Phylogenetic structure in the grass family (Poaceae) as inferred from chloroplast DNA restriction site variation

A cladistic analysis of chloroplast DNA restriction site variation among representatives of all subfamilies of the grass family (Poaceae), using Joinvillea (Joinvilleaceae) as the outgroup, placed most genera into two major clades. The first of these groups corresponds to a broadly circumscribed subfamily Pooideae that includes all sampled representatives of Ampelodesmeae, Aveneae, Brachypodieae, Bromeae, Diarrheneae, Meliceae, Poeae, Stipeae, and Triticeae. The second major clade includes all sampled representatives of four subfamilies (Panicoideae [tribes Andropogoneae and Paniceae], Arundinoideae [Arundineae], Chloridoideae [Eragrostideae], and Centothecoideae [Centotheceae]). Within this group (the “PACC” clade), the Panicoideae are resolved as monophyletic and as the sister group of the clade that comprises the other three subfamilies. Within the latter group, Danthonia (Arundinoideae) and Eragroslis (Chloridoideae) are resolved as a stable monophyletic group that excludes Phragmites (Arundinoideae); this structure is inconsistent with the Arundinoideae being monophyletic as currently circumscribed. The PACC clade is placed within a more inclusive though unstable clade that includes the woody Bambusoideae (Bambuseae) plus several disparate tribes of herbaceous grasses of uncertain affinity that are often recognized as herbaceous Bambusoideae (Brachyelytreae, Nardeae, Olyreae, Oryzeae, and Phareae). Among eight most-parsimonious trees resolved by the analysis, four include a monophyletic Bambusoideae sensu lato (comprising Bambuseae and all five of these herbaceous tribes) as the sister group of the PACC clade; in the other four trees these bambusoid elements are not resolved as monophyletic, and the PACC clade is nested among these tribes. These results are consistent with those of previous analyses that resolve a basal or near-basal branch within the family between Pooideae and all other grasses. However, resolution by the present analysis of the PACC clade, which includes Centothecoideae, Chloridoideae, and Panicoideae, but excludes Bambusoideae, is inconsistent with the results of previous analyses that place Bambusoideae and Panicoideae in a monophyletic group that excludes Centothecoideae and Chloridoideae.     

Chloroplast DNA reassociation and grass phylogeny

Sequence variation in chloroplast DNA (cpDNA) as measured by DNA reassociation was examined in 12 grass species to address systematic problems in thePoaceae at the subfamilial and tribal levels. Two species,Petunia (Solanaceae) andGlycine (Leguminosae), were included to determine degrees of sequence divergence in cpDNA between monocots and dicots. The data were analyzed phenetically and phylogenetically. Species were segregated into four major groups that corresponded to the subfamiliesPooideae, Oryzoideae, Chloridoideae, andPanicoideae. Representatives of thePooideae andOryzoideae grouped together as did members of theChloridoideae andPanicoideae. ThePooideae split into two major groups corresponding to the recently recognized supertribesTriticanae andPoanae. Internodes between subfamily branches were short which might indicate a burst of divergence in the family early in its evolution. Sequence similarity values between the monocot grass species and the two dicot taxa ranged from 0.15 to 0.27, representing the highly conserved sequences of the chloroplast genome.     

The Major Types of Caryopses of the Chinese Gramineae in Relation to Systematics

Examinations were made on the morphology of caryopses of 324 grass species representing over 109 genera and 31 tribes. The evolutionary tendency of the important characteristics and the relation with distribution areas and habitats are discussed. According to the shape of caryopses, the morphology of ventral faces and hilum, the proportion of embryos to caryopses in size, the existence or absence of the top fine hairs, the persistence or shedding of styles, the size of fruits and especially the outline of the middle cross section, etc., the caryopses may be divided into three major types and seven subtypes: Bambusoid (including True Bambusoid, Arundinoid, Oryzoid, Stipoid), Panicoid (including True Panicoid, Eragrostoid) and Pooid (including the Subtype Pooid only). In this study, the different types of caryopses are found to be correlated with the characteristics of embryos, seedlings, habits and chromosomes, and on these grounds, the genera of the Gramineae are grouped into seven corresponding subfamilies: Bambusoideae, Oryzoideae, Arundinoideae, Stipoideae, Eragrostoideae, Panicoideae and Pooideae.     

禾本科叶片表皮结构细胞的组合式样及其分类学意义

利用光学显微镜,对禾本科204属373种植物的叶片表皮进行了观察。发现禾本科叶片表皮细胸细胞在下表面上的分布式样可以划分为5个基本类型,即竹型、稻型、黍型、虎尾草型和早熟禾型,而5个基本类型所附属的植物类群分别是禾本科中的竹亚科、稻亚科、虎尾草亚科早熟禾亚科。同时分析了这5个类型的演化水平,并同类群的外部形态、地理分布相印证,表明竹亚科最原始、稻亚科次之、黍亚科演化居中、虎尾草亚科较高级、早熟禾亚科最高级;禾本科可能起源于世界的热带区域。     

Phylogenetics and character evolution in the grass family (Poaceae): Simultaneous analysis of morphological and Chloroplast DNA restriction site character sets

A phylogenetic analysis of the grass family (Poaceae) was conducted using two character sets, one representing variation in 364 mapped and cladistically informative restriction sites from all regions of the chloroplast genome, the other representing variation in 42 informative “structural characters.” The structural character set includes morphological, anatomical, chromosomal, and biochemical features, plus structural features of the chloroplast genome. The taxon sample comprises 75 exemplar taxa, including 72 representatives of Poaceae and one representative of each of three related families (Flagellariaceae, Restionaceae, and Join-villeaceae);Flagellaria served as the outgroup for the purpose of cladogram rooting. Among the grasses, 24 tribes and all 16 subfamilies of grasses recognized by various modern authors were sampled. Transformations of structural characters are mapped onto the phylogenetic hypotheses generated by the analysis, and interpreted with respect to biogeography and the evolution of wind pollination in the grass family. A major goal of the study was to test the monophyly of several putatively natural groups, including Bambusoideae, Pooideae, Arundinoideae, and the “PACC clade” (the latter comprising subfamilies Panicoideae, Arundinoideae, Chloridoideae, and Centothecoideae), as well as to analyze the phylogenetic structure within these groups and others. Several genera of controversial placement (Amphipogon, Anisopogon, Anomochloa, Brachyelytrum, Diarrhena, Eremitis, Ehrharta, Lithachne, Lygeum, Nardus, Olyra, Pharus, andStreptochaeta) also were included, with the goal of determining their phylogenetic affinities. The two character sets were analyzed separately, and a simultaneous analysis of the combined matrices also was conducted. The combined data set also was analyzed using homoplasy-implied weights. Among major results of the combined unweighted analysis were resolution of a sister-group relationship betweenJoinvillea and Poaceae; resolution of a clade comprisingAnomochloa andStreptochaeta as the sister of all other grasses, withPharus the next group to diverge from the lineage that includes all remaining grasses; and resolution of other taxa often assigned to Bambusoideae s.l. (includingEhrharta and Oryzeae, and excluding a few other taxa as noted) as a paraphyletic assemblage, within which is nested a clade that consists ofBrachyelytrum, the PACC clade (includingAmphipogon), and Pooideae (including Brachypodieae, Stipeae,Anisopogon, Diarrhena, Lygeum, andNardus). Within the PACC clade,Aristida is identified as the sister of all other elements of the group; Chloridoideae, Centothecoideae, and Panicoideae are each resolved as monophyletic, the latter two being sister-groups; and the remaining Arundinoid elements constitute a paraphyletic group within which are nested these three subfamilies. Within the Pooideae, four “core tribes” (Bromeae, Hordeeae [i.e., Triticeae], Agrostideae [i.e., Aveneae], andPoeae, the latter includingSesleria) are resolved as a monophyletic group that is nested among the remaining elements of the subfamily (Brachypodieae, Meliceae, Stipeae,Anisopogon, Diarrhena, Lygeum, andNardus). A second principal goal of the analysis was to identify structural synapomorphies of clades. Among the synapomorphies identified for some of the major clades are the following: gain of a 6.4 kb inversion in the chloroplast genome inJoinvillea and the grasses; reduction to 1 ovule per pistil, gain of a lateral “grass-type” embryo, and gain of an inversion around the gene trnT in the chloroplast genome in the grasses; loss of arm cells in the clade that consists ofBrachyelytrum, Pooideae, and the PACC clade; loss of the epiblast and gain of an elongate mesocotyl internode in the PACC clade; gain of proximal female-sterile florets in female-fertile spikelets, gain of overlapping embryonic leaf margins, and gain ofPanicum- type endosperm starch grains in the clade that comprises Centothecoideae and Panicoideae; and loss of the scutellar tail of the embryo in Pooideae (in one of two alternative placements of Pooideae among other groups). These findings are consistent with an origin and early diversification of grasses as forest understory herbs, followed by one or more radiations into open habitats, concomitant with multiple origins of C₄ photosynthesis and specialization for wind pollination.     

Large multi-gene phylogenetic trees of the grasses (Poaceae): progress towards complete tribal and generic level sampling

In this paper we included a very broad representation of grass family diversity (84% of tribes and 42% of genera). Phylogenetic inference was based on three plastid DNA regions rbcL, matK and trnL-F, using maximum parsimony and Bayesian methods. Our results resolved most of the subfamily relationships within the major clades (BEP and PACCMAD), which had previously been unclear, such as, among others the: (i) BEP and PACCMAD sister relationship, (ii) composition of clades and the sister-relationship of Ehrhartoideae and Bambusoideae + Pooideae, (iii) paraphyly of tribe Bambuseae, (iv) position of Gynerium as sister to Panicoideae, (v) phylogenetic position of Micrairoideae. With the presence of a relatively large amount of missing data, we were able to increase taxon sampling substantially in our analyses from 107 to 295 taxa. However, bootstrap support and to a lesser extent Bayesian inference posterior probabilities were generally lower in analyses involving missing data than those not including them. We produced a fully resolved phylogenetic summary tree for the grass family at subfamily level and indicated the most likely relationships of all included tribes in our analysis.     

Phylogenetic study of Oryzoideae species and related taxa of the Poaceae based on <Emphasis Type="Italic">atpB</Emphasis>-<Emphasis Type="Italic">rbcL</Emphasis> and <Emphasis Type="Italic">ndhF</Emphasis> DNA sequences

Oryzoideae (Poaceae) plants have economic and ecological value. However, the phylogenetic position of some plants is not clear, such as Hygroryza aristata (Retz.) Nees. and Porteresia coarctata (Roxb.) Tateoka (syn. Oryza coarctata). Comprehensive molecular phylogenetic studies have been carried out on many genera in the Poaceae. The different DNA sequences, including nuclear and chloroplast sequences, had been extensively employed to determine relationships at both higher and lower taxonomic levels in the Poaceae. Chloroplast DNA ndhF gene and atpB-rbcL spacer were used to construct phylogenetic trees and estimate the divergence time of Oryzoideae, Bambusoideae, Panicoideae, Pooideae and so on. Complete sequences of atpB-rbcL and ndhF were generated for 17 species representing six species of the Oryzoideae and related subfamilies. Nicotiana tabacum L. was the outgroup species. The two DNA datasets were analyzed, using Maximum Parsimony and Bayesian analysis methods. The molecular phylogeny revealed that H. aristata (Retz.) Nees was the sister to Chikusichloa aquatica Koidz. Moreover, P. coarctata (Roxb.) Tateoka was in the genus Oryza. Furthermore, the result of evolution analysis, which based on the ndhF marker, indicated that the time of origin of Oryzoideae might be 31 million years ago.     

Phylogeny of the grass family (Poaceae) from rpl16 intron sequence data

DNA sequence data from the chloroplast noncoding rpl16 intron are used to address phylogenetic relationships among the major lineages of the grass family, with particular emphasis on the highly heterogeneous subfamily Bambusoideae and the basal lineages. Thirty-five grass sequences representing all six currently recognized major groups of the family and one outgroup sequence were analyzed using both parsimony and distance methods. The phylogenetic analyses indicated: (1) Puelia, a traditionally isolated bambusoid genus, is the most basal lineage in the BOP clade (Bambusoideae, Oryzoideae, and Pooideae); (2) the bambusoid clade is a sister group to the pooid clade; and (3) the monophyletic oryzoid clade is well separated from the bambusoid clade. The study further confirmed the recognition of two primary groups in the grass family: the BOP clade and the PACC clade (Panicoideae, Arundinoideae, Chloridoideae, and Centothecoideae); it also provided further evidence that the traditional subfamily Bambusoideae is highly heterogeneous and phylogenetically unacceptable. The data support Streptochaeteae, Anomochloeae, and Phareae as the most basal lineages among the extant grasses. Within the BOP clade, oryzoids and pooids are confirmed as two monophyletic clades, but the bambusoid clade, including only the woody bamboo tribe Bambuseae and the herbaceous bamboo tribe Olyreae, is relatively weakly supported. The study also indicated that the chloroplast noncoding region sequence data could be useful in phylogenetic analysis at relatively high taxonomic levels.     

Anthocyanins of grasses

The anthocyanin content of 23 grass species (Poaceae) belonging to five subfamilies has been determined. Altogether 11 anthocyanins were identified; the 3-(6″-malonylglucosides) and 3-glucosides of cyanidin, peonidin and delphinidin, the 3-(3″,6″-dimalonylglucoside), 3-(6″-rhamnosylglucoside) and 3-(6″-glucosylglucoside) of cyanidin, in addition to peonidin 3-(dimalonylglucoside) and delphinidin 3-(6″-rhamnosylglucoside). Anthocyanins acylated with one and/or two malonic acid moieties dominated the anthocyanin profiles of all the species in the subfamilies Pooideae and Panicoideae. On the other hand, the 3-glucoside and 3-rutinoside of cyanidin were the major anthocyanins in Sinarundinaria murielae (subfamily Bambusoideae) and Molinia caerulea (subfamily Arundinoideae), while the 3-glucosides of cyanidin and peonidin were the principal anthocyanins in rice, Oryza sativum (subfamily Oryzoideae). Pelargonidin derivatives and free anthocyanidins have previously been reported to occur in several Poaceae species, however, not identified in any of the species included in this survey.     

The Basic Types of the Seedling of the Chinese Gramineae in Relation to Systematics

Investigations have been made on the mode of development and various characteristics of seedling of 203 grass species representing over 76 genera and 22 tribes. The correlation between important characteristics and their main formative conditions in distribution area and habitat were discussed. According to the various developmental forms of the embryo axis and root system, the seedlings of grasses may be divided into three main types: Bambusoid, Festucoid and Panicoid. And according to characteristics of seedling leaves and adventitious roots, these types may be further divided into seven subtypes: True Bambusoid, Oryzoid, Arundinoid, Stipoid, Festucoid, Eragrostoid and True Panicoid. in this study, the different types of seedlings have been found to be associated with other characteristics of embryo and adult plant; and on these grounds, the genera of the Gramineae are grouped into seven corresponding subfamilies: Bambusoideae, Oryzoideae, Arundinoideae, Stipoideae, Festucoideae, Eragrostoideae and Panicoideae.     

A worldwide phylogenetic classification of the Poaceae (Gramineae) III: An update

We present an updated worldwide phylogenetic classification of Poaceae with 11 783 species in 12 subfamilies, 7 supertribes, 54 tribes, 5 super subtribes, 109 subtribes, and 789 accepted genera. The subfamilies (in descending order based on the number of species) are Pooideae with 4126 species in 219 genera, 15 tribes, and 34 subtribes; Panicoideae with 3325 species in 242 genera, 14 tribes, and 24 subtribes; Bambusoideae with 1698 species in 136 genera, 3 tribes, and 19 subtribes; Chloridoideae with 1603 species in 121 genera, 5 tribes, and 30 subtribes; Aristidoideae with 367 species in three generaand one tribe; Danthonioideae with 292 species in 19 generaand 1 tribe; Micrairoideae with 192 species in nine generaand three tribes; Oryzoideae with 117 species in 19 genera, 4 tribes, and 2 subtribes; Arundinoideae with 36 species in 14 genera and 3 tribes; Pharoideae with 12 species in three generaand one tribe; Puelioideae with 11 species in two generaand two tribes; and the Anomochlooideae with four species in two generaand two tribes. Two new tribes and 22 new or resurrected subtribes are recognized. Forty-five new (28) and resurrected (17) genera are accepted, and 24 previously accepted genera are placed in synonymy. We also provide an updated list of all accepted genera including common synonyms, genus authors, number of species in each accepted genus, and subfamily affiliation. We propose Locajonoa, a new name and rank with a new combination, L. coerulescens. The following seven new combinations are made in Lorenzochloa: L. bomanii, L. henrardiana, L. mucronata, L. obtusa, L. orurensis, L. rigidiseta, and L. venusta.     

The Pharus latifolius genome bridges the gap of early grass evolution

The grass family (Poaceae) includes all commercial cereal crops and is a major contributor to biomass in various terrestrial ecosystems. The ancestry of all grass genomes includes a shared whole-genome duplication (WGD), named rho (ρ) WGD, but the evolutionary significance of ρ-WGD remains elusive. We sequenced the genome of Pharus latifolius, a grass species (producing a true spikelet) in the subfamily Pharoideae, a sister lineage to the core Poaceae including the (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, and Danthonioideae (PACMAD) and Bambusoideae, Oryzoideae, and Pooideae (BOP) clades. Our results indicate that the P. latifolius genome has evolved slowly relative to cereal grass genomes, as reflected by moderate rates of molecular evolution, limited chromosome rearrangements and a low rate of gene loss for duplicated genes. We show that the ρ-WGD event occurred approximately 98.2 million years ago (Ma) in a common ancestor of the Pharoideae and the PACMAD and BOP grasses. This was followed by contrasting patterns of diploidization in the Pharus and core Poaceae lineages. The presence of two FRIZZY PANICLE-like genes in P. latifolius, and duplicated MADS-box genes, support the hypothesis that the ρ-WGD may have played a role in the origin and functional diversification of the spikelet, an adaptation in grasses related directly to cereal yields. The P. latifolius genome sheds light on the origin and early evolution of grasses underpinning the biology and breeding of cereals.

The Pharus genome fills an important genomic gap, providing numerous insights into how whole-genome duplication contributed to the origin and diversification of the grass family.     

Phylogenetic structure in the grass family (Poaceae): evidence from the nuclear gene phytochrome B

Phylogenetic analyses of partial phytochrome B (PHYB) nuclear DNA sequences provide unambiguous resolution of evolutionary relationships within Poaceae. Analysis of PHYB nucleotides from 51 taxa representing seven traditionally recognized subfamilies clearly distinguishes three early-diverging herbaceous "bambusoid" lineages. First and most basal are Anomochloa and Streptochaeta, second is Pharus, and third is Puelia. The remaining grasses occur in two principal, highly supported clades. The first comprises bambusoid, oryzoid, and pooid genera (the BOP clade); the second comprises panicoid, arundinoid, chloridoid, and centothecoid genera (the PACC clade). The PHYB phylogeny is the first nuclear gene tree to address comprehensively phylogenetic relationships among grasses. It corroborates several inferences made from chloroplast gene trees, including the PACC clade, and the basal position of the herbaceous bamboos Anomochloa, Streptochaeta, and Pharus. However, the clear resolution of the sister group relationship among bambusoids, oryzoids, and pooids in the PHYB tree is novel; the relationship is only weakly supported in ndhF trees and is nonexistent in rbcL and plastid restriction site trees. Nuclear PHYB data support Anomochlooideae, Pharoideae, Pooideae sensu lato, Oryzoideae, Panicoideae, and Chloridoideae, and concur in the polyphyly of both Arundinoideae and Bambusoideae.     

A worldwide phylogenetic classification of the Poaceae (Gramineae)

Based on recent molecular and morphological studies we present a modern worldwide phylogenetic classification of the ± 12074 grasses and place the 771 grass genera into 12 subfamilies (Anomochlooideae, Aristidoideae, Arundinoideae, Bambusoideae, Chloridoideae, Danthonioideae, Micraioideae, Oryzoideae, Panicoideae, Pharoideae, Puelioideae, and Pooideae), 6 supertribes (Andropogonodae, Arundinarodae, Bambusodae, Panicodae, Poodae, Triticodae), 51 tribes (Ampelodesmeae, Andropogoneae, Anomochloeae, Aristideae, Arundinarieae, Arundineae, Arundinelleae, Atractocarpeae, Bambuseae, Brachyelytreae, Brachypodieae, Bromeae, Brylkinieae, Centotheceae, Centropodieae, Chasmanthieae, Cynodonteae, Cyperochloeae, Danthonieae, Diarrheneae, Ehrharteae, Eragrostideae, Eriachneae, Guaduellieae, Gynerieae, Hubbardieae, Isachneae, Littledaleeae, Lygeeae, Meliceae, Micraireae, Molinieae, Nardeae, Olyreae, Oryzeae, Paniceae, Paspaleae, Phaenospermateae, Phareae, Phyllorachideae, Poeae, Steyermarkochloeae, Stipeae, Streptochaeteae, Streptogyneae, Thysanolaeneae, Triraphideae, Tristachyideae, Triticeae, Zeugiteae, and Zoysieae), and 80 subtribes (Aeluropodinae, Agrostidinae, Airinae, Ammochloinae, Andropogoninae, Anthephorinae, Anthistiriinae, Anthoxanthinae, Arthraxoninae, Arthropogoninae, Arthrostylidiinae, Arundinariinae, Aveninae, Bambusinae, Boivinellinae, Boutelouinae, Brizinae, Buergersiochloinae, Calothecinae, Cenchrinae, Chionachninae, Chusqueinae, Coicinae, Coleanthinae, Cotteinae, Cteniinae, Cynosurinae, Dactylidinae, Dichantheliinae, Dimeriinae, Duthieinae, Eleusininae, Eragrostidinae, Farragininae, Germainiinae, Gouiniinae, Guaduinae, Gymnopogoninae, Hickeliinae, Hilariinae, Holcinae, Hordeinae, Ischaeminae, Loliinae, Melinidinae, Melocanninae, Miliinae, Monanthochloinae, Muhlenbergiinae, Neurachninae, Olyrinae, Orcuttiinae, Oryzinae, Otachyriinae, Panicinae, Pappophorinae, Parapholiinae, Parianinae, Paspalinae, Perotidinae, Phalaridinae, Poinae, Racemobambosinae, Rottboelliinae, Saccharinae, Scleropogoninae, Scolochloinae, Sesleriinae, Sorghinae, Sporobolinae, Torreyochloinae, Traginae, Trichoneurinae, Triodiinae, Tripogoninae, Tripsacinae, Triticinae, Unioliinae, Zizaniinae, and Zoysiinae). In addition, we include a radial tree illustrating the hierarchical relationships among the subtribes, tribes, and subfamilies. We use the subfamilial name, Oryzoideae, over Ehrhartoideae because the latter was initially published as a misplaced rank, and we circumscribe Molinieae to include 13 Arundinoideae genera. The subtribe Calothecinae is newly described and the tribe Littledaleeae is new at that rank.     

EVOLUTIONARY ANALYSIS OF THE LARGE SUBUNIT OF CARBOXYLASE (rbcL) NUCLEOTIDE SEQUENCE AMONG THE GRASSES (GRAMINEAE)

The full nucleotide sequences of the chloroplast encoded large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL) are available for nine grass species and partial sequence data for one species. Relative rate tests of the “molecular clock” hypothesis suggest that rbcL evolved more rapidly in the lineage leading to Zea than in those leading to the other species. The estimated overall substitution rate for rbcL among these grasses is about 5 times 10^?10 substitutions per site per year, or about one-half the synonymous rate. The nine full sequences were analyzed by the UPGMA, Wagner parsimony, maximum likelihood, and Fitch-Margoliash methods. The latter three methods produced trees with the same topology. This topology largely agrees with current taxonomic evidence regarding the relationships among these grasses. UPGMA produced a topology that conflicts more substantially with available taxonomic evidence. Statistical comparison of the three alternative topologies for the subfamilies Panicoideae, Pooideae and Bambusoideae failed to support one of these topologies over the others, reflecting the taxonomic ambiguities surrounding the relationships among these taxa. Phylogenetic analyses based on the partial sequences of all 10 species gave conflicting results with regard to the relationship between Hordeum and Triticum, both members of the tribe Triticeae. This indicates that rbcL sequences contain too little information to resolve relationships among genera within this tribe. Overall, the results suggest that rbcL sequence data can provide some new information concerning grass phylogeny, but that the amount of available data from this gene is too small to differentiate statistically among alternative topologies for the grasses. Conflicting results from parsimony, maximum likelihood, and Fitch-Margoliash methods proved useful in exploring the validity of assumptions underlying these methods.     

Phylogenetic signals in the realized climate niches of Chinese grasses (Poaceae)

Explaining relationships between species richness and biogeographical patterns over a broad geographic scale is a central issue of biogeography and macroecology. We document the realized climate niches for grasses in China’s nature reserves and discuss its formation mechanism using grass richness data combined with climatic, physiological, and phylogenetic data. Our results suggest that climate niche structure of grasses is phylogenetically conservative for BEP (Bambusoideae, Ehrhartoideae, and Pooideae) and PACMAD (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, and Danthonioideae) clades along temperature gradients and for Chloridoideae and Panicoideae along precipitation gradients. At the national scale, the divergence patterns of climate niches between two major clades are more distinguishable than between C₃ and C₄ grasses. High rates of climate niche evolution are found in C₄ clades in the subtropical forest region. There appears to be a strong association between elevation gradients and grass diversity: the specific environmental conditions (e.g. energy) and the rapid shifts of climate conditions drive high grass diversification. Evolutionary conservatism of climate niches may be influenced by the specific adaptive ability to changing environmental conditions within NAD-ME/NADP-ME clades. Our results indicate that adaptations to major climate changes may be accomplished by C₄ grass nodes of high climate niche evolutionary rates in China’s nature reserves.     

Non-monophyly of the woody bamboos (Bambuseae; Poaceae): a multi-gene region phylogenetic analysis of Bambusoideae s.s.

The taxonomy of Bambusoideae is in a state of flux and phylogenetic studies are required to help resolve systematic issues. Over 60 taxa, representing all subtribes of Bambuseae and related non-bambusoid grasses were sampled. A combined analysis of five plastid DNA regions, trnL intron, trnL-F intergenic spacer, atpB-rbcL intergenic spacer, rps16 intron, and matK, was used to study the phylogenetic relationships among the bamboos in general and the woody bamboos in particular. Within the BEP clade (Bambusoideae s.s., Ehrhartoideae, Pooideae), Pooideae were resolved as sister to Bambusoideae s.s. Tribe Bambuseae, the woody bamboos, as currently recognized were not monophyletic because Olyreae, the herbaceous bamboos, were sister to tropical Bambuseae. Temperate Bambuseae were sister to the group consisting of tropical Bambuseae and Olyreae. Thus, the temperate Bambuseae would be better treated as their own tribe Arundinarieae than as a subgroup of Bambuseae. Within the tropical Bambuseae, neotropical Bambuseae were sister to the palaeotropical and Austral Bambuseae. In addition, Melocanninae were found to be sister to the remaining palaeotropical and Austral Bambuseae. We discuss phylogenetic and morphological patterns of diversification and interpret them in a biogeographic context.     

Cereal prolamin evolution and homology revealed by sequence analysis

Prolamin mixtures were isolated from oats, rice, normal and high-lysine sorghum, two varieties of pearl millet, two strains of teosinte, and gamma grass and subjected to NH₂-terminal amino acid sequence determinations. In each case (except for rice, whose prolamins apparently have blocked or unavailable NH₂-terminal residues), primarily a single sequence was observed despite significant heterogeneity, suggesting that prolamin homology in each cereal arose through duplication and mutation of a single ancestral gene. Comparisons were then made to prolamin sequences previously determined for wheat, corn, barley, and rye. Within genera, different varieties or subspecies exhibited few differences, but more distantly related genera, subtribes, and tribes showed increasingly large differences. Within the subfamily Festucoideae, no homology was apparent between prolamins of oats and those of the subtribe Triticinae (including wheat, rye, and barley, for which prolamin homology was previously demonstrated). Within the subfamily Panicoideae, corn was shown to be closely related to teosinte but more distantly to Tripsacum. Sorghum was shown to have diverged less from corn than had millet. These comparisons demonstrate that prolamin sequence analyses can successfully predict and clarify evolutionary relationships of cereals.