Vegetative Reproductive Phases Research Articles

TheCOP1OrthologPPSRegulates the Juvenile–Adult and Vegetative–Reproductive Phase Changes in Rice

Because plant reproductive development occurs only in adult plants, the juvenile-to-adult phase change is an indispensable part of the plant life cycle. We identified two allelic mutants, peter pan syndrome-1 (pps-1) and pps-2, that prolong the juvenile phase in rice (Oryza sativa) and showed that rice PPS is an ortholog of Arabidopsis thaliana CONSTITUTIVE PHOTOMORPHOGENIC1. The pps-1 mutant exhibits delayed expression of miR156 and miR172 and the suppression of GA biosynthetic genes, reducing the GA(3) content in this mutant. In spite of its prolonged juvenile phase, the pps-1 mutant flowers early, and this is associated with derepression of RAP1B expression in pps-1 plants independently of the Hd1-Hd3a/RFT1 photoperiodic pathway. PPS is strongly expressed in the fourth and fifth leaves, suggesting that it regulates the onset of the adult phase downstream of MORI1 and upstream of miR156 and miR172. Its ability to regulate the vegetative phase change and the time of flowering suggests that rice PPS acquired novel functions during the evolution of rice/monocots.

Mating Type and Vegetative Incompatibility in Filamentous Ascomycetes

In filamentous ascomycetes, mating type and vegetative incompatibility con­ fer selflnonself recognition in the sexual and vegetative reproductive phases, respectively. In the first section of this review, we discuss selflnonself recognition in the sexual cycle, with specific emphasis on the ascomycetes, Neurospora crassa, Podospora anserina, and Cochliobolus heterostrophus. The recent cloning and sequencing of the mating-type genes from these organisms has allowed the clarification of molecular aspects regarding the regulation of the sexual cycle. From a practical standpoint, understanding the regulation of mating type can be important to the plant pathologist. The sexual cycle can generate genetic diversity that can adversely affect resistance breeding or chemical control strategies. Sexual reproduction results in asco­ spores that can function as overwintering structures or infective propagules and can be an important component of the disease cycle. The second section of this review covers vegetative incompatibility and its role in self/nonself recognition during asexual reproduction. The genetics of Neurospora crassa, Aspergillus nidulans, and Podospora anserina, and the

Morphology and Cytology of Diplocarpon Maculatum on Crataegus. I. The Entomosporium Stage

(1966). Morphology and Cytology of Diplocarpon Maculatum on Crataegus. I. The Entomosporium Stage. Mycologia: Vol. 58, No. 6, pp. 949-960.