Color of bedded chert and redox condition of depositional environment. 57Fe Moessbauer spectroscopic study on chemical state of iron in Triassic deep-sea pelagic chert.

Abstract

The development and differentiation of anther cells, including specification of cell lineage and cell fate, are well-regulated programs. Sporogenous cells differentiate into pollen mother cells (PMCs) and enter meiosis. In addition, differentiated anther wall cells degrade sequentially during pollen maturation and their dehiscence excludes mature pollen. This degradation process appears to be controlled by programmed cell death (PCD). Maternally-inherited male sterility is common in various plant species and is referred to as cytoplasmic male sterility (CMS). In some examples of CMS, floral organ identity is unperturbed, but the anther tissues degenerate by processes of PCD or necrotic cell death. In addition, abiotic stresses dominantly affect male reproductive development. In particular, high-temperature stress causes male sterility in many plant species. We use the double-rowed barley (Hordeum vulgare L. cv. Haruna-nijyo) as a model for male reproductive development and high-temperature injury in plants. This type of injury relates to premature progression of early developmental programs in anthers and includes proliferation arrest, degradation of anther wall cells and progression to meiosis in PMCs, all of which require comprehensive alterations in transcription. Given the involvement of PCD in anther-specific sequential and cooperative programs, as well as in cell fates, these findings suggest that male reproductive development might be more sensitive to environmental stresses than female reproductive development and vegetative growth. We also introduce certain key genes that have been identified recently and relate specifically to male reproductive development and sterility