Phenotypic Observation And Reactive Oxygen Metabolism Of Cytoplasmic Male Sterile Lines And Maintainer Lines In Rice

Plant cytoplasmic male sterility (CMS) has important value in heterosis utilization. In this study, Tianfeng A of a new wild abortive indica CMS line and its maintainer line Tianfeng B were employed as experimental materials. At first phenotypic differences between CMS line and maintainer line were observed to explore the many morphological changes caused by infertility. Secondly dynamic change differences of active oxygen metabolism and related antioxidant enzymes activity in anthers and leaves from CMS line and maintainer line were studied in the development process to investigate physiological mechanisms of the cytoplasmic male sterile rice. This study aimed to provide a theoretical basis for possible mechanisms of rice infertility and its breeding and production applications, which will have important guiding significance for rice hybrid breeding by using cytoplasmic male sterile line in the future. The results are as follows:1. plant height, length and width of flag leaves between CMS line Tianfeng A and maintainer line Tianfeng B were not significantly different, but heading stage of CMS line was later than that of the maintainer line and panicle length, panicles per plant, spikelets per panicle, spikelets shape, anthers shape were affected by sterility, which indicated that the ability of reproductive organs and its affiliated organizations to resist the adverse effects caused sterility was less than that of phytomas, so that panicles, spikelets and anthers of CMS line plants exhibited significant differences compared with that of fertile lines. In addition, it is possible that abnormal physiological metabolism of male sterile plants make the delivery of nutrients can not be carried out smoothly during the development process, and finally lead to the growth of vegetative period extended and development of reproductive period is delayed. Pollens of male sterile line can not stained with I2-KI solution and were in flat triangles or irregular polygons by scanning electron microscope, which indicated that abnormal metabolism in the process of pollen development may cause the lack of nutrient supply, so that the pollen was out of shape, and ultimately cause male sterility.2. Anthers of CMS line Tianfeng A had higher production rate of O2-, contents of H2O2 and MDA, in comparison with the maintainer line Tianfeng B. The activities of SOD and CAT were obsessively lower in CMS anthers, whereas POD activity of CMS anthers was higher than those of maintainer line. Based on the above results, abnormal metabolism of O2- and H2O2, excessive accumulation of MDA and decline of SOD and CAT activities in the process of CMS anthers development made production and scavenging of reactive oxygen species disordered. Meanwhile rising activity of POD may cause substantial degradation of IAA, which lead to lack of IAA, imbalance of nutritional metabolism, loss of physical energy during anthers development. The interaction of these factors may be an important cause of male infertility.3. Investigation of the leaves on corresponding period found differences of active oxygen metabolism between CMS line Tianfeng A and maintainer line Tianfeng B were also reflected in the leaves. Contents of H2O2 and MDA and activity of CAT in leaves of the two materials was significantly different, but the leaves had no obvious phenotypic differences. The reason may be that physiological metabolic reactions inside anther is fierce in the process of growth and development and that physiological toxicity of abnormal reactive oxygen metabolism caused by cytoplasmic male sterility mainly manifest in the active organization, so the physiological toxicity caused by the abnormal metabolism of reactive oxygen species is more obvious in the anther. It is also further confirmed that the male sterility may be caused by differences in the ability of different tissues or organs to tolerate the injury of reactive oxygen species.