Multiple Flowering Research Articles

RNA sequencing analysis of Cymbidium goeringii identifies floral scent biosynthesis related genes

BackgroundCymbidium goeringii belongs to the Orchidaceae, which is one of the most abundant angiosperm families. Cymbidium goeringii consist with high economic value and characteristics include fragrance and multiple flower colors. Floral scent is one of the important strategies for ensuring fertilization. However, limited genetic data is available in this non-model plant, and little known about the molecular mechanism responsible for floral scent in this orchid. Transcriptome and expression profiling data are needed to identify genes and better understand the biological mechanisms of floral scents in this species. Present transcriptomic data provides basic information on the genes and enzymes related to and pathways involved in flower secondary metabolism in this plant.ResultsIn this study, RNA sequencing analyses were performed to identify changes in gene expression and biological pathways related scent metabolism. Three cDNA libraries were obtained from three developmental floral stages: closed bud, half flowering stage and full flowering stage. Using Illumina technique 159,616,374 clean reads were obtained and were assembled into 85,868 final unigenes (average length 1194 nt), 33.85% of which were annotated in the NCBI non redundant protein database. Among this unigenes 36,082 were assigned to gene ontology and 23,164 were combined with COG groups. Total 33,417 unigenes were assigned in 127 pathways according to the Kyoto Encyclopedia of Genes and Genomes pathway database. According these transcriptomic data we identified number of candidates genes which differentially expressed in different developmental stages of flower related to fragrance biosynthesis. In q-RT-PCR most of the fragrance related genes highly expressed in half flowering stage.ConclusionsRNA-seq and DEG data provided comprehensive gene expression information at the transcriptional level that could be facilitate the molecular mechanisms of floral biosynthesis pathways in three developmental phase’s flowers in Cymbidium goeringii, moreover providing useful information for further analysis on C. goeringii, and other plants of genus Cymbidium.

Two Y-chromosome-encoded genes determine sex in kiwifruit

Dioecy, the presence of male and female individuals, has evolved independently in multiple flowering plant lineages1-3. Although theoretical models for the evolution of dioecy, such as the 'two-mutations' model, are well established4,5, little is known about the specific genes determining sex and their evolutionary history3. Kiwifruit, a major tree crop consumed worldwide, is a dioecious species. In kiwifruit we previously identified a Y-encoded sex-determinant candidate gene acting as the suppressor of feminization (SuF), named Shy Girl (SyGI)6. Here, we identify a second Y-encoded sex-determinant that we named Friendly Boy (FrBy), which exhibits strong expression in tapetal cells. Gene-editing and complementation analyses in Arabidopsis thaliana and Nicotiana tabacum indicated that FrBy acts for the maintenance of male (M) functions, independently of SyGI, and that these functions are conserved across angiosperm species. We further characterized the genomic architecture of the small (<1 megabase pairs (Mb)) male-specific region of the Y chromosome (MSY), which harbours only two genes expressed extensively in developing gynoecia and androecia, respectively: SyGI and FrBy. Re-sequencing of the genome of a natural hermaphrodite kiwifruit revealed that this individual is genetically male but carries deletion(s) of parts of the Y chromosome, including SyGI. Additionally, expression of FrBy in female kiwifruit resulted in hermaphrodite plants. These results clearly indicate that Y-encoded SyGI and FrBy act independently as the SuF and M factors in kiwifruit, respectively, and provide insight into not only the evolutionary path leading to a two-factor sex-determination system, but also a new breeding approach for dioecious species.

Phenological and reproductive traits and their response to environmental variation differ among native and invasive grasses in a Neotropical savanna

Phenology is a key component of the life-history of plants, and non-native plant species with distinctive phenological traits may have an advantage over native species. In tropical savannas, water and light availability are often spatially and temporally heterogeneous, so that non-native species capable of changing their phenology in response to these factors are more likely to succeed in these ecosystems. We compared flowering onset and flowering period among African and native grasses in a Brazilian Neotropical savanna and assessed if these traits and the production of flowering tillers differ between two consecutive years and respond to spatial heterogeneity in water table depth and canopy closure. Non-native species showed multiple flowering patterns; Urochloa decumbens flowered from the mid-rainy season to the mid-dry season, Melinis minutiflora flowered during the dry season and Mepens repens flowered throughout the year. In addition, they were responsive to annual and abiotic variation, as U. decumbens also showed longer flowering period and produced more flowering tillers in the second year, except over shallow groundwater and high canopy closure, whereas M. minutiflora produced fewer flowering tillers under high canopy closure and M. repens showed large reproductive decline in the second year. Native grasses flowered in the middle of the rainy season regardless of annual and abiotic variation, although in the second year one species produced more flowering tillers in seasonally flooded sites. The phenology of M. repens is consistent with a ruderal life-history, so that it is only likely to become dominant under repeated disturbances. By contrast, the ability of changing flowering period and reproductive output according to growing conditions showed by U. decumbens and the distinct flowering timing showed by M. minutiflora may favour these species over less plastic native grasses, suggesting that phenological attributes contribute to the dominance of African grasses in Neotropical savannas.

Genome-wide identification of GhAAI genes reveals that GhAAI66 triggers a phase transition to induce early flowering.

Plants undergo a phase transition from vegetative to reproductive development that triggers floral induction. Genes containing an AAI (α-amylase inhibitor) domain form a large gene family, but there have been no comprehensive analyses of this gene family in any plant species. Here, we identified 336 AAI genes from nine plant species including122 AAI genes in cotton (Gossypium hirsutum). The AAI gene family has evolutionarily conserved amino acid residues throughout the plant kingdom. Phylogenetic analysis classified AAI genes into five major clades with significant polyploidization and showing effects of genome duplication. Our study identified 42 paralogous and 216 orthologous gene pairs resulting from segmental and whole-genome duplication, respectively, demonstrating significant contributions of gene duplication to expansion of the cotton AAI gene family. Further, GhAAI66 was preferentially expressed in flower tissue and as responses to phytohormone treatments. Ectopic expression of GhAAI66 in Arabidopsis and silencing in cotton revealed that GhAAI66 triggers a phase transition to induce early flowering. Further, GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis of RNA sequencing data and qRT-PCR (quantitative reverse transcription-PCR) analysis indicated that GhAAI66 integrates multiple flower signaling pathways including gibberellin, jasmonic acid, and floral integrators to trigger an early flowering cascade in Arabidopsis. Therefore, characterization of the AAI family provides invaluable insights for improving cotton breeding.

How floral displays affect geitonogamy in an upward foraging bumblebee‐pollinated protandrous plant

AbstractReducing geitonogamy (pollen transfer among flowers within the same plant) has been suggested as a major selective force for plants with multiple flowers. The occurrence of geitonogamy is generally different among flowers within inflorescences; however, no researchers have examined whether plants enlarge their display size without increasing the possibility of geitonogamy by presenting more flowers at positions where they are less likely to be geitonogamously pollinated. We observed that bumblebee pollinators foraged upward within the tower‐shaped inflorescences of protandrous Megacodon stylophorus (C. B. Clarke) Harry Sm. Because M. stylophorus did not strictly bloom bottom‐up, there were substantial frequencies of geitonogamous pollination resulting from upward and horizontal pollen transfer. Although there was a strong correlation between total numbers of flowers plants produced and numbers of flowers presented on single days, proportions of flowers possibly geitonogamously pollinated were weakly correlated with total numbers of flowers. This might have been because plants with more resources enlarged their display size by producing more flowers on lower floors where flowers had a low probability of being geitonogamously pollinated. This study shows that the tower‐shaped inflorescences of M. stylophorus enlarge their size without more cost of geitonogamous mating, suggesting that geitonogamy acts as an important selective agent in the evolution of inflorescence architectures.

Morphological characterization of interspecific lily hybrids with multiple flower stalks derived from Lilium concolor Salisb. var. mutsuanum Makino

Lilium concolor Salisb. var. mutsuanum Makino can produce multiple flower stalks from the same bulb, and our ultimate goal is to develop new lily cultivars with this unique trait. Interspecific crosses of L. concolor var. mutsuanum and the Asiatic lily hybrid 'Avignon' were carried out with intrastylar pollination and ovule culture, and 49 hybrid strains were acquired. In this study, morphological characterization of the flowering of 46 hybrid strains was performed in the third year after acclimation. Fifteen hybrid strains produced one stalk per bulb, 10 hybrid strains produced two stalks per bulb and five hybrid strains produced three stalks per bulb, and the strains with the most stalks per bulb had nine stalks. The hybrid strains with a large number of stalks per bulb had lower plant height, thinner stalks, and fewer flowers per stalk. There was no significant correlation between the number of stalks per bulb and the number of flowers per bulb or flower diameter. The average flower diameter was approximately 10 cm. A positive correlation was found between the stalk diameter and number of flowers per stalk; the thicker the stalk, the more flowers set.

Metabolome and Transcriptome Sequencing Analysis Reveals Anthocyanin Metabolism in Pink Flowers of Anthocyanin-Rich Tea (Camellia sinensis).

Almost all flowers of the tea plant (Camellia sinensis) are white, which has caused few researchers to pay attention to anthocyanin accumulation and color changing in tea flowers. A new purple-leaf cultivar, Baitang purple tea (BTP) was discovered in the Baitang Mountains of Guangdong, whose flowers are naturally pink, and can provide an opportunity to understand anthocyanin metabolic networks and flower color development in tea flowers. In the present study, twelve anthocyanin components were identified in the pink tea flowers, namely cyanidin O-syringic acid, petunidin 3-O-glucoside, pelargonidin 3-O-beta-d-glucoside, which marks the first time these compounds have been found in the tea flowers. The presence of these anthocyanins seem most likely to be the reason for the pink coloration of the flowers. Twenty-one differentially expressed genes (DEGs) involved in anthocyanin pathway were identified using KEGG pathway functional enrichment, and ten of these DEG’s screened using venn and KEGG functional enrichment analysis during five subsequent stages of flower development. By comparing DEGs and their expression levels across multiple flower development stages, we found that anthocyanin biosynthesis and accumulation in BTP flowers mainly occurred between the third and fourth stages (BTP3 to BTP4). Particularly, during the period of peak anthocyanin synthesis 17 structural genes were upregulated, and four structural genes were downregulated only. Ultimately, eight critical genes were identified using weighted gene co-expression network analysis (WGCNA), which were found to have direct impact on biosynthesis and accumulation of three flavonoid compounds, namely cyanidin 3-O-glucoside, petunidin 3-O-glucoside and epicatechin gallate. These results provide useful information about the molecular mechanisms of coloration in rare pink tea flower of anthocyanin-rich tea, enriching the gene resource and guiding further research on anthocyanin accumulation in purple tea.

Floral plasticity: Herbivore-species-specific-induced changes in flower traits with contrasting effects on pollinator visitation.

Plant phenotypic plasticity in response to antagonists can affect other community members such as mutualists, conferring potential ecological costs associated with inducible plant defence. For flowering plants, induction of defences to deal with herbivores can lead to disruption of plant–pollinator interactions. Current knowledge on the full extent of herbivore‐induced changes in flower traits is limited, and we know little about specificity of induction of flower traits and specificity of effect on flower visitors. We exposed flowering Brassica nigra plants to six insect herbivore species and recorded changes in flower traits (flower abundance, morphology, colour, volatile emission, nectar quantity, and pollen quantity and size) and the behaviour of two pollinating insects. Our results show that herbivory can affect multiple flower traits and pollinator behaviour. Most plastic floral traits were flower morphology, colour, the composition of the volatile blend, and nectar production. Herbivore‐induced changes in flower traits resulted in positive, negative, or neutral effects on pollinator behaviour. Effects on flower traits and pollinator behaviour were herbivore species‐specific. Flowers show extensive plasticity in response to antagonist herbivores, with contrasting effects on mutualist pollinators. Antagonists can potentially act as agents of selection on flower traits and plant reproduction via plant‐mediated interactions with mutualists.

Construction of a high density genetic map of an interspecific cross of Capsicum chinense and Capsicum annuum and QTL analysis of floral traits

The yield of pepper plants (Capsicum spp.) is their most important trait and is affected by the flower number and flowering time. Capsicum annuum produces a single flower per node and has an early flowering habit. By contrast, Capsicum chinense yields multiple flowers per node and has a late flowering character. However, the genetic mechanism underlying the control of these floral traits remains largely unknown. In this study, 150 F2 populations from an interspecific cross between the inbred lines 740 (C. chinense) and CA1 (C. annuum) and their parents were used to construct a molecular genetic linkage map using the specific length amplified fragment sequencing (SLAF-seq) technique. This linkage map, spanning 1,586.78 cM in length, contained 9,038 markers on 12 chromosomes, with a mean marker distance of 0.18 cM. Phenotypic data on the flowering time and flower number per node were collected over multiple years, and QTL analysis identified 6 QTLs for the flowering time and flower number per node by composite interval mapping (CIM) and genome-wide composite interval mapping (GCIM) methods at least in two environments. The candidate genes within the major QTL were predicted. In the major flowering time QTL, the candidate gene Capana02g000700, which encodes the homeotic protein APETALA2, was identified. Quantitative reverse-transcription PCR (qRT-PCR) analysis indicated that its expression level in 740 was higher than that in CA1. Gene expression analysis indicated that the expression of Capana02g000700 was significantly upregulated in flowers, and many floral development-related genes were found to be coexpressed with Capana02g000700, supporting the function of this gene in association with flowering time in C. chinense and C. annuum species.

Synthesis of Hybrid Nanoflower-Based Carbonic Anhydrase for Enhanced Biocatalytic Activity and Stability

Carbonic anhydrase (CA) has great potential for CO2 capture; however, the application of CA is still a challenge due to its difficult recovery, low operational stability, and poor reusability. This paper reports the synthesis of hybrid nanoflowers (M–CANFs) by self-assembly of CA and metal phosphates. Mn–CANFs were first discovered in this work although their performance is not excellent, and the performance of M–CANFs formed by different metal phosphates was compared in detail. The results of catalyzing p-nitrophenyl acetate (p-NPA) hydrolysis showed that Ca–CANFs exhibited ca. 286% enhancement of catalytic activity. The stability, reusability, and thermal stability of M–CANFs had enhanced remarkably. The newly formed flowerlike hybrid nanostructures presented multiple flower morphology with great biocatalytic activity and stability enhancement by cycle analysis. The excellent performances are meaningful for biology, catalysis science, and nanomaterials science.

RIGIOLEPIS AND VACCINIUM (ERICACEAE) IN BORNEO

Rigiolepis and Vaccinium of Borneo are revised, and their characteristics are discussed. Brief comments on distinguishing Vaccinium and Rigiolepis from related genera in the Ericaceae are made. Vaccinium sect. Bracteata is now considered the only section of Vaccinium occurring in Borneo. The chief reason for reinstating Rigiolepis as a genus is the distinctive 10-locular ovary whose structure has been overlooked in recent studies, while the supporting characters of multiple axillary flower buds, flower size, anther shape and fruit colour provide for easy recognition. New keys are provided to all 42 species, and all accepted taxa are described. Ten taxa are new to science and 17 new combinations are made. An addendum gives the combinations to be used for the two species of Rigiolepis presently known to occur outside Borneo.

Molecular genomic investigations on floral induction using soybean as a model system

Soybean is a major legume crop used for human and animal consumption. The flowering process controls seed set and hence directly affects the productivity of a crop plant. Soybean is a photoperiod sensitive plant whose floral transition is initiated by exposure to short-day conditions. Our knowledge on key molecular regulators of flower initiation in legumes such as soybean is limited. This review gives an overview of the underlying molecular pathways and epigenetic mechanisms that take place during soybean flowering. Comparative genomic and transcriptomic tools have revealed the molecular dynamics during soybean flowering. Multiple flowering gene isoforms and hence allelic variations in soybean are evident. However, understanding how these genetic variations are coordinated at the molecular and physiological level within the plant is lacking. A functional approach to determine the divergent functions of the flowering inducing genes in soybean is essential to understand how crop plants adapt to diverse internal and external environments.

Consequences of multiple flower-insect interactions for subsequent plant-insect interactions and plant reproduction.

Plants often interact simultaneously with multiple antagonists and mutualists that can alter plant traits at the phenotypic or genetic level, subsequent plant-insect interactions, and reproduction. Although many studies have examined the effects of single floral antagonisms on subsequent pollination and plant reproduction, we know very little about the combined, potentially non-additive effects of multiple flower-insect interactions. We simulated increased florivory, nectar robbing, and pollination on field-grown Impatiens capensis, which allowed us to determine interactive effects on five subsequent plant-insect interactions and 16 plant traits, including traits related to plant growth, floral attractiveness, floral defenses, and plant reproduction. All three manipulative treatments had significant non-additive effects on the behavior of subsequent floral visitors, indicating that the effect of floral visitors generally depended on the presence or behavior of others. Pollination increased visitation by both pollinators and nectar larcenists (robbers and thieves), while florivory reduced pollinator and larcenist visits. Surprisingly, supplemental pollination also increased leaf herbivory. Florivores often responded to manipulations in opposite ways than did nectar larcenists and pollinators, suggesting different mechanisms influencing visitors that consume nectar compared to floral tissue. While our treatments did not affect any floral trait measured, they non-additively impacted plant reproduction, with florivory having a larger overall impact than either nectar robbing or pollination. These results emphasize the importance of understanding the context in which flower-insect interactions occur because the composition of the interacting community can have large and non-additive impacts on subsequent insect behavior and plant reproduction.

Mating systems and avoidance of inbreeding depression as evolutionary drivers of pollen limitation in animal-pollinated self-compatible plants.

Most theory addressing the evolution of pollen limitation in flowering plants focuses on stochasticity in the relative abundance of plant and pollinator populations affecting trade-offs in resource allocation to ovule production or pollinator attraction vs. seed maturation. Mating system evolution is an underappreciated but potentially widespread additional mechanism for the evolutionary emergence of pollen limitation in animal-pollinated self-compatible plants. We model individual plant flowering phenologies influencing both pollinator attraction and geitonogamous self-fertilization caused by pollinator movements among flowers within plants, incorporating demographic but not environmental stochasticity. Plant phenology and the resulting pollen limitation are analysed at evolutionarily stable equilibria (ESS). Pollen limitation is measured by two quantities: the proportion of unpollinated flowers and the reduction in maternal fitness caused by inbreeding depression in selfed seeds. When pollinators visit multiple flowers per plant, pollen limitation is never minimized at an ESS and results from the evolution of flowering phenologies balancing the amount and genetic composition (outbred vs. inbred) of pollen receipt. Results are consistent with previous theory demonstrating that pollen limitation can be an evolved property, not just a constraint; they complement existing models by showing that plant avoidance of inbreeding depression constitutes a genetic mechanism contributing to evolution of pollen limitation, in addition to ecological mechanisms previously studied.

Mating consequences of contrasting hermaphroditic plant sexual systems.

For hermaphroditic angiosperms with multiple flowers, the sex roles can be exclusively combined in bisexual flowers (monocliny), strictly separated among different flowers (monoecy), or arrayed in mixtures of bisexual flowers with female flowers (gynomonoecy) or male flowers (andromonoecy). The hypothesized benefits favoring the evolution of these contrasting hermaphroditic sexual systems are typically examined individually, usually by assessing success through only one sex role. We tested predictions of most hypotheses experimentally with an andromonoecious species, Anticlea occidentalis (Melanthiaceae), based on the performance of intact plants (andromonoecy) and those with emasculated bisexual flowers (functionally monoecious) or emasculated male flowers (functionally monoclinous with sterile peripheral flowers). Andromonoecy in this species enables efficient, size-dependent resource allocation, emphasizing female function in large plants. Emasculation revealed that anthers in male flowers promote female mating quality (outcrossing rate and mate diversity), whereas anthers in bisexual flowers promote male mating quantity (pollen dispersal distance and probability of any siring success). Thus, different hermaphroditic sexual systems likely evolve to capitalize on suites of benefits, rather than just one, and provide compromises between quantitative and qualitative reproductive components. These compromises apparently maximize an individual's combined genetic contributions through female and male functions, rather than separate contributions through each sex role.

Development and characterization of penta-flowering and triple-flowering genotypes in garden pea (Pisum sativum L. var. hortense).

This study reports the development of a garden pea genotype ‘VRPM–901–5’ producing five flowers per peduncle at multiple flowering nodes, by using single plant selection approach from a cross ‘VL-8 × PC-531’. In addition, five other stable genetic stocks, namely VRPM-501, VRPM–502, VRPM–503, VRPM–901–3 and VRPSeL–1 producing three flowers per peduncle at multiple flowering nodes were also developed. All these unique genotypes were of either mid- or late- maturity groups. Furthermore, these multi-flowering genotypes were identified during later generations (F4 onward), which might be because of fixation of certain QTLs or recessive gene combinations. Surprisingly, a common parent PC–531, imparting multi-flowering trait in ten cross combinations was identified. Thus, the genotype PC–531 seems to harbor some recessive gene(s) or QTLs that in certain combination(s) express the multi-flowering trait. The interaction between genotype and environment showed that temperature (11–20°C) plays a key role in expression of the multi-flowering trait besides genetic background. Furthermore, the possible relationship between various multi-flowering regulatory genes such as FN, FNA, NEPTUNE, SN, DNE, HR and environmental factors was also explored, and a comprehensive model explaining the multi-flowering trait in garden pea is proposed.

Tailored Robust Hydrogel Composite Membranes for Continuous Protein Crystallization with Ultrahigh Morphology Selectivity.

The tailored and robust hydrogel composite membranes (HCMs) with diverse ion adsorption and interfacial nucleation property are prepared and successfully used in the continuous lysozyme crystallization. Beyond the heterogeneous supporter, the HCMs functioning as an interface ion concentration controller and nucleation generator are demonstrated. By constructing accurately controlled nucleation and growth circumstances in the HCM-equipped membrane crystallizer, the target desired morphology (hexagon cube) and brand-new morphology (multiple flower shape) that differ from the ones created in the conventional crystallizer are continuously and repetitively generated with ultrahigh morphology selectivity. These tailored robust HCMs show great potential for improving current approaches to continuous protein crystallization with specific crystal targets from laboratorial research to actual engineering applications.

Flower heads in Asteraceae\u2014recruitment of conserved developmental regulators to control the flower-like inflorescence architecture

Inflorescences in the Asteraceae plant family, flower heads, or capitula, mimic single flowers but are highly compressed structures composed of multiple flowers. This transference of a flower-like appearance into an inflorescence level is considered as the key innovation for the rapid tribal radiation of Asteraceae. Recent molecular data indicate that Asteraceae flower heads resemble single flowers not only morphologically but also at molecular level. We summarize this data giving examples of how rewiring of conserved floral regulators have led to evolution of morphological innovations in Asteraceae. Functional diversification of the highly conserved flower meristem identity regulator LEAFY has shown a major role in the evolution of the capitulum architecture. Furthermore, gene duplication and subsequent sub- and neofunctionalization of SEPALLATA- and CYCLOIDEA-like genes in Asteraceae have been shown to contribute to meristem determinacy, as well as flower type differentiation—key traits that specify this large family. Future challenge is to integrate genomic, as well as evolutionary developmental studies in a wider selection of Asteraceae species to understand the detailed gene regulatory networks behind the elaborate inflorescence architecture, and to promote our understanding of how changes in regulatory mechanisms shape development.

The early inflorescence of Arabidopsis thaliana demonstrates positional effects in floral organ growth and meristem patterning

Key messageLinear modelling approaches detected significant gradients in organ growth and patterning across early flowers of the Arabidopsis inflorescence and uncovered evidence of new roles for gibberellin in floral development.Most flowering plants, including the genetic model Arabidopsis thaliana, produce multiple flowers in sequence from a reproductive shoot apex to form a flower spike (inflorescence). The development of individual flowers on an Arabidopsis inflorescence has typically been considered as highly stereotypical and uniform, but this assumption is contradicted by the existence of mutants with phenotypes visible in early flowers only. This phenomenon is demonstrated by mutants partially impaired in the biosynthesis of the phytohormone gibberellin (GA), in which floral organ growth is retarded in the first flowers to be produced but has recovered spontaneously by the 10th flower. We presently lack systematic data from multiple flowers across the Arabidopsis inflorescence to explain such changes. Using mutants of the GA 20-OXIDASE (GA20ox) GA biosynthesis gene family to manipulate endogenous GA levels, we investigated the dynamics of changing floral organ growth across the early Arabidopsis inflorescence (flowers 1–10). Modelling of floral organ lengths identified a significant, GA-independent gradient of increasing stamen length relative to the pistil in the wild-type inflorescence that was separable from other, GA-dependent effects. It was also found that the first flowers exhibited unstable organ patterning in contrast to later flowers and that this instability was prolonged by exogenous GA treatment. These findings indicate that the development of individual flowers is influenced by hitherto unknown factors acting across the inflorescence and also suggest novel functions for GA in floral patterning.

Genetic basis of the very short life cycle of \u2018Apogee\u2019 wheat

Background‘Apogee’ has a very short life cycle among wheat cultivars (flowering 25 days after planting under a long day and without vernalization), and it is a unique genetic material that can be used to accelerate cycling breeding lines. However, little is known about the genetic basis of the super-short life of Apogee wheat.ResultsIn this study, Apogee was crossed with a strong winter wheat cultivar ‘Overland’, and 858 F2 plants were generated and tested in a greenhouse under constant warm temperature and long days. Apogee wheat was found to have the early alleles for four flowering time genes, which were ranked in the order of vrn-A1 > VRN-B1 > vrn-D3 > PPD-D1 according to their effect intensity. All these Apogee alleles for early flowering showed complete or partial dominance effects in the F2 population. Surprisingly, Apogee was found to have the same alleles at vrn-A1a and vrn-D3a for early flowering as observed in winter wheat cultivar ‘Jagger.’ It was also found that the vrn-A1a gene was epistatic to VRN-B1 and vrn-D3. The dominant vrn-D3a alone was not sufficient to cause the transition from vegetative to reproductive development in winter plants without vernalization but was able to accelerate flowering in those plants that carry the vrn-A1a or Vrn-B1 alleles. The genetic effects of the vernalization and photoperiod genes were validated in Apogee x Overland F3 populations.ConclusionVRN-A1, VRN-B1, VRN-D3, and PPD-D1 are the major genes that enabled Apogee to produce the very short life cycle. This study greatly advanced the molecular understanding of the multiple flowering genes under different genetic backgrounds and provided useful molecular tools that can be used to accelerate winter wheat breeding schemes.