Differential regulation of the “phytoglobin-nitric oxide respiration” in Medicago truncatula roots and nodules submitted to flooding

IF 4.2 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Plant Science Pub Date : 2025-01-17 DOI:10.1016/j.plantsci.2025.112393

Chaïma Chammakhi , Marie Pacoud , Alexandre Boscari , Antoine Berger , Haythem Mhadhbi , Imène Gharbi , Renaud Brouquisse

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引用次数: 0

Abstract

Flooding induces hypoxia in plant tissues, impacting various physiological and biochemical processes. This study investigates the adaptive response of the roots and nitrogen-fixing nodules of Medicago truncatula in symbiosis with Sinorhizobium meliloti under short-term hypoxia caused by flooding. Four-week-old plants were subjected to flooding for 1–4 days. Physiological parameters as well as the expression of the senescence marker gene MtCP6 remained unchanged after 4 days of flooding, indicating no senescence onset. Hypoxia was evident from the first day, as indicated by the upregulation of hypoxia marker genes (MtADH, MtPDC, MtAlaAT, MtERF73). Nitrogen-fixing capacity was unaffected after 1 day but markedly decreased after 4 days, while energy state (ATP/ADP ratio) significantly decreased from 1 day and was more affected in nodules than in roots. Nitric oxide (NO) production increased in roots but decreased in nodules after prolonged flooding. Nitrate reductase (NR) activity and expression of genes associated with Phytoglobin-NO (Pgb-NO) respiration (MtNR1, MtNR2, MtPgb1.1) were upregulated, suggesting a role in maintaining energy metabolism under hypoxia, but the use of M. truncatula nr1 and nr2 mutants, impaired in nitrite production, indicated the involvement of these two genes in ATP regeneration during initial flooding response. The addition of sodium nitroprusside or tungstate revealed that Pgb-NO respiration contributes significantly to ATP regeneration in both roots and nodules under flooding. Altogether, these results highlight the importance of NR1 and Pgb1.1 in the hypoxic response of legume root systems and show that nodules are more sensitive than roots to hypoxia.

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“植物红蛋白-一氧化氮呼吸”在洪水侵袭下的短叶紫花苜蓿根和根瘤中的差异调控。

洪水引起植物组织缺氧，影响多种生理生化过程。本研究研究了与墨氏中华根瘤菌共生的根和固氮根瘤在洪水引起的短期缺氧条件下的适应性反应。四周大的植物被淹了1到4天。淹水4天后，生理参数及衰老标志基因MtCP6的表达均未发生变化，说明未发生衰老。缺氧标志基因（MtADH、MtPDC、MtAlaAT、MtERF73）的上调表明，从第一天起缺氧就很明显。固氮能力在第1天不受影响，但在第4天显著下降，能量状态（ATP/ADP比值）从第1天开始显著下降，且根瘤受影响大于根。长时间淹水后，根系中一氧化氮（NO）产量增加，而根瘤中一氧化氮（NO）产量下降。硝酸盐还原酶（NR）活性和与植物红蛋白- no （pgp - no）呼吸相关基因（MtNR1, MtNR2, MtPgb1.1）的表达上调，提示其在缺氧条件下维持能量代谢中起作用，但矮根霉nr1和nr2突变体在亚硝酸盐生产中受损，表明这两个基因参与了初始洪水反应中ATP的再生。硝普钠或钨酸钠的加入表明，Pgb-NO呼吸对淹水条件下根和根瘤的ATP再生都有显著的促进作用。综上所述，这些结果突出了NR1和Pgb1.1在豆科植物根系缺氧反应中的重要性，表明豆科植物根瘤比根对缺氧更敏感。

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来源期刊

Plant Science 生物-生化与分子生物学

CiteScore

9.10

自引率

1.90%

发文量

322

审稿时长

33 days

期刊介绍： Plant Science will publish in the minimum of time, research manuscripts as well as commissioned reviews and commentaries recommended by its referees in all areas of experimental plant biology with emphasis in the broad areas of genomics, proteomics, biochemistry (including enzymology), physiology, cell biology, development, genetics, functional plant breeding, systems biology and the interaction of plants with the environment. Manuscripts for full consideration should be written concisely and essentially as a final report. The main criterion for publication is that the manuscript must contain original and significant insights that lead to a better understanding of fundamental plant biology. Papers centering on plant cell culture should be of interest to a wide audience and methods employed result in a substantial improvement over existing established techniques and approaches. Methods papers are welcome only when the technique(s) described is novel or provides a major advancement of established protocols.