Lemma Awn Research Articles

Morphological variations of qualitative traits of barley (Hordeum vulgare L.) accessions in Ethiopia

Ethiopian barley germplasm is a potential source of useful traits to fight the production challenges of barley farming and to enhance yield productivity in favorable and marginal environments. A study was carried out to assess the distribution and patterns of 17 qualitative trait variations among 85 Ethiopian barley accessions using an alpha lattice design with two replications. The Shannon-Weaver diversity (H′) index was used to estimate morphological diversity. Fifteen morphological traits of barley accessions originating from various regions of origins and altitude ranges were polymorphic. However, two traits including stem branching and lemma awn were monomorphic. The highest (0.94) overall mean of H′ was obtained for glume colour, kernel row and kernel shape. The estimated H′ ranged from 0.41 to 0.99 across regions, and 0.52 to 0.99 across altitude ranges with an overall mean of 0.76. The analysis of variance of H′ showed significant variation for most studied traits. Principal components analysis revealed that eight traits were the major loading on the first two principal components that describe 38.3% of the total morphological variance. Heat map analysis based on morphological traits of barley accessions was also grouped into three distinct clusters. Thus, the present finding confirmed that the Ethiopian barley accessions showed vast morphological variations across the region of origins and altitude ranges. Based on the result, further evaluation is ongoing to exploit specific gene variations through phenotyping and genotyping trait association.

Mapping and Characterization of QTLs for Awn Morphology Using Crosses between "Double-Awn" Wheat 4045 and Awnless Wheat Zhiluowumai.

Awns play important roles in seed dispersal, protection against predators, and photosynthesis. The characterization of genes related to the formation of awns helps understand the regulation mechanisms of awn development. In the present study, the “double-awn” wheat 4045, which features super-long lemma awns and long glume awns, and an awnless wheat line, Zhiluowumai, were used to investigate QTLs or genes involved in awn development. QTL analysis identified three loci—Qawn-1D, Qawn-5A, and Qawn-7B—using a population of 101 4045 × ZLWM F2 plants. Fine mapping with a total of 9018 progenies narrowed the mapping interval of Qawn-5A to an 809-kb region, which was consistent with the B1 locus, containing five genes on chromosome 5AL. Gene structure and expression analysis indicated that TraesCS5A02G542800 was the causal gene, which was subsequently verified by overexpression of TraesCS5A02G542800 in a “double-awn” wheat, Yangmai20. The retained “double-awn” phenotype of transgenic plants suggested that B1 represses the elongation but does not influence the emergence of the awns. Moreover, 4045 harbors a new allele of B1 with a 261-bp insertion in the promoter region and a lack of the EAR2 motif in the encoding region, which influences several important agronomic traits. In this study, we identify two novel QTLs and a novel allele of B1, providing new resources for exploration of awn development.

<p><strong><em>Agrostis barikii</em> (Poaceae: Agrostidinae), a new grass species from Western Himalaya, India</strong></p>

A newly discovered species of the genus Agrostis from Western Himalaya is here described and illustrated. The new species, Agrostis barikii, is considered as a member of Agrostis pilosula group and morphologically closely allied to Agrostis griffithiana by its palea 2/3 the length of the lemma and well-developed awn. However, they differ from the latter by means of the shape of the ligule, length of the lower glume, apex of the lemma, and size of anthers. Data on distribution, habitat and phenology is given along with a photo plate and an illustration.

The study of genetic factors that determine the awned glume trait in bread wheat

Ости – тонкие заостренные отростки, сформированные в дистальной части чешуй колоска соцветия некоторых видов злаков, включая такие экономически значимые культуры, как пшеница мягкая (Triticum aestivum L.) и твердая (T. durum Desf.), ячмень (Hordeum vulgare L.), рис (Oryza sativa L.), рожь (Secale cereal L.). Наличие длинных остей на колосковых чешуях характерно для одного вида пшеницы – T. carthlicum Nevski, киль коло- сковой чешуи которого переходит в длинный остевидный отросток или ость, равную по длине ости цветковой чешуи. Колос T. carthlicum имеет удвоенное число остей, а сам признак получил название «тетраостость» или персикоидность. Ости на месте килевого зубца колосковых чешуй могут формироваться у пшениц T. aestivum и T. aethiopicum, однако такие формы встречаются редко. Особенности развития признака тетраостости и его гене- тические детерминанты изучены мало. В настоящем исследовании рассмотрены особенности развития и насле- дования признака «тетраостость» линии CD 1167-8 мягкой пшеницы T. aestivum c применением классического генетического анализа, молекулярно-генетического картирования и сканирующей электронной микроскопии. Показано, что признак наследуется как рецессивный моногенный. Ген, контролирующий тетраостость линии CD 1167-8, картирован в длинном плече хромосомы 5A c использованием 15K-SNP-микрочипа, содержащего 15 000 ассоциированных с генами SNP пшеницы (Illumina Infinium 15K Wheat Array, TraitGenetics GmbH). Резуль- таты теста на аллелизм продемонстрировали, что изучаемый ген аллелен b1, рецессивному аллелю гена-инги- битора остистости B1 (5AL). Таким образом, ген, контролирующий формирование остей на колосковых чешуях мягкой пшеницы, является рецессивным аллелем гена ингибитора остистости B1. Новый аллель обозначен b1.ag (b1. awned glume). Анализ развивающегося соцветия линии CD 1167-8 с помощью сканирующей электронной микроскопии выявил, что зачатки остей колосковых чешуй формируются по мере развития и роста колосковых чешуй одновременно с развитием остей на цветковых чешуях, различий в развитии остей на цветковых и колосковых чешуях не обнаружено.

<p><strong>A new species of <em>Megalachne</em> (Poaceae) endemic to Alejandro Selkirk Island, Juan Fernandez Archipelago, Chile</strong></p>

A new species of Megalachne (Poaceae) endemic to Alejandro Selkirk Island, Juan Fernandez Archipelago, Chile, is described and illustrated, based on morphological characters. This species is differentiated from others of the genus by its long lemma awn (5–8.5 cm) and by the number of flowers in the spikelet (2–4). The taxon has been reported previously for Juan Fernandez endemic flora, but without formal description.

Agro-morphological diversity of Nepalese naked barley landraces

BackgroundNaked barley is a traditional, climate-resilient and highly nutritious crop of the high mountains of Nepal. Knowledge of agro-morphological diversity among the naked barely genotypes is fundamental for their efficient utilization in plant breeding schemes and effective conservation programs. The primary objective of this study is phenotypic characterization and diversity assessment of naked barley landraces in Nepal for pre-breeding purposes.MethodologyData on quantitative and qualitative traits of 25 naked barley landraces from diversity blocks established across the four mountainous locations of Nepal (Humla, Jumla, Dolakha and Lamjung) were subjected to calculation of descriptive statistics and multivariate analysis (UPGMA cluster analysis/principal component analysis). Frequency distribution of various categories of qualitative traits and Shannon–Weaver diversity indices were computed.ResultsThe UPGMA cluster analysis using both quantitative and qualitative traits individually categorized the 25 naked barley landraces in five clusters in each case with no distinct regional grouping patterns in such a way that the landraces from same or adjacent regions of origin and collection amassed in different clusters. NGRC04894, Lamjung Local, NGRC02306, NPGR1579, NGRC02327 and NPGR1579 exhibited morphoagronomical superiority and potentiality for utilization as genitors in crop improvement programs. Principal component analysis revealed the quantitative traits, viz. grain yield, plant height and earliness, and qualitative traits, viz. grain color, overall phenotypic performance, lemma awn/hood and lemma awn barbs, to be the principal discriminatory characteristics of the Nepalese naked barley landrace collection. The Shannon–Weaver diversity index (H′) ranged from 0.32 to 0.99 with a mean value of 0.73, inferring tremendous diversity in the collection for the qualitative traits.ConclusionThe marked diversity observed among the Nepalese naked barley landraces could be utilized in crop improvement for various traits. The information generated complements the robust breeding program of competitive, stable and climate-resilient varieties of end users’ preferences in different mountainous agro-ecologies and also bolsters the employment of innovative and proven participatory plant breeding approach using diversity kits and informal research and development kits to expand and promote the varietal choice options for expeditious benefits to the farmers in the high mountains, considering that only one naked barley variety, viz. Solu Uwa, has been released in Nepal to date.

Polyphyly of Arundinoideae (Poaceae) and evolution of the twisted geniculate lemma awn.

Subfamily Arundinoideae represents one of the last unsolved taxonomic mysteries in the grass family (Poaceae) due to the narrow and remote distributions of many of its 19 morphologically and ecologically heterogeneous genera. Resolving the phylogenetic relationships of these genera could have substantial implications for understanding character evolution in the grasses, for example the twisted geniculate awn - a hygroscopic awn that has been shown to be important in seed germination for some grass species. In this study, the phylogenetic positions of most arundinoid genera were determined using DNA from herbarium specimens, and their placement affects interpretation of this ecologically important trait. A phylogenetic analysis was conducted on a matrix of full-plastome sequences from 123 species in 107 genera representing all grass subfamilies, with 15 of the 19 genera in subfamily Arundinoideae. Parsimony and maximum likelihood mapping approaches were used to estimate ancestral states for presence of a geniculate lemma awn with a twisted column across Poaceae. Lastly, anatomical characters were examined for former arundinoid taxa using light microscopy and scanning electron microscopy. Four genera traditionally included in Arundinoideae fell outside the subfamily in the plastome phylogeny, with the remaining 11 genera forming Arundinoideae sensu stricto . The twisted geniculate awn has originated independently at least five times in the PACMAD grasses, in the subfamilies Panicoideae, Danthonioideae/Chloridoideae and Arundinoideae. Morphological and anatomical characters support the new positions of the misplaced arundinoid genera in the phylogeny, but also highlight convergent and parallel evolution in the grasses. In placing the majority of arundinoid genera in a phylogenetic framework, our study answers one of the last remaining big questions in grass taxonomy while highlighting examples of convergent evolution in an ecologically important trait, the hygroscopic, twisted geniculate awn.

Relationships and genetic structure of North African barley (Hordeum vulgare L.) germplasm revealed by morphological and molecular markers: Biogeographical considerations

Landraces represent a crucial reservoir of gene pool for crop improvement and a valuable germplasm for sustainable agriculture towards climate change. To establish conservation strategies for barley germplasm, 31 North African landraces were characterized by associating morphogenetic data with molecular markers. Partial relationships were found between divergence pattern and geographic origin at morphological level, while molecular dendrogram clearly separated barley landraces into two major groups based on geographic distribution. Grain yield, glum awn and lemma awn barb appear to be the most discriminative agro-morphological traits required for exploitation of these valuable resources. A total of 114 amplification products were scored by RAPD primers exhibiting an overall 84.85% polymorphism. Molecular variance demonstrated that genetic variation was partitioned within (60.31%) rather than between (39.69%) the populations. Data showed considerable gene flow (Nm=1.439) and moderate genetic differentiation (GST=0.257) with highest diversity observed in Tunisian and Egyptian populations. No significant correlation was found between the distance matrices based on molecular and morphological data indicating no influence of genetic background on the observed morphological variation. These results reinforce the integration of both morphogenetic and RAPD markers as a starting point for in situ conservation of these accessions allowing adaptation to local environments.

Grass flowers: An untapped resource for floral evo‐devo

AbstractThe abrupt origin and rapid diversification of the flowering plants presents what Darwin called “an abominable mystery”. Floral diversification was a key factor in the rise of the flowering plants, but the molecular underpinnings of floral diversity remain mysterious. To understand the molecular biology underlying floral morphological evolution, genetic model systems are essential for rigorously testing gene function and gene interactions. Most model plants are eudicots, while in the monocots genetic models are almost entirely restricted to the grass family. Likely because grass flowers are diminutive and specialized for wind pollination, grasses have not been a major focus in floral evo‐devo research. However, while grass flowers do not exhibit any of the raucous morphological diversification characteristic of the orchids, there is abundant floral variation in the family. Here, we discuss grass flower diversity, and review what is known about the developmental genetics of this diversity. In particular, we focus on three aspects of grass flower evolution: (1) the evolution of a novel organ identity—the lodicule; (2) lemma awns and their diversity; and (3) the convergent evolution of sexual differentiation. The combination of morphological diversity in the grass family at large and genetic models spread across the family provides a powerful framework for attaining deep understanding of the molecular genetics of floral evolution.

A Homolog of Blade-On-Petiole 1 and 2 (BOP1/2) Controls Internode Length and Homeotic Changes of the Barley Inflorescence.

Inflorescence architecture in small-grain cereals has a direct effect on yield and is an important selection target in breeding for yield improvement. We analyzed the recessive mutation laxatum-a (lax-a) in barley (Hordeum vulgare), which causes pleiotropic changes in spike development, resulting in (1) extended rachis internodes conferring a more relaxed inflorescence, (2) broadened base of the lemma awns, (3) thinner grains that are largely exposed due to reduced marginal growth of the palea and lemma, and (4) and homeotic conversion of lodicules into two stamenoid structures. Map-based cloning enforced by mapping-by-sequencing of the mutant lax-a locus enabled the identification of a homolog of BLADE-ON-PETIOLE1 (BOP1) and BOP2 as the causal gene. Interestingly, the recently identified barley uniculme4 gene also is a BOP1/2 homolog and has been shown to regulate tillering and leaf sheath development. While the Arabidopsis (Arabidopsis thaliana) BOP1 and BOP2 genes act redundantly, the barley genes contribute independent effects in specifying the developmental growth of vegetative and reproductive organs, respectively. Analysis of natural genetic diversity revealed strikingly different haplotype diversity for the two paralogous barley genes, likely affected by the respective genomic environments, since no indication for an active selection process was detected.

Tripogon bimucronatus (Poaceae: Chloridoideae: Tripogoninae), a new species from India

Tripogon bimucronatus Thoiba & Sunil, a new species of grass from the Nelliyampathy Hills, Palakkad District of Kerala, South India is described and illustrated. It is morphologically similar to Tripogon vellarianus Pradeep but differs by having adaxially scabrid, linear-acuminate leaves; ligules a fringe of hairs to 2.5 mm long; spikelets with 6-8 closely packed florets; lower glume asymmetrical; upper glume awned; lemma awn scabrid; palea elliptic-lanceolate, apex bimucronate and notched at the centre.

English

Barley (Hordeum vulgare L.) has great adaptability to a wide range of environments. To determine genetic diversity in barley landraces, a total of 43 landrace populations were randomly sampled from the farmers’ field on plant basis and characterized for eight qualitative traits; namely, kernel row number, spike density, lemma awn barb, glume color, lemma type, length of rachila hair, kernel covering and lemma/kernel color. Morphological diversity was determined by the Shannon-Weaver index (H’). Overall barley landrace populations showed an average diversity index of 0.59, implying large diversity for the populations. Selection for adaptation to different altitude classes appears to be the main factor that has determined the observed variation, along with population-size effects. The result showed that barley landraces from Gamo highlands, Ethiopia are constituted by highly variable landraces that have large within-population diversity. These landraces are also shown to be locally adapted, with the major driving force that has shaped their population structure being consistent with selection for adaptation along an altitudinal gradient. Overall, this study highlights the potential of such landraces as a source of useful genes that can be exploited in crop improvement programmes. Key words: Barley, characters, landraces/farmer varieties, morphological diversity, altitudinal gradient.

Comments on the variation of spike morphology in selected species of Elytrigia and Elymus (Triticeae)

The structure of spikes of <i>Elytrigia repens</i>, <i>E. intermedia</i> and <i>Elymus caninus</i> was investigated. The number of spikelets per spike reveals the weakest correlations with other characters of the spike. The same concerns some character ratios. The correlations provide information about the segmented structure (metamers) of the spike. There is a great difference between matrices of correlation coefficients for <i>E. repens</i> and <i>E. intermedia</i> related to the development and structure of spike. Characters important for the description of the spike were chosen - in five-character set these are among others: length of glume awn in median spikelet, length of lemma awn in the first floret of the median spikelet, number of spikelets per spike. Length of lemma awn and mean length of the rachis segment were recognized as the best discriminants for species. Ordination of forms along axes of canonical variates does not indicate the subunits within <i>E. repens</i>. Intermediate forms between <i>E. repens</i> and <i>Elymus caninus</i> have not been found. Between <i>E. repens</i> and <i>E. intermedia</i> there exists some proximity. Heteromorphic individuals were described by means of cluster analysis. They prove the mobility of the genome in ramets of a single genet.

Alarista succina gen. et sp. nov. (Poaceae: Bambusoideae) in Dominican amber

Alarista succina gen. et sp. nov. (Poaceae) is described from a single floret preserved in amber of Tertiary age originating from the Dominican Republic. The new genus is characterised by (1) a narrow-winged lemma awn, (2) numerous (as many as 17) lemma nerves, (3) a lengthy rachilla internode (implying a lax spikelet), (4) sinuous-margined long cells, (5) silica cells arranged transversely, (6) stomatal subsidiaries low domed and (7) papillae. The epidermal features are characteristic of the abaxial leaf blade surface of members of the Bambusoideae and the fossil is placed in this group. htp://zoobank.org/033FCBF4-CD61-4C85-97E4-8418C9ABA5E6

<i>Deyeuxia gaoligongensis</i> (Poaceae: Agrostidinae), a new species from Gaoligong Shan in Yunnan, China

Deyeuxia gaoligongensis, a new species from the Gaoligong Shan region of NW Yunnan, SW China, is described and illustrated. The new grass is morphologically similar to D. debilis, but differs from the latter by its well-developed lemma awn that is twisted at the base, geniculate, and inserted on the lower half of the back of the lemma.

Variability of morphological and anatomical traits in natural populations of Festuca rubra and F. nigrescens

Morphological and anatomical variability in 24 subpopulations of two native species of <i>Festuca</i> occurring in Poland was studied. The principal component analysis and cluster analysis of morphometric data and DNA classified specimens or sub-populations of <i>Festuca</i> into two groups, corresponding to the two species. <i>F. rubra</i> and <i>F. nigrescens</i> are similar to each other in most morphological characters: the number of the florets, the length of the spikelet, the length of the lemma awn, the width and thickness of the leaf, the length of the cauline leaf, the length of hairs in the leaf, the number and diameter of vascular bundles in the leaf, the hairiness of branches of the panicle, the hairiness of the lemma. The key morphological features distinguishing both species include the number of ribs in the leaf, the width of the cauline leaf (second from the top), caespitose, presence of rhizomes and quantity of the sclerenchymatous tissue in the leaf blade. Apparent differences were detected between the single sub-populations. However, between the intraspecific sub-populations, diversity in terms of the following traits was observed: the length of the stems, number of florets in the spikelet, the length of the spikelet and lemma awn, the width of the cauline leaves, the number of the ribs and quantity of the sclerenchymatous tissue in the leaf blade.

CALAMAGROSTIS TACOMENSIS (POACEAE): A NEW SPECIES FROM WASHINGTON AND OREGON

We used PCA of morphological characters to confirm the presence of an undescribed Calamagrostis species in Washington and Oregon that has historically been attributed to Calamagrostis vaseyi. We propose to name this grass Calamagrostis tacomensis. It is most similar to C. foliosa although it has often been confused with C. purpurascens and C. sesquiflora all of which have similar lemma awn characteristics (i.e., the awn relatively long, exserted, and bent). Calamagrostis tacomensis has been collected at high elevations (490–2170 m) in the Washington Cascades, the Olympic Peninsula and the Steens Mountains of Oregon. The name C. vaseyi has been misapplied to our new species. The description of C. vaseyi is similar to C. rubescens. We have studied the specimen that has been attributed to be the type of C. vaseyi and it is C. purpurascens. We lectotypify C. vaseyi.

Barley Traits Associated with Resistance to Fusarium Head Blight and Deoxynivalenol Accumulation

ABSTRACT Fusarium head blight (FHB) or scab is a destructive disease of barley in many countries. A better understanding of the interrelationships between plant traits and FHB resistance should help in the development of effective and efficient breeding strategies for FHB-resistant cultivars. Recent mapping studies indicate that many of the quantitative trait loci (QTL) for FHB resistance coincide with the QTL for plant height, heading date, and spike characteristics. Therefore, a study was conducted to investigate the relationship of morphological and physiological traits to FHB infection and deoxynivalenol (DON) accumulation in a barley doubled-haploid (DH) population derived from a Léger x CI9831 cross. Approximately 190 DH lines were grown at Ottawa (Ontario) for 2 years, Charlottetown (Prince Edward Island) for 1 year, and Hangzhou (Zhejiang) for 2 years. The field plots were inoculated with Fusarium graminearum at each location. FHB incidence was positively correlated with DON content. Resistance to FHB was associated with two-row spike, purple lemma, long glume awn, tall stature, and resistance to lodging, but it was not associated with long rachilla hairs, rough lemma awn, or heading date. Two-row spike was associated with tall stature and resistance to lodging. These associations as well as its spike characteristics helped reduce FHB infection and DON accumulation in two-row lines compared with six-row lines. The association between long glume awn and FHB resistance could be due to genetic linkages. Therefore, trait associations should be taken into consideration when breeding for FHB resistance and interpreting data from FHB experiments.

A phylogenetic analysis of the genus Psathyrostachys (Poaceae) based on one nuclear gene, three plastid genes, and morphology

A phylogenetic analysis of the small, Central Asian genus Psathyrostachys Nevski is presented. The analysis is based on morphological characters and nucleotide sequence data from one nuclear gene, DMC1, and three plastid genes, rbcL, rpoA, and rpoC2. Separate analyses of the three data partitions (morphology, nuclear sequences, and plastid sequences) result in mostly congruent trees. The plastid and nuclear sequences produce completely congruent trees, and only the trees based on plastid sequences and morphological characters are incongruent. Combined analysis of all data results in a fairly well-resolved strict consensus tree: Ps. rupestris is the sister to the remaining species, which are divided into two clades: one including Ps. fragilis and Ps. caduca, the other including Ps. juncea, Ps. huashanica, Ps. lanuginosa, Ps. stoloniformis, and Ps. kronenburgii. Pubescent culms and more than 20 mm long spikelets are synapomorphies for the former clade, whereas short lemma awns and leaf epidermis cells with thin, straight walls are synapomorphies for the latter.

Morphological variation in Bromus sect. Ceratochloa germplasm of Patagonia

South American representatives of Bromus sect. Ceratochloa make up a morphologically diverse group of grasses indigenous to the southern Andes of Argentina and Chile. The objectives of the present study were to describe patterns of morphological variation among 30 accessions representing six species (Bromus catharticus Vahl, Bromus coloratus Steud., Bromus lithobius Trin., Bromus mango E. Desv., Bromus stamineus E. Desv., and Bromus tunicatus Phil.) in a common garden, correlate morphological and previously obtained molecular data, and develop a taxonomic treatment within sect. Ceratochloa of South America. Plant materials included 28 hexaploid (2n = 6x = 42) and 2 octoploid (2n = 8x = 56) accessions. Based on multivariate analyses of 24 characters, the two octoploid accessions formed an isolated, well-defined group, while the hexaploids formed two less-defined groups. Characterized by lemma awns longer than 3 mm, one group consisted of those accessions of B. coloratus, B. lithobius, and B. stamineus, whereas the other group consisted of B. catharticus, B. mango, and B. tunicatus. A significant Mantel test statistic (r = 0.70, P = 0.001) suggested a high correlation between morphological variation and DNA polymorphism. Taken together, our results indicated that the hexaploid complex should be described as a single variable species (B. cathar ticus), with two nearly continuous groups: B. catharticus subsp. catharticus (Vahl) Herter and B. catharticus subsp. stamineus (E. Desv.) Massa. Based on nomenclature priority and type specimen designations, the octoploid accessions should be described as Bromus coloratus.Key words: Bromus, morphology, multivariate analysis, Patagonia, taxonomy.