铁促进半叶紫菜华北变种丝状体的生长发育及其生理生化基础

Iron Promotes the Growth and Development of Conchocelis of Pyropia katadae var. hemiphylla and Its Physiological and Biochemical Bases

中文关键词: 半叶紫菜华北变种  铁  生长  孢子囊枝形成  叶绿素荧光参数  生化特性

英文关键词: Pyropia katadae var. hemiphylla  Iron  Growth  Conchosporangial formation  Chlorophyll fluorescence parameters  Biochemical characteristics

中文摘要:

      通过探讨半叶紫菜华北变种(Pyropia katadae var. hemiphylla)丝状体在不同铁浓度下的相对生长速率(RGR)、孢子囊枝形成率及若干生理生化指标(叶绿素荧光参数、活性氧含量、抗氧化剂含量、抗氧化酶活性等)的变化规律，以期获得适宜其生长及孢子囊枝形成的铁浓度范围，并初步揭示其在不同铁浓度下的生理生化变化特征。研究结果显示，在0.040 mg/L铁浓度下，半叶紫菜华北变种营养藻丝有较高的RGR、光系统Ⅱ最大量子产量(Fv/Fm)和调节性能量耗散的量子产量[Y(NPQ)]，表明此铁浓度可促进营养藻丝的光能转换效率和光保护能力的提高，并利于其生长。高铁浓度(0.160~0.800 mg/L)组的营养藻丝RGR显著降低，而贝壳丝状体孢子囊枝形成率显著增加，表明高铁浓度抑制了藻丝的营养生长，而促进了藻丝营养生长状态向发育状态的转变。贝壳丝状体的孢子囊枝比例与Fv/Fm呈显著的正相关关系，表明营养藻丝向孢子囊枝转变后，贝壳丝状体的光能转换效率显著提高。铁的添加使藻丝中活性氧(ROS)含量显著增加，而类胡萝卜素和脯氨酸含量以及抗氧化酶[超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)]活力与ROS含量均呈显著正相关关系，表明藻丝的抗氧化系统可对铁介导的过量ROS作出积极应答，以平衡ROS的产生和清除。本研究可为半叶紫菜华北变种的苗种培育提供理论依据。

英文摘要:

      Pyropia katadae var. hemiphylla is an important Pyropia species in China. Increasing consumer demand for P. katadae var. hemiphylla has led to its commercial breeding and floating raft cultivation in Jiangsu Province and Shandong Province in China in the past two years. However, it remains to be determined what the optimum iron concentrations for the growth of conchocelis and conchosporangial formation of P. katadae var. hemiphylla are and to understand the physiological and biochemical adaptability to different iron concentrations. Therefore, relative growth rate, ratio of conchosporangial formation, and physiological and biochemical indexes (including chlorophyll fluorescence parameters, contents of reactive oxygen species, contents of antioxidant, and activities of antioxidant enzymes) under different iron concentrations were studied. From the results of these experiments, the main conclusions are as follows: Growth, maximum photochemical efficiency of photosystem Ⅱ (Fv/Fm), and quantum yield of regulated non-photochemical energy loss in photosystem Ⅱ [Y(NPQ)] of P. katadae var. hemiphylla increased significantly at an iron concentration of 0.040 mg/L, suggesting that this iron concentration improved the photosynthetic efficiency and photoprotective efficiency of vegetative conchocelis. Relative growth rate (RGR) decreased significantly in groups with high iron concentrations (0.160~0.800 mg/L), while the ratio of conchosporangial formation increased significantly at high iron concentrations. These results indicate that high iron concentrations inhibited the vegetative growth of conchocelis, while promoting the transition from vegetative growth state to developmental state. There was a significant positive correlation between the ratio of conchosporangial formation and Fv/Fm, indicating that the photosynthetic efficiency of conchocelis was significantly improved after the transformation of vegetative conchocelis to conchosporangia filaments. The addition of iron resulted in significant accumulation of reactive oxygen species (ROS) in conchocelis. The contents of carotenoids and proline, and the activities of SOD, POD, and GR in P. katadae var. hemiphylla may have increased so that the ROS level was reduced under high iron stress, thus balancing ROS production and ROS clearance. These results can provide a theoretical basis for the application of iron nutrition in the cultivation of P. katadae var. hemiphylla.