Abstract:

【Objective】 Barley starchy endosperm cell has become dead cell during endosperm development, the purpose of this study was to reveal that the death of starchy endosperm was a special form of programmed cell death (PCD). 【Method】 Structural morphology of nucleus was observed with transmission electron microscope and fluorescence microscope, the breakage of nuclear DNA was analyzed with agarose gel electrophoresis and TUNEL, the activity of antioxidant enzyme and grain filling ratio were also investigated. 【Result】 The nucleus of barley starchy endosperm showed nucleus deformation, chromatin condensation, nuclear envelope disruption, and nuclear residue formation from degraded nucleus, which were typical features of PCD, along with the development of the starchy endosperm in barley. Breakage of nuclear DNA was observed with agarose gel and TUNEL method. Nuclear residues, which were not completely lost, were observed among starch granules in starchy endosperm cells after staining with DAPI. Evan’s blue staining indicated that starchy endosperm cell death occurred unsynchronously among the starchy endosperm cells with initiation points randomly distributed in the endosperm tissue. Antioxidant enzymes showed high activities, and grain weight increased during degradation of nucleus and development of cytoplasm without nucleus. 【Conclusion】 Barley starchy endosperm cell remained alive, kept its normal metabolism, the synthesis and accumulation of starch and storage protein during degradation of nucleus and developemt of cytoplasm without nucleus. The starchy endosperm cell finally become death cell when it is completely filled with reserves. The development of starchy endosperm in barley is a special form of PCD.

Key words: barley, starchy endosperm, PCD, degradation of nucleus, breakage of DNA, antioxidant enzyme