Institute of Molecular and Cellular Biosciences (IMCB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Published: February 2007
AI Article Synopsis
Article Abstract
While mammals and fungi possess nicotinate/nicotinamide mononucleotide adenyltransferase (NMNAT) isoforms, Arabidopsis thaliana only contains a single NMNAT gene, AtNMNAT (At5g55810). We analyzed the enzymatic activity of the AtNMNAT-encoded protein to determine the role of AtNMNAT in plant development. AtNMNAT catalyzed the synthesis of nicotinate adenine dinucleotide (NaAD) from nicotinate mononucleotide (NaMN) in the Preiss-Handler-dependent pathway, and of nicotinamide adenine dinucleotide (NAD) from nicotiamide mononucleotide (NMN) in the Preiss-Handler-independent pathway. Prominent AtNMNAT expression was detected in the male gametophyte. Moreover, AtNMNAT expression was spatio-temporally regulated during microspore development and pollen tube growth. Disruption of the AtNMNAT gene (atnmnat mutant) was characterized by a decrease in NAD content in pollen. Cytological examinations revealed that the atnmnat mutant was gametophytically impaired in in vivo and in vitro pollen tube growth. Our results suggest that metabolic fulfillment via the NAD pathway is indispensable for normal pollen growth and subsequent normal seed production.
Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA. Electronic address:
Phosphatidic acid (PA) is an important class of signaling lipids involved in various biological processes in plants. Functional characterization of the mutants of PA's metabolizing enzymes coupled with lipidomics and protein-lipid interaction analyses have revealed that PA signaling is involved in plant response to biotic and abiotic stress. Moreover, PA and its metabolizing enzymes have been found to affect various reproductive steps, including gametogenesis, pollen tube growth, self-incompatibility, haploid embryo formation, embryogenesis, and seed development.
Pollen development and germination play a crucial role in the sexual reproduction of plants. This study analysis of transcriptional dynamics of foxtail millet pollen with other tissues and organs (ovule, glume, seedling and root) through RNA-sequencing revealed that a total of 940 genes were up-regulated in foxtail millet pollen. Based on this, we analyzed the genes involved in pollen tube growth of receptor kinases and small peptides, calcium signaling, small G proteins, vesicle transport, cytoskeleton, cell wall correlation, and transcription factors that are up-regulated in pollen.
Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou, Guangdong, P. R. China.
Genetic transformation is a pivotal approach in plant genetic engineering. Peanut (Arachis hypogaea L.) is an important oil and cash crop, but the stable genetic transformation of peanut is still difficult and inefficient.
Several agriculturally valuable plants store their pollen in tube-like poricidal anthers, which release pollen through buzz pollination. In this process, bees rapidly vibrate the anther using their indirect flight muscles. The stiffness and resonant frequency of the anther are crucial for effective pollen release, yet the impact of turgor pressure on these properties is not well understood.
In flowering plants, pollen grain must undergo a series of critical processes, including adhesion, hydration, and germination, which are dependent on the stigma, to develop a pollen tube. This pollen tube then penetrates the stigma to reach the internal tissues of pistil, facilitating the transport of non-motile sperm cells to the embryo sac for fertilization. However, the dry stigma, characterized by the absence of an exudate that typically envelops the wet stigma, functions as a multi-layered filter in adhesion, hydration, germination and penetration that permits the acceptance of compatible pollen or tubes while rejecting incompatible ones, thereby protecting the embryo sac from ineffective fertilization and maintaining species specificity.
