Iron (Fe)-deficiency causes chlorosis and growth inhibition in sunflower, an important commercial crop. This study examines whether and how arbuscular mycorrhizal fungi (AMF) ameliorate Fe-deficiency symptoms in Fe-deficiency sensitive sunflower plants. AMF supplementation showed a significant improvement in plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), suggesting its beneficial effect under Fe deficiency. This AM-driven amelioration of Fe deficiency was further supported by the improvement of biochemical stress indicators, such as cell death, electrolyte leakage, superoxide anion, and hydrogen peroxide. In this study, the AMF supplementations resulted in significant improvement in Fe as well as Zn concentrations in root and shoot of sunflower under Fe deficiency. One of the primary Strategy-I responses, ferric reductase activity along with the expression of its respective gene (HaFRO1), significantly increased in roots due to AMF ensuring Fe availability in the rhizosphere under Fe deficiency. Our qPCR analysis also showed a significant upregulation of HaIRT1, HaNramp1, and HaZIP1 in roots of sunflower in the presence of AMF, suggesting that Fe and Zn transporters are concurrently involved with AMF-mediated alleviation of Fe deficiency. Further, AMF accelerates the activities of CAT and SOD, predominantly in roots to protect sunflower plants from Fe-deficiency reactive oxygen species (ROS). This study unveils the mechanistic basis of AMF to limit Fe deficiency retardation in sunflower.

缺铁（Fe）会导致向日葵（一种重要的商业作物）萎黄并抑制其生长。这项研究调查了是否以及如何丛枝菌根真菌（AMF）改善了缺铁敏感向日葵植物中的缺铁症状。补充AMF可使植物生物量，叶绿素得分，Fv / Fm（光系统II的量子效率）和Pi_ABS（光合作用性能指数）显着提高，表明其在铁缺乏时的有益作用。这种AM驱动的铁缺乏症的缓解进一步得到了生化应激指标的改善的支持，例如细胞死亡，电解质泄漏，超氧阴离子和过氧化氢。在这项研究中，AMF的添加显着改善了缺铁条件下向日葵根和茎中的铁以及锌的锌含量。HaFRO1）在根系中显着增加，这是由于AMF确保了铁缺乏时根际中铁的有效性。我们的qPCR分析还显示，在存在AMF的向日葵根中，HaIRT1，HaNramp1和HaZIP1显着上调，表明Fe和Zn转运蛋白同时参与AMF介导的铁缺乏症的缓解。此外，AMF加速CAT和SOD的活动，主要是在根部保护向日葵植物免受铁缺乏的活性氧（ROS）的侵害。这项研究揭示了AMF限制向日葵中铁缺乏的延迟机理。