Abstract

Wheat starchy endosperm is fated to die prior to seed maturation. To reveal the death process of wheat starchy endosperm, morphological variations of the nucleus, the breakage of nuclear DNA, the activities of enzymes related to starch synthesis and antioxidization, and grain weight were investigated. Results showed that wheat starchy endosperm death consisted of two main steps: Nucleus degeneration and subsequent denucleated cell development. Nucleus degeneration showed deformation, chromatin condensation, nuclear envelope disruption, and nuclear residue formation from the degenerative nucleus, which were typical features of programmed cell death (PCD), along with starchy endosperm development. Evans blue staining indicated that starchy endosperm cell death occurred asynchronously among the starchy endosperm cells with initiation points randomly distributed in the endosperm tissue. Enzymes related to starch synthesis and anti-oxidization showed high activities and grain weight increased during nucleus degeneration and denucleated cell development stages. These results suggested that the death of wheat starchy endosperm is a special form of PCD.

Key words: Wheat, starchy endosperm cell, programmed cell death, endosperm development, nucleus degeneration, denucleated cell development.