Abstract：
CONCLUSIONS: ZmRLCK58, a negative growth regulator, reduces tolerance of maize seedlings to low Mg via enhancing H2O2 accumulation in the shoot. Magnesium (Mg) deficiency is one of critical limiting factors for crop production in widespread acidic soils worldwide. However, the molecular mechanism of crop response to Mg deficiency is still largely unclear. Here, we found higher concentrations of H2O2, soluble sugars, and starch (1.5-, 1.9-, and 1.4-fold, respectively) in the shoot of low-Mg-treated maize seedlings, compared with Mg sufficient plants under hydroponic culture. Consistent with over-accumulation of H2O2, transcriptome profiling revealed significant enrichment of 175 differentially expressed genes (DEGs) in \"response to oxygen-containing compound\" out of 641 DEGs in the shoot under low Mg. Among 175 DEGs, a down-regulated receptor-like cytoplasmic kinase ZmRLCK58 underwent a recent duplication event before Poaceae divergence and was highly expressed in the maize shoot. ZmRLCK58 overexpression enhanced H2O2 accumulation in shoots by 21.3% and 29.8% under control and low-Mg conditions, respectively, while reducing biomass accumulation compared with wild-type plants. Low Mg further led to 39.7% less starch accumulation in the ZmRLCK58 overexpression shoot and lower Mg utilization efficiency. Compared with wild-type plants, overall down-regulated expression of genes related to response to carbohydrate, photosynthesis, H2O2 metabolic, oxidation-reduction, and ROS metabolic processes in ZmRLCK58 overexpression lines preconditioned aforementioned physiological alterations. Together, ZmRLCK58, as a negative growth regulator, reduces tolerance of maize seedlings to low Mg via enhancing H2O2 accumulation.
摘要：
结论：ZmRLCK58，一种负增长调节剂，通过增强芽中H2O2的积累降低了玉米幼苗对低Mg的耐受性。镁（Mg）缺乏是全球广泛的酸性土壤中作物生产的关键限制因素之一。然而,作物对镁缺乏反应的分子机制尚不清楚。这里,我们发现高浓度的H2O2，可溶性糖，和淀粉（1.5-，1.9-，和1.4倍，分别)在低镁处理的玉米幼苗的芽中，与水培条件下镁充足的植物相比。与H2O2的过度积累一致，转录组分析显示，在低Mg条件下，芽中的641个DEG中，“对含氧化合物的反应”中有175个差异表达基因（DEG）显着富集。在175个DEG中，下调的受体样细胞质激酶ZmRLCK58在禾本科植物分化之前经历了最近的复制事件，并在玉米芽中高表达。在对照和低镁条件下，ZmRLCK58过表达使芽中H2O2的积累增加了21.3％和29.8％，分别,与野生型植物相比，同时减少了生物量积累。低Mg进一步导致ZmRLCK58过表达芽中淀粉积累减少39.7％，并降低Mg的利用效率。与野生型植物相比,与碳水化合物反应相关的基因的整体表达下调，光合作用,H2O2代谢，氧化还原，ZmRLCK58过表达系中的ROS代谢过程预先调节了上述生理变化。一起,ZmRLCK58，作为负增长调节剂，通过增强H2O2积累降低玉米幼苗对低镁的耐受性。
