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The changes in niche roles and functions caused by competition for survival resources have implications in various domains, with natural science and social science standing out. Currently, expanding the ecological niche concept and its practical interpretation in the fields of social ecology, geography and sustainable science is becoming a crucial challenge. This paper is based on niche theory to observe niche evolution and resulting socio-ecological effects of 1186 towns in 19 prefecture cities in Yangtze River delta. The results indicate that: Towns around the Taihu Lake displayed obvious spatial agglomeration, which was leading the development of the entire region. The town niche shows obvious characteristics of north-south differences and hierarchy distribution. The niche coordination degree of Jiangsu Province was higher than that of Zhejiang Province. The higher the subsystem coordination degree, the better the town development. Towns with poor ecological conditions are often subject to competition, while towns with better ecological conditions often benefit from cooperative development. The niche separation and collaboration could enhance niche competition of towns and cities in the region. The proposed framework can facilitate interdisciplinary exchanges among geography, sociology, landscape ecology and regional planning and provide insights for understanding regional co-opetition relationship and regional sustainable development.

We studied the growth of roots of white mulberry (Morus alba) trees in response to different water and nutrient conditions in sets of three or five containers connected via small pipes and arranged so as to simulate the heterogeneous soil conditions associated with rocky desertification. The experiment was conducted to improve understanding of the adaptation of M. alba to this stressful environment. The trees were grown for a year under constant water and nutrient conditions in the soils within each container of any set of containers. Differences in root activity and endogenous hormones within root tips were measured at the end of the experiment. We compared four treatment groups: H (variable moisture among containers), F (variable nutrients among containers), HF (both moisture and nutrients varied among containers), and CK (non-varied control). Results showed the following: (1) Mulberry roots showed obvious hydrotropic and chemotropic growth patterns, but chemotropism did not occur in the condition of water shortage. (2) Measurement of growth indices (root surface area, total root length, number of root tips, root biomass) showed that growth status was best in group HF once the roots were able to access containers with sufficient water and nutrients, followed by group H. The indices were significantly poorer in groups F and CK. (3) The content of auxin, cytokinin, and gibberellins in roots under soil drought conditions were lower than under wetter soil conditions. In contrast, abscisic acid content and root activity were higher under soil drought conditions than under wetter soil conditions. The results indicated that water is the key factor restricting growth of white mulberry trees in areas of rocky desertification but that the trees adjust endogenous hormones in their roots to promote tropic growth and obtain sufficient moisture and nutrients over the long term. Moreover, under long-term drought stress conditions, mulberry trees retained high root activity which appears to be adaptive in that all of the trees survived.

This paper considers effects of a climate-induced range shift on outcomes of two competitive species, which is modeled by a reaction–diffusion system with the increasing growth rates of species along a shifting habitat gradient. Analytical conditions are established for the coexistence or competitive exclusion of two-competitors under the climate change, which present the control strategies to maintain the persistence of species.

The need to produce crops with higher yields is critical due to a growing global population, depletion of agricultural land, and severe climate change. Compared with the “source” and “sink” transport systems that have been studied a lot, the development and utilization of vascular bundles (conducting vessels in plants) are increasingly important. Due to the complexity of the vascular system, its structure, and its delicate and deep position in the plant body, the current research on model plants remains basic knowledge and has not been repeated for crops and applied to field production. In this review, we aim to summarize the current knowledge regarding biomolecular strategies of vascular bundles in transport systems (source-flow-sink), allocation, helping crop architecture establishment, and influence of the external environment. It is expected to help understand how to use sophisticated and advancing genetic engineering technology to improve the vascular system of crops to increase yield.

Abstract Background Medicinal plants have always played an important role in the history of human health. However, the populations and sustainable use of medicinal plants have been severely affected by human activities and climate change. Little is known about the current conservation status and distribution pattern of medicinal plants. In this study, based on accurate geographical distribution information of 9756 medicinal plants, we identified diversity hotspots and conservation gaps, evaluated conservation effectiveness of nature reserves, and predicted suitable habitat areas for medicinal plants in China to provide scientific guidance for their long-term conservation and sustainable use. Results A total of 150 diversity hotspot grid cells, mainly concentrated in central and southern China, were identified. These only accounted for 5% of the total distribution area but contained 96% of the medicinal plants of the country. The hotspot grid cells included all traditional hotspot areas, but we also detected three new hotspots, namely Mufu-Lushan Mountains, Tianshan-Altai Mountains, and Changbai Mountains. The current national and provincial nature reserves protect 125 hotspot grid cells, which harbor 94% of all medicinal plants. However, 25 hotspot grid cells, distributed in the Tianshan-Altai Mountains and Hengduan Mountains, are located outside the national and provincial nature reserves. An analysis of the predicted effects of climate change indicated that the suitable habitat areas will shift from southern to northern China, and that southern China will face a considerable loss of suitable habitat areas, while the east and west parts of China will encompass remarkably more suitable habitat areas in the future. Conclusions The current conservation networks have achieved high conservation effectiveness with regard to medicinal plants; however, the conservation gaps we identified should not be neglected, and conservation planning needs to take into account the predicted shifts of some hotspots of medicinal plants due to climate change.

Self-organised patterns of vegetation are a characteristic feature of semi-deserts. In this paper, we find the internal competition reaction between plants can lead to the formation of spatial vegetation patterns, which is different from the normal formation mechanism of long-range competition and short-range facilitation. It is also found that the internal competition between biomass has an effect on the characters of banded vegetation. In particular, it is shown that the internal competition reaction leads to the decrease of the migration speed and the increase of the wavelength of the stripe patterns.

SummaryDrought and salinity are two major environmental factors limiting crop production worldwide. Improvement of drought and salt tolerance of crops with transgenic approach is an effective strategy to meet the demand of the ever‐growing world population. Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a homeodomain‐START transcription factor, has been demonstrated to significantly improve drought tolerance in Arabidopsis, tobacco, tall fescue and rice. Here we report that AtHDG11 also confers drought and salt tolerance in upland cotton (Gossypium hirsutum) and woody plant poplar (Populus tomentosa Carr.). Our results showed that both the transgenic cotton and poplar exhibited significantly enhanced tolerance to drought and salt stress with well‐developed root system. In the leaves of the transgenic cotton plants, proline content, soluble sugar content and activities of reactive oxygen species‐scavenging enzymes were significantly increased after drought and salt stress compared with wild type. Leaf stomatal density was significantly reduced, whereas stomatal and leaf epidermal cell size were significantly increased in both the transgenic cotton and poplar plants. More importantly, the transgenic cotton showed significantly improved drought tolerance and better agronomic performance with higher cotton yield in the field both under normal and drought conditions. These results demonstrate that AtHDG11 is not only a promising candidate for crops improvement but also for woody plants.

Abstract Background The bermudagrass (Cynodon dactylon (L.) Pers) roots responded differently in terms of morphological and anatomical characteristics under diverse submergence conditions, and they developed aerenchyma under non-flooding condition. In order to understand these mechanisms, bermudagrass cuttings were used as experimental material to examine their biomass, root morphology, and aerenchyma formation under three different water treatments, including control (CK), shallow submergence (SS), and deep submergence (DS). Results The total root length, root volume, root surface area, and biomass of bermudagrass were largest in CK, followed by SS and DS. However, the average root diameter was greater in each of DS and SS than that in CK. Root aerenchyma formation was observed in CK, and submergence boosted the aerenchyma formation and the root cavity rate. Furthermore, our study found that the process of aerenchyma formation began with the increase of cell volume and cell separation to form a narrow space, and these cells gradually died to form matured aerenchyma cavity, which belongs to schizo-lysigenous aerenchyma. Meanwhile, typical biomarkers of programmed cell death were also observed. Conclusion Overall, these results suggested that submergence inhibited the accumulation of biomass and root growth, but facilitated aerenchyma formation by increasing root diameter.

AbstractSugarcane is an established industrial crop providing sugar, ethanol and biomass‐derived electricity worldwide. Cane sugar content is an important breeding target, but its improvement remains very slow in many breeding programmes. Biotechnology strategies to improve sucrose accumulation made little progress at the crop level, mainly due to the limited understanding of its regulation. miRNAs regulate many metabolic processes in plants. However, their roles and target genes associated with sugarcane sucrose accumulation remain unknown. Here, we conducted high‐throughput sequencing of transcriptome, small RNAs and degradome of leaves and stem of two early‐maturing sugarcane genotypes with contrasting sucrose content from the early to late stages of sucrose accumulation stages, which provided more insights into miRNA‐associated gene regulation during sucrose accumulation. The stem sucrose content in both genotypes increased steadily with time during sucrose accumulation stage. Transcriptome analysis identified 18,722 differentially expressed genes (DEGs) between both genotypes during sucrose accumulation. The major DEGs identified were involved in starch and sucrose metabolism, and photosynthesis. miRNA sequencing identified 563 known and 281 novel miRNAs from both genotypes during sucrose accumulation. Of these, 311 miRNAs were differentially expressed. A combined transcriptome and miRNA data analysis revealed differentially expressed miRNA‐target mRNA pairs related to sugar metabolism, of which 46 targets were transcription factors (TFs). miR172, miR164, miR396 and miR169 appear to regulate AP2/ERF, NAC, GRF and bZIP TF members associated with sugar metabolism. This is the first report of sugarcane miRNAs associated with sugar accumulation.

The Qinghai-Tibetan Plateau (QTP) harbors abundant and diverse plant life owing to its high habitat heterogeneity. However, the distribution pattern of biodiversity hotspots and their conservation status remain unclear. Based on 148,283 high-resolution occurrence coordinates of 13,450 seed plants, we identified hotspots by integrating data from species richness, species complementarity and spatial phylogenetics. Nine hotspot areas were identified that contained 89% of species but covered only 7% of the total land area of the QTP. Four of nine hotspots were identified firstly, including west Nyainqentanglha Mountains, the middle reaches of Lancang and Jinsha Rivers, the upper reaches of Yellow River and Qilian Mountains. Analysis of conservation efficiency indicated national nature reserves (NNRs) covered 55% of the hotspots, whereas NNRs and provincial nature reserves (PNRs) together protected 73% of the hotspots. Conservation efforts, such as establishing new protected areas and upgrading the level of existing nature reserves, should be strengthened in the conservation gaps. Targeted conservation should be carried out for species endemic to QTP due to their narrow distribution range and low conservation effectiveness. Niche modeling for 336 threatened plants indicated there were apparent range shifts of suitable habitat areas from the eastern edge to the center of the plateau under future climate scenarios, and conservation priority should be focused on the southern QTP for where have stable habitats.