The role of ABF family bZIP class transcription factors in stress response

Adverse environmental conditions, such as drought, high salinity and chilling/freezing, are major limiting factors of crop productivity worldwide. According to Boyer [Science 1982;218:443–448], approximately 70% of the genetic potential yield of major crops is lost by these environmental factors. Thus, understanding how plants respond to the 'abiotic stresses' is of agronomic importance. Being sessile, plants have the capability to perceive and respond adaptively to various abiotic stresses. The adaptive capability of plants is largely dependent on the plant hormone abscisic acid (ABA), which regulates, among others, the expression of numerous genes involved in stress adaptation. Extensive genetic and molecular studies have been carried out during the last decade or so, and, as a result, a large body of information is available on the regulatory components of ABA-responsive gene expression under stress conditions. In this article, recent advances in the area are summarized, focusing on the regulatory components of ABA-dependent stress-responsive gene expression.     

The role of laterally transferred genes in adaptive evolution

Background

Bacterial genomes develop new mechanisms to tide them over the imposing conditions they encounter during the course of their evolution. Acquisition of new genes by lateral gene transfer may be one of the dominant ways of adaptation in bacterial genome evolution. Lateral gene transfer provides the bacterial genome with a new set of genes that help it to explore and adapt to new ecological niches.

Methods

A maximum likelihood analysis was done on the five sequenced corynebacterial genomes to model the rates of gene insertions/deletions at various depths of the phylogeny.

Results

The study shows that most of the laterally acquired genes are transient and the inferred rates of gene movement are higher on the external branches of the phylogeny and decrease as the phylogenetic depth increases. The newly acquired genes are under relaxed selection and evolve faster than their older counterparts. Analysis of some of the functionally characterised LGTs in each species has indicated that they may have a possible adaptive role.

Conclusion

The five Corynebacterial genomes sequenced to date have evolved by acquiring between 8 – 14% of their genomes by LGT and some of these genes may have a role in adaptation.

     

The emerging role of platelets in adaptive immunity

Platelets' foremost role in survival is hemostasis. However, a significant quantity of research has demonstrated that platelets are an integral part of inflammation and can also be potent effector cells of the innate immune response. CD154, a molecule of vital importance to adaptive immune responses, is expressed by activated platelets and has been implicated in platelet-mediated modulation of innate immunity and inflammatory disease states. Recent studies in mice extend the role of platelet CD154 to the adaptive immune response demonstrating that platelets can enhance antigen presentation, improve CD8 T cell responses, and play a critical function in normal T-dependent humoral immunity. The latter studies suggest that the current paradigm for the B cell germinal center response should be modified to include a role for platelets.     

植物WRKY转录因子在应对盐胁迫中的作用研究进展

土壤中的高含盐量严重限制了植物的生长和作物的产量。植物的许多转录因子在植物逆境胁迫中发挥着重要的作用,但仍有很多转录因子的分子机制目前尚不清楚。WRKY转录因子作为高等植物中最大的转录因子家族之一,参与并影响着植物生长发育的多个方面,在盐胁迫的多种不同响应途径中发挥重要作用。WRKY蛋白对基因表达的调控主要是通过与DNA特定顺式调控元件——W-box元件（TTGACC）的结合来实现的。近年来,从模式植物拟南芥（Arabidopsis）到农作物,已经有许多研究揭示了WRKY家族成员的作用和机制。本文综述了WRKY转录因子在应对盐胁迫方面的最新研究进展,探讨了WRKY转录因子研究目前存在的问题和未来的展望。     

The evolution of new structures: clues from plant cytoskeletal genes.

How large numbers of genes were recruited simultaneously to build new organ structures is one of the greatest puzzles in evolutionary biology. Here, we present data suggesting that the vegetative and reproductive classes of actins and other cytoskeletal proteins arose concurrently with the macroevolutionary divergence of leaves and reproductive structures in the earliest land plants. That the cytoskeleton is essential for physically programming the development of organs and tissues is well established. Thus, we propose that this regulatory dichotomy represents an ancient landmark event in the global regulation of hundreds of higher-plant genes, an event that is linked to the macroevolution of plant vegetative and reproductive organs. The recent availability of sequence and expression data for large numbers of plant genes should make it possible to dissect this and other major macroevolutionary events.     

bZIP转录因子调控植物次生代谢产物生物合成的研究进展

植物次生代谢产物是通过次生代谢产生的一类小分子有机化合物,是植物适应环境的表现,次生代谢产物也是重要药物和化工原料的来源。bZIP转录因子是普遍存在于真核生物中的一类多基因家族,可有效调控植物次生代谢产物的生物合成。本文概述了植物bZIP转录因子的结构和类型,重点阐述了bZIP转录因子调控萜类、黄酮类和生物碱等植物次生代谢产物生物合成的研究进展,并对研究前景进行了展望。深入探讨bZIP转录因子的调控机制,有助于利用基因工程技术优化植物次生代谢途径,提高次生代谢产物的含量,在新药创制、工农业生产等方面具有广泛的应用前景。     

The role of founder effects on the evolution of reproductive isolation

Several theories argue that large changes in allele frequencies through genetic drift after a small founding population becomes allopatrically isolated can lead to significant changes in reproductive isolation and thus trigger the origin of new species. For this reason, founder speciation has been proposed as a potent force in the generation of new species. Nonetheless, the relative importance of such ‘founder effects’ remains largely untested. In this report, I used experimental evolution to create one thousand replicates that underwent an extreme bottleneck and to study whether founder effects can lead to an increase in reproductive isolation in Drosophila yakuba. Even though the most common outcome of inbreeding is extinction, founder effects can lead to increased premating reproductive isolation in a very small proportion of cases. Changes in reproductive isolation after a founding population bottleneck are similar to changes in other phenotypic traits, in which inbreeding might displace the mean phenotypic value and substantially increase the phenotypic variance. This increase in phenotypic variance does not confer an increase in the response to selection for reproductive isolation in artificial selection experiments, indicating that the increased phenotypic variance is not caused by increases in additive genetic variance. These results also demonstrate that, similar to morphological and life‐history traits, behavioural traits can be affected by inbreeding and genetic drift.     

The role of adaptive strategies in plant naturalization

Determining the factors associated with the naturalization of alien species is a central theme in ecology. Here, we tested the usefulness of a metric for quantifying Grime's seminal concept of adaptive strategies – competitors, stress‐tolerators and ruderals (CSR) – to explain plant naturalizations worldwide. Using a global dataset of 3004 vascular plant species, and accounting for phylogenetic relatedness and species’ native biomes, we assessed the associations between calculated C‐, S‐ and R‐scores and naturalization success for species exhibiting different life forms. Across different plant life forms, C‐scores were positively and S‐scores negatively associated with both the probability of naturalization and the number of regions where the species has naturalized. R‐scores had positive effects on the probability of naturalization. These effects of the scores were, however, weak to absent for tree species. Our findings demonstrate the utility of CSR‐score calculation to broadly represent, and potentially explain, the naturalization success of plant species.