Spikelet Length Research Articles

Cellulose synthase-like OsCSLD4: a key regulator of agronomic traits, disease resistance, and metabolic indices in rice.

Cellulose synthase-like OsCSLD4 plays a pivotal role in regulating diverse agronomic traits, enhancing resistance against bacterial leaf blight, and modulating metabolite indices based on the multi-omics analysis in rice. To delve deeper into this complex network between agronomic traits and metabolites in rice, we have compiled a dataset encompassing genome, phenome, and metabolome, including 524 diverse accessions, 11 agronomic traits, and 841 metabolites, enabling us to pinpoint eight hotspots through GWAS. We later discovered four distinct metabolite categories, encompassing 15 metabolites that are concurrently present on the QTL qC12.1, associated with leaf angle of flag and spikelet length, and finally focused the cellulose synthase-like OsCSLD4, which was pinpointed through a rigorous process encompassing sequence variation, haplotype, ATAC, and differential expression across diverse tissues. Compared to the wild type, csld4 exhibited significant reductions in the plant height, flag leaf length, leaf width, spikelet length, 1000-grain weight, grain width, grain thickness, fertility, yield per plant, and bacterial blight resistance. However, there were significant increase in tiller numbers, degree of leaf rolling, flowering period, growth period, grain length, and empty kernel rate. Furthermore, the content of four polyphenol metabolites, excluding metabolite N-feruloyltyramine (mr1268), notably rose, whereas the levels of the other three polyphenol metabolites, smiglaside C (mr1498), 4-coumaric acid (mr1622), and smiglaside A (mr1925) decreased significantly in mutant csld4. The content of amino acid L-tyramine (mr1446) exhibited a notable increase, whereas the alkaloid trigonelline (mr1188) displayed a substantial decrease among the mutants. This study offered a comprehensive multi-omics perspective to analyze the genetic mechanism of OsCSLD4, and breeders can potentially enhance rice's yield, bacterial leaf blight resistance, and metabolite content, leading to more sustainable and profitable rice production.

Exploring traditional and novel spike traits associated with seed retention in perennial ryegrass by integrating 2D and 3D image analysis

AbstractSeed shattering is a major economic problem in seed production of perennial ryegrass (Lolium perenne L.). The objective was to identify potential relationships between phenotypic traits and seed retention in a 2‐year field trial with 21 diverse global accessions of perennial ryegrass. Accessions were grouped according to level of seed retention. Phenotypic traits examined were growth habit, spike length, curvature of the spike, spikelets per spike, spikelet length, internode length between spikelets, angle of spikelet insertion into the rachis, seeds per spike, and seed weight. Traits were captured and measured by use of novel two‐dimensional (2D) and three‐dimensional (3D) imaging tools. Among accessions, median seed retention values for the high and low seed retention groups were 61% and 36%, respectively. Four traits were found to significantly impact seed shattering: spike length (p ≤ 0.01), seed weight (p ≤ 0.001), seeds per spike (p ≤ 0.05), and internode length between spikelets (p ≤ 0.01). Seed retention was highest in accessions with short spikes. Most of the accessions that had high seed retention also had lower mean seed weight than the commercial plant materials. Accession (PI 231620) had both high levels of seed retention and a mean seed weight that is acceptable in the marketplace. These qualities may be used to improve seed retention in the breeding of perennial ryegrass cultivars. The 2D and 3D imaging methods have applicability in measurement of other plant morphological traits and across a broad range of plant species.

Влияние предпосевной обработки семян и агрохимикатов на урожайность озимой пшеницы

High yields cannot be achieved without the use of fertilizers, but how much they can pay off in modern economic realities and in drought conditions is unknown. In this regard, it is important to have new knowledge about effective systems of application of mineral fertilizers and agrochemicals in winter wheat cultivation in the zone of chestnut soils of the Lower Volga region. Therefore, the purpose of our research was to study the effect of growth stimulants in pre-sowing seed treatment and leaf fertilization with liquid fertilizers on the productivity of winter wheat in the Volgograd region. On average for 2021-2023 years, the minimum photosynthetic potential of winter wheat - 1288 thousand m2 day/ha was formed on plots without UAN 32 and growth regulators, and the highest - 2063 thousand m2 day/ha on plots with two fertilizers UAN 32 and growth regulator Emistim. Autumn fertilization with UAN 32 increased dry aboveground biomass of winter soft wheat in the variety Kamyshanka 6 at earing phase by 13%, two and three fertilizations by 26 and 27%, respectively. Growth regulator Polidon increased dry aboveground biomass of winter wheat at earing phase by 4%, Alfastim by 7%, Emistim by 12%. In the phase of milk ripeness dry biomass from growth regulator Polidon increased by 6%, Alfastim by 11%, Emistim by 14%. The lowest plant height of the variety Kamyshanka 6 was formed on the control - 0.89 m, the highest was on plots with two fertilizers and all variants on factor B and averaged 0.94 m, which is 0.05 m higher than the control. Spikelet length in the experiment was maximum in plots with two fertilizers and growth regulator Emistim. The minimum biological yield of winter wheat Kamyshanka 6 - 4.04 t/ha was obtained in the control variant, the maximum yield - 5.66 t/ha was observed in plots with two fertilizers UAN 32 and application of Emistim.

Comparative evaluation of the promising lines of winter soft wheat in the south of the Rostov region

The analysis of variability of winter soft wheat lines by quantitative traits is presented. The research was conducted in 2020–2023 in the Rostov region. Seven lines of winter soft wheat of the competitive variety trial were taken as an object of research. The Ermak variety was used as a standard. The yields of the lines during the years of study averaged from 9.78 to 10.12 t/ha with an average of 9.76 t/ha in the experiment. Plant height ranged from 85.0 to 115.0 cm. All the lines studied were classified as small- to medium-grained (32.9–45.9 g) in terms of 1000 grain weight. On average for the years of study, the minimum mass of 1000 grains was formed by the line 1638/19 (34.6 g), and the maximum – by the line 1361/19 (43.5 g). The lines had different groups of ripeness according to the indicator of the earing date. The spikelet length varied from 7.3 to 10.0 cm. The highest spikelet length was formed by the line 1361/19 (10.0 cm), the shortest – by the line 1120/19 (7.3 cm). The number of productive stems ranged from 471 to 924 stems/m2. The maximum number of productive stems for the years of the study was formed by the line 1921/20 (758 pcs./m2), the minimum – by the line 1361/19 (689 pcs./m2). The number of grains per plant ranged from 61.6 to 110.6. On average, the highest number of grains per plant was formed by the line 1638/19 (100.6 pcs.), the lowest – 1343/19 (70.4 pcs.). The grain weight per plant averaged 3.54 g and ranged from 2.26 to 4.56 g. The number of grains per ear varied from 28.9 to 51.5 pieces, the maximum number was formed by the lines 1361/19 (42.7 pcs.) and 1638/19 (41.2 pcs.). In terms of the grain weight per ear the standard was exceeded by the line 1361/19 (1.93 g), the values for the indicator varied from 1.02 to 2.28 g.

Development of 3‐D point cloud imaging and 2‐D image processing methods for high‐throughput phenotyping of perennial ryegrass spikes

AbstractAdvances in technology have increased the adoption of high‐throughput phenotyping (HTP) methodologies, potentially replacing laborious and time‐consuming measurements and data recording. One promising HTP tool for fine‐featured and small‐sized characteristics is the three‐dimensional (3‐D) scanning and imaging system, but the utility of present two‐dimensional (2‐D) technology has not been fully explored for this purpose. The objective of this work was to reduce assessment and field evaluation time by developing 2‐D photogrammetric and 3‐D point cloud imaging methods for HTP of spike characteristics in perennial ryegrass (Lolium perenne L.), with special attention to traits that might be associated with seed retention. These HTP imaging systems were compared with direct data capture by hand on spikes of 21 diverse global accessions of perennial ryegrass. The Fiji (ImageJ) open‐source imaging software was used for photogrammetric analysis of spike structure, including spike length, spikelet number, internode length, and 2‐D curvature of the spike. An original approach to nondestructive HTP for crop characterization was developed using the commercially available Artec Space Spider. This 3‐D optical sensor was used to generate dense 3‐D point clouds to measure spike length, spikelet number, internode length, spikelet length, spikelet angle, and 3‐D curvature of the spike. Both methods were found to accurately characterize the subject; the 3‐D method was slower than 2‐D but was more precise (p ≤ 0.01) than 2‐D image analysis with a linear measurement deviation of only 0.17%. Fiji was effectively used for post‐processing image analysis, and the Space Spider can be used directly in the field to support HTP data collection. This non‐destructive field measurement system facilitates HTP in perennial ryegrass spikes and likely in other applications.

Evolutionary history, traits, and weediness inDigitaria(Poaceae: Panicoideae)

AbstractDigitaria is a large pantropical genus, which includes a number of economically problematic agricultural weeds. Difficulties in species identification and the circumscription of the genus have previously hindered progress in understanding its evolution and developing a stable classification. We investigate the evolutionary history of Digitaria by combining two approaches: (i) phylogenetic analyses of the currently available Sanger sequence data with previously unpublished sequences mainly from South East Asia, and (ii) newly generated genomic data from low-copy nuclear genes obtained using the Angiosperms353 probe kit, with new data mainly from Madagascar. Both methods gave congruent results. The combination of these results allowed us to confirm a new clade structure within Digitaria lineages, in partial agreement with the previous morphology-based classifications. We confirm that Digitaria as traditionally circumscribed is not monophyletic, comprising Anthephora, Baptorhachis, Chaetopoa, and Chlorocalymma. We present an inference of key character evolution with morphological support for clades with spikelets arranged in binate and ternate groups, with variable trichome morphology, spikelet length, and culm length. Geographical clade structure is also observed. No phylogenetic signal of weedy function was observed.

Seed treatments with salicylic acid and Azospirillum brasilense enhance growth and yield of maize plants (Zea mays L.) under field conditions

Salicylic acid and Azospirillum brasilense stimulate plant growth and productivity. In some environments, plant physiology similarly responds to both bioactive products. Considering this, a field experiment was conducted to study the physiological effect of Salicilic acid and A. brasilense on growth and grain yield of maize plants. The experiment involved three treatments consisting of imbibed seeds in an aqueous solution of SA (0.01 mM), inoculated seeds with A. brasilense and a control treatment. Seed imbibition in SA and inoculation with A. brasilense improved vegetative growth in the early stages of crop ontogeny, increasing leaf growth, plant height, stem diameter and biomass accumulation. Spikelet length and weight were greater in plants first inoculated with A. brasilense and then treated with SA. Results indicated that SA stimulated biomass partitioning towards leaves, root and stem, while A. brasilense mainly affected leaf growth, plant height, ear dimensions and grain yield. Such results turn crucial for biological fertilization strategies aimed at reducing pollutant loads that accompany chemical fertilizers. Both products can be part of maize management practices given competitive economic advantages and sustainability. Highlights: Seed imbibition in SA and inoculation with brasilense improved vegetative growth in the early stages of crop ontogeny, increasing leaf growth, plant height, stem diameter and biomass accumulation. Salicylic Acid stimulated biomass partitioning towards leaves, root and stem in maize plants. Azospirillum brasilense stimulates leaf growth, plant height, as well as ear dimensions and grain yield in corn plants.

The Harmfulness of Common Root Rot in Winter Wheat Varieties in Kazakhstan

One of the main drawbacks of winter wheat varieties cultivated in Kazakhstan is their lack of resistance to common root rot. In 2020-2022, samples affected by root rot were taken in the earing phase in stationary experiments of the department of field crops and plant protection of the Kazakh research institute of agriculture and plant growing in the Almaty region. The research aimed to study the harmfulness of common root rot in commercial varieties of winter wheat. The weather did not significantly affect the harmfulness of common root rot. The harmfulness of the disease depended on the variety and degree of disease infestation. These indicators correlated with indicators of plant height, spike length, number of spikelets, and number and weight of grains (p<0.05). All varieties were affected by the disease to a low and moderate degree. In the varieties Almaly and Steklovidnaya 24, yield losses from the disease were 6.4-6.8%; in Farabi, Azharly, and Zhetysu 8.8-9.4%; and in Naz 13.0%. A total of 32-41% of plants were affected by the disease to a low degree and 10-21% to moderate and severe degrees. With a low degree of infestation, yield decreased by 2.4-7.1%, and with moderate and severe degrees by 4.5-12.1%. Factors of the degree of plant infestation and variety correlated (p<0.05) with dependent variables of productive business, stem length, spike length, number of spikelets, and weight of 1,000 grains. Using the method of linear regression, the authors concluded that the winter wheat spikelet number variable was significantly influenced by the variables of stem number (medium correlation) and spikelet length (strong correlation).

Salt Stress Affects the Growth and Yield of Wheat ( L.) by Altering the Antioxidant Machinery and Expression of Hormones and Stress-Specific Genes

Understanding physiological responses in saline agriculture may facilitate wheat breeding programs. Based on a screening test, the Ningmai-14 (NM-14) and Yangmai-23 (YM-23) wheat cultivars were selected for further experiments to understand the underlying salinity tolerance mechanism. This study investigated the effects of five salinity levels such as Control (CK) = 0 (without NaCl stress), S1 = 0.20%, S2 = 0.25%, S3 = 0.30% and S4 = 0.35% of NaCl concentrations of soil on wheat plants. The results showed that increased salinity concentration reduced the growth and yield of wheat cultivars (NM-14 and YM-23). However, YM-23 (12.7%) yielded more than NM-14 at maximum salinity stress. The higher salinity (S4) increased the concentration of Na+ (4.3 to 5.8-fold) and P contents (2.5 to 2.2-fold), while reducing the average concentrations of K+, Cu, and K+/Na+ ratio. The higher salinity (S4) reduced the spikelet length by 21.35% (followed by grain spike−1), and the starch content by 18.81%. In the YM-23 cultivar, higher salinity increased superoxide dismutase (SOD), total antioxidant capacity (TAC), and amylase. Compared to NM-14, induced expression of TaYUC2, 6, and TaGA13ox, 20ox genes were recorded in YM-23. Similarly, in YM-23 the stress-specific genes such as TaHSP70, 90 were enhanced whereas, TaSOS1, 2 were suppressed. Overall, our study revealed that salt tolerant cultivars modulate hormonal and antioxidant activities, thus maintaining high growth.

Genetic variability, correlation and principal component analyses in grain amaranth under water limited conditions of Bundelkhand region

Two hundred amaranth (Amaranthus sp.) germplasm accessions were evaluated for nine quantitative and ten qualitative traits with five checks under water limited conditions of Bundelkhand region during kharif, 2019. The accessions, IC35373, IC583610 and IC38039 showed early inflorescence emergence i.e. 28.0, 28.0 and 29.0 days, respectively. Out of 200 germplasm accessions, 64.88% showed green inflorescence colour followed by red and light yellow colours. High heritability estimates were observed for 1000 grain weight (81.94%), followed by grain yield per plant (67.04%) and leaf length (66.94%), whereas, leaf length, leaf width, lateral spikelet length and 1000 grain weight exhibited moderate range for genetic advance as per cent of mean. Grain yield per plant revealed positive and significant correlation with plant height (0.345**), followed by lateral spikelet length (0.220**), leaf length (0.199**) and 1000 grain weight (0.143*). In principal component analysis the first principal component (PC1) showed the highest contribution of 73.5% followed by PC2 (11.10%) and PC3 (9.30%), respectively. Petiole length, lateral spikelet length and inflorescence length were identified as contributors towards genetic variation in PCA analysis. The genotypes, EC146534, IC38193, IC289386, IC396963, IC540832 and IC415314 were found promising under water limited conditions of Bundelkhand region.

Splitting analysis of the second-generation rice hybrid ‘Bakhus x Kontakt’

The current paper has presented the study results of the second-generation hybrid population of ‘Bakhus x Kontakt’ combination. The variety ‘Bakhus’ is large-kernelled, vigorously growing, tall, unresistant to lodging, the variety ‘Kontakt is short, resistant to lodging, medium-kernelled. The purpose of the study was to analyze the inheritance of a number of quantitative traits in the F2 rice hybrid ‘Bakhus x Kontakt’ and select the best plants for the further breeding process. In the process of hybridological analysis, there have been established the patterns of inheritance of the main quantitative traits affecting productivity, there have been identified the best undersized forms, in which there were formed compact erect panicles and large kernels, and there has been selected the source material for breeding work. The study was carried out on the plots of OP «Proletarskoe» in the Rostov region in 2019–2021. The crossing was carried out in 2019, F1 was reproduced in 2020, F2 rice plants were grown in 2021. There has been found that according to ‘plant height’ there was a partial dominance of lower trait values and allelic differences in parental varieties for one pair of genes. There was no dominance according to ‘panicle length’; there were found digenic differences in the initial varieties. According to the trait ‘number of spikelets in a panicle’, there was a dominance of large values and positive transgression. According to spikelet length in F2 hybrids, there was a wide variation of the trait within the variability of parental varieties from 6.8 to 11.0 mm. there was no dominance. There was noted a digenic splitting in a ratio of 1:4:6:4:1. According to 1000-kernel weight, there has been identified a monohybrid splitting of 3:1. There were selected the best morphotype F2 forms, which differed in optimal plant height, long panicles, their increased kernel percentage and 1000-kernel weight.

Farmers’ knowledge on cultivation, utilization and conservation practices of barley (Hordeum vulgare L.) in three selected districts in Ethiopia

BackgroundFarmers’ knowledge has a role in maintaining barley (Hordeum vulgare L.) genetic resource, which plays an important role in food security, and provides socio-cultural value to the Ethiopian farmers. However, farmers’ knowledge has been ignored in the decision-making process in Misha, Gumer, and Hetosa districts, Ethiopia.MethodsIn this study, a semi-structured interview guide was used to carry out comprehensive house-to-house interviews with 357 purposively selected farmers to document their knowledge of barley cultivation, utilization and conservation practices.ResultsThe majority of farmers (57.1%) grow barley on 0.5–0.75 hectares. Farmers identified and described 68 barley varieties with various local names, which were given to barley based on different characteristics such as plant height, spikelet length, row type, seed size and color, yield, place of origin, and use-values. Farmers are familiar with the nature, characteristics, end-uses, and preparation of different well-appreciated local meals and drinks. Farmers noticed that the number of barley local varieties has been decreasing in recent years. Introduction of improved varieties was perceived by all farmers as the main cause for the decrease in the number of barley local varieties in their localities. Another factor for the reduction in local barley varieties, according to 24.2% of farmers, was soil fertility degradation. Most of the farmers (65.7%) use their own barley seeds, which they select and save for the next growing season for specific attributes. They have their own indigenous knowledge that they have acquired through experience by growing, selecting, and conserving barley for the last 20–30 years or more.ConclusionThe majority of farmers gave attention to commercial cultivars due to their better market value. Thus, the introduction of improved cultivars has imposed on local varieties. The indigenous knowledge that the famers acquired through experience could be considered an advantage for the conservation of barley genetic resources by using farmers’ participatory approach to widen cultivation and to improve barley local varieties for future use.

A homologous gene of OsREL2/ASP1, ASP-LSL regulates pleiotropic phenotype including long sterile lemma in rice

BackgroundPanicle is a harvesting organ of rice, and its morphology and development are closely associated with grain yield. The current study was carried on a mutant screened through an EMS (ethyl-methane sulphonate) mutagenized population of a Japonica cultivar Kitaake (WT).ResultsA mutant, named as asp-lsl (aberrant spikelet-long sterile lemma), showed a significant decrease in plant height, number of tillers, thousand-grains weight, seed setting rate, spikelet length, kernel length and effective number of grains per panicle as compared to WT. Asp-lsl showed a pleiotropic phenotype coupled with the obvious presence of a long sterile lemma. Cross-sections of lemma showed an increase in the cell volume rather than the number of cells. Genetic segregation analysis revealed its phenotypic trait is controlled by a single recessive nuclear gene. Primary and fine mapping indicated that candidate gene controlling the phenotype of asp-lsl was located in an interval of 212 kb on the short arm of chromosome 8 between RM22445 and RM22453. Further sequencing and indels markers analysis revealed LOC_Os08g06480 harbors a single base substitution (G→A), resulting in a change of 521st amino acid(Gly→Glu. The homology comparison and phylogenetic tree analysis revealed mutation was occurred in a highly conserved domain and had a high degree of similarity in Arabidopsis, corn, and sorghum. The CRISPR/Cas9 mutant line of ASP-LSL produced a similar phenotype as that of asp-lsl. Subcellular localization of ASP-LSL revealed that its protein is localized in the nucleus. Relative expression analysis revealed ASP-LSL was preferentially expressed in panicle, stem, and leaves. The endogenous contents of GA, CTK, and IAA were found significantly decreased in asp-lsl as compared to WT.ConclusionsCurrent study presents the novel phenotype of asp-lsl and also validate the previously reported function of OsREL2 (ROMOSA ENHANCER LOCI2), / ASP1(ABERRANT SPIKELET AND PANICLE 1).

Integrating GWAS and transcriptomics to identify genes involved in seed dormancy in rice.

Several QTLs and genes responsible for seed dormancy were detected and SNP candidates were shown to cause changes in seed germination. Seed dormancy is a key agricultural trait to prevent pre-harvest sprouting in crop plants such as rice (Oryza sativa L.), wheat (Triticum aestivum), and barley (Hordeum vulgare L.). However, our knowledge of seed dormancy is hampered by the complexities of studying a trait that changes over time after seed harvest, and is complicated by interactions between phytohormones, seed coat components and the environment. Here, we have conducted a genome-wide association study using a panel of 311 natural accessions of cultivated rice, examining a total of 519,158 single nucleotide polymorphisms (SNPs). Eight quantitative trait loci (QTLs) were found to associate with seed dormancy in the whole panel and five in the Japonica and Indica subpanel; expression of candidate genes within 100kb of each QTL was examined in two published, germination-specific transcriptomic datasets. Ten candidate genes, differentially expressed within the first four days post-imbibition, were identified. Five of these genes had previously been associated with awn length, heading date, yield, and spikelet length phenotypes. Two candidates were validated using Quantitative Reverse Transcription (qRT)-PCR. In addition, previously identified genes involved in hormone signaling during germination were found to be differentially expressed between a japonica and an indica line; SNPs in the promoter of Os9BGlu33 were associated with germination index, with qRT-PCR validation. Collectively, our results are useful for future characterization of seed dormancy mechanism and crop improvement, and suggest haplotypes for further analysis that may be of use to boost PHS resistance in rice.

Genetic dissection of QTLs associated with spikelet-related traits and grain size in sorghum

Although spikelet-related traits such as size of anther, spikelet, style, and stigma are associated with sexual reproduction in grasses, no QTLs have been reported in sorghum. Additionally, there are only a few reports on sorghum QTLs related to grain size, such as grain length, width, and thickness. In this study, we performed QTL analyses of nine spikelet-related traits (length of sessile spikelet, pedicellate spikelet, pedicel, anther, style, and stigma; width of sessile spikelet and stigma; and stigma pigmentation) and six grain-related traits (length, width, thickness, length/width ratio, length/thickness ratio, and width/thickness ratio) using sorghum recombinant inbred lines. We identified 36 and 7 QTLs for spikelet-related traits and grain-related traits, respectively, and found that most sorghum spikelet organ length- and width-related traits were partially controlled by the dwarf genes Dw1 and Dw3. Conversely, we found that these Dw genes were not strongly involved in the regulation of grain size. The QTLs identified in this study aid in understanding the genetic basis of spikelet- and grain-related traits in sorghum.

Effects of plant height on population dynamics of Wheat crop (Triticum aestivum L.)

The wheat (Triticum aestivum L.) is an important staples crop of Pakistan and the Central Asia. The present research is an effort to clarify the super wheat genotypes, which were carried out at the experimental field area of Lasbela University of Agriculture, Water and Marine Sciences (LUAWMS), Pakistan, in order to study the effect of intra-specific competition on individual plants of Wheat (variety Sahar 2006) during the 2013-2014 wheat growing season. The experiment was carried out in a randomized complete block design comprising of two rows spacing (15 and 30 cm) and broadcasting method of seeding with four replicates at a 30 days’ interval by destruction method. Final harvest was carried out at the end of growing season (150 days after seeding). The agronomic characteristics of wheat have shown non-significant response for effect of row spacing at final harvest. However, application of Gini Coefficient and Lorenz Curve clearly indicated the inequalities in plant height, number and length of spike and spikelet among the individual plants. The Gini values are more pronounced at mid-season harvest compared with final harvest. The results of present study explained the reasons of inequality in plant height and growth within the pure-line of wheat crop. Keywords: Gini Coefficient; Lorenz Curve; Physiological traits; Row spacing; Wheat http://dx.doi.org/10.19045/bspab.2020.90279

A New Species of Agrostis (Poaceae, Pooideae, Poeae, Agrostidinae) from the Andean Páramos of Colombia and Ecuador

Agrostis laegaardii A. M. Molina &amp; Rúgolo (Poaceae), a new species restricted to the high páramos from Colombia and Ecuador, is described and illustrated. It is morphologically most similar to A. breviculmis Hitchc. but differs in spikelet length, pedicel apex, glume texture, relative distance between upper glume and floret, lemma and palea length, and the presence of an awn on the lemma. Micromorphology of the spikelet is discussed, and a Trichodium net is reported on the epidermis of the lemma. A distribution map and a key to the Colombian and Ecuadorean species of Agrostis L. with contracted inflorescences are provided.&#x0D;

Enumeration of genetic diversity of wild rice through phenotypic trait analysis

Nine species of wild rice viz. Oryza alta, O. australiensis, O. barthii, O. longistaminata, O. punctata, O. officinalis, O. brachyantha, O. rhizomatis and O. rufipogon were used for morphological trait analysis. Analyzed traits were number of node and internodes, flag leaf length and breadth, leaf blade length and width, leaf blade area, ligule length, height of tiller, tiller base thickness, auricle length, awn length, culm length, panicle length, length of primary branches, spikelet length and width, grain length and width, spikelet per panicle, peduncle length, thickness of awn, anther length and days of flower initiation. A significant variation was found for all qualitative and quantitative parameters among all the nine species of wild rice.

Comparative Expression Profiling Reveals Genes Involved in Megasporogenesis.

Megasporogenesis is a key step during ovule development in angiosperms, but the small number and inaccessibility of these cells have hampered molecular and genome-wide studies. Thus, many questions remain regarding the molecular basis of cell specification, differentiation, and development in the female gametophyte. Here, taking advantage of the correlation between spikelet length and ovule development in rice (Oryza sativa), we studied the transcriptome dynamics of young ovules at three stages, the archesporial cell, the megaspore mother cell before meiosis, and the functional megaspore after meiosis, using expression profiling based on RNA sequencing. Our analysis showed that 5,274 genes were preferentially expressed in ovules during megasporogenesis as compared to ovules at the mature female gametophyte stage. Out of these, 958 (18.16%) genes were archesporial cell- and/or megaspore mother cell-preferential genes, and represent a significant enrichment of genes involved in hormone signal transduction and plant pathogen interaction pathways, as well as genes encoding transcription factors. The expression patterns of nine genes that were preferentially expressed in ovules of different developmental stages, including the OsERECTA2 (OsER2) receptor-like kinase gene, were confirmed by in situ hybridization. We further characterized the OsER2 loss-of-function mutant, which had an excessive number of female germline cells and an abnormal female gametophyte, suggesting that OsER2 regulates germline cell specification during megasporogenesis in rice. These results expand our understanding of the molecular control of megasporogenesis in rice and contribute to the functional studies of genes involved in megasporogenesis.

Measurement of Genetic Diversity of Chinese Seashore Paspalum Resources through Morphological and Sequence-related Amplified Polymorphism Analysis

Seashore paspalum (Paspalum vaginatum) is a notable warm-season turfgrass. Certain germplasm resources are distributed in the southern regions of China. The objectives of this study were to investigate the genetic diversity and genetic variation of Chinese seashore paspalum resources. Morphological characteristics and sequence-related amplified polymorphism (SRAP) markers were used to assess genetic relationships and genetic variation among 36 germplasm resources from China and six cultivars from the United States. The results showed significant variation for 13 morphological characteristics among 42 tested seashore paspalum accessions, and that the phenotypic cv was, in turn, turf height &gt; turf density &gt; internode length &gt; inflorescence density &gt; leaf width &gt; reproductive branch height &gt; spikelet width &gt; leaf length &gt; spikelet number &gt; inflorescence length &gt; internode diameter &gt; inflorescence width &gt; spikelet length. According to the morphological characteristics and cluster analysis, 42 seashore paspalum accessions were divided into six morphological types. In total, 374 clear bands were amplified using 30 SRAP primer combinations; among these bands, 321 were polymorphic with 85.83% polymorphism. SRAP marker cluster analysis showed that 42 seashore paspalum accessions were grouped into seven major groups, with a genetic similarity coefficient ranging from 0.4385 to 0.9893 and genetic distance values ranging from 0.0108 to 0.8244. The high level of genetic diversity occurred among Chinese germplasm, and the genetic distance was relatively high between Chinese germplasm and cultivars introduced from the United States. The patterns in morphological trait variations and genetic diversity will be useful for the further exploitation and use of Chinese seashore paspalum resources.