Institute of Biological Sciences, University of Rajshahi, Rajshahi, 6205, Bangladesh; Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh; Department of Genetic Engineering and Biotechnology, University of Rajshahi, Rajshahi, 6205, Bangladesh.
Molecular Plant Physiology Laboratory, Department of Botany, University of Rajshahi, Rajshahi, 6205, Bangladesh.
Plant Physiol Biochem. 2019 Mar;136:22-33. doi: 10.1016/j.plaphy.2019.01.007. Epub 2019 Jan 7.
Excess cadmium (Cd) is a serious threat to agriculture and the environment. High Cd availability showed no significant decline in growth, chlorophyll synthesis, soluble protein, cell and membrane stability in Sonarbangla (Cd-tolerant), while these were severely affected in BRRI 72 (Cd-sensitive). Atomic absorption spectroscopy analysis demonstrated a huge increment of Cd and Fe in root and shoot of BRRI 72; however, Sonarbangla only exhibited a significant increase of Cd in roots. It suggests that excess Cd in Sonarbangla possibly retained in roots through vacuolar sequestration without interfering cell functions. This was further confirmed by the increased accumulation of cysteine, glutathione, and phytochelatin along with OsPCS1 and OsHMA3 upregulation, possibly facilitated by nitric oxide in roots of Sonarbangla. Further, Fe chelate reductase activity in conjunction with the genes (OsFRO1, OsNRAMP1, OsIRT1, and OsYSL15) associated with Fe availability significantly upregulated in BRRI 72 but not in Sonarbangla in response to Cd. It advises that Fe acquisition and transport were tightly regulated in Cd-tolerant Sonarbangla. Furthermore, elevated CAT, APX, GR, NO in root along with shoot sugar helps rice plants to withstand Cd-induced oxidative damage. Finally, reciprocal grafting combining Sonarbangla rootstock with either BRRI 72 or Sonarbangla scion showed Sonarbangla type tolerance along with no changes of HO and Fe reductase activity in roots under high Cd. It indicates that the signal inducing the responses to adjust Cd stress is originated in the root system. These messages deliver essential background for further breeding program to produce Cd-free rice.
过量的镉 (Cd) 对农业和环境是一个严重的威胁。高 Cd 供应并没有显著降低 Sonarbangla（Cd 耐受型）的生长、叶绿素合成、可溶性蛋白、细胞和膜的稳定性，而这些在 BRRI 72（Cd 敏感型）中受到严重影响。原子吸收光谱分析表明，BRRI 72 的根和茎中 Cd 和 Fe 的含量大幅增加；然而，Sonarbangla 仅在根部表现出 Cd 的显著增加。这表明过量的 Cd 可能通过液泡隔离储存在 Sonarbangla 中，而不会干扰细胞功能。这进一步得到 Sonarbangla 根部中半胱氨酸、谷胱甘肽、植物螯合肽以及 OsPCS1 和 OsHMA3 的上调，以及可能由根中一氧化氮促进的积累的证实。此外，铁螯合还原酶活性以及与 Fe 可用性相关的基因（OsFRO1、OsNRAMP1、OsIRT1 和 OsYSL15）在 BRRI 72 中显著上调，但在 Sonarbangla 中没有上调，以应对 Cd。这表明在 Cd 耐受型 Sonarbangla 中，Fe 的获取和运输受到严格调控。此外，根中 CAT、APX、GR、NO 的升高以及茎中的糖有助于水稻植株抵御 Cd 诱导的氧化损伤。最后，将 Sonarbangla 根砧与 BRRI 72 或 Sonarbangla 接穗进行互惠嫁接，显示出 Sonarbangla 型耐受性，同时在高 Cd 下根中的 HO 和 Fe 还原酶活性没有变化。这表明诱导对 Cd 应激做出反应的信号源自根系。这些信息为进一步的培育计划提供了必要的背景，以生产无 Cd 的水稻。
