Fluorescent protein fusions are a powerful tool to monitor the localization and trafficking of proteins. Such studies are particularly easy to carry out in the budding yeast Saccharomyces cerevisiae due to the ease with which tags can be introduced into the genome by homologous recombination. However, the available yeast tagging plasmids have not kept pace with the development of new and improved fluorescent proteins. Here, we have constructed yeast optimized versions of 19 different fluorescent proteins and tested them for use as fusion tags in yeast. These include two blue, seven green, and seven red fluorescent proteins, which we have assessed for brightness, photostability and perturbation of tagged proteins. We find that EGFP remains the best performing green fluorescent protein, that TagRFP-T and mRuby2 outperform mCherry as red fluorescent proteins, and that mTagBFP2 can be used as a blue fluorescent protein tag. Together, the new tagging vectors we have constructed provide improved blue and red fluorescent proteins for yeast tagging and three color imaging.

Proper regulation of anther differentiation is crucial for producing functional pollen, and defects in or absence of any anther cell type result in male sterility. To deepen understanding of processes required to establish premeiotic cell fate and differentiation of somatic support cell layers a cytological screen of maize male-sterile mutants has been conducted which yielded 42 new mutants including 22 mutants with premeiotic cytological defects (increasing this class fivefold), 7 mutants with postmeiotic defects, and 13 mutants with irregular meiosis. Allelism tests with known and new mutants confirmed new alleles of four premeiotic developmental mutants, including two novel alleles of msca1 and single new alleles of ms32, ms8, and ocl4, and two alleles of the postmeiotic ms45. An allelic pair of newly described mutants was found. Premeiotic mutants are now classified into four categories: anther identity defects, abnormal anther structure, locular wall defects and premature degradation of cell layers, and/or microsporocyte collapse. The range of mutant phenotypic classes is discussed in comparison with developmental genetic investigation of anther development in rice and Arabidopsis to highlight similarities and differences between grasses and eudicots and within the grasses.