Allogamous Species Research Articles

Heritability of floral traits in Allium cepa L. populations from biparental crosses

AbstractOnions (Allium cepa L.) are one of the main vegetable crops worldwide. As an allogamous species with entomophilous pollination, floral traits play a critical role in seed production. Improving seed yield, especially for hybrid seed production, is very important. In this work, we obtained genetic information for floral traits using segregating populations from three male‐sterile lines and one open‐pollinated variety. Data on 16 floral traits, including perianth, gynoecium, stamens, and receptacle structures, were collected from the parental cultivars, their hybrids, and from segregating populations in the F2 and F3 generations. This dataset underpinned a comprehensive analysis of genetic variability, broad‐ and narrow‐sense heritability estimation, genetic gain predictions, and trait correlations. The evaluated traits exhibited high broad‐sense heritability values (0.08–0.85), but moderate narrow‐sense heritability values (0.01–0.68), implying that the observed phenotypic variance is mainly explained by genetic factors, with a minor additive genetic factors contribution. Consequently, the study revealed effective genetic gain for the analyzed traits. The phenotypic correlations observed in the parental cultivars were not always maintained in the segregating populations, suggesting random correlations. Meanwhile, genetic correlations were moderate to low, suggesting that the analyzed traits can be independently selected without affecting the expression of other floral traits. Notably, correlations among floral traits were significant in stable cultivars but weak in segregating populations, excluding pleiotropic effects. This work has successfully demonstrated the heritability of onion floral traits and provided a sound basis for selecting individuals with desirable attributes, with valuable practical implications for onion breeding and seed production.

Flower size constrains reproductive potential in three Andean monkeyflower species

AbstractPlants exhibit contrasting flower morphologies depending on their reproductive strategy, with autogamous species typically having smaller flowers than allogamous ones. Flower size can restrict the reproductive potential of species, as the development among flower parts is interrelated. This can result in a constraint on ovary size in adult plants, reducing the number of ovules produced, particularly in autogamous species with small flowers, in contrast to allogamous species with larger flowers. To test this hypothesis, we studied the static allometric relationships (allometry measured at mature flowers) of monkeyflower species (Erythranthe) endemic to the Andean region, including an autogamous species (E. glabrata), two allogamous species (E. depressa and E. lutea), and hybrids obtained from E. depressa × E. lutea crosses. We measured flower traits, counted ovules, and determined the static allometric relationships among traits for all taxa. Our study revealed that static allometric relationships are highly maintained among studied Erythranthe, with flower length serving as a crucial indicator of the dimensions that different flower parts reach. This suggests that flower length is an important factor determining the maternal reproductive potential in Erythranthe, with both autogamous and allogamous species showing a positive relationship between flower length and ovule number. Overall, investigating allometric relationships in Erythranthe, including hybrids, can shed light on the complex interactions between flower morphology and reproductive strategies in plants.

Use of olive pomace extract as a pollinator attractant to increase onion (Allium cepa L.) seed crop production

Onion is an allogamous species with protandry, as anthers release pollen before the stigma is receptive. Thus, insect pollination is needed to produce seeds. When male sterile lines are used, an efficient pollinator is important to ensure pollen transfer to the stigma. Therefore, increasing seed yield depends on increasing bee activity. Seed yield is variable in hybrid lines and lower than open-pollinated varieties, with a decrease of up to 60%. Bee attractants sometimes are used to influence worker bees towards flowers for pollination. The objective of this work is to use a food industry waste, such as olive pomace, as bee attractant upon application of the water extract on onion umbels. The effectiveness of this by-product in enhancing pollination efficiency was evaluated and compared to untreated controls. Male-sterile lines, as well as a fertile line, were used in commercial fields and environmental variables were registered. Pollination effectiveness was measured by seed yield. Olive pomace water extracts (OPWE), rich in bioactive compounds, from local industries were evaluated. Some compounds present in the OPWE were analyzed, identified and quantified. The OPWEs were applied during flowering, at different times and correlated with seed yield and the frequency of bee visits. After 3 years of study, we can assert that the application of OPWE enhances honeybee pollination efficiency, and as consequence improves onion seed yield.

Floral nectary structure, nectar presentation and morpho-anatomical analysis of male‐fertile and male‐sterile anthers in onion (Allium cepa, Amaryllidaceae)

Background and aims: The onion (Allium cepa var. cepa) is an allogamous species in which male-sterile lines have been developed. However, the structure of the flower and floral nectaries have only been briefly described. The objective of this study is to update the floral anatomy data, comparing the gynoecium and androecium of male-fertile and male-sterile lines, and to analyze the three-dimensional structure of the floral nectary. M&M: Conventional optical and scanning electron microscopy techniques were used. Results: Fertile and sterile male flowers have the same structural organization. The septal or gynopleural nectary is organized in three zones: 1) production area formed by the glandular tissue arranged radially in the septa of the ovary, 2) discharge zone: a small channel at the apex connects the nectariferous tissue with the pocket formed between the ovary wall and the overlying ridge, and 3) presentation and harvest zone, where the excreted nectar accumulates, formed between the widened base of the inner staminal filaments opposite the ovary. Conclusions: The only anatomical differences in the flowers sterile male lines are the lack of pollen production and the absence of dehiscence, despite having a normal stomium and anther wall. The floral nectaries of onion are a clear example of secondary presentation of nectar.

Clonal Propagation of Walnuts (Juglans spp.): A Review on Evolution from Traditional Techniques to Application of Biotechnology.

Walnuts (Juglans sp.) are allogamous species. Seed-derived plants are not always superior to the selected parent. Clonal propagation of selected stock plants is an essential requirement for the clonal fidelity of the descendants and to maintain their genetic structure. Selection of the desired plant is realized only after reaching maturity, and characterizing and evaluating the performance of adult trees require a long time. Clonal propagation methods ensure proper transmission of characters to descendants and can be used effectively in breeding programs. The commercialization of a cultivar or rootstock depends on the success of vegetative propagation. Walnuts, like other tree species, are recalcitrant to conventional vegetative propagation methods and even non-conventional in vitro culture (micropropagation). Elucidation of factors determining the success of cloning of desired plants would contribute to understanding current limitations for most genotypes of Juglans. We outline the role of grafting and cuttings and stool layering, as well as in vitro culture on walnut multiplication. These techniques are, in practice, entirely different; nevertheless, they are affected by common factors. The incompatibility of stock-scion and the reduced ability of stem cuttings to root are the main bottlenecks for grafting and cutting, respectively. Genotype, age, and physiological status, reinvigoration or rejuvenation-treatment of donor plant, period of harvesting and processing of explants critically affect the results of methods followed. The in vitro culture technology is the most suitable for walnut cloning. This also has constraints that affect commercial propagation of most desired genotypes. We describe comprehensive results and synthesis in this review on the asexual reproduction of walnuts, providing a better comprehension of the limiting factors and the ways to overcome them, with direct implications on commercial propagation and the releasing of outstanding genotypes.

Genotyping marker density and prediction models effects in long-term breeding schemes of cross-pollinated crops.

In genomic recurrent selection, the more markers, the better because they buffer the linkage disequilibrium losses caused by recombination over cycles, and consequently, provide higher responses to selection. Reductions of genotyping marker density have been extensively evaluated as potential strategies to reduce the genotyping costs of genomic selection (GS). Low-density marker panels are appealing in GS because they entail lower multicollinearity and computing time and allow more individuals to be genotyped for the same cost. However, statistical models used in GS are usually evaluated with empirical data, using "static" training sets and populations. This may be adequate for making predictions during a breeding program's initial cycles but not for the long-term. Moreover, studies that focus on long selective breeding cycles generally do not consider GS models with the effect of dominance, which is particularly important for breeding outcomes in cross-pollinated crops. Hence, dominance effects are important and unexplored in GS for long-term programs involving allogamous species. To address it, we employed two approaches: analysis of empirical maize datasets and simulations of long-term breeding applying phenotypic and genomic recurrent selection (intrapopulation and reciprocal schemes). In both schemes, we simulated twenty breeding cycles and assessed the effect of marker density reduction on the population mean, the best crosses, additive variance, selective accuracy, and response to selection with models [additive, additive-dominant, general (GCA), and this plus specific combining ability (GCA + SCA)]. Our results indicate that marker reduction based on linkage disequilibrium levels provides useful predictions only within a cycle, as accuracy significantly decreases over cycles. In the long-term, without training set updating, high-marker density provides the best responses to selection. The model to be used depends on the breeding scheme: additive for intrapopulation and additive-dominant or GCA + SCA for reciprocal.

Thermal amplitude of the air influences the emergence and vigor of seedlings of sour passion fruit

The sour passion fruit is an allogamous species which presents high genetic variability. It is being propagated commercially via seeds. The propagation of species through seeds can be affected by several factors such as the thermal amplitude throughout the day during the germination and the genetic characteristics of the individual. The objective of this study was to evaluate the germination and vigor of seedlings of genotypes of sour passion fruit under different thermal amplitudes of the air. The experiment was conducted in a germination chamber. The factorial scheme was 5 × 3, referring to the five thermal amplitudes of the air (25.0; 22.5-27.5; 20.0-30.0; 17.5-32.5 and 15.0-35.0 ° C) and three genotypes of sour passion fruit (BRS SC1, BRS GA1 and FB-200) in a completely randomized design with six replicates of 25 seeds per plot. The variables analyzed were percentage of velocity index, mean time of emergence, total length, shoot and root and dry mass of seedlings. The thermal amplitude close to 20.0-30.0 °C favored the emergence and vigor of sour passion fruit genotypes. The germination process and the biometric growth of the passion fruit seedlings are adversely affected in high thermal air amplitudes

Spatial and Temporal Variability of the Floral Scent Emitted by Barlia robertiana (Loisel.) Greuter, a Mediterranean Food-Deceptive Orchid

This study on Barlia robertiana aims to: (1) assess whether scent is variable between populations; (2) evaluate whether scent composition may be related to geographical variables; (3) assess whether there are VOC differences during the flowering phase; and (4) assess whether there are yearly VOC variabilities. SPME sampling was used. Fourteen plants, collected along an ecological gradient, were analyzed. A multivariate analysis was performed through ordination and hierarchical cluster analysis. Compositions versus geographic distances were also analyzed using Mantel test. Seventy compounds were identified. Multivariate analyses and Mantel tests detected no correlations between VOC composition and both geographic and ecological variables. These results may suggest that there is no adaptation of floral scent to local environments. VOC compositions during the flowering phase showed a slight change but a strong variability between individuals. A huge difference was found in the pairwise comparison of the plants analyzed in different years. The high scent variability can be interpreted as a strategy of a non-rewarding but allogamous species to not allow the learning by pollinators. In fact, disrupting the association among floral scent signals with the lack of nectar may enhance the fruit set via a higher probability of being visited by insects.

Aspects of the reproductive biology of Zingiber spectabile (Zingiberaceae)

Ginger (Zingiber spectabile) is cultivated worldwide as a floriculture and landscaping species. Studies on the biology and floral morphology of this species are important for its improvement; however, they are scarce. We investigated the reproductive biology and floral morphology of gingers grown in a germplasm bank. Floral development was monitored during the pre-anthesis and anthesis periods. Floral morphometry, pollen viability, stigmatic receptivity, volume and concentration of nectar sugar, and performance of possible pollinators were evaluated. Ginger flowers had a 24-h durability. Ginger torch is an allogamous species that exhibits floral hercogamy like other Zingiberaceae. Ginger flowers had a 12-h anthesis. During anthesis, floral structures related to reproduction such as the style, stigma, and anther crest continued to develop, increasing floral herkogamy. Pollen viability was above 70% and the stigma remained receptive throughout the anthesis period. Hummingbirds were the only pollinators recorded in the study area that were able to move the anther crest. Fruiting was determined in a natural pollination system. The occurrence of nocturnal anthesis characterized by an increase in the development of reproductive structures and nectar production suggests that the species is adapted to nocturnal visitors.

Floral and reproductive biology of Matisia cordata (fam: malvaceae)

Abstract In Colombia there is a large diversity of promising fruit trees, one of them is Matisia cordata. Sapoti species is appreciated by the consumers, although it is produced in small volumes by traditional productors. The objective of this research is to describe the floral and reproductive biology of sapoti, including floral visitors that act as biotic pollination agents. The study was conducted in two farms, between February/2016 and July/2017. In the first farm, floral buds were marked to follow the stages until fruit formation, pollination mechanism was studied, and floral visitors were collected for identification. In the second farm, flowers were marked to measure the floral nectar production. The duration from floral bud to ripe fruit was 269 days, the 2.7% of the flowers reached the fruit stage. Twenty-five floral visitors were registered, seven of which contacted the sexual whorls, specially Meliponini bees, hummingbirds and bats from Artibeus and Glossophaga genus. M. cordata is a prevalently allogamous species, it attracts diurnal and nocturnal animals, which can contribute to the pollination process. The flowers produced 1.6 ml of nectar with a sugar content from 6.2 to 11 °Brix. The sapoti flowers constitute an abundant and valuable resource for animals from the region.

Study of the efficiency of creeping clover pollination (Trifolium repens L.) by honey bees (Apis mellifera L.)

The creeping clover (Trifolium repens L.) is a natural allotetraploid allogamous species and is characterized by an entomophilic xenogamous pollination method. One of the reasons for the low yield of clover seeds is the insufficient provision of its flowering grass stands with pollinating insects. The main pollinators are representatives of the order of hymenoptera insects (Himenoptera) from the family of true bees (Apidae) – the honey bee Apis mellifera L. and various species of bumblebees (Bombus). Studies have shown that in the conditions of the Central Non-Chernozem region of Russia, the role of bumblebees in the pollination of creeping clover did not exceed 12-13%. In the presence of bumblebees in different growing seasons in the amount of 30-80 to 110-170 indivi-duals/ha during the mass flowering of creeping clover, they -ensured the formation of seed yields of no more than 90 kg/ha. It is established that honey bees perform up to 87-88% of clover pollination. The highest collections of creeping clover seeds are formed at the flight density of bees of 18-21 thousand individuals per hectare. This makes it possible to form a biological clover yield over 720 kg/ha. To ensure such a rich flight of bees, it is necessary to have at least 2-3 strong bee colonies on clover crops.

A method for obtaining flexible broccoli varieties for sustainable agriculture

BackgroundThe use of high inputs in agriculture resulted in few varieties (hybrids and pure lines) used in all agricultural systems. Also varieties of vegetables, including broccoli, for organic and low-input agriculture, are almost exclusively hybrids, since there are very few specific breeding programs and varieties for sustainable agriculture systems.A strategy to overcome this issue is the adoption of specific breeding programs for developing heterogeneous varieties (i.e. synthetics, open pollinated varieties, composite cross populations and mixtures). In fact, heterogeneous varieties are able to evolve and adapt to specific agro-climatic conditions.The aim of this study was to develop a method (an Evolutionary Breeding Program, EBP) for obtaining heterogeneous varieties of broccoli and test its efficiency in developing highly diverse varieties, as needed in sustainable agriculture.A synthetic variety originated from a landrace was multiplied in different environments for 3 cycles and morpho-phenological and genetic diversity of the derived populations were assessed.ResultsThe presented results are the first and unique indication about the efficiency of a short-time EBP for an allogamous species like broccoli.Few morphological changes were observed among varieties multiplied in different environments with different agro-climatic conditions. This could be probably due to the initial genetic diversity of the landrace from which the populations were selected and also to the great plasticity of the crop. However, SSR data highlighted a genetic differentiation among populations multiplied for two/three years across Europe and in Central Italy, that was not so evident when considering morphological data only.ConclusionsFew years of multiplication in different environments resulted in genetically differentiated broccoli populations that nonetheless preserved the original genetic diversity and productivity level and appear to evolve in relationship to different environments: the applied EBP is useful for developing heterogeneous materials for sustainable agriculture.

Morphological and molecular variability of wild diploid and polyploid populations of Chrysolaena flexuosa (Sims) H. Rob.: relevance for ornamental breeding

Chrysolaena flexuosa is a South American species of ornamental interest, whose variability has not been explored. The objective of this work was to perform joint analyses of morphological and molecular traits in seven accessions from its geographic distribution in Argentina: diploid, tetraploid and hexaploid, along an approximately 1400 km transect. To this end, 26 morphological traits were recorded in 10–24 plants/accession, and two combination of AFLP markers were used for molecular characterization. The data was subjected to multivariate and AMOVA analyses, and the genetic diversity among accessions was evaluated by using the Fst index. The multivariate analyses for morphological traits allowed the differentiation of groups that were in accordance with their geographical origin and, thus, their respective ploidies; with the diploids exhibiting smaller-sized organs but higher numbers of leaves and heads. In the AMOVA, differences between accessions according to geographic origin were not significant (p = 0.123), and the highest percentage of the molecular variance corresponded to intra-population variation (88.1%). The Fst index indicated moderate genetic differentiation among accessions (Fst = 0.11), as observed in other allogamous species as a consequence of inter-population gene flow. In turn, the detected variability for morphological traits of interest would allow the use of these accessions in ornamental breeding for cultivar development.

Flowers and climate change: a metabolic perspective.

Adverse climatic conditions at the time of flowering severely hinder crop yields and threaten the interactions between plants and their pollinators. These features depend on a common trait: the metabolism of flowers. In this Viewpoint article, we aim to provide insight into the metabolic changes that occur in flowers in response to changes in climate and emphasize that these changes severely impact the fitness of autogamous and allogamous species, plant-pollinator interactions, and overall ecosystem health. We review the biochemical processes that lead to failure of gamete development and to alterations of color, scent and nectar secretion. Then, making use of open access expression data, we examine the expression of genes that may drive these changes in response to heat and drought. Finally, we present measurements of metabolites from flowers exposed to a heat wave and discuss how the results of this short-term experiment may give rise to misleading conclusions regarding the positive effect of heat on flower fitness. We hope this article draws attention to this often-neglected dynamic and its important consequences.

Genotyping by Sequencing and Plastome Analysis Finds High Genetic Variability and Geographical Structure in Dactylis glomerata L. in Northwest Europe Despite Lack of Ploidy Variation

Large collections of the forage and bioenergy grass Dactylis glomerata were made in northwest (NW) Europe along east to west and north to south clines for genetic resource conservation and to inform breeding programmes of genetic diversity, genepools, and ploidy. Leaves were sampled for genetic analysis and seed and rhizome for ex-situ conservation. Genotyping by sequencing (GBS) was used to assay nuclear DNA diversity and plastome single nucleotide polymorphism (SNP) discovery was undertaken using a long-read PCR and MiSeq approach. Nuclear and plastid SNPs were analysed by principal component analysis (PCA) to compare genotypes. Flow cytometry revealed that all samples were tetraploid, but some genome size variation was recorded. GBS detected an average of approximately 10,000 to 15,000 SNPs per country sampled. The highest average number of private SNPs was recorded in Poland (median ca. 2000). Plastid DNA variation was also high (1466 SNPs, 17 SNPs/kbp). GBS data, and to a lesser extent plastome data, also show that genetic variation is structured geographically in NW Europe with loose clustering matching the country of plant origin. The results reveal extensive genetic diversity and genetic structuring in this versatile allogamous species despite lack of ploidy variation and high levels of human mediated geneflow via planting.

Iterative allogamy-autogamy transitions drive actual and incipient speciation during the ongoing evolutionary radiation within the orchid genus Epipactis (Orchidaceae).

The terrestrial orchid genus Epipactis has become a model system for the study of speciation via transitions from allogamy to autogamy, but close phylogenetic relationships have proven difficult to resolve through Sanger sequencing. We analysed with restriction site-associated sequencing (RAD-seq) 108 plants representing 29 named taxa that together span the genus, focusing on section Epipactis. Our filtered matrix of 12 543 single nucleotide polymorphisms was used to generate an unrooted network and a rooted, well-supported likelihood tree. We further inferred genetic structure through a co-ancestry heat map and admixture analysis, and estimated inbreeding coefficients per sample. The 27 named taxa of the ingroup were resolved as 11 genuine, geographically widespread species: four dominantly allogamous and seven dominantly autogamous. A single comparatively allogamous species, E. helleborine, is the direct ancestor of most of the remaining species, though one of the derived autogams has generated one further autogamous species. An assessment of shared ancestry suggested only sporadic hybridization between the re-circumscribed species. Taxa with the greatest inclination towards autogamy show less, if any, admixture, whereas the gene pools of more allogamous species contain a mixture alleles found in the autogams. This clade is presently undergoing an evolutionary radiation driven by a wide spectrum of genotypic, phenotypic and environmental factors. Epipactis helleborine has also frequently generated many local variants showing inclinations toward autogamy (and occasionally cleistogamy), best viewed as incipient speciation from within the genetic background provided by E. helleborine, which thus becomes an example of a convincingly paraphyletic species. Autogams are often as widespread and ecologically successful as allogams.

Linkage Map of a Gene Controlling Zero Tannins (zt-1) in Faba Bean (Vicia faba L.) with SSR and ISSR Markers

Faba bean (Vicia faba L.), a partially allogamous species, is rich in protein. Condensed tannins limit the use of faba beans as food and feed. Two recessive genes, zt-1 and zt-2, control the zero tannin content in faba bean and promote a white flower phenotype. To determine the inheritance and develop a linkage map for the zt-1 gene in the faba bean germplasm M3290, F2 and F3 progenies were derived from the purple flower and high tannin content genotypes Qinghai12 and zt-1 line M3290, respectively. Genetic analysis verified a single recessive gene for zero tannin content and flower colour. In total, 596 SSR markers and 100 ISSR markers were used to test the polymorphisms between the parents and bulks for the contrasting flower colour via Bulked Segregant Analysis (BSA). Subsequently, six SSR markers and seven ISSR markers were used to genotype the entire 413 F2 population. Linkage analysis showed that the zt-1 gene was closely linked to the SSR markers SSR84 and M78, with genetic distances of 2.9 and 5.8 cM, respectively. The two flanked SSR markers were used to test 34 faba bean genotypes with different flower colours. The closely linked SSR marker SSR84 predicted the zt-1 genotypes with absolute accuracy. The results from the marker-assisted selection (MAS) from this study could provide a solid foundation for further faba bean breeding programmes.

Determination of compatibility relationships between olive cultivars: an overview of available methods

Olive (Olea europaea L.) is a wind-pollinated, preferentially allogamous species. However, inconsistent results are often reported for the classification of some cultivars as either self-compatible or self-incompatible, probably because of the influence of management and environmental conditions during bloom. Cross- pollination significantly enhances fertilization and fruit set in most olive cultivars. However, this improvement partly depends on the compatibility relationships between recipient and pollinizer trees in the species, where a few cases of cross- incompatibility have been reported recently. Different methods have been used to evaluate the success and inter-compatibility in pollination assays. The most common method for the determination of inter-compatibility is based on the observation of pollen-pistil interactions in cross-pollination trials. This method requires the usage of pollination bags to prevent the access of unwanted pollen grains to the stigmas of recipient flowers and the subsequent observation of pollen-pistil interaction features (pollen adhesion, pollen germination, pollen tube growth in the pistil and fertilization) and/or initial and final fruit set in response to experimental crosses. Lately, simple sequence repeats (SSRs) or microsatellites are increasingly becoming the markers of choice for paternity analysis of seeds to measure the success of crosses, especially when potential pollen donors are multiple and not applied by hand. SSRs offer a reliable way to test the paternity of seeds by checking the presence of parental alleles in the progenies. Knowledge of self-compatibility and cross-compatibility relationships of olive cultivars is a vital factor in the success of olive crosses and, therefore, of breeding programs. The advantages and drawbacks of the different methods to evaluate compatibility relationships within and between olive cultivars are presented in this work.

Effect of thermal shock in the development of androgenic plants of Anemone coronaria L.: influence of genotype and flower parameters

Anemone is an allogamous species marketed as a cut flower. Pure lines formation in this species is expensive and inefficient because progeny suffers from inbreeding depression. Pure lines obtained from plant anthers are a widely used material to produce new hybrids in short time. The aim of this study is the optimization of production of A. coronaria androgenic plants. Flower buds of eight cultivars were measured, disinfected for 20′ in 1% sodium hypochlorite and rinsed with distilled sterile water. Development stage of microspores and their size were evaluated. Anthers were distributed in Petri plates containing a double layer constituted of Nitsch and Nitsch agarized substrate enriched with activated charcoal (1%) and with or without sucrose (3%) and the same substrate in liquid phase without activated charcoal. Anthers were shocked with a preculture at 5 or 33 °C for 5 days and then incubated in the dark at 23 °C. After 21 weeks, the number of regenerants was counted. Plants were transferred into the flask with modified MS substrate and placed at 18 °C. After 3 months of in vitro culture, the survival rate of plants was evaluated. Among the varieties, significant differences in anther number, microspore size, and presence of abnormal microspores were observed. Heat shock pretreatment at 33 °C increases the number and survival of embryos and plants, but the varieties respond to the thermal shock in different ways. The influence of genotype and the maturation phase of flower buds, anthers and microspores are discussed related to the androgenic plant development.

Development of transgenic male-sterile rice by using anther-specific promoters identified by comprehensive screening of the gene expression profile database 'RiceXPro'.

Because genomic selection is designed for the population breeding of allogamous species, a successive outcrossing system is required for efficient use of genomic selection in autogamous crops, such as Oryza sativa L. (rice). Transgenic and dominant male-sterility is a suitable tool for efficient outcrossing of autogamous crops. Though there have been some reports of dominant male-sterile rice developed using transgenic technology, the flowering habit was substandard. Here, to isolate promoters that, when linked to a lethal gene, induce dominant male-sterility while retaining a good flowering habit, we identified 38 candidate genes with anther-specific expression by using the ‘RiceXPro’ database. We then evaluated the abilities of the near-upstream regions of these genes to induce male-sterility when linked to the lethal gene barnase and introduced into the rice cultivar ‘Nipponbare’. Seven of the 38 promoters induced clear dominant male-sterility; promoters expressed in the later stage of anther development induced male-sterility while retaining better flowering habits when compared to ones expressed in the early stage. These seven promoters could potentially be used to facilitate development of an efficient outcross-based breeding system in rice.