小麦矮秆突变体jm22d响应赤霉素处理的转录组学分析

为拓宽小麦矮秆遗传资源,利用γ射线辐照济麦22获得了一个赤霉素不敏感型矮秆突变体jm22d。株高相关性状调查结果及茎秆细胞学试验显示,jm22d株高为53±1.8 cm,比野生型（WT）低约20 cm。jm22d整株茎秆共有4节,比WT少一节且各节间长度显著小于WT。与WT相比,jm22d茎秆细胞长度缩短。赤霉素含量测定发现,jm22d叶片中赤霉素含量高于WT,而茎秆中赤霉素含量低于WT（P<0.01）,因此,jm22d株高降低与赤霉素转运途径出现异常有关。为了深入研究jm22d对赤霉素的响应机理,对jm22d和WT幼苗进行赤霉素处理,分别收取处理0（D0）、1（D1）和3 d（D3）的样品进行转录组学分析。结果表明,与WT相比,在jm22d中共筛选到696个上调和1 067个下调的表达基因,其中62个和349个基因在3个时间点分别表现为上调和下调表达。叶绿素含量测定表明,jm22d中叶绿素含量随赤霉素处理时间的延长而降低,聚类分析结果表明,差异表达基因主要富集在光合作用-天线蛋白（photosynthesis-antenna proteins,ko00196）、卟啉和叶绿素代谢（porphyrin and chlorophyll metabolism,ko00860）、亚油酸新陈代谢（linoleic acid metabolism,ko00591）等通路,因此赤霉素处理对jm22d体内叶绿素含量的积累具有抑制作用。通过KEGG分析在植物激素信号转导途径中挖掘到5个差异表达基因（TraesCS2B01G582300、TraesCS2B01G600800、TraesCS2B01G556600、TraesCS2B01G630000和TraesCS6B01G439600）参与生长素、细胞分裂素等激素代谢途径,这些基因在jm22d中显著下调,这可能是jm22d矮化的重要原因。研究结果为矮秆突变体矮化机制的解析提供了重要参考。     

The long-run heterogeneous effects of a cholera pandemic on stature: Evidence from industrializing Japan

The recent COVID-19 pandemic poses the general question on how infectious diseases can persistently affect human health. A growing body of literature has found a significant amount of evidence on the long-term adverse effects of infectious diseases, such as influenza, typhoid fever, and yellow fever. However, we must be careful about the fact that little is known about the long-term consequences of the acute diarrheal disease pandemic cholera – Vibrio cholerae bacillus – which still threatens the health of the population in many developing countries. To bridge this gap in the body of knowledge, we utilized unique census-based data on army height at age 20 in early 20th-century Japan, with a difference-in-differences estimation strategy using regional variation in the intensity of cholera pandemics. We found that early-life exposure to a cholera pandemic had heterogeneous stunting effects on the final height of men; the magnitude of the stunting effects increased as the intensity of exposure increased.     

The influence of light conditions and interspecific competition on the root foraging traits and seedling growth of two tree species

Abstract

Enriched nutrient patches within natural soil represent an important source of nutrients for tree growth. In the present study, pot experiments in a heterogeneous nutrient environment were conducted to investigate the influence of light conditions and interspecific competition on the root foraging traits and seedling growth of Pinus massoniana and Schima superba. The root foraging scale and the whole-seedling biomass of both species were decreased by shading. The result of this treatment was a lower sensitivity to nutrient heterogeneity in plants that underwent the shading treatment than in plants that were exposed to full-light conditions. The above-ground biomass and whole-seedling biomass of S. superba were not affected by competition with P. massoniana. In contrast, the above-ground biomass and whole-seedling biomass of P. massoniana were negatively affected by competition with S. superba. The more rapid rate of root extension and the more efficient resource uptake of S.superba appear to explain this effect. The species-specific patterns of the influence of environmental factors on foraging ability and seedling growth should be given thorough consideration and should be applied to afforestation and to the management of tree plantations.     

Spatial segregation of four coexisting processional termites (Termitidae: Nasutitermitinae) in tropical rainforest

In Lambir Hills National Park, Sarawak, Malaysia, there are four species of processional termites that coexist: Hospitalitermes hospitalis, H. lividiceps, H. rufus and Longipeditermes longipes. This paper presents the results of our investigation on the spatial distribution of nests and the foraging activities of the four species in coexistence. The results show that there are fairly marked differences in nesting sites, as well as in foraging activities, among the four species. It is noteworthy that H. rufus inhabits only the canopy area over 20 m above ground, apparently segregated from the other three species, and that their foraging activities are limited also to tree canopies over 10 m above ground. In contrast, L. longipes nests underground and forages exclusively on the forest floor. Hospitalitermes hospitalis and H. lividiceps inhabit and forage over wide areas, from the forest floor to tree canopies. The upper parts of the tree canopy (over 10 m) are also foraging territories of the secluded H. rufus, but there were no observations of simultaneous foraging of the three Hospitalitermes species in the same canopy areas.     

Plant functional traits and community assembly along interacting gradients of productivity and fragmentation

Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes.In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south–north productivity gradient.We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m × 0.25 m). All traits varied significantly along the S–N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S–N gradient.Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass).Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits.     

Limited niche differentiation within remarkable co‐occurrences of congeneric species: Monomorium ants in the Australian seasonal tropics

Niche theory predicts that few closely related species can co‐occur because such species tend to be ecologically similar and niche differentiation is required to avoid competitive exclusion. We analyse the co‐occurrence of a remarkable 10–15 species of the ant genus Monomorium occurring within single 10 × 10 m plots in a tropical savanna of northern Australia. Most of the species are undescribed, so we use genetic analysis to validate our species demarcations. We document nest dispersion patterns, and investigate differentiation in the three primary niche dimensions: space, time and food. We also examine species differences in competitive abilities, by describing rates of foraging activity, foraging ranges, worker aggression, and levels of behavioural dominance. Analyses of nest and forager distributions showed very limited evidence of spatial segregation within plots. The great majority of species foraged either exclusively or primarily during daylight hours. Body size and isotopic analyses indicated very limited dietary differentiation. Such limited niche partitioning occurred despite the species differing markedly in their competitive abilities as measured by rates of resource discovery, recruitment and monopolization. Our findings defy the traditional assumption that multiple closely related and ecologically similar species of highly interactive taxa cannot co‐occur. It seems very likely that species coexistence in our study system is determined to a very large degree by stochastic processes relating to dispersal and establishment, as predicted by neutral theory. However, neutral theory assumes competitive equivalence, whereas we found very marked differences in the competitive abilities of our co‐occurring species. We suggest that competitive exclusion is prevented by the modular nature of ant colonies, with competition limiting colony performance but not preventing occurrence. We conclude that other factors that allow species persistence, and not just competitive equivalence, can allow dispersal and establishment processes to drive species coexistence.     

No evidence for rapid evolution of seed dispersal ability in range edge populations of the invasive species Senecio madagascariensis

Theory suggests that range edge populations of invading plants and animals may experience runaway selection for increased dispersal ability. This theory has been supported by field data for cane toads in Australia, and for Senecio inaequidens in Europe. In this study, we asked whether range edge populations of Senecio madagascariensis (Asteraceae), an invasive plant in eastern Australia, displayed higher dispersal ability that did populations from the established range. We measured 1363 diaspores from 33 populations. There was no significant difference in dispersal potential between populations from the range edge, and those from the established range (P = 0.19). We also used a glasshouse study to determine whether the range edge populations differed from populations in the established range in three critical life history traits: germination success, plant size and time to first reproduction. The only significant difference was for higher germination in range edge populations. The null result for dispersal ability is excellent news for land managers, as this is the first published evidence that selection for ever‐increasing dispersal rates is not ubiquitous in invading populations.     

Integrating frugivory and animal movement: a review of the evidence and implications for scaling seed dispersal

General principles about the consequences of seed dispersal by animals for the structure and dynamics of plant populations and communities remain elusive. This is in part because seed deposition patterns emerge from interactions between frugivore behaviour and the distribution of food resources, both of which can vary over space and time. Here we advocate a frugivore‐centred, process‐based, synthetic approach to seed dispersal research that integrates seed dispersal ecology and animal movement across multiple spatio‐temporal scales. To guide this synthesis, we survey existing literature using paradigms from seed dispersal and animal movement. Specifically, studies are discussed with respect to five criteria: selection of focal organisms (animal or plant); measurement of animal movement; characterization of seed shadow; animal, plant and environmental factors included in the study; and scales of the study. Most studies focused on either frugivores or plants and characterized seed shadows directly by combining gut retention time with animal movement data or indirectly by conducting maternity analysis of seeds. Although organismal traits and environmental factors were often measured, they were seldom used to characterize seed shadows. Multi‐scale analyses were rare, with seed shadows mostly characterized at fine spatial scales, over single fruiting seasons, and for individual dispersers. Novel animal‐ and seed‐tracking technologies, remote environmental monitoring tools, and advances in analytical methods can enable effective implementation of a hierarchical mechanistic approach to the study of seed dispersal. This kind of mechanistic approach will provide novel insights regarding the complex interplay between the factors that modulate animal behaviour and subsequently influence seed dispersal patterns across spatial and temporal scales.