Production Of Viable Seeds Research Articles

FLOWER DEVELOPMENT OF MALE AND FEMALE INFLORESCENCE OF OIL PALM, Elaeis guineensis Jacq.

Oil palm (Elaeis guineensis Jacq.) is monoecious plants that relies on cross pollination to ensure the production of viable seeds and prevent parthenocarpy. Understanding the phenology of Elaeis guineensis flower development enables to optimize the timing of assisted pollination and harvesting. The aim of this study is to describe the development of male and female inflorescence of oil palm, Elaeis guineensis var. Tenera. The frequency of observation of development was daily, starting from pre-anthesis until post-anthesis for female inflorescence and spikelet degradation for male inflorescence. The flower developments were coded according to Biologische Bundesantalt Bundessortenamt und Chemische Industrie (BBCH) scales. The anthesis period for male inflorescence occurs around four to five days. A male inflorescence consists of spikelets that accommodate almost 30% of rachis. Spikelets are full with yellow flowers and contains millions of pollen grains in form of dust particles during anthesis. Spikelet are arranged in spiral around the rachis in one direction and are fully elongated and exposed. The size of spikelet is between 102 mm and 215 mm in length. Female flowers are fully receptive for three to four days where rachillae are elongated and fully exposed. The total number of rachillae cover 36% of rachis length. Each rachilla composes of eight to 25 flowers in a female inflorescence. Anthesis phase of male inflorescence is longer than female inflorescence. The phenological information about inflorescences can be used to enhance the pollination techniques and optimize fruit formation.

Introducción a cultivo de vitroplantas de “Peperina de las Lomas”(Hedeoma multiflora Benth.) como contribución para su conservación ex situ

Hedeoma multifloraBenth. (Lamiaceae) is an aromatic-medicinal species native to Argentina, Uruguay and southern Brazil that is in a state of vulnerability due to overexploitation. It is used in the preparation of flavored yerba mate and in popular medicine, mainly in abdominal conditions. The objective of this work was to adjust the micropropagation technique, study the field behavior of vitroplants, compare the seeds generated and close their cultivation cycle. Different concentrations of growth regulators were evaluated on Murashige-Skoog medium. The implantation was successful. There are no differences between the evaluated plants. It was possible to efficiently close the complete cycle in vitro, with 100% survival, flowering and production of viable seeds. This methodology will serve for its introduction to the field, subsequent domestication, reintroduction into its natural environment and mitigate the process of degradation of the populations.

Choosing the Right Path for the Successful Storage of Seeds

Seeds are the most commonly used source of storage material to preserve the genetic diversity of plants. However, prior to the deposition of seeds in gene banks, several questions need to be addressed. Here, we illustrate the scheme that can be used to ensure that the most optimal conditions are identified to enable the long-term storage of seeds. The main questions that need to be answered pertain to the production of viable seeds by plants, the availability of proper protocols for dormancy alleviation and germination, seed tolerance to desiccation and cold storage at -20 °C. Finally, it is very important to fully understand the capability or lack thereof for seeds or their explants to tolerate cryogenic conditions. The proper storage regimes for orthodox, intermediate and recalcitrant seeds are discussed.

Timing of a plant-herbivore interaction alters plant growth and reproduction.

Phenological shifts have the potential to change species interactions, but relatively few studies have used experimental manipulations to examine the effects of variation in timing of an interspecific interaction across a series of life stages of a species. Although previous experimental studies have examined the consequences of phenological timing in plant-herbivore interactions for both plants and their herbivores, less is known about their effects on subsequent plant reproduction. Here, we conducted an experiment to determine how shifts in the phenological timing of monarch (Danaus plexippus) larval herbivory affected milkweed (Asclepias fascicularis) host plant performance, including effects on growth and subsequent effects on flower and seed pod phenology and production. We found that variation in the timing of herbivory affected both plant growth and reproduction, with measurable effects several weeks to several months after herbivory ended. The timing of herbivory had qualitatively different effects on vegetative and reproductive biomass: early-season herbivory had the strongest effects on plant size, whereas late-season herbivory had the strongest effects on the production of viable seeds. These results show that phenological shifts in herbivory can have persistent and qualitatively different effects on different life stages across the season.

Cyperus iria Weed Growth, Survival, and Fecundity in Response to Varying Weed Emergence Times and Densities in Dry-Seeded Rice Systems

Cyperus iria is amongst the most threatening weeds of rice in Sri Lanka, India, Pakistan, and the Philippines. Broad knowledge about the ecology and fecundity of C. iria is important for its effective management. Field studies were conducted over two seasons (wet (WS) and dry seasons (DS)) to investigate the influence of C. iria populations (40 and 80 plants m−2) on its growth, survival, and fertility, with four emergence times, 3, 15, 30, and 45 d after rice emergence (DARE), during 2013. We postulated that (a) higher plant density of this weed would result in more biomass production and viable seeds per unit area, (b) interference of rice would reduce the biomass production and fecundity of this weed, and (c) delaying weed emergence would lead to downsizing of its percent survival and seed bank enrichment in soil. The results indicated that rice interference decreased C. iria growth and seed production as compared with those of plants established without rice interference. A linear decrease in the percent survival of C. iria without rice and a sigmoid decrease with rice were observed during both seasons. Plant height of C. iria was moderately affected up to 30 DARE, and a significant reduction was observed at 45 DARE. There was a linear relationship between C. iria shoot dry weight and seed number plant −1, across-weed density, seeding rate of rice, and emergence time. C. iria seed production, 1000-seed weight, and seed yield were greater when seedlings emerged simultaneously with the rice crop (3 DARE) than when they emerged late. Under rice weed interference growth, the production of viable seeds was completely stopped at 45 DARE. The delay in the emergence of C. iria up to 45 DARE was unable to produce seed in both seasons. The results of the current studies advocate that the emergence, weed biomass, and seed production of C. iria can be checked by adopting suitable cultural weed management practices, which can impede the emergence of weed relative to rice. These practices, enabling the respective crops to be more competitive, will foster integrated weed management approaches, thus offering a key role in seed detection to the soil seed reservoir or pool by notorious weeds in the field.

Thermal tolerance of purple mud crab, Scylla tranquebarica (Fabricius, 1798), during egg incubation, larval rearing and juveniles’ production

Interest in the production of crustacean aquaculture has focussed primarily on mud crab species; however, mud crab production still relies on wild-caught juveniles due to the low production of viable seeds of mud crab. Thus, the aim of this study was to enhance mass propagation of purple mud crab seed by studying the relation of temperature on growth performance of the early life stage of purple mud crab. Several data such as survival, incubation duration and morphometric measurements were evaluated after temperature was exposed on the egg, larval and crablet stages. For the egg stage, high hatching success (78.95% and 75.00%) was noted within a limited temperature range (28°C and 30°C respectively). Also, significant increment of final egg diameter (0.33 ± 0.05 mm) after the berried crab incubated at 30℃. For larval stage, the highest survival rate was found when the larvae were reared at 30℃ and 31°C with 68.79 ± 2.69 and 66.98 ± 2.63% respectively. The largest morphometric measurements for megalopa (CW: 2.80 ± 0.15 mm) and C1 (CW: 2.86 ± 0.12 mm) were observed at 31℃. The yielded total juvenile at the end of the larval experiment indicated the highest production was obtained for temperature 31°C (1,095 ± 47.3 individuals) followed by 30°C (1,002 ± 84.7 individuals). For the crablet stage, the crablets were able to survive in a wide range of temperatures (26°C–32°C) with >95% survival; however, the temperature 26℃–29°C indicated larger morphometric measurements (CW: 6.24–6.39 mm). In brief, the optimal temperature for egg, larval and crablet stages was recommended within 28℃–30℃, 30℃–31℃ and 26℃–29℃ respectively.

OsCOP1 regulates embryo development and flavonoid biosynthesis in rice (Oryza sativa L.)

Key messageNovel mutations ofOsCOP1 were identified to be responsible for yellowish pericarp and embryolethal phenotype, which revealed that OsCOP1 plays a crucial role in flavonoid biosynthesis andembryogenesis in rice seed.Successful production of viable seeds is a major component of plant life cycles, and seed development is a complex, highly regulated process that affects characteristics such as seed viability and color. In this study, three yellowish-pericarp embryo lethal (yel) mutants, yel-hc, yel-sk, and yel-cc, were produced from three different japonica cultivars of rice (Oryza sativa L). Mutant seeds had yellowish pericarps and exhibited embryonic lethality, with significantly reduced grain size and weight. Morphological aberrations were apparent by 5 days after pollination, with abnormal embryo development and increased flavonoid accumulation observed in the yel mutants. Genetic analysis and mapping revealed that the phenotype of the three yel mutants was controlled by a single recessive gene, LOC_Os02g53140, an ortholog of Arabidopsis thaliana CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1). The yel-hc, yel-sk, and yel-cc mutants carried mutations in the RING finger, coiled-coil, and WD40 repeat domains, respectively, of OsCOP1. CRISPR/Cas9-targeted mutagenesis was used to knock out OsCOP1 by targeting its functional domains, and transgenic seed displayed the yel mutant phenotype. Overexpression of OsCOP1 in a homozygous yel-hc mutant background restored pericarp color, and the aberrant flavonoid accumulation observed in yel-hc mutant was significantly reduced in the embryo and endosperm. These results demonstrate that OsCOP1 is associated with embryo development and flavonoid biosynthesis in rice grains. This study will facilitate a better understanding of the functional roles of OsCOP1 involved in early embryogenesis and flavonoid biosynthesis in rice seeds.

Auxin: Hormonal Signal Required for Seed Development and Dormancy.

The production of viable seeds is a key event in the life cycle of higher plants. Historically, abscisic acid (ABA) and gibberellin (GAs) were considered the main hormones that regulate seed formation. However, auxin has recently emerged as an essential player that modulates, in conjunction with ABA, different cellular processes involved in seed development as well as the induction, regulation and maintenance of primary dormancy (PD). This review examines and discusses the key role of auxin as a signaling molecule that coordinates seed life. The cellular machinery involved in the synthesis and transport of auxin, as well as their cellular and tissue compartmentalization, is crucial for the development of the endosperm and seed-coat. Thus, auxin is an essential compound involved in integuments development, and its transport from endosperm is regulated by AGAMOUS-LIKE62 (AGL62) whose transcript is specifically expressed in the endosperm. In addition, recent biochemical and genetic evidence supports the involvement of auxins in PD. In this process, the participation of the transcriptional regulator ABA INSENSITIVE3 (ABI3) is critical, revealing a cross-talk between auxin and ABA signaling. Future experimental aimed at advancing knowledge of the role of auxins in seed development and PD are also discussed.

Lack of strong selection pressures maintains wide variation in floral traits in a food-deceptive orchid.

Angiosperms vary remarkably in traits such as colour, size and shape of flowers, yet such variation generally tends to be low within species. In deceptive orchids, however, large variation in floral traits has been described, not only between but also within populations. Nonetheless, the factors driving variation in floral traits in deceptive orchids remain largely unclear. To identify determinants of variation in floral traits, we investigated patterns of fruit set and selection gradients in the food-deceptive orchid Orchis purpurea, which typically presents large within-population variation in the colour and size of the flowers. Using long-term data, fruit set was quantified in two populations over 16 consecutive years (2004-2019). Artificial hand pollination was performed to test the hypothesis that fruit set was pollinator-limited and that selfing led to decreased seed set and viability. Annual variation (2016-2019) in selection gradients was calculated for three colour traits (brightness, contrast and the number of spots on the labellum), flower size (spur length, labellum length and width) and plant size (number of flowers, plant height). Fruit set was, on average, low (~12 %) and severely pollinator-limited. Opportunities for selection varied strongly across years, but we found only weak evidence for selection on floral traits. In contrast, there was strong and consistent positive selection on floral display. Selfing led to reduced production of viable seeds and hence severe inbreeding depression (δ = 0.38). Overall, these results demonstrate that the large variation in flower colour and size that is regularly observed in natural O. purpurea populations is maintained by the consistent lack of strong selection pressures on these traits through time.

Dry matter production and nitrogen, phosphorus and potassium uptake in Crotalaria juncea and Crotalaria spectabilis

ABSTRACT There are several benefits in the cultivation of Crotalaria spp., including high levels of biomass production and N accumulation, nutrient cycling and antagonistic activity against some nematodes. However, information on nutritional demand is still scarce for these species. This study aimed to determine the dry matter production and macronutrient uptake in shoots of Crotalaria juncea and Crotalaria spectabilis. Two experiments (one for each species) were carried out in a randomized block design, with three replications, assessing thirteen harvest times for C. juncea and ten for C. spectabilis. After each harvest, the samples were dried, weighed and submitted to laboratory analysis, in order to determine the nutrient contents in different parts of the plant. The nutrient accumulation on the shoots, for both species, occurred in the order K > N > P, being the stem the main organ of nutrient accumulation. Also for both species, the export of nutrients by the grains followed the order N > K > P. The maximum dry matter accumulation occurred at 135 and 104 days after emergence (DAE), respectively for C. juncea and C. spectabilis, while the production of viable seeds, in both species, had already begun at 90 DAE.

Invasion potential of herbaceous ornamental perennials in northern climate conditions

We studied invasion potential of perennial herbaceous ornamental plants in Finland by using their reproduction success as an indicator. Altogether, 220 clones from 166 species were included in the studies. In common gardens, 50% of the species were found to produce seedlings and 75% rhizomes, respectively. Twelve of the clones produced neither seedlings nor rhizomes. Rankings of the invasion potential based on the two reproduction modes did not correlate. The species known for their invasion potential in temperate or cool climates were among the highest ranking seedling producers in the common gardens. In the field experiment, the highest seedling production (73%) was found in the semi-dry moisture regime, followed by the dry (40%) and the moist (27%) regimes. In the greenhouse experiment, 83% of the studied clones and 84% of the species emerged. Temperature sum required for the production of viable seeds for one third of the studied species is reached at least every second year in latitudes 62–63°N. Several perennial herbaceous ornamentals have potential for northward range expansion.

Sexual Reproduction of Kudzu (Pueraria montana [Lour.] Merr.) in Oklahoma

Non-native invasive plants pose major threats to biodiversity across the globe. In the southeastern United States, kudzu ( Pueraria montana [Lour.] Merr.) was introduced as a flowering, ornamental vine. In many areas, it quickly escaped cultivation and has caused major disruption to native ecosystems. Over the past two decades, kudzu has gradually spread north and west, being found as far north as Illinois and Indiana, and as far west as Kansas and Oklahoma. Only recently has the species distribution been thoroughly assessed in Oklahoma, and these studies have found its statewide range to be more extensive than previously thought. As a result of the species being understudied in the region, the reproductive ecology of kudzu in Oklahoma has gone largely unexamined. Our research provides evidence of sexual reproduction at two sites in southeastern Oklahoma. This is the first documentation of germination of kudzu in Oklahoma. While kudzu reproduces primarily through rhizomatous vegetative growth, the production of viable seeds is essential to the maintenance of genetic diversity and is often important at range limits. This research, coupled with further plant demographic research, could provide key details surrounding the potential further spread of kudzu in Oklahoma.

Limonium homoploid and heteroploid intra‐ and interspecific crosses unveil seed anomalies and neopolyploidy related to sexual and/or apomictic reproduction

AbstractApomixis is a form of asexual reproduction that consists in cloning through seeds. In Limonium (Plumbaginaceae) species present a pollen–stigma dimorphism linked to a sporophytic self‐incompatibility system associated with sexual and/or apomictic reproductive modes. Previous work in other genera suggests that the emergence of apomixis is associated with hybridization and/or polyploidy. In this study, our goal was to test the ability of diploid and tetraploid species to hybridize and to evaluate the variate outcomes from these crosses. To achieve this, sexual diploid (L. nydeggeri, L. ovalifolium) and facultative apomict tetraploid (L. binervosum, L. dodartii) plants from cultivated material, previously cytogenetically and reproductively characterized, were used for experimental intra‐ and interspecific crosses. Genome sizes, ploidy levels and morphology were examined in the resulting progenies. Results showed a high production of viable seeds in particular in plants from tetraploid × diploid (heteroploid) crosses. In these crosses, some seedlings exhibited pleiocotyly (tricotyl, tetracotyl), while others showed polyembryony. In both homoploid (diploid × diploid) and heteroploid (tetraploid × diploid) crosses, most of the offspring plants were morphologically and in their ploidy similar to the female receiver, although some morphological abnormalities were found. Molecular progeny tests using the nrDNA ITS1‐ITS2 sequence demonstrated an astounding range of diploid offspring plants originated from diploid × diploid crosses that were either genetically similar or distinct from parental plants. Although in intraspecific crosses most of the resulting progeny was diploid, one triploid plant was formed. Moreover, in homoploid interspecific crosses, neopolyploids (two tetraploid plants) were produced. Progeny plants from heteroploid crosses always showed nrDNA ITS1‐ITS2 sequences identical to the parental plant used as female receiver. In conclusion, diploid homoploid crosses presented genetically diverse offspring arising from sexual reproduction. By contrast, heteroploid crosses generated clonal, maternal (apomictic) offspring.

A variably imprinted epiallele impacts seed development.

The contribution of epigenetic variation to phenotypic variation is unclear. Imprinted genes, because of their strong association with epigenetic modifications, represent an opportunity for the discovery of such phenomena. In mammals and flowering plants, a subset of genes are expressed from only one parental allele in a process called gene imprinting. Imprinting is associated with differential DNA methylation and chromatin modifications between parental alleles. In flowering plants imprinting occurs in a seed tissue - endosperm. Proper endosperm development is essential for the production of viable seeds. We previously showed that in Arabidopsis thaliana intraspecific imprinting variation is correlated with naturally occurring DNA methylation polymorphisms. Here, we investigated the mechanisms and function of allele-specific imprinting of the class IV homeodomain leucine zipper (HD-ZIP) transcription factor HDG3. In imprinted strains, HDG3 is expressed primarily from the methylated paternally inherited allele. We manipulated the methylation state of endogenous HDG3 in a non-imprinted strain and demonstrated that methylation of a proximal transposable element is sufficient to promote HDG3 expression and imprinting. Gain of HDG3 imprinting was associated with earlier endosperm cellularization and changes in seed weight. These results indicate that epigenetic variation alone is sufficient to explain imprinting variation and demonstrate that epialleles can underlie variation in seed development phenotypes.

Endogamy costs and reproductive biology of Laelia autumnalis, an endemic orchid of Mexico

It has been hypothesized that the fitness of selfed progeny must be lowered by inbreeding depression. Most research into the breeding systems of orchids shows a similar fruit set from outcrossing and self-pollination, but few studies have measured seed production and viability. In five populations of Laelia autumnalis, in central Mexico, we studied the species reproductive system and the early costs of endogamy. We performed spontaneous self-pollination, apomixis, assisted self-pollination, cross-pollination, and exogamous pollination (using pollen from a different population) treatments of bagged flowers and measured fruit set, seed production, and germination. No fruits were produced in the apomixis and spontaneous self-pollination treatments. Reproductive success from self-pollination was lower than that from cross- and exogamous pollination and no difference was found between the latter two treatments. The ratio between self-pollination and cross-pollination success in different traits ranged from 0.80 ± 0.18 (fruit set) to 0.22 ± 0.13 (seeds with embryo). The latter value suggests a high endogamy costs in the production of viable seeds. The concatenated success of the different traits studied showed that the relative fitness of self-pollination was 63% lower than with cross-pollination. Laelia autumnalis is a self-compatible non-autogamous species in which the cost of endogamy occurs at seed production and cannot be compensated for at other early stages. This also occurs in other orchid species and is likely to be a general pattern.

Producción de frutos de Gleditsia amorphoides (Griseb.) Taub. (Fabaceae) y abundancia de Bruchidius endotubercularis Arora (Coleoptera: Chrysomelidae) durante tres años consecutivos en el SE de la provincia de Formosa (Argentina)

Gleditsia amorphoides (Griseb.) Taub. is a tree species native to South America. It is known for its good quality wood and for its fruits that contain a rubber for industrial uses. One of the causes for the reduction of the production of viable seeds in forest trees is the damage caused by predators of fruits and seeds. The relationship between fruit production and predators is not known for G. amorphoides. Therefore, in this study, we evaluated the fruit production in this three species and the abundance of specimens of the Subfamily Bruchinae associated to G. amorphoides. The study was carried out in three localities of the Formosa Province in the Northeast of Argentina for three consecutive years. We found a single species of Bruchinae, identified as Bruchidius endotubercularis Arora. The results showed the existence of variability in the production of G. amorphoides fruits between years, but not between locations. The abundance of insects remained constant, not responding to the variation in the production of fruits between years. In this study, we report for the first time, the occurrence of B. endotubercularis associated with G. amorphoides in Argentina

Floral and reproductive biology of Alcantarea nahoumii (Bromeliaceae), a vulnerable endemic species of the Atlantic Forest

Alcantarea nahoumii occurs exclusively in the state of Bahia, Brazil, and is classified as vulnerable due to deforestation and frequent fires in the region. Knowledge of floral and reproductive biology is fundamental to understanding ecological interactions, as well as the reproductive success of plant species. The objective of this study was to evaluate the floral and reproductive biology of A. nahoumii in an Atlantic Forest fragment with regard to phenology, pollen viability, stigma receptivity, pollination ecology and reproductive systems, all of which are important parameters for of the development of conservation strategies for the species. Anthesis is diurnal and heterogeneous, starting at 6:30 a.m. and lasting until 8:00 a.m. Highest germination percentages and greatest pollen tube lengths were obtained in BK culture medium. Histochemical tests revealed high pollen viability (89.71 %). Stigma receptivity occurred during anthesis and lasted for up to 24 hours after floral opening. Alcantarea nahoumii exhibited preferential allogamy and self-compatibility, and required a pollinator to production of viable seeds. Sixteen species of pollinators were observed visiting A. nahoumii, among which were five hummingbird species. Even though its reproductive system is efficient, this bromeliad remains threatened mainly due to habitat fragmentation caused by deforestation, burning and predatory extractivism.

Pollination and reproductive system of synchronopatric species of Cactaceae (Cactoideae) subject to interspecific flow of pollen: an example of ecological adaptation in the Brazilian Chaco.

Three synchronopatric Cactaceae species, Echinopsis rhodotricha, Harrisia balansae and Praecereus saxicola, have mostly nocturnal anthesis and similar flowers, characteristics that motivated us to perform a comparative study of reproductive ecology. Reproductive phenology was sampled monthly from December 2014 to November 2015. We describe floral biology, breeding system via pollination treatments and evaluate floral visitors from focal and filming observations. Pollen grains found on moth proboscis were compared among cactus species under light microscopy. We used fluorescent dye particles to test intra- and interspecific pollen flow. These three species have extended flowering with greater intensity in the wet season, causing high overlap. They have white and hypocrateriformis flowers that open at twilight or nightfall and last about 15h. H.balansae seems to be self-incompatible, while E.rhodotricha presented self-compatibility. P.saxicola presented self-fertility, but most of the population seems to be self-incompatible. We suggest sphingophily for the three species, but only P.saxicola was visited by Manduca rustica (Sphingidae). However, we observed pollen grains of all three species on the proboscis of moths, especially M.rustica and M.sexta. Prolonged anthesis allowed bees (herein considered as secondary pollinators) to visit flowers of E.rhodotricha and P.saxicola. It can be concluded that the studied species share nocturnal and diurnal pollinators, suggesting interspecific pollen flow, which, however, could not be detected with fluorescent dye particles. In view of the low frequency of primary pollinators, it appears that these three species have different reproductive strategies, ensuring the fruiting and production of viable seeds.

Beyond biomass: Soil feedbacks are transient over plant life stages and alter fitness

Abstract Plants influence associated soil biotic communities that in turn can alter the performance of the subsequently growing plants. Although such “plant–soil feedbacks” (PSFs) are considered as important drivers of plant community assembly, past PSF studies have mainly addressed plant biomass production. However, plant performance is not only the production of biomass but comprises a sequence of different life stages: from seed germination over vegetative growth up to the production of a viable progeny. Here, we assessed the effects of soil biotic communities that were previously conditioned for 3 years by a focal plant species monoculture or species mixtures on key plant life stages from germination and vegetative growth to flowering and the production of viable seeds. We used three common grassland herb species that were grown in a sterile substrate and inoculated with a sterile control soil or with living soils. Living soils were conditioned either by the focal species in monoculture or a four‐ or eight‐species mixture that included the focal species to represent a decrease in the target plants’ conspecific influence on the soil communities. We show that the effect of soil biota changed from positive at the plants’ juvenile life stages to neutral or negative at the plants’ adult life stages and ultimately decreased plant fitness. A higher conspecific influence on the soil communities pronounced the positive effects at the juvenile life stage but also the negative effects at adult life stages. Further, we observed direct soil biotic effects on flower production and plant fitness that were not mediated by adult biomass production. This suggests that soil biotic effects may alter plant resource allocation and even may have transgenerational effects on plant fitness. Synthesis. We conclude that there is no overarching effect of soil biota that remains consistent at all the life stages of a plant. Thus, our results highlight the importance to consider plant life stage and ultimately plant fitness especially when plant–soil interactions are used to explain plant community dynamics.

Heritable heading time variation in wheat lines with the same number of Ppd-B1 gene copies.

The ability of plants to identify an optimal flowering time is critical for ensuring the production of viable seeds. The main environmental factors that influence the flowering time include the ambient temperature and day length. In wheat, the ability to assess the day length is controlled by photoperiod (Ppd) genes. Due to its allohexaploid nature, bread wheat carries the following three Ppd-1 genes: Ppd-A1, Ppd-B1 and Ppd-D1. While photoperiod (in)sensitivity controlled by Ppd-A1 and Ppd-D1 is mainly determined by sequence changes in the promoter region, the impact of the Ppd-B1 alleles on the heading time has been linked to changes in the copy numbers (and possibly their methylation status) and sequence changes in the promoter region. Here, we report that plants with the same number of Ppd-B1 copies may have different heading times. Differences were observed among F7 lines derived from crossing two spring hexaploid wheat varieties. Several lines carrying three copies of Ppd-B1 headed 16 days later than other plants in the population with the same number of gene copies. This effect was associated with changes in the gene expression level and methylation of the Ppd-B1 gene.