Genome Assembly and Population Resequencing Reveal the Geographical Divergence of 'Shanmei'(Rubus corchorifolius)

Rubus corchorifolius (Shanmei or mountain berry, 2n =14) is widely distributed in China, and its fruit has high nutritional and medicinal values. Here, we report a high-quality chromosome-scale genome assembly of Shanmei, with a size of 215.69 Mb and encompassing 26696 genes. Genome comparisons among Rosaceae species show that Shanmei and Fupenzi(Rubus chingii Hu) are most closely related, and then is blackberry (Rubus occidentalis). Further resequencing of 101 samples of Shanmei collected from four regions in provinces of Yunnan, Hunan, Jiangxi and Sichuan in South China reveals that the Hunan population of Shanmei possesses the highest diversity and may represent the relatively more ancestral population. Moreover, the Yunnan population undergoes strong selection based on nucleotide diversity, linkage disequilibrium and the historical effective population size analyses. Furthermore, genes from candidate genomic regions that show strong divergence are significantly enriched in flavonoid biosynthesis and plant hormone signal transduction, indicating the genetic basis of adaptation of Shanmei to the local environments. The high-quality genome sequences and the variome dataset of Shanmei provide valuable resources for breeding applications and for elucidating the genome evolution and ecological adaptation of Rubus species.

Insecticidal efficacy of Rubus steudneri and Rubus apetalus against Aedes (Diptera: Culicidae) and Culex (Diptera: Culicidae) mosquitoes

Introduction and Aim: Rubus steudneri Schweinf. and Rubus apetalus Poir. belonging to the family Rosaceae is one of the ethnomedicinal plants used widely in Ethiopia as food, for construction and as medicine. To the best of our knowledge, insecticidal activity of R. steudneri and R. apetalus has not been investigated so far. In this study, we report insecticidal efficacy of R. steudneri and R. apetalus in terms of larvicidal effect against II and III instar larvae of Aedes and Culex mosquitoes. Materials and Methods: The shade-dried and powdered leaves were extracted using methanol by maceration process. Insecticidal activity of leaf extract was determined by larvicidal assay against II and III instar larvae of Aedes and Culex species. LC50 and LC90 values were calculated. Results: The leaf extract of both Rubus species exhibited concentration dependent larvicidal effect. II instar larvae were shown to be highly susceptible than III instar larvae. Among leaf extracts, extract of R. steudneri exhibited marked insecticidal activity when compared to extract of R. apetalus as revealed by lower LC50 and LC90 values. Culex larvae displayed marked susceptibility to leaf extracts when compared to Aedes larvae. Conclusion: Marked larvicidal effect was observed against larvae of Culex species when compared to Aedes species as indicated by lower LC50 and LC90 values. It is evident that the leaf extracts of both Rubus contain insecticidal principles.

Surviving or thriving: trade-offs between growth, defense, and reproduction in a native versus in an invasive Rubus

Little is known about limits to reproduction in plants, especially as to how their other life history functions (growth and defense) may constrain reproductive investment. Understanding these constraints can help researchers refine best practices for cultivating species like Rubus (Family: Rosaceae) that produce nutritious fruits as well as controlling invasive species. Here, we sought to elucidate potential trade-offs between growth, defense, and reproduction in native Rubus allegheniensis (common blackberry) and invasive R. phoenicolasius (wineberry) while accounting for the effects of varying insect herbivory and resource availability levels. We observed traits related to physical defense (e.g., prickle intensity), growth (e.g., cane length), and floral reproduction (e.g., ripe fruits) as well as carbon availability (e.g., canopy cover). We then used multiple regressions to characterize relationships between these variables for both species. We found potential evidence for two induced defenses in the invasive wineberry. Also, five models returned significant results indicative of trade-offs between reproduction and growth, reproduction and defense, and defense and growth in one or both species. Our results highlight the importance of understanding the defensive strategies utilized by these species because inducible defenses may result in trade-offs that could reduce yields and also increase the invasive potential of Rubus species.

Pollen morphology and variability of species from the genus Rubus L. (Rosaceae) alien and invasive in Poland

Rubus L. is one of the most species-rich and most taxonomically challenging genera in the family Rosaceae. The aim of this study was to investigate pollen morphology and the ranges of inter- and intraspecific variability of the studied Rubus alien species, as well as verify the taxonomic usefulness of these traits in distinguishing studied taxa from this genus. We analysed six quantitative pollen characteristics and the following qualitative ones: exine ornamentation, pollen outline and shape. The study was conducted on 24 samples of six alien Rubus species found in Poland. 720 pollen grains were measured in total. The most important pollen features included exine ornamentation and length of the polar axis (P). In the conducted studies there were no features of pollen indicating “invasiveness”. The results of our research fill the gap in knowledge on pollen structure in Rubus species alien to Poland and Europe. They may constitute a foundation for further research on the reproduction of these species (e.g. pollen viability and fertility), thus facilitating identification of features determining their expansive character.

Morphological characteristics of Indonesian Rubus flowers

Normasiwi S, Salamah A, Surya MI. 2021. Morphological characteristics of Indonesian Rubus flowers. Biodiversitas 22: 1441-1447. Rubus spp. are woody or herbaceous plants that can be used for fruit, ornamental and medicinal purposes. The increasing use of Rubus as a commercial species is highly dependent on the formation of high-quality genetic material. However, the lack of basic biological knowledge is one of the limiting factors in this development. This research aims to describe the morphological characters of Indonesian Rubus flowers at Cibodas Botanical Garden, Indonesian Institute of Sciences, Cianjur, West Java, Indonesia. From January to June 2020, we observed nine Rubus species with five replications, namely R. alceifolius, R. chrysophyllus, R. ellipticus, R. fraxinifolius, R. linneatus, R. moluccanus, R. pyrifolius, R. rosifolius, and Rubus sp (Blackberry) in Cibodas Botanical Garden, Indonesia. The results showed variations in the characteristics of the pistil, stamens, torus shape, and duration of flowering stages between species. The mean value of the stamen-pistil ratio for R. pyrifolius was highest among other species (8.27), and R. fraxinifolius was the lowest (0.16). Furthermore, a correlation analysis between stamens and pistils for nine Rubus species was relatively positive (r = 0.598), similarly distinctly positive between pistils and fruits with r = 0.763. Flower development duration takes ranging 10-12 days from initiation to anthesis, depending on the species.

Effects of explant position and orientation, medium ph and nitrogen sources on micropropagation of blackberry

Composition of the medium and the explant origin are factors that interfere on success of micropropagation of Rubus species. For blackberry cultivar LochNess it was not investigated yet how the position and orientation of explant, pH levels and nitrogen source interfere on micropropagation. In this work, focused on the establishment of in vitro culture, variables were studied on R. fruticosus cv Loch Ness, such as the choice of the explants depending on their original position on the mother plant, pH level and nitrogen sources of the culture medium. For the first time in vitro on Rubus, the downward orientation (capogatto) of shoot tips explants was compared with the normal upward orientation. The highest weight and length values were recorded for the shoots proliferated from basal and nodal explants. For the initiation medium, the best multiplication rate were obtained in pH adjusted to 4.5. Shoot length was influenced by the nitrogen source; when associated with an increased light intensity, the complete substitution of ammonium by nitrate allowed results comparable with those obtained with the control medium containing both sources. The use of aminoacids did not improve the results. Apex orientation did not affect anatomical parameters or rooting rates of wild Rubus, but more efforts should be devoted on in vitro capogatto technique considering that advantages like reduction of plant growth regulators, cultivation on the same medium culture for more time and easily rooting can be established.

Colonization of Wild Blackberry Plants in California by Fusarium oxysporum f. sp. mori

Fusarium oxysporum f. sp. mori, the causal agent of Fusarium wilt of blackberry, was first reported in California and Mexico in 2016. A limited survey of the population revealed this pathogen to be one of the most diverse formae speciales of F. oxysporum. We explored the possibility that strains of F. oxysporum pathogenic to commercial blackberry could also be recovered from wild blackberry (Rubus spp.) in California. For this purpose, wild Rubus species in blackberry nurseries, fruit production fields, and nearby areas were collected between 2017 and 2019. Thirty-four isolates of F. oxysporum were recovered from asymptomatic Rubus armeniacus and Rubus ursinus plants. Based on sequence of the translation elongation factor 1-α, somatic compatibility, and pathogenicity to blackberry, 16 isolates were confirmed as F. oxysporum f. sp. mori. These isolates were associated with three somatic compatibility groups, one of which was first identified in this study. Recovery of the pathogen confirmed that wild blackberry plants can act as a reservoir of inoculum of F. oxysporum f. sp. mori and that it can move from wild blackberry plants to commercial cultivars or vice versa.