The chromosome-level genomes of the herbal magnoliids Warburgia ugandensis and Saururus chinensis.

Warburgia ugandensis and Saururus chinensis are two of the most important medicinal plants in magnoliids and are widely utilized in traditional Kenya and Chinese medicine, respectively. The absence of higher-quality reference genomes has hindered research on the medicinal compound biosynthesis mechanisms of these plants. We report the chromosome-level genome assemblies of W. ugandensis and S. chinensis, and generated 1.13 Gb and 0.53 Gb genomes from 74 and 27 scaffolds, respectively, using BGI-DIPSEQ, Nanopore, and Hi-C sequencing. The scaffold N50 lengths were 82.97 Mb and 48.53 Mb, and the assemblies were anchored to 14 and 11 chromosomes of W. ugandensis and S. chinensis, respectively. In total, 24,739 and 20,561 genes were annotated, and 98.5% and 98% of the BUSCO genes were fully represented, respectively. The chromosome-level genomes of W. ugandensis and S. chinensis will be valuable resources for understanding the genetics of these medicinal plants, studying the evolution of magnoliids and angiosperms and conserving plant genetic resources.

Chromosome-scale genomes of five Hongmu species in Leguminosae.

The Legume family (Leguminosae or Fabaceae), is one of the largest and economically important flowering plants. Heartwood, the core of a tree trunk or branch, is a valuable and renewable resource employed for centuries in constructing sturdy and sustainable structures. Hongmu refers to a category of precious timber trees in China, encompassing 29 woody species, primarily from the legume genus. Due to the lack of genome data, detailed studies on their economic and ecological importance are limited. Therefore, this study generates chromosome-scale assemblies of five Hongmu species in Leguminosae: Pterocarpus santalinus, Pterocarpus macrocarpus, Dalbergia cochinchinensis, Dalbergia cultrata, and Senna siamea, using a combination of short-reads, long-read nanopore, and Hi-C data. We obtained 623.86 Mb, 634.58 Mb, 700.60 Mb, 645.98 Mb, and 437.29 Mb of pseudochromosome level assemblies with the scaffold N50 lengths of 63.1 Mb, 63.7 Mb, 70.4 Mb, 61.1 Mb and 32.2 Mb for P. santalinus, P. macrocarpus, D. cochinchinensis, D. cultrata and S. siamea, respectively. These genome data will serve as a valuable resource for studying crucial traits, like wood quality, disease resistance, and environmental adaptation in Hongmu.

Trait matching in a multi-species geographic mosaic of leafflower plants, brood pollinators, and cheaters.

Trait matching between mutualistic species is usually expected to maintain mutualism, but empirical studies of trait complementarity and coadaptation in multi-species assemblages-which represent the reality of most interactions in nature-are few. Here, we studied trait matching between the leafflower shrub Kirganelia microcarpa and three associated seed-predatory leafflower moths (Epicephala spp.) across 16 populations. Behavioral and morphological observations suggested that two moths (E. microcarpa and E. tertiaria) acted as pollinators while a third (E. laeviclada) acted as a cheater. These species differed in ovipositor morphology but showed trait complementarity between ovipositor length and floral traits at both species level and population level, presumably as adaptations to divergent oviposition behaviors. However, this trait matching varied among populations. Comparisons of ovipositor length and floral traits among populations with different moth assemblages suggested an increase of ovary wall thickness where the locular-ovipositing pollinator E. microcarpa and cheater E. laeviclada were present, while stylar pit depth was less in populations with the stylar pit-ovipositing pollinator E. tertiaria. Our study indicates that trait matching between interacting partners occurs even in extremely specialized multi-species mutualisms, and that although these responses vary, sometimes non-intuitively, in response to different partner species. It seems that the moths can track changes in host plant tissue depth for oviposition.

The genome of Acorus deciphers insights into early monocot evolution.

Acorales is the sister lineage to all the other extant monocot plants. Genomic resource enhancement of this genus can help to reveal early monocot genomic architecture and evolution. Here, we assemble the genome of Acorus gramineus and reveal that it has ~45% fewer genes than the majority of monocots, although they have similar genome size. Phylogenetic analyses based on both chloroplast and nuclear genes consistently support that A. gramineus is the sister to the remaining monocots. In addition, we assemble a 2.2 Mb mitochondrial genome and observe many genes exhibit higher mutation rates than that of most angiosperms, which could be the reason leading to the controversies of nuclear genes- and mitochondrial genes-based phylogenetic trees existing in the literature. Further, Acorales did not experience tau (τ) whole-genome duplication, unlike majority of monocot clades, and no large-scale gene expansion is observed. Moreover, we identify gene contractions and expansions likely linking to plant architecture, stress resistance, light harvesting, and essential oil metabolism. These findings shed light on the evolution of early monocots and genomic footprints of wetland plant adaptations.

Diversity and species-specificity of brood pollination of leafflower trees (Phyllanthaceae: Glochidion) by leafflower moths (Lepidoptera: Epicephala) in tropical Southeast Asia (Cambodia).

Glochidion (Phyllanthaceae; leafflower trees) is a genus of trees which is widely reported to be pollinated by leafflower moths (Gracillariidae: Epicephala) in temperate and subtropical Asia, Australia, and the Pacific islands. However, the pollination ecology of Glochidion is not well described from tropical Asia, the region where it is most species-rich at both local (≤9 spp.) and regional (~200 spp.) scales. Here we report investigations of pollination biology and species-specificity of five Glochidion species in tropical Southeast Asia (Cambodia). Through nocturnal observations and fruit dissections, we find that at least three and likely five Glochidion species in Cambodia are pollinated by seed-parasitic leafflower moths. We find no evidence that any of these leafflower moths are non-mutualistic parasites, despite known examples of such parasites of this mutualism elsewhere in Asia. While the presence of a single larva in a fruit results in only a fraction of seeds being consumed, the presence of more than one larva per fruit-a frequent occurrence in some species-can result in almost all seeds within the fruit being infested. Multilocus phylogenetic analysis indicates that there are five different minimally monophyletic leafflower moth clades, each of which pollinates a unique Glochidion host species. Our results indicate that in its center of diversity in tropical Asia this system is an obligate pollination mutualism as previously described at the global margins of its distribution. These findings provide insights into the processes that generate and maintain biodiversity and maintain mutualism stability in plant-insect interactions in this biodiversity hotspot.

Tackling the Taxonomic Challenges in the Family Scoliidae (Insecta, Hymenoptera) Using an Integrative Approach: A Case Study from Southern China.

Species of the family Scoliidae are larval parasitoids of scarabaeoid beetles and pollinators of various plants. Despite their great importance in pest biological control and plant pollination, the taxonomy and systematics of these parasitoids are far from clear. Some species of the family are extremely morphologically similar and difficult to identify, especially in males. In this study, an integrative taxonomic approach, combining morphology and molecular data, was used to discriminate the species of Scoliidae from southern China. In total, 52 COI sequences belonging to 22 morphospecies of 9 genera in two tribes were obtained. The COI sequences worked well for the identification of all the studied species, with intraspecific genetic distances generally less than 2%, while interspecific distances ranged between 5.3% and 20.8%. The delimitations of the problematic species and subspecies of Scolia and Megacampsomeris are well solved by COI sequences, suggesting that DNA barcoding could be a useful identification tool for Scoliidae. Based on both morphological and molecular evidence, we discovered one undescribed cryptic species of the polytypic species Solia (Discolia) superciliaris Saussure, 1864, five newly recorded species, i.e., Scolia (Discolia) sikkimensis Bingham, 1896, Sericocampsomeris flavomaculata Gupta and Jonathan, 1989, Megacampsomeris asiatica (Saussure, 1858), Megacampsomeris pulchrivestita (Cameron, 1902) and Megacampsomeris shillongensis (Betrem, 1928) and one pending subspecies of Scolia (Discolia) watanabei (Matsumura, 1912) from China. Our study indicates that such an integrative approach, combing both molecular and morphological evidence, is a potent tool to tackle the taxonomic challenges in the family Scoliidae, or even, in other diverse groups of Aculeata, of which sexual dimorphism and cryptic species are common.

Taxonomic revision of the genus Glochidion (Phyllanthaceae) in Taiwan, China.

A comprehensive taxonomic revision of the genus Glochidion J.R. Forst. & G. Forst. from Taiwan in China was carried out based on the examination of herbarium specimens and filed investigations. Eight species and three varieties are recognized, including a new species endemic to Taiwan, G. lanyuense Gang Yao & S.X. Luo, which is described and illustrated. Three names, viz. G. chademenosocarpum Hayata, G. kusukusense Hayata, and G. ovalifolium F.Y. Lu & Y.S. Hsu, are reduced to the new synonyms of G. rubrum Blume, G. lanceolatum Hayata, and G. ellipticum Wight, respectively. Two names, viz. G. lanceolatum Hayata and G. suishaense Hayata, are lectotypified here. A key to the Glochidion species in Taiwan is provided.

Taxonomic studies of Glochidion (Phyllanthaceae) from the Indo-China Peninsula (II): The identities of G.anamiticum and G.annamense.

The names Glochidionanamiticum (Kuntze) Kuntze ex Merrill and G.annamense Beille were previously reduced to synonyms of G.eriocarpum Champ. ex Benth. However, literature examination and morphological comparison suggest that G.annamense is conspecific with G.anamiticum and the species can be readily distinguished from G.eriocarpum by its styles connate into a long cylindric column and up to 3 mm long, ovaries usually 3-locular, stigma usually 3-lobed, capsules pubescent and usually 6-grooved, persistent styles 3‒4 mm long. Thus, the specific status of G.anamiticum is here reinstated and G. annamense is treated as its synonym.

Taxonomic studies of Glochidion (Phyllanthaceae) from the Indo-China Peninsula (I): G. shanense, a new species from Myanmar.

Based on morphological studies performed on live plants in the field and specimens deposited in herbaria, a new species, Glochidion shanense Gang Yao & Shixiao Luo (Phyllantheae, Phyllanthaceae), is here described and illustrated. The species is morphologically most similar to G. ellipticum Wight, but can be distinguished from the latter by having hairy branchlets, longer pedicels, uniseriate and narrowly triangular sepals of female flowers, 4-5-locular ovaries, stout and cylindric persistent style on fruits.

The largest early-diverging angiosperm family is mostly pollinated by ovipositing insects and so are most surviving lineages of early angiosperms.

Insect pollination in basal angiosperms is assumed to mostly involve 'generalized' insects looking for food, but direct observations of ANITA grade (283 species) pollinators are sparse. We present new data for numerous Schisandraceae, the largest ANITA family, from fieldwork, nocturnal filming, electron microscopy, barcoding and molecular clocks to infer pollinator/plant interactions over multiple years at sites throughout China to test the extent of pollinator specificity. Schisandraceae are pollinated by nocturnal gall midges that lay eggs in the flowers and whose larvae then feed on floral exudates. At least three Schisandraceae have shifted to beetle pollination. Pollination by a single midge species predominates, but one species was pollinated by different species at three locations and one by two at the same location. Based on molecular clocks, gall midges and Schisandraceae may have interacted since at least the Early Miocene. Combining these findings with a review of all published ANITA pollination data shows that ovipositing flies are the most common pollinators of living representatives of the ANITA grade. Compared to food reward-based pollination, oviposition-based systems are less wasteful of plant gametes because (i) none are eaten and (ii) female insects with herbivorous larvae reliably visit conspecific flowers.

Coevolution with pollinating resin midges led to resin-filled nurseries in the androecia, gynoecia and tepals of Kadsura (Schisandraceae).

Background and Aims: Resin is a defence against herbivores and a floral reward in a few African and South American species whose bee pollinators collect it for nest construction. Here we describe a new role for floral resin from the Asian genus Kadsura (Schisandraceae). Kadsura tepals tightly cover a globe formed by carpels (in females) or near-fused stamens with fleshy connectives (in male flowers of most, but not all species). Methods: We carried out field observations at four sites in China and used pollinator behavioural assays, chemical analyses and time-calibrated insect and plant phylogenies to investigate the specificity of the interactions and their relationship to floral structure. Key Results: Nocturnal resin midges ( Resseliella , Cecidomyiidae) walk around on the flowers' sexual organs to oviposit, thereby transferring pollen and wounding tissues. The larvae then develop in resin-filled chambers. Male and female floral scents are dominated by α-pinene, while the resinous exudate is dominated by caryophyllene. As revealed by barcoding of multiple midge larvae per flower species, the mutualisms are species specific and appear to have evolved over the past 6-9 million years. Conclusions: Resin feeding, not pollen or ovule feeding, by midge larvae explains the abundant Kadsura exudates, highlighting the poorly known world of nocturnal flower-fly interactions.

A Novel, Enigmatic Basal Leafflower Moth Lineage Pollinating a Derived Leafflower Host Illustrates the Dynamics of Host Shifts, Partner Replacement, and Apparent Coadaptation in Intimate Mutualisms.

Leafflower plant/leafflower moth brood pollination mutualisms are widespread in the Paleotropics. Leafflower moths pollinate leafflower plants, but their larvae consume a subset of the hosts' seeds. These interactions are highly phylogenetically constrained: six clades of leafflower plants are each associated with a unique clade of leafflower moths (Epicephala). Here, we report a previously unrecognized basal seventh pollinating Epicephala lineage-associated with the highly derived leafflower clade Glochidion-in Asia. Epicephala lanceolaria is a pollinator and seed predator of Glochidion lanceolarium. Phylogenetic inference indicates that the ancestor of E. lanceolaria most likely shifted onto the ancestor of G. lanceolarium and displaced the ancestral allospecific Epicephala pollinator in at least some host populations. The unusual and apparently coadapted aspects of the G. lanceolarium/E. lanceolaria reproductive cycles suggest that plant-pollinator coevolution may have played a role in this displacement and provide insights into the dynamics of host shifts and trait coevolution in this specialized mutualism.

Assembled Plastid and Mitochondrial Genomes, as well as Nuclear Genes, Place the Parasite Family Cynomoriaceae in the Saxifragales.

Cynomoriaceae, one of the last unplaced families of flowering plants, comprise one or two species or subspecies of root parasites that occur from the Mediterranean to the Gobi Desert. Using Illumina sequencing, we assembled the mitochondrial and plastid genomes as well as some nuclear genes of a Cynomorium specimen from Italy. Selected genes were also obtained by Sanger sequencing from individuals collected in China and Iran, resulting in matrices of 33 mitochondrial, 6 nuclear, and 14 plastid genes and rDNAs enlarged to include a representative angiosperm taxon sampling based on data available in GenBank. We also compiled a new geographic map to discern possible discontinuities in the parasites' occurrence. Cynomorium has large genomes of 13.70-13.61 (Italy) to 13.95-13.76 pg (China). Its mitochondrial genome consists of up to 49 circular subgenomes and has an overall gene content similar to that of photosynthetic angiosperms, while its plastome retains only 27 of the normally 116 genes. Nuclear, plastid and mitochondrial phylogenies place Cynomoriaceae in Saxifragales, and we found evidence for several horizontal gene transfers from different hosts, as well as intracellular gene transfers.

Gelechiidae moths are capable of chemically dissolving the pollen of their host plants: first documented sporopollenin breakdown by an animal.

BACKGROUND: Many insects feed on pollen surface lipids and contents accessible through the germination pores. Pollen walls, however, are not broken down because they consist of sporopollenin and are highly resistant to physical and enzymatic damage. Here we report that certain Microlepidoptera chemically dissolve pollen grains with exudates from their mouthparts. METHODOLOGY/PRINCIPAL FINDINGS: Field observations and experiments in tropical China revealed that two species of Deltophora (Gelechioidea) are the exclusive pollinators of two species of Phyllanthus (Phyllanthaceae) on which their larvae develop and from which the adults take pollen and nectar. DNA sequences placed the moths and plants phylogenetically and confirmed that larvae were those of the pollinating moths; molecular clock dating suggests that the moth clade is younger than the plant clade. Captive moths with pollen on their mouthparts after 2-3 days of starvation no longer carried intact grains, and SEM photographs showed exine fragments on their proboscises. GC-MS revealed cis-ß-ocimene as the dominant volatile in leaves and flowers, but GC-MS analyses of proboscis extracts failed to reveal an obvious sporopollenin-dissolving compound. A candidate is ethanolamine, which occurs in insect hemolymphs and is used to dissolve sporopollenin by palynologists. CONCLUSIONS/SIGNIFICANCE: This is the first report of any insect and indeed any animal chemically dissolving pollen.

Flower heating following anthesis and the evolution of gall midge pollination in Schisandraceae.

PREMISE OF THE STUDY: Flower heating is known from a few species in 11 of the c. 450 families of flowering plants. Flowers in these families produce heat metabolically and are adapted to beetles or flies as pollinators. Here, we focus on the Schisandraceae, an American/Asian plant family known to exhibit flower heating in some species, but not others, raising the question of the adaptive function of heat production. • METHODS: We used field observations, experiments, and ancestral trait reconstruction on a molecular phylogeny for Schisandraceae that includes the investigated species. • KEY RESULTS: At least two Chinese species of Illicium are exclusively pollinated by gall midges that use the flowers as brood sites (not for pollen feeding). Continuous monitoring of flower temperatures revealed that the highest temperatures were attained after the flowers' sexual functions were over, and experiments showed that post-anthetic warming benefited larval development, not fruit development. Midge larvae in flowers with trimmed tepals (and hence a lower temperature) died, but fruit set ratios remained unchanged. Based on the DNA phylogeny, gall midge pollination evolved from general fly/beetle pollination several times in Schisandraceae, with some species adapted to flower-breeding midges, others to pollen-feeding midges. • CONCLUSIONS: Flower heating may be an ancestral trait in Schisandraceae that became co-opted in species pollinated by flower-breeding midges requiring long-persistent warm chambers for larval development.

Duodichogamy and androdioecy in the Chinese Phyllanthaceae Bridelia tomentosa.

Flowering plants commonly separate male and female function in time, but rarely are the two stages synchronized within and among individuals. One such temporal mating system is duodichogamy in which each plant produces two batches of male flowers that are temporally separated by a batch of female flowers, with within-individual synchrony and among-individual asynchrony to ensure mating partners. Duodichogamy is known only from a few species in four genera in unrelated families. We report on duodichogamy in the Chinese tree species Bridelia tomentosa (Phyllanthaceae), a common colonizer of disturbed habitats. In three populations monitored over 2 yr, most trees flowered in the order male → female → male, and resting periods between flowering bouts precluded selfing almost completely. Individuals flowered for several weeks, with the onset of flowering slightly asynchronous among trees. Pollination was by flies, and experimental pollen supplementation of a subset of a tree's flowers did not increase fruit set, suggesting high levels of insect visitation and possible resource limitation. Nineteen percent of the 166 trees monitored skipped the first male phase, and another 13% skipped the female phase, remaining male in both years (and also a third year). The regular presence of pure males, if genetically fixed, would make B. tomentosa androdioecious in addition to duodichogamous. Comparison of duodichogamous taxa known so far shows that all have few ovules, fitting with the hypothesis that duodichogamy may result from male competition for access to a small supply of ovules.

Oxalis debilis in China: distribution of flower morphs, sterile pollen and polyploidy.

BACKGROUND AND AIMS: Oxalis debilis is a South American tristylous species that is currently naturalizing in China. Based on field observations and herbarium data a report is made on its pollination, morph frequencies, pollen viability, seed set and chromosome number. In addition, a new chromosome count for the species in Africa is provided. METHODS: Field observations were conducted in six provinces in south-east China. Flower visitors were recorded and nectar sugar was measured with a refractometer. The species' compatibility system was determined by carrying out experimental self- and cross-pollinations on bagged inflorescences. Stigma receptivity and pollen viability was determined using the MTT test. KEY RESULTS AND CONCLUSIONS: Populations of O. debilis in China contain either the mid-style-length morph or the short morph, but not both. Pollination is by nectar- and pollen-foraging bees; pollen viability is low; and seed set in natural and experimentally self- or cross-pollinated flowers is extremely low. Chromosome counts indicate that O. debilis contains diploid and tetraploid forms in its native as well as introduced range, which does not support a previous hypothesis that the predominant vegetative reproduction in this species is an escape from pentaploidy.