CAJ | 학술논문

以水稻(Oryza sativa L.)品种Agucena(铁耐性)和IR64(铁敏感)为材料,研究了Fe2+毒胁迫下附着于根尖边缘细胞(即原位边缘细胞)的数目、存活率,根尖细胞形态结构、根尖保护酶活性的变化.结果显示,Fe2+毒对根边缘细胞的产生有抑制作用.相对于敏感性品种而言,一定浓度的Fe2+(100～200 μmol/L)有利于耐性品种边缘细胞的产生;Fe2+毒对边缘细胞有致死效应,随Fe2+浓度的提升,边缘细胞的存活率呈下降趋势,根尖外围细胞壁增厚,并出现细胞程序性死亡特征(敏感性品种).同时,Fe2+毒对根尖保护酶活性有一定的影响,200～400 μmol/L Fe2+处理下,耐性品种过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物岐化酶(SOD)活性都超过对照;敏感品种只有SOD活性超过对照.说明Fe2+毒胁迫下,水稻根尖可通过增加边缘细胞数目、提高细胞拒铁作用,维持较高水平的POD、CAT和SOD活性来对抗Fe2+毒,缓解铁毒害.
이수도(Oryza sativa L.)품충Agucena(철내성)화IR64(철민감)위재료,연구료Fe2+독협박하부착우근첨변연세포(즉원위변연세포)적수목、존활솔,근첨세포형태결구、근첨보호매활성적변화.결과현시,Fe2+독대근변연세포적산생유억제작용.상대우민감성품충이언,일정농도적Fe2+(100～200 μmol/L)유리우내성품충변연세포적산생;Fe2+독대변연세포유치사효응,수Fe2+농도적제승,변연세포적존활솔정하강추세,근첨외위세포벽증후,병출현세포정서성사망특정(민감성품충).동시,Fe2+독대근첨보호매활성유일정적영향,200～400 μmol/L Fe2+처리하,내성품충과양화물매(POD)、과양화경매(CAT)、초양화물기화매(SOD)활성도초과대조;민감품충지유SOD활성초과대조.설명Fe2+독협박하,수도근첨가통과증가변연세포수목、제고세포거철작용,유지교고수평적POD、CAT화SOD활성래대항Fe2+독,완해철독해.
Toxicity of Fe2+ is one of the major constraints for lowland rice production in tropical and subtropical areas. However the mechanism of Fe-induced inhibition of root growth and the reasons for the spatial variations in Fe2+sensitivi-ty among the apical root zones are still poorly understood. The root tip is a primary site of Fe2+ toxicity in rice. The root border cells (BC), which originate from the root cap meristem by mitosis, can separately carry out metabolism and resist adverse stress through a series of distinct responses. In this study, the response mechanism of the root tip cells to Fe2+ toxicity were tested by comparing response of rice varieties Azucena (Fe-tolerance) and IR64 (Fe-sensitive) known to vary in Fe2+resistance at a whole-root level. Results showed that Fe2+ toxicity inhibited the development of BC. Howev-er, compared to IR64, Fe2+ at 100 - 200μmol/L was propitious to the development of BC in Azucena. With increase of Fe2+ concentration, the viability of the rice BC became lower, the cell wall of root tip outermost cells became thicker, and some characteristics of programmed cell death were observed in the ceils (Fe-sensitive variety). Meanwhile, Fe2+ concentration affected the activities of poroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). Higher enzyme activities were found in Fe-tolerance variety under high concentration Fe2+ ( ≥ 200 μmol/L) compared to control. These results indicated that, under the Fe2+ toxicity, root tip could resist Fe2+ toxicity by increasing BC, thickening cell wall, maintaining high POD, CAT and SOD activities.