Stay-green mutants of all botanical species have similar phenotypic features.The senescence is delayed,and chlorophyll degradation is blocked or slowed.Nevertheless,the molecular mechanism of stay-green in these mutants is quite different owing to different genetic basis.The authors summarize the progresses in research on the physiological and biochemical behaviors(mostly concentrated on the enzyme-catalyzed metabolic pathway of chlorophyll),hereditary features and molecular biological aspects in various stay-green mutants.They also describe the importance of stay-green mutation to the research of chlorophyll metabolism,leaf senescence,photosynthesis and other physiological processes in plants,as well as the perspective of exploiting the advantages of these mutants in many aspects of agriculture.Among the many types of stay-green mutants,the most promising and significant can be the functional Type A and Type B which are distinguished for their increased yields and improved resistance against stresses.Furthermore,thorough understanding of changes in the molecular mechanism of stay-green is a potential access to consummately solving the presenility problem of crops.