Plants have evolved complex mechanisms to adapt to the changing nitrogen levels in the environment. In Arabidopsis, more than a dozen nitrate signaling regulatory genes have been characterized, including the NODULE INCEPTION-LIKE PROTEIN (AtNLP) genes, which play essential roles in nitrate signaling. However, whether NLP genes in the Triticeae crops are involved in nitrate regulation and nitrogen use efficiency (NUE) remains unknown. Here, we isolated a barley (Hordeum vulgare L.) mutant, hvnlp2-1, from a TILLING (Targeting Local Lesions IN Genomes) population and constructed two RNAi lines, hvnlp2-2 and hvnlp2-3, to study the function of HvNLP2. The expression of the nitrate-responsive genes was substantially inhibited after nitrate treatment in the hvnlp2 mutants, indicating that HvNLP2 controls nitrate signaling. Nitrate content was significantly higher in the hvnlp2 mutants, which may result from the decreased assimilation of nitrogen caused by reduced nitrate reductase activity and expression of nitrate assimilatory genes. HvNLP2 is localized to the nucleus in the presence of nitrate. Further investigation showed that HvNLP2 binds to and activates the nitrate-responsive cis-elements. Moreover, hvnlp2 exhibited reduced biomass, seed yield, and NUE. Therefore, HvNLP2 controls nitrate signaling and plays an important role in NUE.

本研究探究了叶面喷施不同浓度(0、20、40 μg·L-1)宛氏拟青霉提取物(ZNC)对盐碱胁迫下小白菜(Brassica chinensis)幼苗的生长和生理特性的影响.结果 表明,重度盐碱处理后,与不喷施ZNC处理相比,喷施20 μg·L-1ZNC的小白菜,叶片中可溶性糖和脯氨酸(Pro)的含量升高,平衡了细胞内外的渗透压,减少了水分散失;超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性升高,降低了丙二醛(MDA)的含量,减少了细胞膜的氧化损伤;玉米素(ZT)和赤霉素(GA)的含量提高,脱落酸(ABA)含量降低,促进了小白菜的生长,提高了其产量.同时,ZNC增加叶片中多种氨基酸的含量,维持了细胞内外的离子平衡并提高了小白菜的品质.上述结果说明ZNC能有效缓解盐碱胁迫对小白菜幼苗的伤害,提高小白菜的产量和品质.

以品种郑单958为材料,宛氏拟青霉提取物(ZNC)为诱抗剂,探讨施氮量、氮肥种类和ZNC对夏玉米产量、氮素利用和经济收益的影响.结果表明,与没有配施ZNC相比,氮肥配施ZNC后,玉米增产2.14％～9.00％,氮素利用率显著提高11.21％～104.00％,净收益显著增加379.05～1743.38元/hm2.控释尿素配施ZNC(CRUZ)较尿素配施ZNC处理(UZ)产量、氮素利用率和净收益分别显著增加5.73％、185.00％和1311.61元/hm2.尿素减氮20％配施ZNC(80％UZ)处理与未减量处理(U)产量差异不显著,但其氮素利用率、氮肥农学效率和氮肥偏生产力显著增加,净收益显著增加647.89元/hm2,实现了减肥稳产.因此控释尿素配施ZNC可实现对玉米产量、氮肥利用率和净收益的协同增效,减施20％普通尿素配施ZNC可实现对其减肥增效.

N-6-methyladenosine (m(6)A), a ubiquitous internal modification of eukaryotic mRNAs, plays a vital role in almost every aspect of mRNA metabolism. However, there is little evidence documenting the role of m(6)A in regulating alternative polyadenylation (APA) in plants. APA is controlled by a large protein-RNA complex with many components, including CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR30 (CPSF30). In Arabidopsis, CPSF30 has two isoforms and the longer isoform (CPSF30-L) contains a YT512-B Homology (YTH) domain, which is unique to plants. In this study, we showed that CPSF30-L YTH domain binds to m(6)A in vitro. In the cpsf30-2 mutant, the transcripts of many genes including several important nitrate signaling-related genes had shifts in polyadenylation sites that were correlated with m(6)A peaks, indicating that these gene transcripts carrying m(6)A tend to be regulated by APA. Wild-type CPSF30L could rescue the defects in APA and nitrate metabolism in cpsf30-2, but m(6)A-binding-defective mutants of CPSF30-L could not. Taken together, our results demonstrated that m(6)A modification regulates APA in Arabidopsis and revealed that the m(6)A reader CPSF30-L affects nitrate signaling by controlling APA, shedding new light on the roles of the m(6)A modification during RNA 30-end processing in nitrate metabolism.