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Male sterility induced by a chemical hybridization agent (CHA) is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in this study. CHA induced programmed cell death (PCD) as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) and DNA laddering analysis. In the early phase, CHA-SQ-1 trig-gered organelle changes and PCD in wheat leaves accompanied by excess production of reactive oxygen species (O2 and H2O2) and down-regulation of the activities of superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD). Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-1-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.

为进一步研究杀雄剂SQ-1诱导小麦雄性不育的机制，采用电子克隆的方法分离 TaPDC-E1a 基因，并利用半定量RT-PCR技术分析该基因及其调节酶基因 PDK 和 PDP 的表达特性。结果表明， TaPDC-E1a 基因编码388个氨基酸，具有TPP保守结构域，可能存在2个丝氨酸磷酸化位点；与可育系相比， TaPDC-E1a 基因在生理型不育系和遗传型不育系中表达下调； PDK 基因在生理型不育系中表达下调，而在遗传型不育系中表达上调； PDP 基因在可育系及不育系中的表达趋势无明显变化。表明经杀雄剂SQ-1诱导形成的生理型不育系在败育过程中其能量代谢途径更容易受到影响，推测对 PDK 基因进行调节的上游信号机制在小麦生理型不育系与遗传型不育系中可能不一致。

Malondialdehyde (MDA), which is thought to be important inducible factor of cell apoptosis if excessively accumulated in cells, is often regarded as a widely used marker of oxidative lipid injury whose concentration varies in response to biotic and abiotic stress. To elucidate the metabolic mechanism of ROS production and scavenging of the male sterility, normal fertility and male sterility wheat, including genetic and physiologically male sterility, by comparing MDA content and antioxidant enzymes changes in the sterile and fertile leaves, spikes, florets, rachillaes, ovaries and anthers at different developmental anther stages, were employed for studying the relationship between the male sterility and membrane lipid peroxidation, antioxidant enzymes. The results showed that tissue of male sterility had roughly higher content of MDA than corresponding fertile plants, and ovary performance was not obvious but most obvious in anther. Simultaneously, the higher activities of antioxidant enzymes were measured in the anthers of male sterility plant, in which an increase of ROS in anthers of abortion stage had an inducible effect on the antioxidant enzymes. MDA content and scavenging-enzyme activities had difference in the sterile and fertile leaves, spikes, florets, rachillaes at different anther stages, indicating that different tissues of ROS metabolism had noticeable difference in male sterility and normal wheat. It can be considered that the disorder of scavenging-enzyme activities and accumulation of MDA in the male organ, and supplier of nutrition blades were causing a further substance metabolism disorder, energy loss, leading to the occurrence of male sterility. Key words: Wheat - male sterility – malondialdehyde - antioxidant enzymes Abbreviations: CAT---Catalase; CMS---Cytoplasmic male sterility; CHA---Chemical Hybridization Agent; GS---Cytoplasmic male sterile line (S)-1376; MDA---Malondialdehyde; NW---Wheat cultivar 1376; PMS---CHA-SQ-1 induced male sterility wheat; POD---Peroxidase; ROS---Reactive oxygen species; SOD---Superoxide dismutase; SEM---Scanning electronm icroscopy.