National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
Microelement Research Center, College of Resources & Environment, Huazhong Agricultural University, Wuhan, China.
Plant Cell Environ. 2024 Oct;47(10):3732-3748. doi: 10.1111/pce.14959. Epub 2024 May 22.
Boron (B) is an essential microelement in plant growth and development. However, the molecular mechanisms underlying B uptake and translocation in Brassica napus are poorly understood. Herein, we identified a low-B (LB)-inducible gene, namely BnaC4.BOR2, with high transcriptional activity in root tips, stele cells, leaves, and floral organs. The green fluorescence protein labelled BnaC4.BOR2 protein was localised to the plasma membrane to demonstrate the B efflux activity in yeast and Arabidopsis. BnaC4.BOR2 knockout considerably reduced B concentration in the root and xylem sap, and altered B distribution in different organs at low B supply, exacerbating B sensitivity at the vegetative and reproductive stages. Additionally, the grafting experiment showed that BnaC4.BOR2 expression in the roots contributed more to B deficiency adaptability than that in the shoots. The pot experiments with LB-soil revealed B concentration in leaves and siliques of BnaC4.BOR2 mutants were markedly reduced, showing an obvious B-deficient phenotype of 'flowering without seed setting' and a considerable reduction in seed yield in B-deficient soil. Altogether, the findings of this study highlight the crucial role of BnaC4.BOR2 in B uptake and translocation during B. napus growth and seed yield under LB conditions.
硼（B）是植物生长发育所必需的微量元素。然而，油菜（Brassica napus）中硼吸收和转运的分子机制还知之甚少。在此，我们鉴定了一个低硼（LB）诱导的基因，即 BnaC4.BOR2，在根尖、中柱细胞、叶片和花器官中具有高转录活性。用绿色荧光蛋白标记的 BnaC4.BOR2 蛋白定位于质膜，以证明其在酵母和拟南芥中的硼外排活性。BnaC4.BOR2 敲除显著降低了根部和木质部汁液中的硼浓度，并在低硼供应下改变了不同器官中的硼分布，加重了营养生长和生殖生长阶段的硼敏感性。此外，嫁接实验表明，根部的 BnaC4.BOR2 表达比地上部的表达对硼缺乏的适应性贡献更大。LB 土壤的盆栽实验表明，BnaC4.BOR2 突变体叶片和角果中的硼浓度明显降低，表现出明显的“开花不结实”的硼缺乏表型，在缺硼土壤中种子产量也显著降低。综上所述，本研究结果强调了 BnaC4.BOR2 在油菜生长过程中硼吸收和转运中的关键作用，以及在 LB 条件下对种子产量的重要性。
