Some Like It Hot, Some Like It Warm: Phenotyping To Explore Thermotolerance Diversity

Plants have evolved overlapping but distinct cellular responses to different aspects of high temperature stress. These responses include basal thermotolerance, short- and long-term acquired thermotolerance, and thermotolerance to moderately high temperatures. This ‘thermotolerance diversity’ means that multiple phenotypic assays are essential for fully describing the functions of genes involved in heat stress responses. A large number of genes with potential roles in heat stress responses have been identified using genetic screens and genome wide expression studies. We examine the range of phenotypic assays that have been used to characterize thermotolerance phenotypes in both Arabidopsis and crop plants. Three major variables differentiate thermotolerance assays: (1) the heat stress regime used, (2) the developmental stage of the plants being studied, and (3) the actual phenotype which is scored. Consideration of these variables will be essential for deepening our understanding of the molecular genetics of plant thermotolerance

Mutation breeding, genetic diversity and crop adaptation to climate change

This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.illustrato

How the other half lives: CRISPR-Cas's influence on bacteriophages

CRISPR-Cas is a genetic adaptive immune system unique to prokaryotic cells used to combat phage and plasmid threats. The host cell adapts by incorporating DNA sequences from invading phages or plasmids into its CRISPR locus as spacers. These spacers are expressed as mobile surveillance RNAs that direct CRISPR-associated (Cas) proteins to protect against subsequent attack by the same phages or plasmids. The threat from mobile genetic elements inevitably shapes the CRISPR loci of archaea and bacteria, and simultaneously the CRISPR-Cas immune system drives evolution of these invaders. Here we highlight our recent work, as well as that of others, that seeks to understand phage mechanisms of CRISPR-Cas evasion and conditions for population coexistence of phages with CRISPR-protected prokaryotes.Comment: 24 pages, 8 figure

Effects of space flight factors on genetic diversity of Buchloe dactyloides seeds

The objective of this research was to investigate the effects of space flight factors on Buchloe dactyloides “Jingyin No.3” seeds. After the retrieval, basic turf characters of plants were tested. Among the 100 plants tested, 21 showed great change on phenotype characters, including leaf blade length and width, height, stem diameter, number of tillers, number and length of stolon, length of stolon inter node, leaf color and extent of leaf turning yellow. 33 primers were screened in inter-simple sequence repeats (ISSR) analysis to evaluate DNA variation between mutations and their ground controls. Results show that 15.6 reliable bands were generated by 7 primers, of which 12.9 (80.9%) were polymorphic. Based on the study, we can conclude that the space flight factors could induce inheritable mutagenic changes on B. dactyloides seeds, and do further research to demonstrate these changes in genetic material of the mutants.Key words: Genetic diversity, Buchloe dactyloides, spaceflight, inter-simple sequence repeats

Phenotypic robustness can increase phenotypic variability after non-genetic perturbations in gene regulatory circuits

Non-genetic perturbations, such as environmental change or developmental noise, can induce novel phenotypes. If an induced phenotype confers a fitness advantage, selection may promote its genetic stabilization. Non-genetic perturbations can thus initiate evolutionary innovation. Genetic variation that is not usually phenotypically visible may play an important role in this process. Populations under stabilizing selection on a phenotype that is robust to mutations can accumulate such variation. After non-genetic perturbations, this variation can become a source of new phenotypes. We here study the relationship between a phenotype's robustness to mutations and a population's potential to generate novel phenotypic variation. To this end, we use a well-studied model of transcriptional regulation circuits. Such circuits are important in many evolutionary innovations. We find that phenotypic robustness promotes phenotypic variability in response to non-genetic perturbations, but not in response to mutation. Our work suggests that non-genetic perturbations may initiate innovation more frequently in mutationally robust gene expression traits.Comment: 11 pages, 5 figure

Regulation and Identity of Florigen: Flowering Locus T Moves Center Stage

The transition from vegetative to reproductive growth is controlled by day length in many plant species. Day length is perceived in leaves and induces a systemic signal, called florigen, that moves through the phloem to the shoot apex. At the shoot apical meristem (SAM), florigen causes changes in gene expression that reprogram the SAM to form flowers instead of leaves. Analysis of flowering of Arabidopsis thaliana placed the CONSTANS/FLOWERING LOCUS T (CO/FT) module at the core of a pathway that promotes flowering in response to changes in day length. We describe progress in defining the molecular mechanisms that activate this module in response to changing day length and the increasing evidence that FT protein is a major component of florigen. Finally, we discuss conservation of FT function in other species and how variation in its regulation could generate different flowering behaviors

Plant responses to photoperiod

Photoperiod controls many developmental responses in animals, plants and even fungi. The response to photoperiod has evolved because daylength is a reliable indicator of the time of year, enabling developmental events to be scheduled to coincide with particular environmental conditions. Much progress has been made towards understanding the molecular mechanisms involved in the response to photoperiod in plants. These mechanisms include the detection of the light signal in the leaves, the entrainment of circadian rhythms, and the production of a mobile signal which is transmitted throughout the plant. Flowering, tuberization and bud set are just a few of the many different responses in plants that are under photoperiodic control. Comparison of what is known of the molecular mechanisms controlling these responses shows that, whilst common components exist, significant differences in the regulatory mechanisms have evolved between these responses

The physicist's guide to one of biotechnology's hottest new topics: CRISPR-Cas

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated proteins (Cas) constitute a multi-functional, constantly evolving immune system in bacteria and archaea cells. A heritable, molecular memory is generated of phage, plasmids, or other mobile genetic elements that attempt to attack the cell. This memory is used to recognize and interfere with subsequent invasions from the same genetic elements. This versatile prokaryotic tool has also been used to advance applications in biotechnology. Here we review a large body of CRISPR-Cas research to explore themes of evolution and selection, population dynamics, horizontal gene transfer, specific and cross-reactive interactions, cost and regulation, non-immunological CRISPR functions that boost host cell robustness, as well as applicable mechanisms for efficient and specific genetic engineering. We offer future directions that can be addressed by the physics community. Physical understanding of the CRISPR-Cas system will advance uses in biotechnology, such as developing cell lines and animal models, cell labeling and information storage, combatting antibiotic resistance, and human therapeutics.Comment: 75 pages, 15 figures, Physical Biology (2018

Fungal model systems and the elucidation of pathogenicity determinants

Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.Peer reviewedPublisher PD