A wheat COP9 subunit 5‐like gene is negatively involved in host response to leaf rust

The COP9 (constitutive photomorphogenesis 9) signalosome (CSN) is a protein complex involved in the ubiquitin proteasome system and a common host target of diverse pathogens in Arabidopsis. The known derubylation function of the COP9 complex is carried out by subunit 5 encoded by AtCSN5A or AtCSN5B in Arabidopsis. A single CSN5‐like gene (designated as TaCSN5) with three homeologues was identified on the long arms of wheat (Triticum aestivum L.) group 2 chromosomes. In this study, we identified and characterized the function of TaCSN5 in response to infection by the leaf rust pathogen. Down‐regulation of all three TaCSN5 homeologues or mutations in the homeologues on chromosomes 2A or 2D resulted in significantly enhanced resistance to leaf rust. Enhanced leaf rust resistance corresponded to a seven‐fold increase in PR1 (pathogenesis‐related gene 1) expression. Collectively, the data indicate that the wheat COP9 subunit 5‐like gene acts as a negative regulator of wheat leaf rust resistance.     

Reshaping of the tumor microenvironment by cellular senescence: An opportunity for senotherapies

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Restoration of CPEB4 prevents muscle stem cell senescence during aging

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河南省16个主栽小麦品种抗叶锈基因分析

为了明确河南省小麦品种的抗叶锈性及抗叶锈基因的分布,为小麦品种推广与合理布局、叶锈病防治及抗病育种提供依据,本研究利用2015年采自河南省的5个小麦叶锈菌流行小种混合菌株,对近几年河南省16个主栽小麦品种进行了苗期抗性鉴定,然后选用12个小麦叶锈菌生理小种对这些品种进行苗期基因推导,同时利用与24个小麦抗叶锈基因紧密连锁(或共分离)的30个分子标记对该16个品种进行了抗叶锈基因分子检测。结果显示,供试品种苗期对小麦叶锈菌混合流行小种均表现高度感病;基因推导与分子检测结果表明,供试品种可能含有Lr1、Lr16、Lr26和Lr30这4个抗叶锈基因,其中先麦8号含有Lr1和Lr26;郑麦366和郑麦9023含有Lr1;西农979和怀川916含有Lr16;中麦895、偃展4110、郑麦7698、平安8号、众麦1号、周麦16、衡观35和矮抗58含有Lr26;周麦22中含有Lr26,还可能含有Lr1和Lr30;豫麦49-198和洛麦23可能含有本研究中检测以外的其他抗叶锈基因。因此,河南省主栽小麦品种的抗叶锈基因丰富度较低,今后育种工作应注重引入其他抗叶锈性基因,提高抗叶锈性,有效控制小麦叶锈病。     

Hybrid crosses and the genetic basis of interspecific divergence in lifespan in Pristionchus nematodes

Characterizing the genetic basis of among‐species variation in lifespan is a major goal of evolutionary gerontology research, but the very feature that defines separate species – the inability to interbreed – makes achieving this goal impractical, if not impossible, for most taxa. Pristionchus nematodes provide an intriguing system for tackling this problem, as female lifespan varies among species that can be crossed to form viable (although infertile) hybrids. By conducting reciprocal crosses among three species – two dioecious (long‐lived Pristionchus exspectatus and short‐lived Pristionchus arcanus) and one androdioecious (short‐lived Pristionchus pacificus) – we found that female lifespan was long for all hybrids, consistent with the hypothesis that the relatively short lifespans seen for P. pacificus hermaphrodites and P. arcanus females are caused by independent, recessive alleles that are masked in hybrid genomes. Cross‐direction had a small effect on survivorship for crosses involving P. exspectatus, indicating that nuclear–mitochondrial interactions may also influence Pristionchus longevity. Our findings suggest that long lifespan in P. exspectatus reflects the realization of an ancestral potential for extended longevity in the P. pacificus species complex. This work demonstrates the utility of interspecific hybrids for ageing research and provides a foundation for future work on the genetic architecture of interspecific lifespan variation.     

Do reef corals age?

Hydra is emerging as a model organism for studies of ageing in early metazoan animals, but reef corals offer an equally ancient evolutionary perspective as well as several advantages, not least being the hard exoskeleton which provides a rich fossil record as well as a record of growth and means of ageing of individual coral polyps. Reef corals are also widely regarded as potentially immortal at the level of the asexual lineage and are assumed not to undergo an intrinsic ageing process. However, putative molecular indicators of ageing have recently been detected in reef corals. While many of the large massive coral species attain considerable ages (>600 years) there are other much shorter‐lived species where older members of some populations show catastrophic mortality, compared to juveniles, under environmental stress. Other studies suggestive of ageing include those demonstrating decreased reproduction, increased susceptibility to oxidative stress and disease, reduced regeneration potential and declining growth rate in mature colonies. This review aims to promote interest and research in reef coral ageing, both as a useful model for the early evolution of ageing and as a factor in studies of ecological impacts on reef systems in light of the enhanced effects of environmental stress on ageing in other organisms.     

A hierarchical multi‐scale analysis of the spatial relationship between parasitism and host density in urban habitats

Studies on spatial density dependence in parasitism have paid scarce attention to how changes in host density at different hierarchical scales could influence parasitism in an herbivore at a particular scale. Here, we evaluated if rates of parasitism per leaf (by the whole parasitic complex and by dominant species) of the specialist leaf miner Liriomyza commelinae (Diptera: Agromyzidae) respond to variations in host density at the leaf, plant patch and site levels in an urban setting. We used multi‐level Bayesian models that incorporate the spatial hierarchy occurring in this system, as well as habitat factors previously found to have an effect on the L. commelinae parasitoid community in an urban context (patch size, patch isolation and urbanization level). According to the fitted model, overall parasitism rates decreased with increasing number of mines per leaf, being independent of host‐density variations at patch and site level. Patch structure was found to have a strong effect on parasitism rates per leaf. The analysis of parasitism by parasitoid species separately showed consistent results with the response at community level. These results suggest that parasitism of the parasitoid community here studied would be sensitive to hierarchical cues related to the host at the leaf level and to the host habitat at the patch level.