Tribe Aveneae Research Articles

Genome-wide expansion and reorganization during grass evolution: from 30 Mb chromosomes in rice and Brachypodium to 550 Mb in Avena

BackgroundThe BOP (Bambusoideae, Oryzoideae, and Pooideae) clade of the Poaceae has a common ancestor, with similarities to the genomes of rice, Oryza sativa (2n = 24; genome size 389 Mb) and Brachypodium, Brachypodium distachyon (2n = 10; 271 Mb). We exploit chromosome-scale genome assemblies to show the nature of genomic expansion, structural variation, and chromosomal rearrangements from rice and Brachypodium, to diploids in the tribe Aveneae (e.g., Avena longiglumis, 2n = 2x = 14; 3,961 Mb assembled to 3,850 Mb in chromosomes).ResultsMost of the Avena chromosome arms show relatively uniform expansion over the 10-fold to 15-fold genome-size increase. Apart from non-coding sequence diversification and accumulation around the centromeres, blocks of genes are not interspersed with blocks of repeats, even in subterminal regions. As in the tribe Triticeae, blocks of conserved synteny are seen between the analyzed species with chromosome fusion, fission, and nesting (insertion) events showing deep evolutionary conservation of chromosome structure during genomic expansion. Unexpectedly, the terminal gene-rich chromosomal segments (representing about 50 Mb) show translocations between chromosomes during speciation, with homogenization of genome-specific repetitive elements within the tribe Aveneae. Newly-formed intergenomic translocations of similar extent are found in the hexaploid A. sativa.ConclusionsThe study provides insight into evolutionary mechanisms and speciation in the BOP clade, which is valuable for measurement of biodiversity, development of a clade-wide pangenome, and exploitation of genomic diversity through breeding programs in Poaceae.

Phylogenetic lineages and the role of hybridization as driving force of evolution in grass supertribe Poodae

AbstractTo investigate the evolutionary diversification and morphological evolution of grass supertribe Poodae (subfam. Pooideae, Poaceae) we conducted a comprehensive molecular phylogenetic analysis including representatives from most of its accepted genera. We focused on generating a DNA sequence dataset of plastid matK gene–3′trnK exon and trnL‐trnF regions and nuclear ribosomal (nr) ITS1–5.8S gene–ITS2 and ETS that was taxonomically overlapping as completely as possible (altogether 257 species). The idea was to infer whether phylogenetic trees or certain clades based on plastid and nrDNA data correspond with each other or discord, revealing signatures of past hybridization. The datasets were analysed separately, in combination, by excluding taxa with discordant placements in the individual gene trees and with duplication of these taxa in a way that each duplicate has only one data partition (plastid or nrDNA). We used maximum likelihood, maximum parsimony and Bayesian approaches. Instances of severe conflicts between the phylogenetic trees derived from both datasets, some of which have been noted earlier, point to hybrid origin of several lineages such as the ABCV clade encompassing several subtribes and subordinate clades, subtribes Airinae, Anthoxanthinae, Antinoriinae, subtr. nov., Aristaveninae, Avenulinae, subtr. nov., Helictochloinae, subtr. nov., Holcinae, Phalaridinae, Scolochloinae, Sesleriinae, Torreyochloinae and genera Arctopoa, Castellia, Graphephorum, Hyalopodium, Lagurus, Macrobriza, Puccinellia plus Sclerochloa, Sesleria, Tricholemma, Tzveleviochloa, etc. ‘Calamagrostis’ flavens appears to be an intergeneric hybrid between Agrostis and Calamagrostis. Analyses excluding all lineages with demonstrably cytonuclear discordance revealed three supported main clades within Poodae that were present in both the plastid and nrDNA trees. They fully corresponded in their delineation but were phylogenetically differently arranged, pointing to hybrid origin of one of them. We propose to consider these main clades in classification as separate tribes Aveneae, Poeae s.str. and Festuceae with a phylogenetic arrangement of Aveneae(Poeae,Festuceae) in plastid versus Festuceae(Aveneae,Poeae) in nrDNA trees. Phylogenetic incongruence of the plastid and nuclear markers extends across all hierarchical taxonomic levels of Poodae, ranging from species (not studied here) to genera, subtribes and tribes, therefore the deepest taxonomic levels, emphasizing the enormous significance of reticulate evolution in this large group of grasses. A partly revised classification is presented, including the introduction of a new tribe Festuceae and a re‐instatement of tribe Aveneae. Following a comparatively narrow delineation of preferably monophyletic subtribes, Antinoriinae, Avenulinae, Brizochloinae, Helictochloinae and Hypseochloinae are described as new. New genera are Arctohyalopoa and Hyalopodium. New combinations are Anthoxanthum glabrum subsp. sibiricum, A. nitens subsp. kolymense, Arctohyalopoa ivanovae, A. jurtzevii, A. lanatiflora, A. momica, Colpodium biebersteinianum, C. kochii, C. pisidicum, C. trichopodum, C. verticillatum, Dupontia fulva, Festuca masafuerana, F. robinsoniana, Graphephorum canescens, G. cernuum, Hyalopodium araraticum, Paracolpodium baltistanicum, Parapholis cylindrica, P. ×pauneroi. Festuca dolichathera and F. masatierrae are new names.

Chromosome Numbers and Male Meiotic Course Analysis in Some Wild Grasses of Tribe Aveneae from Uttarkashi District Hills, Uttarakhand, India

Present study on male meiotic analysis of wild grass species from Uttarkashi district hills, Uttarakhand, India provides chromosome numbers for 10 species belonging to tribe Aveneae, family Poaceae. The study reports chromosome numbers firstly for Helictotrichon uniyalii (2n=4x=28, Rarhi Valley), Trisetum aeneum (2n=2x=14, Assi Ganga Valley) and Tr. clarkei (2n=4x=28, Assi Ganga Valley), and confirmed in the Indian species, Avena fatua (2n=6x=42, Purola Valley), Koeleria macrantha (2n=2x=14, Bhagirathi Valley), Phleum alpinum (2n=4x=28, Har Ki Dun Valley), P. pratense (2n=4x=28, Assi Ganga Valley), Trisetopsis aspera (2n=6x=42,; Assi Ganga Valley), T. virescens (2n=4x=28, Assi Ganga Valley and Bhagirathi Valley) and Tr. spicatum (2n=4x=28, Assi Ganga Valley, Bhagirathi Valley, and Har Ki Dun Valley). The meiotic course was normal in most of the species, although suggested a paracentric inversion in a plant of Tr. spicatum.

Morpho-anatomical and physiological adaptations to high altitude in some Aveneae grasses from Neelum Valley, Western Himalayan Kashmir

Five grasses of tribe Aveneae were collected from low (1100 m.a.s.l.) and highland (2300 m.a.s.l.) mountain range of Western Himalaya, Neelum Valley, to evaluate the physio-anatomical adaptations to altitudinal variability. An evidence to confirm the hypothesis that plants vegetating different altitudes must be different structurally (internal modifications) and functionally due to heterogeneity in environmental gradients. The general response of all grasses to high altitude was growth retardation in terms of total leaf area per plant and dry matter. With exception of Ca2+ content, most of the ionic and chlorophyll content were significantly low at high elevations. Anatomical alterations such as, leaf thickness, intensive sclerification around the vascular bundle and pith area, reduced metaxylem vessel area, high pubescence (increased microhair and trichome density) played an important role in high degree of tolerance of these grasses to cope with altitudinal stresses. The mechanical strength of leaf, which is critical for preventing damage under harsh climate and overall survival of high altitudinal populations, seems to be depended on intensity of sclerification and dense pubescence at abaxial and adaxial surfaces of the leaf. Increase in overall thickness of leaf in high altitude grasses in response to low temperature may protect metabolically active tissue like mesophyll. Also high density of trichomes may be involved in blocking transpiration water and internal heat. Differential response of low and high altitude grasses is highly related to air temperature, pattern of rainfall, and availability of nutrients.

Variation of reproduction in some species of the tribe Aveneae (Poaceae)

Patterns of reproduction were studied in a series of inter- and intraspecific units in the genus Avena. The range of variation of the mating system is from autogamy to allogamy. The first system is expressed in cultivated types, while the second is observed in wild and weedy ones. In a wild oat of putative hybrid origin or being a mutation, the development of pollen grains deviates from that noted in grasses as normal.

Taxonomic Significance of Glume Morphology and Leaf Epidermal Characteristics in some Taxa of Tribe Aveneae (Poaceae)

The numerical classification of tribe Aveneae (Poaceae) is discussed regarding the glume morphology and silica skeleton morphologies. The present study dealt with 18 species belonging to 10 genera of the tribe to cover as many groups as possible within Aveneae. The total of 31 structural characters and 71 character states were scored comparatively. The resulted data matrix was analyzed under a combination of Euclidean distance measure and Ward’s clustering method included in the program package PC-ORD version 5. The resulted dendrogram separated the tribe into five basic sub-ordinate groups created from three major groups A, B and C. The taxonomic significance of these results was discussed. The results showed congruence between the clustering and PCA method, in suggesting three major groups and 5 sub-ordinate groups.

Foliar epidermal anatomy as an aid to the identification of grasses in tribe Aveneae (subfamily Pooideae, Poaceae) from saltrange of Pakistan

In the present studies foliar epidermal anatomy regarding 7 species belonging to 5 genera of tribe Aveneae (Poaceae) was carried out. The studies revealed that different leaf anatomical characters, such as presence or absence of rounded short cells, length of long cells, size of stomatal complex and shape of silica bodies, are helpful in the identification of different species and genera within the tribe. Large cells with maximum length and largest stomatal complex are found in Avena sp. In genus Agrostis, Phalaris and Koeleria variations exist in the morphology of silica bodies. The studies revealed that diversity in different anatomical characters present within the species and genera is a valuable tool for the differentiation and correct identification of species in tribe Aveneae. Key words: Foliar, Aveneae, Poaceae, salt range, Pakistan.

Characterisation of cDNAs for ribulose bisphosphate carboxylase small subunit genes in different species of Avena (Poaceae)

ABSTRACT We report the cloning and sequencing of 14 rbcS cDNAs in six species of Avena (Poaceae) with different genome and ploidy levels. The nucleotide sequences 504 bp long were aligned with the published sequences of cultivated hexaploid oat, wheat, barley, rye, rice and corn and subjected to cladistic and phenetic analyses. The parsimonious analysis generated a tree with a topology very similar to the phenogram generated by the Neighbor-Joining analysis based on the Jukes and Cantor distances. Within the monophyletic assemblage of the tribe Aveneae, consistent clades composed of rbcS clones belonging to different species are recognized. It is suggested that they correspond to orthologous genes belonging to different subfamilies, and that the “within-species˚d homogenisation may have occurred at a slow rate with respect to species evolution. In the monophyletic group of Pooideae, the topologies place barley rbcS sequences closer to wheat and rye than to oat sequences. This grouping agrees with most taxonomic and phylogenetic views.

Puccinia coronata var. Hordei var. nov.: Morphology and Pathogenicity

A new variety of Puccinia coronata causing a disease on barley and other gramineous species is described. The fungus is different from other re- ported forms of P coronata in both morphology and pathogenicity. Its most prominent characters are the elongated teliospore appendages with dichotomous branching and wide pathogenicity on species in the tribe Triticeae, particularly the genus Hordeum. The name of P coronata var. hordei is proposed for the rust fungus. The common name 'crown rust of bar- ley' is proposed for the disease of barley caused by this rust fungus. Results of inoculation indicated that P coronata var. hordei is pathogenic on species of Ae- gilops, Agropyron, Elymus, Elytrigia, Leymus, Pascopy- rum, Psathyrostachys, Secale, and Triticum in the tribe Triticeae, and some species of Brachypodium, Bromus, Festuca, and Lolium in the tribe Poeae, and Phalaris in the tribe Aveneae. In the northern Great Plains of

Puccinia coronata var. hordei var. nov.: morphology and pathogenicity

A new variety of Puccinia coronata causing a disease on barley and other gramineous species is described. The fungus is different from other reported forms of P. coronata in both morphology and pathogenicity. Its most prominent characters are the elongated teliospore appendages with dichotomous branching and wide pathogenicity on species in the tribe Triticeae, particularly the genus Hordeum. The name of P. coronata var. hordei is proposed for the rust fungus. The common name ‘crown rust of barley’ is proposed for the disease of barley caused by this rust fungus. Results of inoculation indicated that P. coronata var. hordei is pathogenic on species of Aegilops, Agropyron, Elymus, Elytrigia, Leymus, Pascopyrum, Psathyrostachys, Secale, and Triticum in the tribe Triticeae, and some species of Brachypodium, Bromus, Festuca, and Lolium in the tribe Poeae, and Phalaris in the tribe Aveneae. In the northern Great Plains of the USA, the following native and introduced gramineous species were found naturally infected by P. coronata var. hordei: Bromus tectorum, Elymus canadensis, E. trachycaulus, E. virginicus, Elytrigia intermedia, E. repens, Hordeum jubatum, H. vulgare, Leymus angustus, L. cinerius, L. dahuricus, L. racemosus, Pascopyrum smithii, Psathyrostachys juncea, and Secale cereale.

Trisetum Pers. (Gramineae: Aveneae) in New Zealand**

Trisetum Pers. (tribe Aveneae) is revised for New Zealand. Nine indigenous species are recognised; eight are endemic, and T. spicatum occurs in alpine regions of both hemispheres. Four species, T. arduanum, T. drucei, T. lepidum, and T. serpen‐tinum, are described as new, and T. antacticum var. lasiorhachis is raised to specific rank as T. lasiorhachis.

An Infrageneric Classification for Poa in North America, and Other Notes on Sections, Species, and Subspecies of Poa, Puccinellia, and Dissanthelium (Poaceae)

An infrageneric classification for the genus Poa L. in North America, new taxa, combinations, names, hybrid status, and lectotypes are proposed for forthcoming treatments of the genus in the Americas. New names, combinations, and taxa are: Dissanthelium atropidiforme (Hackel) Soreng, D. atropidiforme var. patagonicum (Parodi) Soreng, D. calycinum subsp. mathewsii (Ball) Soreng, Poa sect. Alpinae (Hegetschweiler ex Nyman) Soreng, P. sect. Dasypoa (Pilger) Soreng, P. sect. Sylvestres V. L. Marsh ex Soreng, P arnowiae Soreng, P chambersii Soreng, P tovari Soreng, P unilateralis subsp. pachypholis (Piper) D. D. Keck ex Soreng, P. Xgaspensis Fernald, and Puccinellia atacamensis (Parodi) Soreng. Lectotypes are proposed for the following taxa: Dissanthelium sclerochloides Steudel ex E. Fournier, Poa [unranked] Arenariae Hegetschweiler, Poa [unranked] Caespitosae Fries ex Lange, Poa [unranked] Fasciculiferae Fries ex Lange, Poa [unranked] Glareosae Hegetschweiler, Poa [unranked] Hydrophilae Hegetschweiler, Poa [unranked] Macranthela K. Koch, Poa [unranked] Micranthela K. Koch, Poa [unranked] Stoloniferae Fries ex Lange, Poa [unranked] Subbulbosae Fries ex Andersson, Poa sect. Incanae V. Jirisek, Poa sect. Nervosae Rouy, Poa sect. Obsoletae Rouy, Poa sect. Spizopoa Dumortier. In the course of working on Poa for North America (Soreng, 1985, 1990, 1991a, 1991b, 1986; Soreng & Hatch, 1983) it became apparent that the number of sections of Poa needed to be expanded, and the taxonomy of certain introduced Old World and circumboreal sections needed to be straightened out. Some of the changes proposed here stem from the results of chloroplast DNA (cpDNA) restriction site analyses for the genus. Other changes stem from a better understanding of the importance of the branching system to the taxonomy of Poa, and experience gained through having worked with the genus for 20 years. Physiographic divisions for distributions follow Takhtajan (1986). In addition, two new species are described, and five new combinations and one new name are proposed. A. Two NEW SECTIONS OF POA Poa [subg. Poa] sect. Dasypoa (Pilger) Soreng, comb. et stat. nov. Basionym: Dasypoa Pilger, Bot. Jahrb. Syst. 25: 716. 1898. TYPE: Dasypoa tenuis Pilger (= Poa conglomerata Ruprecht ex Peyritsch). Slender, caespitose, annuals or short-lived perennials, without rhizomes, to 30 cm tall; branching intravaginal; leaf sheaths weakly keeled to terete, not persisting on the plant for more than one season, without bulbous thickened bases, those of the uppermost culm leaves closed ?-~25 their length; leaf blades thin, flat, lax, at most sparsely scabrous above, with two lengthwise adaxial grooves, one on either side of the central vascular bundle; panicles densely flowered, cylindrical, somewhat lobed; spikelets 2-3-flowered; lemmas mostly 1-3 mm long, strongly to obscurely 5-veined, strongly keeled, sparsely pubescent (rarely glabrous); florets with one or three tufts of hair on the callus (callus rarely glabrous); palea keels scabrous and sometimes strigose below; flowers perfect, with three anthers 0.3-0.5 mm long. Species included: Poa conglomerata Ruprecht ex Peyritsch, of the volcanic highlands of central Mexico and Guatemala, and P. parviceps Hackel and PR scaberula Hooker f. (= P conglomerata), Andean and Chile-Patagonian regions of South America and Tierra del Fuego. Watson and Dallwitz (1992) placed the genus Dasypoa Pilger in tribe Aveneae, without explanation, whereas Clayton and Renvoize (1986) placed it in synonymy within Poa. Tzvelev (1989) recognized the genus as a member of his broadly defined tribe Poeae (including Aveneae). On morphological grounds the type of the genus, Dasypoa tenuis, cannot be distinguished from Poa. Poa conglomerata, which is not morphologically distinct from P scaberula (under which D. tenuis has been synonymized in the past), shares derived cpDNA restriction sites with cpDNA group IV species (see section D, below), including sections Homalopoa, NovoN 8: 187-202. 1998. This content downloaded from 157.55.39.138 on Mon, 27 Jun 2016 05:37:45 UTC All use subject to http://about.jstor.org/terms

Cytogenetic studies in some representatives of the subfamily Pooideae (Poaceae) in South Africa. 2. The tribe Aveneae, subtribes Phalaridinae and Alopecurinae

This is a report on chromosome numbers for the subtribes Phalaridinae and Alopecurinae (tribe Aveneae) which are. to a large extent, naturalized in South Africa. Chromosome numbers of 34 specimens, representing nine species and four genera, are presented. These numbers include the first report on Agrostis avenacea Gmel. (n = 4x = 28). New ploidv levels are reported for Phalaris aquatica L. (n = x = 7), Agrostis barbuligera Stapf var. barbuligera (n = 2x = 14 and n = 4x = 28) and A. lachnantha Nees var. lachnantha (n = 3x = 21).

Cytogenetic studies in some representatives of the subfamily Pooideae (Poaceae) in South Africa. 1. The tribe Aveneae, subtribe Aveninae

This is a report on chromosome numbers for 14 species of the subtribe Aveninae. which is largely naturalized in South Africa. This is the first chromosome number report for Helictotrichon longifolium (Nees) Schweick. (n = 14). H. longum (Stapf)Schweick. (n = 14). H. namaquensis Schweick. (n = 14) and Lophochloa cristata (L.) Hyl. (n = 7, 21/2. 14). The subtribe has a basic chromosome number of seven, and fewer ploidy levels occur in the naturalized species in South Africa than in the same species in other parts of the world. All tetraploid specimens were alloploids.

Chloroplast DNA Similarity of Smooth Bromegrass with Other Pooid Cereals: Implications for Plant Breeding

Restriction site (RS) variation in the chloroplast genome has been useful in discerning evolutionary relationships. This information enables plant breeders to determine the primary, secondary, and tertiary gene pools of crop plants. In this study, chloroplast DNA (cpDNA) RS maps of smooth bromegrass (Bromus inermis Leyss.) were compared with those of wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.), and oat (Arena sativa L.). The number of common RS for the enzymes KpnI, PstI, PvuII, SalI and XhoI was scored, providing data to calculate the genetic distance (p) among the taxa. Clustering analysis showed that smooth bromegrass (tribe Bromeae) is very closely related to wheat, rye and barley of the tribe Triticeae and more distantly related to oat (tribe Aveneae). It was of interest to find that smooth bromegrass was more closely related than barley to wheat and rye. The cpDNA relationships suggest that bromegrasses are a potentially important component of the gene pool in the breeding of pooid cereals. Bromegrasses are a useful source of genes for disease resistance, agronomic properties, and nutritional value that could be introgressed into their close relatives.

Embryological studies in some grasses and their taxonomic significance

BHANWRA, R. K., KAUR, N., KAUR, N. & GARG, A., 1991. Embryological studies in some grasses and their taxonomic significance. The species investigated are Lolium multiftorum Lam (tribe Poeae), Rostraria cristata (Linn.) Tzevlev (tribe Aveneae), Cenchrus setigerus Vahl, Digitaria abludens (Roem. et Schult.) Veld, and D. ciliaris (Retz.) Koel (tribe Paniceae). Apart from the number of microsporocytes in a median longitudinal section of each anther lobe, microsporogenesis and male gametophyte development are similar. However, members of subfamilies Pooideae and Panicoideae show marked differences in structure of the ovary, ovule and post-fertilization development. Lolium multiftorum and R. cristata vary in the structure of the dorsal ovary wall, degree of curvature in the megagemetophyte in relation to the longtitudinal axis of the ovule, and structure of the pericarp. Cenchrus setigerus is an aposporic apomict and differs markedly from species of Digitaria in this respect, in the extent of development of the inner integument and in the constitution of the dorsal ovary wall. The two species of Digitaria show minor embryological differences.

Checklist of pooid grasses naturalised in New Zealand. 1- Tribes Nardeae, Stipeae, Hainardieae, Meliceae, and Aveneae

Abstract Reported as naturalised in New Zealand are one taxon of tribe Nardeae, thirteen taxa of tribe Stipeae, three of tribe Hainardieae, seven of tribe Meliceae, and, in tribe Aveneae, nineteen taxa of subtribe Aveninae, nine of subtribe Phalaridinae, and twenty-one of subtribe Alopecurinae. Ten other records (one tribe Stipeae, one tribe Meliceae, eight tribe Aveneae) are unsubstantiated. A synopsis of tribes is provided as well as keys, to native and naturalised genera, to naturalised species, and to native species where they occur with naturalised species in the same genus.

Notas agrostológicas sobre la flora balear

Se estudia el material original del herbario de H. Knoche para discutir la corología de algunas especies de gramíneas de la tribu Aveneae. Se citan tres nuevos táxones para las Islas Baleares: Avena sterilis L. var. maxima Pérez Lara, Arrhenatherum elatius subsp. baeticum Romero Zarco y A. Album (Vahl) W.D. Clayton var. album.

A NEW METHOD FOR ESTIMATING KARYOTYPE ASYMMETRY

SummaryTwo numerical parameters are used to estimate the karyotype asymmetry in twenty‐two taxa of the tribe Aveneae (Gramineae) from the Iberian Peninsula and Baleares. The new method is useful when there are only slight differences in karyotype asymmetry and when karyograms or idiograms are available.

Phytogeographical studies ofCalamagrostis sachalinensis (Gramineae)

The place of origin and the direction of migration ofCalamagrostis sachalinensis, which has the boreal—montane distribution pattern and represents an apo-amphimictic complex by itself, have been discussed on the basis of the combination of the information on the internal structure of this species and the existing circumstantial evidence. It is without a doubt thatCalamagrostis belongs to a primitive group within the tribe Aveneae, and its existence in Eurasia since the late Miocene period can not be questioned. Amphimictic tetraploids ofC. sachalinensis seem to have originated in the mountains of Japan from some ancestors which invaded Japan in the Neogene period or earlier, considering the distributional and ecological attributes of the tetraploids and the related tetraploid species. The hexaploids and octoploids ofC. sachalinensis with the apomictic manner of seed formation are apparently of a derived type and have most probably been brought forth from the tetrapoid races in the mountains of Japan. The climatic oscillations during the Pleistocene period seem to have greatly facilitated the northward migration of the hexaploids and octoploids. The present range ofC. sachalinensis extending from the mountains of Japan to Sakhalin and southern Kamtchatka may therefore have been established mainly by the migration from the southern montane areas to the northern lowlands. The usual interpretation for the derivation of the boreal—montane distribution which postulates the migration from the north to the south can hardly be applicable in the case ofC. sachalinensis. It is pointed out that the role of autochthonous development in the formation of the montane flora of Japan has probably been more important than hitherto recognized.