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Differential responses of the sunn4 and rdn1-1 super-nodulation mutants of Medicago truncatula to elevated atmospheric CO2
Annals of Botany ( IF 3.6 ) Pub Date : 2021-07-23 , DOI: 10.1093/aob/mcab098
Yunfa Qiao 1, 2 , Shujie Miao 1 , Jian Jin 2 , Ulrike Mathesius 3 , Caixian Tang 2
Affiliation  

Background and Aims Nitrogen fixation in legumes requires tight control of carbon and nitrogen balance. Thus, legumes control nodule numbers via an autoregulation mechanism. ‘Autoregulation of nodulation’ mutants super-nodulate are thought to be carbon-limited due to the high carbon-sink strength of excessive nodules. This study aimed to examine the effect of increasing carbon supply on the performance of super-nodulation mutants. Methods We compared the responses of Medicago truncatula super-nodulation mutants (sunn-4 and rdn1-1) and wild type to five CO2 levels (300–850 μmol mol−1). Nodule formation and nitrogen fixation were assessed in soil-grown plants at 18 and 42 d after sowing. Key Results Shoot and root biomass, nodule number and biomass, nitrogenase activity and fixed nitrogen per plant of all genotypes increased with increasing CO2 concentration and reached a maximum at 700 μmol mol−1. While the sunn-4 mutant showed strong growth retardation compared with wild-type plants, elevated CO2 increased shoot biomass and total nitrogen content of the rdn1-1 mutant up to 2-fold. This was accompanied by a 4-fold increase in nitrogen fixation capacity in the rdn1-1 mutant. Conclusions These results suggest that the super-nodulation phenotype per se did not limit growth. The additional nitrogen fixation capacity of the rdn1-1 mutant may enhance the benefit of elevated CO2 for plant growth and N2 fixation.

中文翻译:

蒺藜苜蓿 sunn4 和 rdn1-1 超结瘤突变体对大气 CO2 升高的差异响应

背景和目的 豆科植物的固氮需要严格控制碳氮平衡。因此,豆类通过自动调节机制控制结节数量。由于过度结节的高碳汇强度,“结瘤的自动调节”突变体超结瘤被认为是碳限制的。本研究旨在检查增加碳供应对超结瘤突变体性能的影响。方法 我们比较了蒺藜苜蓿超结瘤突变体(sunn-4 和 rdn1-1)和野生型对五种 CO2 水平(300-850 μmol mol-1)的反应。在播种后 18 天和 42 天,在土壤生长的植物中评估根瘤形成和固氮情况。主要结果 芽和根生物量、根瘤数量和生物量,所有基因型的固氮酶活性和单株固定氮含量都随着 CO2 浓度的增加而增加,并在 700 μmol mol-1 时达到最大值。虽然 sunn-4 突变体与野生型植物相比表现出强烈的生长迟缓,但升高的 CO2 使 rdn1-1 突变体的枝条生物量和总氮含量增加了 2 倍。这伴随着 rdn1-1 突变体的固氮能力增加了 4 倍。结论 这些结果表明,超结瘤表型本身并不限制生长。rdn1-1 突变体额外的固氮能力可能会增强二氧化碳浓度升高对植物生长和固氮的益处。升高的 CO2 使 rdn1-1 突变体的枝条生物量和总氮含量增加了 2 倍。这伴随着 rdn1-1 突变体的固氮能力增加了 4 倍。结论 这些结果表明,超结瘤表型本身并不限制生长。rdn1-1 突变体额外的固氮能力可能会增强二氧化碳浓度升高对植物生长和固氮的益处。升高的 CO2 使 rdn1-1 突变体的枝条生物量和总氮含量增加了 2 倍。这伴随着 rdn1-1 突变体的固氮能力增加了 4 倍。结论 这些结果表明,超结瘤表型本身并不限制生长。rdn1-1 突变体额外的固氮能力可能会增强二氧化碳浓度升高对植物生长和固氮的益处。
更新日期:2021-07-23
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