As Arabidopsis flowers mature, specialized cells within the anthers undergo meiosis, leading to the production of haploid microspores that differentiate into mature pollen grains, each containing two sperm cells for double fertilization. During pollination, the pollen grains are dispersed from the anthers to the stigma for subsequent fertilization. Transcriptomic studies have identified a large number of genes expressed over the course of male reproductive development and subsequent functional characterization of some have revealed their involvement in floral meristem establishment, floral organ growth, sporogenesis, meiosis, microsporogenesis, and pollen maturation. These genes encode a plethora of proteins, ranging from transcriptional regulators to enzymes. This review will focus on the regulatory networks that control male reproductive development, starting from flower development and ending with anther dehiscence, with a focus on transcription factors and some of their notable target genes.

• Klíčová slova
• anther, flower, pathways, pollen, reproductive development, transcription factors,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Heat stress (HS) is a major abiotic stress that negatively impacts crop yields across the globe. Plants respond to elevated temperatures by changing gene expression, mediated by transcription factors (TFs) functioning to enhance HS tolerance. The involvement of Group I bZIP TFs in the heat stress response (HSR) is not known. In this study, bZIP18 and bZIP52 were investigated for their possible role in the HSR. Localization experiments revealed their nuclear accumulation following heat stress, which was found to be triggered by dephosphorylation. Both TFs were found to possess two motifs containing serine residues that are candidates for phosphorylation. These motifs are recognized by 14-3-3 proteins, and bZIP18 and bZIP52 were found to bind 14-3-3 ε, the interaction of which sequesters them to the cytoplasm. Mutation of both residues abolished 14-3-3 ε interaction and led to a strict nuclear localization for both TFs. RNA-seq analysis revealed coordinated downregulation of several metabolic pathways including energy metabolism and translation, and upregulation of numerous lncRNAs in particular. These results support the idea that bZIP18 and bZIP52 are sequestered to the cytoplasm under control conditions, and that heat stress leads to their re-localization to nuclei, where they jointly regulate gene expression.

• Klíčová slova
• 14–3–3, Arabidopsis, bZIP, heat stress, localization, transcriptomics,
• MeSH
• Arabidopsis genetika   růst a vývoj   MeSH
• buněčné jádro genetika   MeSH
• proteiny 14-3-3 genetika   MeSH
• proteiny huseníčku genetika   MeSH
• reakce na tepelný šok genetika   MeSH
• regulace genové exprese u rostlin genetika   MeSH
• RNA dlouhá nekódující genetika   MeSH
• transkripční faktory genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteiny 14-3-3 MeSH
• proteiny huseníčku MeSH
• RNA dlouhá nekódující MeSH
• transkripční faktory MeSH

Some viroids-single-stranded, non-coding, circular RNA parasites of plants-are not transmissible through pollen to seeds and to next generation. We analyzed the cause for the elimination of apple fruit crinkle viroid (AFCVd) and citrus bark cracking viroid (CBCVd) from male gametophyte cells of Nicotiana tabacum by RNA deep sequencing and molecular methods using infected and transformed tobacco pollen tissues at different developmental stages. AFCVd was not transferable from pollen to seeds in reciprocal pollinations, due to a complete viroid eradication during the last steps of pollen development and fertilization. In pollen, the viroid replication pathway proceeds with detectable replication intermediates, but is dramatically depressed in comparison to leaves. Specific and unspecific viroid degradation with some preference for (-) chains occurred in pollen, as detected by analysis of viroid-derived small RNAs, by quantification of viroid levels and by detection of viroid degradation products forming "comets" on Northern blots. The decrease of viroid levels during pollen development correlated with mRNA accumulation of several RNA-degrading factors, such as AGO5 nuclease, DICER-like and TUDOR S-like nuclease. In addition, the functional status of pollen, as a tissue with high ribosome content, could play a role during suppression of AFCVd replication involving transcription factors IIIA and ribosomal protein L5.

• Klíčová slova
• AFCVd and CBCVd propagation and eradication, Nicotiana tabacum, TUDOR S-nuclease, male gametophyte, recombinant AGO, small RNA, strand-specific viroid RT-qPCR, viroid degradation, viroid replication,
• MeSH
• fenotyp MeSH
• interakce hostitele a patogenu MeSH
• konformace nukleové kyseliny MeSH
• nemoci rostlin virologie   MeSH
• pyl virologie   MeSH
• replikace viru MeSH
• RNA virová MeSH
• tabák virologie   MeSH
• viroidy * MeSH
• virová nálož MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA virová MeSH

Callose is a plant-specific polysaccharide (β-1,3-glucan) playing an important role in angiosperms in many developmental processes and responses to biotic and abiotic stresses. Callose is synthesised at the plasma membrane of plant cells by callose synthase (CalS) and, among others, represents the main polysaccharide in the callose wall surrounding the tetrads of developing microspores and in the growing pollen tube wall. CalS proteins involvement in spore development is a plesiomorphic feature of terrestrial plants, but very little is known about their evolutionary origin and relationships amongst the members of this protein family. We performed thorough comparative analyses of callose synthase family proteins from major plant lineages to determine their evolutionary history across the plant kingdom. A total of 1211 candidate CalS sequences were identified and compared amongst diverse taxonomic groups of plants, from bryophytes to angiosperms. Phylogenetic analyses identified six main clades of CalS proteins and suggested duplications during the evolution of specialised functions. Twelve family members had previously been identified in Arabidopsis thaliana. We focused on five CalS subfamilies directly linked to pollen function and found that proteins expressed in pollen evolved twice. CalS9/10 and CalS11/12 formed well-defined clades, whereas pollen-specific CalS5 was found within subfamilies that mostly did not express in mature pollen vegetative cell, although were found in sperm cells. Expression of five out of seven mature pollen-expressed CalS genes was affected by mutations in bzip transcription factors. Only three subfamilies, CalS5, CalS10, and CalS11, however, formed monophyletic, mostly conserved clades. The pairs CalS9/CalS10, CalS11/CalS12 and CalS3 may have diverged after angiosperms diversified from lycophytes and bryophytes. Our analysis of fully sequenced plant proteins identified new evolutionary lineages of callose synthase subfamilies and has established a basis for understanding their functional evolution in terrestrial plants.

• MeSH
• fylogeneze MeSH
• glukosyltransferasy genetika   MeSH
• molekulární evoluce * MeSH
• proteiny huseníčku genetika   MeSH
• pyl * MeSH
• rostlinné geny MeSH
• transkripční faktory genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 1,3-beta-glucan synthase MeSH Prohlížeč
• glukosyltransferasy MeSH
• proteiny huseníčku MeSH
• transkripční faktory MeSH