Anatomy and cytology of microsporogenesis in cytoplasmic male sterile angiosperms

Interactions of Mitochondrial and Nuclear Genes That Affect Male Gametophyte Development

“…Before PCD was recognized as a specific phenomenon, many investigators documented microscopic evidence of premature breakdown of the tapetal layer and mitochondrial morphology changes in dying anther cells (reviewed by Laser and Lersten, 1972;Kaul, 1988). As in animals, plant mitochondria appear to play a role in interpreting signals for cell death (Lam et al, 2001).…”

“…Unfortunately, as discussed above, the mitochondrial disruption leading to CMS often occurs very early in pollen development, when anthers are very small and it is difficult to obtain quantities of tissue for biochemical analysis. Furthermore, the microscopic analysis of CMS plants in many species has indicated that disruption of mitochondrial integrity in the tapetal layer is the first sign of abnormal development and thus may be the cause of microspore abortion (Laser and Lersten, 1972;Kaul, 1988). Because the tapetal layer represents only a small percentage of the total anther tissue, features of the expression of CMS-associated regions in CMS versus restored lines may not be reflected accurately by analysis of total anther transcripts and proteins.…”

“…Although all of the other restorer systems discussed in this review, which require only a single dominant allele, are known to have an effect on the expression of the CMS-associated mtDNA region, it is possible that some of the complex, multigenic restorer systems found in some species (reviewed by Laser and Lersten, 1972;Kaul, 1988) may include genes that act by rescuing the developing pollen through a metabolic effect, compensating for the presence of a toxic protein rather than preventing its expression.…”

Multi-step formation, evolution, and functionalization of new cytoplasmic male sterility genes in the plant mitochondrial genomes

“…Studies have shown that in the angiosperm mitochondrial genomes, frequent DNA recombination may result in genomic rearrangements, yielding multiple types of recombinant structures that may vary dramatically in copy number (substoichiometric shifting (SSS)); the recombinant structures may contain new open reading frames (ORFs) and some of them can cause cytoplasmic male sterility (CMS) [3][4][5]. CMS is a widespread phenomenon observed in more than 150 flowering plant species [6] and often associated with unusual ORFs present in the mitochondrial genomes [5]. To date, a number of CMS genes have been cloned from various plant species, and they are usually chimeric, involving sequences homologous to mitochondrial essential genes for ATPase, cytochrome c oxidase, or ribosomal proteins [4,5].…”

Novel genetic male sterility developed in (Capsicum annuum x C. chinense) x C. pubescens and induced by HNO2 showing Mendelian inheritance and aborted at telophase of microspore mother cell stage

“…Pollen abortion occurred through microspore mother cell stage and binucleus microspore stage, but the pattern and stage varied in different plants (Laser and Lersten, 1972). The chromosome bridge and fragments appearing in the later stage of meiosis caused irregular division during meiosis (Zenkteler, 1962).…”