The flora and vegetation of oceanic islands have been deeply affected by human settlement and further landscape modifications during prehistoric and historical times. The study of these transformations is of interest not only for understanding how current island biotas and ecological communities have been shaped but also for informing biodiversity and ecosystem conservation. This paper compares two oceanic insular entities of disparate geographical, environmental, biological, historical and cultural characteristics – Rapa Nui (Pacific Ocean) and the Azores Islands (Atlantic Ocean) – in terms of human settlement and further landscape anthropization. The similarities and differences between these islands/archipelagos are discussed considering their permanent colonization, the possibility of earlier settlements, the removal of the original forests and the further landscape transformations leading to either full floristic/vegetational degradation (Rapa Nui) or major replacement (Azores). This comparison uses evidence from varied disciplines, notably paleoecology, archaeology, anthropology and history, to obtain a holistic view of the development of the respective socioeconomic systems from a human ecodynamic perspective. The most relevant issues still to be resolved are identified and some prospects for future research are suggested. The cases of Rapa Nui and Azores Islands may help set a conceptual basis for ocean-wide global comparisons among oceanic islands/archipelagos.

Heterosis plays a significant role in enhancing variety, boosting yield, and raising economic value, but the molecular mechanism is still unclear. We analyzed the transcriptomes and 3D genomes of hybrid (F1) and its parents (w30 and 082). Analysis of the expression revealed a total of 485 specially expressed genes (SEGs), 173 differentially expressed genes (DEGs) above parental expression level, more actively expressed genes and up-regulated DEGs in F1. Further study revealed that the DEGs detected in F1 and its parents were mainly involved in response to auxin, plant hormone signal transduction, DNA metabolic process, Purine metabolism, starch and sucrose metabolism, which suggested that these biological processes may play a crucial role in the heterosis of B. rapa. The analysis of 3D genome data revealed that hybrid F1 tend to contain more transcriptionally active A compartments after hybridization. Additionally, F1 had a smaller TAD (topologically associated domain) genome length, but the number was the highest, and the expression change of activated TAD was higher than repressed TAD. More specific TAD boundaries were detected between parents and F1. Subsequently, 140 DEGs with genomic structural variants were selected as potential candidate genes. Among them, we found two DEGs with consistent expression changes in A/B compartments and TADs. Our findings suggest that genomic structural variants, such as TADs and A/B compartments, may affect gene expression and contribute to heterosis in B. rapa. This study provides further insight into the molecular mechanism of heterosis in B. rapa.

The largest gene families in plants were found to be Glutathione transferase (GSTs), which played significant roles in regulating plant growth, development, and stress response. Within the GSTs gene family, members were found to play a crucial role in the low-temperature response process of plants. A comprehensive study identified a total of 70 BraGSTs genes. Cluster analysis results demonstrated that the BraGSTs in Brassica rapa(B.rapa) could be categorized into eight sub-families and were unevenly distributed across ten chromosomes. The 39 BraGSTs genes were found to be organized into 15 tandem gene clusters, with the promoters containing multiple cis-elements associated with low-temperature response. Cold stress was observed to stimulate the expression of 15 genes, with the BraGSTF2 gene exhibiting the highest level of expression, sug-gesting its significant involvement in winter B.rapa's response to low-temperature stress. Sub-cellular localization analysis of the BraGSTF2 protein indicated its potential expression in both the cell membrane and nucleus. The analysis of stress resistance in BraGSTF2 transgenic Arabidopsis thaliana lines emon-strated that the over-expression of this gene resulted in significantly elevated levels of SOD, POD activity, and SP content compared to the wild type following exposure to low temperatures. These levels reached their peak after 24 hours of treatment. Conversely, the MDA content was lower in the transgenic plants compared to the wild type. Additionally, the survival rate of BraGSTF2 transgenic Arabidopsis thaliana was higher than that of the wild type, suggesting that the BraG-STF2 gene may play a crucial role in enhancing the cold stress tolerance of winter B. rapa. This study lay a foundation for further study on the role of BraGSTs gene in the molecular regulation of cold resistance in winter B.rapa.

The discovery and settlement of the tiny and remote Easter Island (Rapa Nui) has been a classical controversy for decades. Present-day aboriginal people and their culture are undoubtedly of Polynesian origin but it has been debated whether Native Americans discovered the island before the Polynesian settlement. Until recently, the paradigm was that Easter Island was discovered and settled just once by Polynesians in their millennial-scale eastward migration across the Pacific. However, the evidence for cultivation and consumption of an American plant, the sweet potato (Ipomoea batatas), on the island before the European contact (1722 CE), even prior to the Europe-America contact (1492 CE), revived the controversy. This paper reviews the classical archaeological, ethnological and paleoecological literature on the subject and summarizes the information into four main hypotheses to explain the sweet potato enigma: the long-distance-dispersal hypothesis, the back-and-forth hypothesis, the Heyerdahl hypothesis and the newcomer’s hypothesis. These hypotheses are evaluated in light of the more recent evidence (last decade), including molecular DNA phylogeny and phylogeography of humans and associated plants and animals, physical anthropology (craniometry, dietary analysis) and new paleoecological findings. It is concluded that, with the available evidence, none of the former hypotheses may be rejected and, therefore, all possibilities remain open. For future work, it is recommended to use the multiple-working-hypothesis framework and the strong inference method of hypothesis testing, rather than the ruling theory approach, very common in Easter Island’s research.

Declining agricultural productivity caused by soil salinization are becoming global dilemmas in recent years. Biofertilizers show great potential as a sustainable and environmentally friendly fertilization strategy for soil improvement, but their effectiveness for saline soil amendment and improving plant growth under saline stress is not well understood. Assess the effectiveness of biofertilizers in improving saline soils and enhancing crop growth under saline stress, as well as investigate its related potential mechanisms. Changes in soil physico-chemical properties, plant physiological parameters and soil microbial communities were analyzed through pot experiments. The results showed that the application of biofertilizer reduced total soluble salts (TSS) in soil by 30.8% and increased the Brassica rapa L. biomass by 8.4 times. Biofertilizer application increased soil organic matter (SOM), total nitrogen (TN) and available phosphorus (AP). Biofertilizer applications also increased the SOD, CAT, chl.a, chl.b, total soluble sugars, and Proline content. Biofertilizers present plant growth promotion and potential pathogenic fungi reduction by increasing the abundance of Bacillus and Planococcus and decreasing the abundance of Mortierella and Aspergillus. Overall, the results of this study demonstrated the excellent efficacy of biofertilizers in improving saline soils, and the application of biofertilizer strategies will greatly promote agricultural production.

Easter Island (Rapa Nui) deforestation has traditionally been viewed as a single event, synchronous in time and space across the island and caused by Polynesian settlers. However, recent studies have challenged this idea introducing the concept of spatio-temporal heterogeneity and suggesting a role for climate change. This paper presents a continuous paleovegetation record of the last millennium (~960 to ~1710 CE), based on palynological analysis of a peat core from Lake Kao. During this time interval, deforestation was gradual, with three main pulses at ~1070 CE, ~1410 CE and ~1600 CE, likely driven by drought, anthropogenic practices (mostly fire) or the coupling of both. Some forest regeneration trends have been documented after the first and the second deforestation pulses. Forests were totally removed by 1600 CE, coinciding with the full permanent human settlement of the Kao area. Comparison with other continuous palynological records available for the last millennium (Aroi marsh and Lake Raraku), confirms that forest clearing was heterogeneous in time and space, rather than synchronous island-wide.