D in wheat drought tolerance. The phenotypic and physiological changes were examined in the TaH2B-7D knock-down plants. RESULTS: In the TaH2B-7D knock-down plants, relative electrolyte leakage rate and malonaldehyde (MDA) content significantly increased, while relative water content (RWC) and proline content significantly decreased compared with those in the non-knocked-down plants under drought stress conditions. TaH2B-7D knock-down plants exhibited severe sagging, wilting and dwarf phenotypes under drought stress conditions, but not in the non-knocked-down plants, suggesting that the former were more sensitive to drought stress. CONCLUSION: These results indicate that TaH2B-7D potentially plays a vital role in conferring drought tolerance in wheat.

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.