Antisense expression of a staygreen gene (SGR) delays leaf senescence in creeping bentgrass

Abstract

ABSTRACT: Loss of chlorophyll is the visible symptom of leaf senescence and staygreen refers to the delayed leaf senescence in plants. The staygreen gene (SGR) in rice (Oryza sativa L.) has been identified as its mutation maintains greenness during leaf senescence, and encodes a chloroplast protein required for the initiation of chlorophyll breakdown in plants. In this study, we isolated a rice SGR-homologous gene in creeping bentgrass (Agrostis stolonifera L.), and transgenic creeping bentgrass plants were obtained by introducing pCAMBIA3301 vector harboring antisense SGR gene under control of the senescence-specific SAG12 promoter. Transgenic plants were selected by herbicide resistance assays and genomic integration of the transgenes was confirmed by PCR analysis. Subsequent analyses demonstrated the staygreen phenotype of the transgenic creeping bentgrass plants with decreased chlorophyll loss during leaf senescence. These results suggest that the antisense SGR expression in creeping bentgrass delays leaf senescence, which provides a way to develop genetically engineered turfgrass varieties with the commercially useful staygreen trait. Staygreen refers to the heritable delayed foliar senescence character in plants, usually due to impaired or delayed chlorophyll catabolism.