结论:Cd诱导柑橘的光合抑制和氧化应激损伤,动员抗氧化系统并调节相应基因的表达以适应Cd和Pb胁迫。Cd和Pb是造成严重污染的重金属,对生物具有高度危害。将生理测量和转录组学分析相结合,以研究5mMCd或Pb对HemerocalliscitrinaBaroni的影响。Cd显著抑制了H.citrina的生长,而Pb的影响很小。Cd和Pb都抑制了关键叶绿素合成基因的表达水平,导致叶绿素含量下降。同时,Cd加速叶绿素降解。它降低了光系统(PS)II的最大光化学效率,破坏氧气释放复合物并导致类囊体解离。相比之下,在铅胁迫下没有观察到这种现象。Cd还通过下调Rubisco和SBPase基因的表达来抑制卡尔文循环,最终破坏光合过程。Cd通过破坏天线蛋白影响光反应过程,PSII和PSI活动,和电子转移速率,而Pb的影响较弱。Cd显著增加活性氧和丙二醛的积累,并抑制抗氧化酶的活性和相应基因的表达水平。然而,H.citrina通过募集抗氧化酶及其相应基因的上调来适应铅胁迫。总之,Cd和Pb抑制叶绿素合成,阻碍光捕获和电子转移过程,Cd比Pb具有很大的毒性。这些结果阐明了柑橘对Cd和Pb胁迫的生理和分子机制,并为柑橘在重金属污染土地绿化中的潜在利用提供了坚实的基础。
CONCLUSIONS: Cd induces photosynthetic inhibition and oxidative stress damage in H. citrina, which mobilizes the antioxidant system and regulates the expression of corresponding genes to adapt to Cd and Pb stress. Cd and Pb are heavy metals that cause severe pollution and are highly hazardous to organisms. Physiological measurements and transcriptomic analysis were combined to investigate the effect of 5 mM Cd or Pb on Hemerocallis citrina Baroni. Cd significantly inhibited H. citrina growth, while Pb had a minimal impact. Both Cd and Pb suppressed the expression levels of key chlorophyll synthesis genes, resulting in decreased chlorophyll content. At the same time, Cd accelerated chlorophyll degradation. It reduced the maximum photochemical efficiency of photosystem (PS) II, damaging the oxygen-evolving complex and leading to thylakoid dissociation. In contrast, no such phenomena were observed under Pb stress. Cd also inhibited the Calvin cycle by down-regulating the expression of Rubisco and SBPase genes, ultimately disrupting the photosynthetic process. Cd impacted the light reaction processes by damaging the antenna proteins, PS II and PS I activities, and electron transfer rate, while the impact of Pb was weaker. Cd significantly increased reactive oxygen species and malondialdehyde accumulation, and inhibited the activities of antioxidant enzymes and the expression levels of the corresponding genes. However, H. citrina adapted to Pb stress by the recruitment of antioxidant enzymes and the up-regulation of their corresponding genes. In summary, Cd and Pb inhibited chlorophyll synthesis and hindered the light capture and electron transfer processes, with Cd exerting great toxicity than Pb. These results elucidate the physiological and molecular mechanisms by which H. citrina responds to Cd and Pb stress and provide a solid basis for the potential utilization of H. citrina in the greening of heavy metal-polluted lands.