Short Awns Research Articles

Awn length variation in Australia’s most widespread grass, Themeda triandra, across its distribution

Themeda triandra (kangaroo grass) is the most widespread plant species in Australia. Using herbarium specimens, we quantified awn-length variation across its distribution in relation to climate. We found that awn lengths were shortest around the eastern and southern coast of Australia (with short awns also concentrated in the Pilbara), increasing in length progressively inland and towards the north. There was a significant positive relationship between awn length and mean annual temperature. Further research is needed to understand why awn lengths vary, and how awn-length variation affects seed and seedling fitness in natural habitats.

Anatomical and Physiological Characteristics of Awn Development in Elymus nutans, an Important Forage Grass in Qinghai-Tibet Plateau

Awns are the important structures of inflorescence in many crops that belong to the Poaceae family. In addition, they actively participate in photosynthesis, transpiration, seed dispersal, and self-planting. The Elymus nutans Griseb. is an important, self-pollinated, allohexaploid (2n = 6x = 42) and perennial native forage grass in Qinghai-Tibet Plateau that shows variation in awns length. However, the changes in the anatomical structure, physiological traits, and biochemical characteristics during awn development remain unclear in E. nutans. Therefore, this study investigated the changes in anatomical structures, enzymatic activities, and hormonal regulations of awns at four developmental stages, i.e., booting, heading, flowering, and maturity stages of three E. nutans accessions having different awn lengths. The results showed that the cross-sections of E. nutans awns had an acute triangular shape and structural similarities to wheat awns. In addition, the growth of long awns was recorded faster than short awns at the heading stage, but no significant differences in awns lengths were found at the heading, flowering, and maturity stages. The differences in the sizes of barbs and stomata of three accessions were statistically non-significant; however, the accession with long awns had more stomata than the accession with shorter awns at all developmental stages. In addition, the content of cytokinin (CTK), abscisic acid (ABA), and ethylene (ETH), and activities of superoxide dismutase (SOD) and peroxidase (POD) were significantly related to the development of awn. At the flowering stage, the content of CTK, and activities of SOD and POD of long awn accession were significantly higher than the short awn accession. Therefore, the obtained results provide a sound basis for future research on the molecular mechanisms of awn development and their potential role in E. nutans.

Efeitos de fatores ambientais na germinação sazonal de diferentes biótipos de arroz vermelho (Oryza sativa L.)

ABSTRACT: Weedy biotypes of Oryza sativa L., (weedy rice) are a serious threat to rice production because of their flexibility in seed germination timing, variable growth forms, and high genetic diversity. Experiments were designed to determine the effects of storage conditions, osmotic stress, pH, salt stress, and burial depth on germination of weedy rice seeds in flooded or non-flooded conditions. Mature weedy rice seeds were gathered from rice fields in the different regions of Turkey. Three biotypes were selected and classified according to awn length; long awn, short awn and awnless. Seasonal germination patterns of weedy rice seeds in the laboratory after retrieval from various depths and timing were affected by burial depth, water regime, and exhumation timing across the treatments for all biotypes. The long and short awn biotypes had higher germination rates than the awnless biotype and did not have a seasonal germination pattern. Seed germination was initiated in the spring, peaked in summer and declined in the fall in flooded and non-flooded treatments for the awnless biotype. The most distinct differences in seedling emergence patterns were observed in awnless and long awn biotypes, and they emerged from 10 cm depth. Our results suggested that flooded conditions reduced the germination of weedy rice biotypes. Flooding rice paddies for a period of time after harvest may improve weedy rice control and decrease the weed population. In addition to deeper cultivation would be more effective in controlling all weedy biotypes since the majority of weed seedling emergence was from shallow depths.

Control of awn length in rice breeding programs in Hokkaido

Understanding genetic diversity among local populations may facilitate the development of new crop varieties and is a primary goal of the molecular evolution of genes. Awn length is a well-documented phenotype among domestication traits in rice (Oryza sativa L.), from long to short awns. Short awned or awnless varieties have been selected in rice breeding programs. Awnlessness is favored by rice farmers in the current agriculture system. Here, we identified the genetic basis of awn length during rice breeding programs in Hokkaido, Japan. We found variation in awn length ranging from 0.0 to 37.6 mm among a local population consisted of breeding lines. Genetic analysis of awn length identified that RAE1 and RAE2 on chromosomes 4 and 8, respectively, accounted for awn presence. These genes are well known to be significant during Asian rice domestication. Sequence variations in these genes may clarify the molecular evolution of the genes for awn length in rice breeding programs. Firstly, a loss-of-function allele in RAE1, rae1, was selected for short awn length. Then, alleles of RAE2, RAE2-H01 to RAE2-H04, were targeted for the selection of short awns or awnlessness. The selections of an awnlessness phenotype can diversify these alleles in the genes RAE1 and RAE2 exhibiting variation in awn length.

О таксонах рода × Trisetokoeleria (Poaceae) в российской Арктике

An amplified description of the Siberian Arctic species × Trisetokoeleria taimyrica Tzvelev is compiled, based on the study and measurements of about 100 reproductive shoots (10 herbarium sheets) stored in the Herbarium of the Komarov Botanical Institute RAS (LE), including the neotype designated by the authors and 4 authentic herbarium specimens identified by N. N. Tzvelev. The main distinctive characters of the three species of the genus × Trisetokoeleria are given in the table, taking into account additional data on × T. taimyrica. The difficulty of recognizing the × Trisetokoeleria species in nature (the use of optics is necessary) is complicated by a weak difference in key features, primarily between T. gorodkowii (Roshev.) Tzvelev and T. taimyrica. The third species, namely T. jurtzevii Prob., clearly differs from the other two by pubescent (hairy) inflorescence branchlets and longer awns. × T. taimyrica differs from × T. gorodkowii by narrower, few-flowered panicles, glumes of slightly (vs. strongly) unequal length, and acuminate (vs. obtuse) lemma tips, and from × T. jurtzevii by glabrous stem, panicle branchlets and lemmas, as well as by shorter awns and narrower few-flowered panicles. Its differences from postulated parent species are as follows: from Koeleria asiatica Pers. — a short straight awn extending below the lemma tip (vs. extending from the very tip of the lemma, that is sometimes observed in K. asiatica), and glabrous stems and panicle branchlets; from Trisetum agrostideum (Laest.) Fr.) — a very short, straight awn extending slightly below the lemma tip (vs. twice articulated and extending slightly above ½ or at upper ⅓ of the lemma), as well as spike-like panicles. A map of the localities of the three × Trisetokoeleria species is compiled.

Arundinella tengchongensis (Poaceae), a name at new rank and newly combined based on morphological and molecular data

To clarify the taxonomic status of Arundinella setosa var. tengchongensis and its relationships with A. setosa var. setosa and other related species, molecular phylogenetic analyses based on nuclear ITS and two plastid DNA (matK and trnL‐F) sequences, and morphological comparisons using one‐way ANOVA were carried out. Our results reveal that A. setosa var. tengchongensis phylogenetically belong in a different clade separated from the type variety. Morphologically, A. setosa var. tengchongensis is easily distinguished from A. setosa var. setosa and other varieties by its smaller spikelets, shorter awns and bearded nodes. Thus, A. setosa var. tengchongensis is here elevated to species rank and newly combined as A. tengchongensis.

Is a long hygroscopic awn an advantage for Themeda triandra in drier areas?

Themeda triandra has bigeniculate hygroscopic lemma seed awns that twist when wet and drying, thereby transporting the caryopsis across the soil surface into suitable germination microsites. The prediction that awns would be longer in drier grassland and have greater motility to enable them to move quickly and farther to find scarce germination sites was tested in KwaZulu-Natal. Awns (n = 100) were collected from 16 sites across a mean annual precipitation gradient (575–1 223 mm), ranging from 271−1 097 m asl. The daily movement of hydrated long and short awns (n = 10) across blotting paper was tracked for five days, and the rotational speed of anchored awns was measured. Awn length varied considerably (mean: 41.4–63.2 mm; SD: 3.44–8.99), but tended to increase (r = 0.426, p = 0.099) not decline, with increasing MAP. Awn length was unrelated to elevation, temperature and aridity indices. Long awns rotated at the same rate (2 min 48 sec), but moved twice as fast (46.3 vs 22.1 mm day−1) and much farther (maximum: 82.1 vs 38.6 mm day−1) than short awns. Whether moisture limits awn development, the benefit of longer awns to negotiate densely tufted mesic grassland, and the multifunctionality of awns require investigation.

Fine mapping and characterization of the awn inhibitor B1 locus in common wheat (Triticum aestivum L.)

Awns play an important role in seed dispersal and photosynthesis of spikes. Three major awn inhibitors (Hd, B1, and B2) are reported in wheat. However, the molecular mechanism underlying awnlessness remained unknown until recently. In this study, we identified two F8 recombinant inbred lines (RILs) that were segregating for awn length. In order to identify the causal gene for awn length in the heterozygous inbred families (HIFs), SNPs were called from RNA sequencing (RNA-Seq) data for HIF-derived progenies with long and short awns. SNPs between long and short awn plants were evenly distributed on chromosomes (chr) other than chromosome 5A. SNPs on chr 5A were clustered in a region distal 688 Mb on the long arm, where inhibitor B1 was located. This suggested that B1 was the causal segregating locus. We precisely mapped B1 to ~1 Mb region using two HIF-derived families. Considering that the lines segregated for long, intermediate and short awn phenotypes we speculated that B1 should have a dosage effect on awn length. Two differentially expressed genes (DEGs) located in the candidate region were regarded as candidate genes for B1, because the molecular expression pattern was consistent with the phenotype. HIFs with long and short awns showed no difference on grain yield and other agronomic traits.

Natural alleles of GLA for grain length and awn development were differently domesticated in rice subspecies japonica and indica.

SummaryRice (Oryza sativa L.) cultivars harbour morphological and physiological traits different from those of wild rice (O. rufipogon Griff.), but the molecular mechanisms underlying domestication remain controversial. Here, we show that awn and long grain traits in the near‐isogenic NIL‐GLA are separately controlled by variations within the GLA (Grain Length and Awn Development) gene, a new allele of GAD1/RAE2, which encodes one member of the EFPL (epidermal patterning factor‐like protein) family. Haplotype analyses and transgenic studies revealed that InDel1 (variation for grain length, VGL) in the promoter region of GLA (GLAVGL) increases grain length by promoting transcription of GLA. Absence of InDel3 (variation for awn formation, VA) in the coding region (CDS) of GLA (GLA va) results in short awn or no awn phenotypes. Analyses of minimum spanning trees and introgression regions demonstrated that An‐1, an important gene for awn formation, was preferentially domesticated and its mutation to an‐1 was followed by GLA and An‐2. Gene flow then occurred between the evolved japonica and indica populations. Quality analysis showed that GLA causes poor grain quality. During genetic improvement, awnlessness was selected in ssp. indica, whereas short–grained and awnless phenotypes with good quality were selected in japonica. Our findings facilitate an understanding of rice domestication and provide a favourable allele for rice breeding.

Diversity of Echinochloa spp. in Palakkad rice tracts of Kerala

Surveys were conducted twice in the major rice tracts of Palakkad, once during January-February, and the other during August-September in 2016. Three major Echinochloa types were identified infesting rice fields, causing severe crop competition. The three types were E. colona, with awnless spikelets and two types of E. crus-galli, viz.E. crus-galli (type A) having short awns and E. crusgalli (type B) having long awns. Other than the length and arrangement of awns, there were no significant differences in the morphological characters of the latter two types. Frequency and relative frequency was the highest for E. crus-galli (type B). There was no specific association between the Echinochloa types and soil nutrient parameters, probably as there were no drastic differences in the chemical properties among the different locations. Cluster analysis classified Echinochloa types in to 5 groups at 66.67% similarity level. The study concludes that in a less productive environment, the awned types of Echinochloa could have a better chance of survival.

Three dominant awnless genes in common wheat: Fine mapping, interaction and contribution to diversity in awn shape and length.

The awn is a long needle-like structure formed at the tip of the lemma in the florets of some grass species. It plays a role in seed dispersal and protection against animals, and can contribute to the photosynthetic activity of spikes. Three main dominant inhibitors of awn development (Hd, B1 and B2) are known in hexaploid wheat, but the causal genes have not been cloned yet and a genetic association with awn length diversity has been found only for the B1 allele. To analyze the prevalence of these three awning inhibitors, we attempted to predict the genotypes of 189 hexaploid wheat varieties collected worldwide using markers tightly linked to these loci. Using recombinant inbred lines derived from two common wheat cultivars, Chinese Spring and Mironovskaya 808, both with short awns, and a high-density linkage map, we performed quantitative trait locus analysis to identify tightly linked markers. Because this linkage map was constructed with abundant array-based markers, we converted the linked markers to PCR-based markers and determined the genotypes of 189 hexaploids. A significant genotype-phenotype correlation was observed at the Hd and B1 regions. We also found that interaction among these three awning inhibitors is involved in development of a membranous outgrowth at the base of awn resembling the Hooded mutants of barley. For the hooded awn phenotype, presence of the Hd dominant allele was essential but not sufficient, so B2 and other factors appear to act epistatically to produce the ectopic tissue. On the other hand, the dominant B1 allele acted as a suppressor of the hooded phenotype. These three awning inhibitors largely contribute to the genetic variation in awn length and shape of common wheat.

Haplodontium zangii X.R.Wang & J.C.Zhao, sp. nov. (Bryaceae, Bryopsida) from Xizang, China

Haplodontium zangii X.R.Wang & J.C.Zhao, a new moss species from Xizang, China, is described and illustrated. Previously, specimens of H. zangii have been identified as Mielichhoferia himalayana Mitt. However, H. zangii is distinctly different from M. himalayana in having excurrent costae with short awns (vs long denticulate awns), short-pyriform capsules, 0.8–1 mm (vs long-pyriform capsules, 2.5–3 mm), and densely papillose exostome teeth (vs smooth or vertically striped exostome teeth). Haplodontium zangii is similar to H. macrocarpum (Hook.) J.R.Spence, which was traditionally placed in Mielichhoferia Nees & Hornsch. as M. macrocarpa (Hook.) Bruch & Schimp. The main differences between H. zangii and H. macrocarpum are in the morphology of the leaves, capsules, guide cells, and stomata. Mielichhoferia himalayana and another Chinese species of Mielichhoferia, M. sinensis Dix., are also transferred to Haplodontium Hampe, a new genus in the bryoflora of China, as H. himalayanum (Mitt.) X.R.Wang & J.C.Zhao and H. sinensis (Dix.) X.R.Wang & J.C.Zhao. A morphological comparison and a key to the three species of Haplodontium in China as well as to H. macrocarpum, a species that is likely to be found in China, are provided.

GAD1 Encodes a Secreted Peptide That Regulates Grain Number, Grain Length, and Awn Development in Rice Domestication.

Cultivated rice (Oryza sativa) was domesticated from wild rice (Oryza rufipogon), which typically displays fewer grains per panicle and longer grains than cultivated rice. In addition, wild rice has long awns, whereas cultivated rice has short awns or lacks them altogether. These changes represent critical events in rice domestication. Here, we identified a major gene, GRAIN NUMBER, GRAIN LENGTH AND AWN DEVELOPMENT1 (GAD1), that regulates those critical changes during rice domestication. GAD1 is located on chromosome 8 and is predicted to encode a small secretary signal peptide belonging to the EPIDERMAL PATTERNING FACTOR-LIKE family. A frame-shift insertion in gad1 destroyed the conserved cysteine residues of the peptide, resulting in a loss of function, and causing the increased number of grains per panicle, shorter grains, and awnless phenotype characteristic of cultivated rice. Our findings provide a useful paradigm for revealing functions of peptide signal molecules in plant development and helps elucidate the molecular basis of rice domestication.

Determination of Candidate Breeding Resource from Sri Lankan Traditional Rice Mudukiri Al

Most of the traditional rice varieties conserved at Plant Genetic Resources Centre, Sri Lanka, possess more than one accession. Determination of morphological variation and yield potential among accession within same variety would be useful for breeding new varieties and farmer introductions. Six accessions of Mudukiri Al variety were selected for this study. The objective of this study was to determine the morphological variation among accessions of Mudukiri Al for selecting candidates for future breeding. Six accessions obtained from the Plant Genetics Resources Centre, Sri Lanka, were grown in Kamburupitiya with three replicates in a completely randomised design from November 2013. Days to fifth leaf (DFL), seedling height at fifth leaf (SHT), leaf area of fifth leaf (LA), days to flowering (DF), plant height at flowering (PH), culm number at flowering (CN), total number of panicles (PN), number of grains per first panicle (GN), grain length (GL) and width (GW) were recorded which varied from 51 to 59 days, 63.8 to 80.3 cm, 6.5 to 44.4 cm2, 86 to 102 days, 112.7 to 148.6 cm, 16 to 38, 7 to 29, 103 to 255, 0.7 to 0.9 cm and 0.3 to 0.4 cm respectively. Accession 4,144 produced significantly higher GN of 255 while accession 3,970, 4,145 and 3,758 produced 184, 160 and 166 respectively. Accessions 3,970 and 5,536 were with short awns. A positive correlation between DFL and PH (0.870) had been observed. Higher GN and the highest CN (38) would be favourable for selecting accession 4,144 as a candidate breeding resource. Keywords: Mudukiri Al, Morphological variation, Breeding resource

The Genus <I>Sartidia</I> (Poaceae: Aristidoideae) in Madagascar

Abstract The uncommon southern African and Malagasy genus Sartidia in the Aristidoideae, Poaceae resembles the closely related Aristida but has a C3 photosynthetic system, 3–5-veined lower glumes, and a ventrally grooved caryopsis. We present a revision of Sartidia in Madagascar with two species. Sartidia isaloensis is described as new based on its interrupted inflorescence structure, small spikelets, and short awns. A leaf anatomical study and a δ13C analysis confirm that S. isaloensis is a C3 species. Sartidia perrieri is likely extinct in the wild. We present descriptions, typification, illustrations, distribution maps, an identification key, and IUCN conservation assessments. A key to the Aristidoideae in Madagascar is also included.

Two new species of Schistidium (Grimmiaceae, Bryophyta) from western North America

Schistidium splendens and Schistidium squarrosum are described as new species from western North America. Schistidium splendens is characterized mainly by 2-stratose striae in the distal leaf laminae, thick and strongly recurved leaf margins, relatively short awns, and more or less isodiametric or short-elongate, irregularly shaped exothecial cells. Schistidium squarrosum is characterized by often abruptly narrowed, ovate-lanceolate, usually curved or falcate leaves that often lack awns, 2(–3) stratose upper leaf laminae, and large, broadly ovate-lanceolate or lanceolate perichaetial leaves that tightly surround the capsule.

Carex procumbens (Carex sect. Rhomboidales, Cyperaceae), a new species from Hainan, China

Carex procumbens, a new species of Carex sect. Rhomboidales from Hainan, China, is described and illustrated. The new species is similar to C. longipetiolata but differs in culms soft and usually prostrate on the ground, having narrower leaves with the leaf base gradually narrowed, with 2–3 spikes, terminal spike 8–12 mm long, lateral spikes 5–15 mm long and loosely flowered, staminate glumes ovate with green middle vein and apex rounded, pistillate glumes ovate-lanceolate ca. 6 mm and middle vein excurrent into a short awn for ca. 2 mm, perigynia fusiform and glabrous, nutlet brown to dark brown and ovate-rhomboid, nutlet ca. 7 mm long and with a short curved beak.

Stipa klimesii (Poaceae), a new species from Western Himalayas (India)

Stipa klimesii sp. nov. from the Western Himalayas (India: Ladakh) and its variety S. klimesii var. pubescens var. nov. are described. The new species is similar to S. roborowskyi but differs by its longer anthecium, longer ligules of vegetative shoots, longer hairs on seta and shorter awns. Stipa klimesii is also similar to S. purpurea, but differs by longer ligules of vegetative shoots, shorter awns, slightly shorter hairs on seta and by the character of the panicle, which is compressed and with straight branches in S. klimesii vs. lax and with flexuous branches in S. purpurea. Epidermal patterns of the lemma in S. klimesii and both above-mentioned species, were examined by scanning electron microscopy. Images of macromorphological and micromorphological structures are provided.

Morphological and Anatomical Traits of Short-Lived Ryegrass

The ryegrass species are visually similar, and therefore, correct identification of short-lived species is very important in breeding work. The aim of the current study was to identify short-lived ryegrass species and subspecies using anatomical and morphological characteristics. The study was carried out at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry (during 2007-2010). The assessment of morphological and anatomical traits showed that average values for species diverged, but values for individual plants often overlapped between species. One of the most characteristic traits of Lolium. x hybridum was darker leaf colour (6.7 score). Awns are characteristic for both Lolium multiflorum subspecies, while perennial ryegrass plants are awn-less. Lolium x hybridum has a short awn or no awn, depending on which parental (Lolium perenne or Lolium multiflorum) species trait was stronger. As a result, identification of short-lived species according to this trait is difficult, and sometimes impossible. Analysis of leaf cross-section of short-lived ryegrass species indicated that a characteristic of Lolium multiflorum subsp. multiflorum was conjugation of sclerenchyma fibres not only in the central but also in lateral bundles, in contrast with Lolium multiflorum subsp. italicum and Lolium x hybridum. Lolium multiflorum subsp. multiflorum. This difference occurs only at the inflorescence emergence stage

충남지역의 벼 줄무늬잎마름병 발생감소 요인 분석

충남지역의 벼 줄무늬잎마름병 발생변화 원인을 구명하기 위해 월동 애멸구 밀도와 보독충률, 줄무늬잎마름병 발생정도, 중간기주, 감수성 품종 등을 조사하였다. 충남지역의 월동 애멸구 밀도는 2008년부터 2010년까지 해마다 감소하였으며 월동 애멸구의 RSV 보독충률은 3년간 각각 2.9, 4.0, 그리고 3.9%로 큰 변화는 없었다. 애멸구의 중간기주로 알려진 보리와 둑새풀, 새포아풀에서 RSV의 감염은 확인되지 않았다. 2009년 중국으로부터 애멸구가 대량 비래하였고, 이들의 보독률은 5.4%이었으나 2008년과 2010년에는 비래가 확인되지 않았다. 본답에서의 줄무늬잎마름병 발생은 2008년과 2009년에 1.0% 이하로 유지되었고, 2007년부터 2009년까지 감수성품종의 재배면적 또한 41%에서 19%로 크게 감소하였다. 전염원의 대량유입으로 인한 충남지역 벼 줄무늬잎마름병의 감소 요인은 적절한 예찰과 화학적 방제, 저항성 품종의 재배, 재배방법의 변화, 그리고 겨울-봄의 낮은 온도에 의한 것으로 해석되었다. The incidence factors of Rice stripe virus (RSV) were analyzed by studying the population density and the viruliferous insect rate (VIR) of small brown planthopper (SBPH), the incidence of stripe disease, alternate host, and susceptible cultivar in Chungnam Province. The population of overwintering SBPH had been decreasing, but the VIR of overwintering SBPH had not been differing for three years, 2008 to 2010. No RSV was detected in the natural host plants, such as short awn, annual bluegrass, and barley. In 2009, relatively large population of SBPH with the VIR of 5.4% migrated from China. However, there was no evidence relating of migration large amount of SBPH from China in 2008 and 2010. Also the infection rate of RSV in rice was less than 1% in these periods. The cultivation area of the susceptible varieties had steadily decreased from 41% to 19% from 2007 to 2009. Therefore, the reduction factors of rice stripe disease in Chungnam Province with higher influx of inoculum could be with an appropriate forecasting and chemical control, cultivation of resistant varieties, changes in the cropping system, and the low winter-spring temperature.