Self-pollinated Species Research Articles

Identification of genetic loci and candidate genes related to soybean flowering through genome wide association study

BackgroundAs a photoperiod-sensitive and self-pollinated species, the growth periods traits play important roles in the adaptability and yield of soybean. To examine the genetic architecture of soybean growth periods, we performed a genome-wide association study (GWAS) using a panel of 278 soybean accessions and 34,710 single nucleotide polymorphisms (SNPs) with minor allele frequencies (MAF) higher than 0.04 detected by the specific-locus amplified fragment sequencing (SLAF-seq) with a 6.14-fold average sequencing depth. GWAS was conducted by a compressed mixed linear model (CMLM) involving in both relative kinship and population structure.ResultsGWAS revealed that 37 significant SNP peaks associated with soybean flowering time or other growth periods related traits including full bloom, beginning pod, full pod, beginning seed, and full seed in two or more environments at -log10(P) > 3.75 or -log10(P) > 4.44 were distributed on 14 chromosomes, including chromosome 1, 2, 3, 5, 6, 9, 11, 12, 13, 14, 15, 17, 18, 19. Fourteen SNPs were novel loci and 23 SNPs were located within known QTLs or 75 kb near the known SNPs. Five candidate genes (Glyma.05G101800, Glyma.11G140100, Glyma.11G142900, Glyma.19G099700, Glyma.19G100900) in a 90 kb genomic region of each side of four significant SNPs (Gm5_27111367, Gm11_10629613, Gm11_10950924, Gm19_34768458) based on the average LD decay were homologs of Arabidopsis flowering time genes of AT5G48385.1, AT3G46510.1, AT5G59780.3, AT1G28050.1, and AT3G26790.1. These genes encoding FRI (FRIGIDA), PUB13 (plant U-box 13), MYB59, CONSTANS, and FUS3 proteins respectively might play important roles in controlling soybean growth periods.ConclusionsThis study identified putative SNP markers associated with soybean growth period traits, which could be used for the marker-assisted selection of soybean growth period traits. Furthermore, the possible candidate genes involved in the control of soybean flowering time were predicted.

Preliminary Environmental Risk Assessment of Genetically Modified Oilseed Rape MON 88302 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/BE/2011/101)

Preliminary Environmental Risk Assessment of Genetically Modified Oilseed Rape MON 88302 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/BE/2011/101)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape T45 for Food and Feed Uses, Import and Processing under Regulation (EC) No 1829/2003 (Application EFSA/GMO/UK/2005/25)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape MS8, RF3 and MS8 x RF3 for Import, Processing and Feed Uses under Directive 2001/18/EC (Notification C/BE/96/01)

Environmental Risk Assessment of Glufosinate-Tolerant Genetically Modified Oilseed Rape MS8, RF3 and MS8 x RF3 for Import, Processing and Feed Uses under Directive 2001/18/EC (Notification C/BE/96/01)

Review on Sesame (Sesamum indicum L.) Breeding in Ethiopia

Sesame (Sesamum indicum L.) is a self-pollinated diploid species with 2n = 26 chromosomes. Sesame improvement research in Ethiopia was started in the late l960s at Werer Agricultural Research Center. The objective of sesame breeding in Ethiopia is to develop the potential by creating cultivars which meet the demands of the sesame farmers, processor and user. The improvement of sesame has lagged behind due to a lack of research shortage of trained personnel, limited financial support and limited international cooperation. Although Indeterminate flowering nature and shattering of capsules at maturity, insects, pests and diseases, heat and drought, among other things are the major factors for low yields of sesame are seen as the challenges of the crop breeding. Suitability of different agro ecology, availability of genetic resource and diversities, market proximity, mutation breeding and different biotechnology approaches are some opportunities of Sesame breeding in Ethiopia. Application of biotechnology together with conventional breeding methods is a valuable approach for breeding superior varieties in a short period of time. Keywords: diversity, importance, opportunities and Sesame (Sesamum indicum L.) DOI : 10.7176/JBAH/9-17-07 Publication date :September 30 th 2019

Patterns of nucleotide diversity for different domains of centromeric histone H3 (CENH3) gene in Secale L.

Rye (Secale) is among staple cereals along with other members of the Triticeae tribe: wheat and barley. The genus Secale includes perennial and annual, cross-pollinating and self-pollinating species, and they can be donors of valuable genes in wheat and rye breeding programs. Studies of the structure of the gene for centromeric histone H3 (CENH3), essential for centromere functions, are relevant to the breeding of agronomically important crops. We have investigated the nucleotide diversity of sequences of two variants of the rye CENH3 gene inside the N-terminal tail (NTT) and the conservative HFD (histone fold domain) domain in the genus Secale. The mean values of nucleotide diversity in the NTT and HFD of wild cross- and self-pollinating taxa are close in αCENH3: πtot = 0.0176–0.0090 and 0.0136–0. 0052, respectively. In the case of βCENH3, the mean values for NTT (πtot = 0.0168–0.0062) are lower than for HFD (πtot = 0.0259–0.084). The estimates of nucleotide and haplotype diversity per site for the CENH3 domains are considerably lower in taxa with narrow geographic ranges: S. cereale subsp. dighoricum and S. strictum subsp. kuprijanovii. Commercial breeding reduces the nucleotide sequence variability in αCENH3 and βCENH3. Cultivated rye varieties have π values within 0.0122–0.0014. The nucleotide and haplotype diversity values in αCENH3 and βCENH3 are close in S. sylvestre, which is believed to be the oldest rye species. The results of this study prove that the frequency of single nucleotide polymorphisms and nucleotide diversity of sequences in genes for CENH3 in Secale species are influenced by numerous factors, including reproduction habits, the geographic isolation of taxa, breeding, and the evolutionary age of species.

Comparative studies of reproductive biology, seed morphology and anatomy of new salt tolerant accessions of Quinoa (Chenopodium quinoa Willd.) introduced in Kur-Araz lowland (Azerbaijan)

Investigated salt tolerant top-ranking accessions of Quinoa introduced on drought prone and salt affected soils with higher clay contents, water holding capacity, evapotranspiration and shallow water in Kur-Araz (Azerbaijan) undergone all ontogenetic reproductive (pollen grain productivity, embryo and fruit developmental stages) and produce viable seeds. The floral initiation stage varies between 66-77 days depending on genotype, plant height, days to flowering and to seed maturity, and dry weight biomass (p > 0.05). The interaction effect of location and genotypes was significant for days to flowering and seed maturity and dry weight, though not for plant height and seed yield. Three early-middle and late-flowering, and thus early-middle and late seed maturation clusters of quinoas was described. Quinoa is predominantly self-pollinating species, but pollination inside the inflorescence by means of wind (anemophilous) or with support of small insects (entomophilous) occurs. There was no significant difference in the fruit and seed morphology among investigated accessions of quinoa cultivated under new environments. Fruits of quinoa are simple, dry, indehiscent, achene, monosperm with white pericarp in the mature state and remainans of perigonium, albuminous white or yellowish seed 1.8-2.5 mm in diameter. In quinoa seeds the pericarp is very thin; as a result, the achene is also referred to as utricle.Viable seed contains a peripheral, curved embryo surrounding by perisperm and pericarp. Pronounced micropylar endosperm (a non-embryonic tissue) of one or two cell layers thick forms a cone surrounds the root apical meristem of the embryo. Anatomy of quinoa micropylar endosperm revealed similarities in structure with coleorhiza cells in cereals. Both tissues serve as store reserve and play vital role by protecting the root apical meris-tem in the quiescent seed and control dormancy during germination. Further investigation of micropylar cellular tissue of quinoa, where stores lipids, proteins and minerals should be considered to select better adapted genotypes with high seed yields and nutritional qua-lity combined with salt-and drought-tolerance. Freshly collected quinoa seeds have endogenous physiological type of dormancy. All investigated quinoa accessions, except Quinoa-Q2 showed high germination rate (78-85%) through 16 hours at room temperature (24-25 ºC). Identification of desirable genotypes needs to be followed by work on optimization of cultural practices and seed storage to maximize productivity under the drought-prone and salt affected of Kur-Araz farming areas. Early seed sowing in the field is required, thus early flowering and seed maturation occurs long before heat summer season starts.

Targeted recombination to increase genetic gain in self-pollinated species.

If we can induce or select for recombination at targeted marker intervals, genetic gains for quantitative traits in self-pollinated species may be doubled. Targeted recombination refers to inducing or selecting for a recombination event at genomic positions that maximize genetic gain in a cross. A previous study indicated that targeted recombination could double the rate of genetic gains in maize (Zea mays L.), a cross-pollinated crop for which historical genetic gains have been large. Our objectives were to determine whether targeted recombination can sufficiently increase predicted gains in self-pollinated species, and whether prospective gains from targeted recombination vary across crops, populations, traits, and chromosomes. Genomewide marker effects were estimated from previously published marker and phenotypic data on 21 biparental populations of soybean [Glycine max (L.) Merr.], wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and pea (Pisum sativum L.). With the predicted gain from nontargeted recombination as the baseline, the relative gains from creating a doubled haploid with up to one targeted recombination [RG(x ≤ 1)] and two targeted recombinations [RG(x ≤ 2)] per chromosome or linkage group were calculated. Targeted recombination significantly (P = 0.05) increased the predicted genetic gain compared to nontargeted recombination for all traits and all populations, except for plant height in barley. The mean RG(x ≤ 1) was 211%, whereas the mean RG(x ≤ 2) was 243%. The predicted gain varied among traits and populations. For most traits and populations, having targeted recombination on less than a third of all the chromosomes led to the same or higher predicted gain than nontargeted recombination. Together with previous findings in maize, our results suggested that targeted recombination could double the genetic gains in both self- and cross-pollinated crops.

New data on the genus Epipactis (Orchidaceae) in the North Caucasus with description of a new species

A new self-pollinating species, Epipactis euxina, is described from Gelendzhik District of Krasnodar Territory. The species is closely related to E. persica from which it differs by its remarkable long pedicel, distinctly longer epichile, and indistinct or absent viscidium. It grows in sparse pine forest mixed with oak, on calcareous soils. Four other taxa collected in different localities of Krasnodar Territory are new for the North Caucasus: E. krymmontana, E. leptochila subsp. leptochila, E. leptochila subsp. neglecta, and E. muelleri. A new synonymy is proposed for E. persica = E. helleborine subsp. transcaucasica. An updated key to the species of the genus Epipactis in the North Caucasus is provided. The lectotype of E. muelleri is designated.

Population structure, genetic relatedness and linkage disequilibrium blocks in cultivars of tropical soybean (Glycine max)

Soybean (Glycine max L.) is an annual, self-pollinated species, whose genetic base in Brazil is the result of several cycles of selection and effective recombination among a relatively small number of genotypes selected from the USA cultivars. This frequent selection, admixed population, and the crossing of a small number of cultivars can lead to increase the genetic relationship and affect the patterns of population structure. These factors affect the patterns of linkage disequilibrium (LD) blocks, which can be an effective approach for the screening of target loci for agricultural traits in cultivars of tropical soybean. The objectives of this research were to analyze LD blocks, estimate population structure and relatedness through of genotyping of 169 cultivars of tropical soybean by using a BARCSoySNP6K of Illumina iScan platform. The genotyping revealed a high genetic relatedness and population structure among the cultivars of soybean in Brazil, suggesting the existence of a shared genetic base. Our results provide a help to understand the distribution of genetic variation contained within the Brazilian soybean cultivar collection. We showed that the extensive use of a small number of elite genotypes in Brazilian breeding program further reduced the genetic variability, generate extensive LD and probably increase the haplotype block size. These results are in agreement with results of USDA soybean collection, mainly with accessions of north American, when compared with wild and landraces accessions. We constructed a small haplotype block maps (941 blocks), which may be useful for association studies aimed at the identification of genes controlling traits of economic importance in soybean.

Frequency of Heterotic Hybrids in Relation to Parental Genetic Divergence and General Combining Ability in Dolichos Bean

Though F1 hybrids are not the immediate cultivar option, development of heterotic F1 hybrids is relevant from view point of deriving pure lines, the only cultivar choice in dolichos bean, a predominantly self-pollinated grain legume crop species. Heterotic F1 generates a high frequency of productive derivatives in F3 and later generations as compared to non-heterotic F1. The criteria such as combining ability and genetic diversity between parents are being commonly used to develop heterotic hybrids. In this context, an investigation was carried out at University of Agricultural Sciences, Bengaluru, India, to test the predictability of frequency of heterotic hybrids based on parental gca effects and genetic diversity in dolichos bean. The 48 F1 hybrids generated by crossing 12 lines and 4 testers were evaluated along with their parents for 6 quantitative characters. The overall gca status (high and low) of each parent and overall sca and heterotic status (high and low) of each hybrid for 6 characters were determined. Based on overall gca status and genetic divergence of parents, the hybrids were grouped into different classes. The hybrids involving parents contrasting for overall gca status and/or those involving parents with intermediate genetic divergence were more frequently heterotic than those involving comparable gca status with extreme genetic divergence. Thus, there exists a limit to parental divergence for the occurrence of heterosis. It is hence, desirable to involve parents with intermediate genetic divergence and contrasting gca effects to recover higher frequencies of heterotic hybrids for economic traits in dolichos bean.

Breeding systems in Angiosperms: novel inferences from a new analytical approach

A novel analytical approach to classify breeding systems in Angiosperms combining statistical and conceptual criteria is proposed, which will allow to describe and compare available mating system data in an unified form. Four breeding system indexes (BSI) were combined: Index of Agamospermy, Index of Spontaneous Self-Pollination (ISSP), Index of Self-Fertility (ISF), and Index of Self-incompatibility. Their values, ranging from 0 to ∞, were analyzed using t tests to discriminate experimental breeding index values from 0 and 1.0. For each index, five discrete categories were described. The composite of the four BSI assigned to a species represents an integrated characterization of its reproductive system. A magnitude measure (M) describes the strength of each BSI assigned to a species. Indexes of inbreeding and outbreeding depression were also examined for each species. Published data from 1908 taxa were used to determine composite breeding systems. Frequencies of breeding index categories across the four BSI for the entire data set were determined. Non-agamospermous species dominated. Non-spontaneous self-pollinating and xenogamous species were the most frequent categories observed for ISSP and ISF indexes, respectively. The largest group of species examined was partially self-incompatible. Actual number of composite breeding systems inferred based on our analysis represents a small fraction (8.9 %) of all mathematically possible ones. Similarly, the observed combinations between results obtained from the four pollination tests and estimates of natural reproductive efficiency were only 22.1 % of all mathematically possible combinations. Within Angiosperms, there is a marked trend toward evolution of partial self-incompatibility with significant inbreeding depression.

Haplotag: Software for Haplotype-Based Genotyping-by-Sequencing Analysis.

Genotyping-by-sequencing (GBS), and related methods, are based on high-throughput short-read sequencing of genomic complexity reductions followed by discovery of single nucleotide polymorphisms (SNPs) within sequence tags. This provides a powerful and economical approach to whole-genome genotyping, facilitating applications in genomics, diversity analysis, and molecular breeding. However, due to the complexity of analyzing large data sets, applications of GBS may require substantial time, expertise, and computational resources. Haplotag, the novel GBS software described here, is freely available, and operates with minimal user-investment on widely available computer platforms. Haplotag is unique in fulfilling the following set of criteria: (1) operates without a reference genome; (2) can be used in a polyploid species; (3) provides a discovery mode, and a production mode; (4) discovers polymorphisms based on a model of tag-level haplotypes within sequenced tags; (5) reports SNPs as well as haplotype-based genotypes; and (6) provides an intuitive visual “passport” for each inferred locus. Haplotag is optimized for use in a self-pollinating plant species.

Silencing of dominant genes in heterozygous genotypes of interspecific hybrids Fagopyrum esculentum Moench. × C2026 F. homotropicum Ohnishi

Fagopyrum homotropicum Ohnishi is a very polymorphic self-pollinating species with homostylous flowers, which morphologically different lineages are differ also in ability to hybridize with F. esculentum Moench. (closely related outcrosser with heterostyly). A lineage C2026 F. homotropicum diverged from F. esculentum with forming noticeable pre-zygotic and post-zygotic barriers: the most successful interspecific crossing F esculentum x C2026 resulted wrinkled hybrid seeds germinated in Petri dishes. These interspecific hybrids and backcrosses F. esculentum x F₁, being heterozygous at loci DET/det, SHT/sht and homostyly gene of F. homotropicum, in our experiments often formed phenotype like a recessive homozygote for at least one of these genes, i.e. dominant alleles were silenced. Apparently, these effects can be caused by disorders of epigenetic regulation associated with the divergence of hybridized species. Such disorders, especially those that occur at the stage of seed development, represent one of the main experimentally confirmed mechanisms of pre-zygotic isolation between species. Apparently, F. esculentum and the lineage C2026 of F. homotropicum represent an example of intermediate stage of post-zygotic isolation development process which based on epigenetic deregulation of gene expression in the hybrids. Sometimes it may be revealed not only at the stage of seed development, but also at later stages of ontogenesis.

De Novo Assembly and Transcriptome Analysis of Wheat with Male Sterility Induced by the Chemical Hybridizing Agent SQ-1.

Wheat (Triticum aestivum L.), one of the world’s most important food crops, is a strictly autogamous (self-pollinating) species with exclusively perfect flowers. Male sterility induced by chemical hybridizing agents has increasingly attracted attention as a tool for hybrid seed production in wheat; however, the molecular mechanisms of male sterility induced by the agent SQ-1 remain poorly understood due to limited whole transcriptome data. Therefore, a comparative analysis of wheat anther transcriptomes for male fertile wheat and SQ-1–induced male sterile wheat was carried out using next-generation sequencing technology. In all, 42,634,123 sequence reads were generated and were assembled into 82,356 high-quality unigenes with an average length of 724 bp. Of these, 1,088 unigenes were significantly differentially expressed in the fertile and sterile wheat anthers, including 643 up-regulated unigenes and 445 down-regulated unigenes. The differentially expressed unigenes with functional annotations were mapped onto 60 pathways using the Kyoto Encyclopedia of Genes and Genomes database. They were mainly involved in coding for the components of ribosomes, photosynthesis, respiration, purine and pyrimidine metabolism, amino acid metabolism, glutathione metabolism, RNA transport and signal transduction, reactive oxygen species metabolism, mRNA surveillance pathways, protein processing in the endoplasmic reticulum, protein export, and ubiquitin-mediated proteolysis. This study is the first to provide a systematic overview comparing wheat anther transcriptomes of male fertile wheat with those of SQ-1–induced male sterile wheat and is a valuable source of data for future research in SQ-1–induced wheat male sterility.

Genome-wide association study for flowering time, maturity dates and plant height in early maturing soybean (Glycine max) germplasm.

BackgroundSoybean (Glycine max) is a photoperiod-sensitive and self-pollinated species. Days to flowering (DTF) and maturity (DTM), duration of flowering-to-maturity (DFTM) and plant height (PH) are crucial for soybean adaptability and yield. To dissect the genetic architecture of these agronomically important traits, a population consisting of 309 early maturity soybean germplasm accessions was genotyped with the Illumina Infinium SoySNP50K BeadChip and phenotyped in multiple environments. A genome-wide association study (GWAS) was conducted using a mixed linear model that involves both relative kinship and population structure.ResultsThe linkage disequilibrium (LD) decayed slowly in soybean, and a substantial difference in LD pattern was observed between euchromatic and heterochromatic regions. A total of 27, 6, 18 and 27 loci for DTF, DTM, DFTM and PH were detected via GWAS, respectively. The Dt1 gene was identified in the locus strongly associated with both DTM and PH. Ten candidate genes homologous to Arabidopsis flowering genes were identified near the peak single nucleotide polymorphisms (SNPs) associated with DTF. Four of them encode MADS-domain containing proteins. Additionally, a pectin lyase-like gene was also identified in a major-effect locus for PH where LD decayed rapidly.ConclusionsThis study identified multiple new loci and refined chromosomal regions of known loci associated with DTF, DTM, DFTM and/or PH in soybean. It demonstrates that GWAS is powerful in dissecting complex traits and identifying candidate genes although LD decayed slowly in soybean. The loci and trait-associated SNPs identified in this study can be used for soybean genetic improvement, especially the major-effect loci associated with PH could be used to improve soybean yield potential. The candidate genes may serve as promising targets for studies of molecular mechanisms underlying the related traits in soybean.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1441-4) contains supplementary material, which is available to authorized users.

Gene set by de novo assembly of Perilla species and expression profiling between P. frutescens (L.) var. frutescens and var. crispa

Perilla frutescens (L.) Britt. is a self-pollinating annual species and is widely cultivated in China, Korea and Japan as an economic crop and a source of medicine and spices. In this study, we sequenced one cultivar variety (PF98095) of P. frutescens (L.) var. frutescens Britt., which was assembled as reference and other three varieties (PF11109, weedy of var. frutescens, PF06336 and PF06353, cultivars of varieties crispa) in order to carry out comparative expression profiling within cultivar and weedy in varieties frutescens and between varieties frutescens and varieties crispa of cultivar type in P. frutescens. Assembly of PF98095, annotation mapping, DEG (differentially expressed gene) profiling, and comparative analysis were performed. We found that more than 65% of the reads were mapped to the reference of P. frutescens gene set. Moreover, we detected 22,962 DEGs in the weedy variety compared to the cultivar, and also, 22,138 and 23,845 DEGs were identified in two cultivars according to the reference, respectively. The DEGs and functional classification were developed to analyze the differences between weedy and cultivar and between varieties frutescens and varieties crispa of Perilla. Furthermore, candidate genes for the different color and seed size of Perilla were identified that could be further investigated in future study. The herein results may play a significant role, and contribute in functional transcriptome studies of Perilla.

Genome-wide development of novel miRNA-based microsatellite markers of rice (Oryza sativa) for genotyping applications

Rice (Oryza sativa L.) plays a crucial role in assuring food security to the world’s population and is recognized as a superior model plant of monocot crops. Molecular markers, especially co-dominant markers such as simple sequence repeats (SSRs), play an important role in marker-assisted breeding of rice. Although a large number of SSRs are available, most of them are either from protein-coding regions or untranslated regions of the rice genome. SSRs from non-coding regions of the rice genome are almost undiscovered, but discovery of new SSR markers remains a challenge for molecular breeders. The development of novel markers from the conserved regions of different genomes will thus be useful for studying the genetic diversity of closely related species or self-pollinated species. In the present study, a genome-wide investigation yielded a total of 129 SSR markers from the conserved microRNA (miRNA) genes of rice, and 20 of them with repeat numbers ≥7, from all the 12 chromosomes, were validated among 24 diverse rice genotypes. The highest number of repeat motifs corresponded to di-nucleotides, while the tetra-nucleotides were repeated the lowest number of times. Our results therefore show that the number of repeats is inversely related to the length of repeat. The genetic diversity was found to be higher among the exotic material than the Indian landraces, as indicated by their polymorphic information content values of 0.31 and 0.29, respectively. The results hence showed that the miRNA-based microsatellite marker system is a very proficient, novel and breeder-friendly source for genetic diversity analysis or genotyping of rice. The present study is the first report on genome-wide identification and characterization of rice miRNA-SSRs.

An Overview on Flax (Linum usitatissimumL.) and its Genetic Diversity

Flax (Linum usitatissimum L.) is an annual, self-pollinated species with a genome size of ~ 370 Mb. Flax provides raw materials for food, medicine and textiles and hence it has been of great importance to human culture and development. Linseed oil is well-known for its health benefits mainly attributed to its high content of omega-3 alpha linolenic acid (55–57%). Consumption of grounded seeds adds nutritional benefits because flax seeds are also a rich source of lignans, having anticancer properties. India contributes to almost 20% of world's linseed production and governs linseed production among the Asian countries whereas, the scenario is just reverse in case of fibre flax. In the last decade, the fibre industry has devoted some effort to develop high-value products from linseed stems with applications in the pulp, technical fibre and biofuel industries. Therefore, understanding its genetic diversity is important for the continued improvement of this crop and as well as for its utilization as a truly dual purpose crop. Diversity analysis based on morphology alone has a significant limitation in the fact that it is highly influenced by the environment, to overcome this problem; molecular characterization can play an important role. However, systematic studies regarding the genetic diversity of flax in India are meagre. Hence, in-depth studies based on both morphological and molecular markers will help in better conceiving the genetic diversity of flax germplasm.

Are breeding system and florivory associated with the abundance ofTillandsiaspecies (Bromeliaceae)?

Plant species abundance is partly determined by reproductive success and the factors that limit this success. We studied the flowering phenology, breeding systems and florivory in a community of seven epiphytic Tillandsia spp. in a tropical dry forest in central Mexico. Flowering periods were distributed throughout the year, and corolla sizes suggested that most species share pollinators. The most common breeding system was self-incompatibility (Tillandsia achyrostachys, T. caput-medusae and T. hubertiana), T. lydiae was infertile, T. circinnatioides was partially self-compatible and T. recurvata and T. schiedeana were self-compatible with high autonomous self-pollination. Floral morphology suggests that delayed selfing occurs in the autonomous self-pollinated species, and separation between stigma and stamens could result in self-pollination in the remaining species being avoided. Less than 5% of the inflorescences in the most abundant species (T. recurvata) suffered damage by florivores, but > 40% of inflorescences were damaged in the other species. In damaged inflorescences, fruit set decreased by up to 89%. Our data show that the dominant species (T. recurvata) is autogamous and its reproductive success is slightly reduced by resource constraints and florivory. In the less abundant species, resource limitation and florivory dramatically reduced reproductive success, but the strength of these limiting factors is season dependent.