Zang Jie, Yao Xueyan, Zhang Tengfei, Yang Boming, Wang Zhen, Quan Shuxuan, Zhang Zhaogui, Liu Juan, Chen Huabang, Zhang Xiansheng, Hou Yifeng
National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agricultural Sciences in Weifang, Shandong, China.
State Key Laboratory of Plant Cell and Chromosome Engineering, Innovative Academy of Seed Design, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
J Cell Physiol. 2024 Dec;239(12):e31427. doi: 10.1002/jcp.31427. Epub 2024 Sep 6.
Iron (Fe) storage in cereal seeds is the principal source of dietary Fe for humans. In maize (Zea mays), the accumulation of Fe in seeds is known to be negatively correlated with crop yield. Hence, it is essential to understand the underlying mechanism, which is crucial for developing and breeding maize cultivars with high yields and high Fe concentrations in the kernels. Here, through the successful application of in vitro kernel culture, we demonstrated that excess Fe supply in the medium caused the kernel to become collapsed and lighter in color, consistent with those found in yellow strip like 2 (ysl2, a small kernel mutant), implicated a crucial role of Fe concentration in kernel development. Indeed, over-accumulation of Fe in endosperm inhibited the abundance and activity of ADP-glucose pyrophosphorylase (AGPase) and the kernel development defect was alleviated by overexpression of Briittle 2 (Bt2, encoding a small subunit of AGPase) in ysl2 mutant. Imaging and quantitative analyses of reactive oxygen species (ROS) and cell death showed that Fe stress-induced ROS burst and severe DNA damage in endosperm cells. In addition, we have successfully identified candidate genes that are associated with iron homeostasis within the kernel, as well as upstream transcription factors that regulate ZmYSL2 by yeast one-hybrid screening. Collectively, our study will provide insights into the molecular mechanism of Fe accumulation-regulated seed development and promote the future efficient application of Fe element in corn improvement.
谷物种子中的铁（Fe）储存是人类膳食铁的主要来源。在玉米（Zea mays）中，已知种子中铁的积累与作物产量呈负相关。因此，了解其潜在机制至关重要，这对于培育籽粒产量高且铁含量高的玉米品种至关重要。在这里，通过体外籽粒培养的成功应用，我们证明培养基中过量的铁供应会导致籽粒塌陷且颜色变浅，这与在类黄色条纹2（ysl2，一种小籽粒突变体）中发现的情况一致，这表明铁浓度在籽粒发育中起关键作用。事实上，胚乳中铁的过度积累抑制了ADP-葡萄糖焦磷酸化酶（AGPase）的丰度和活性，并且通过在ysl2突变体中过表达脆性2（Bt2，编码AGPase的一个小亚基）缓解了籽粒发育缺陷。活性氧（ROS）和细胞死亡的成像及定量分析表明，铁胁迫诱导胚乳细胞中ROS爆发和严重的DNA损伤。此外，我们通过酵母单杂交筛选成功鉴定了与籽粒中铁稳态相关的候选基因，以及调控ZmYSL2的上游转录因子。总的来说，我们的研究将为铁积累调控种子发育的分子机制提供见解，并促进未来铁元素在玉米改良中的高效应用。
