Lack Of Germination Research Articles

Verified hypotheses on the "nurse" and "burial" effects on introduced Quercus rubra regeneration in a mesic Scots pine forest.

A previous study on the encroachment of North American northern red oak Quercus rubra L. into the mesic Scots pine forest (in central Poland) revealed high abundances of seedlings and saplings under shrubs, with lower abundances in open areas or clumps of bilberry Vaccinium myrtillus L. It was unclear whether the regeneration success of Q. rubra is enhanced by the presence of shrubs due to their "nurse effect", and how burying acorns of different sizes in soil or moss affects the survival of oak seeds and seedlings (a "burial effect"). Results of a previous observational study were verified in an experimental study: a pool of 900 large-, medium-, and small-sized acorns was sown under moss cover in open areas and within bilberry clumps and in soil under shrubs in 2018 and monitored for 3 years in natural conditions. The majority of sown acorns were lost, mainly due to acorn pilferage, lack of germination and the death of sprouting acorns. However, acorn and seedling survival depended significantly on acorn size and differed among the microsites studied. Viable seedlings were twice as likely to develop from large- and medium-sized as from small-sized acorns, and they grew mainly from acorns sown under moss cover, confirming a positive "burial effect." Seedling survival was three times higher in bilberry and open areas, than under shrubs; however, seedlings "nursed" by shrubs were less threatened by large ungulates. Only a small part of the pool of sown acorns contributes to the reproductive success of Q. rubra in the mesic Scots pine forest. Microsites characteristic to this type of forest are suitable for northern red oak regeneration; however, bilberry favors acorn survival and germination and early seedling growth, moss cover favors acorn survival and germination, while shrubs protect surviving seedlings from herbivory.

Biotic Interactions between the Gametophytes of Wall Rue (Asplenium ruta-muraria) and Other Fern Species

Premise of research. The gametophytes of ferns are nutritionally independent of the sporophytes and are potentially hermaphroditic. The sexual expression of fern gametophytes is based on environmental cues. To prevent excessive self-fertilization, fern gametophytes employ strategies to increase mating between gametophytes. One of these strategies relies on antheridiogens, pheromones released by older gametophytes and absorbed by younger gametophytes. There are multiple distinct antheridiogen types, some of which are poorly understood and in need of further examination. A still-unresolved antheridiogen type was described in Asplenium ruta-muraria.Methodology. We employed cultivation experiments using spores of 12 fern species to assess the extent and uniqueness of the antheridiogen released by A. ruta-muraria. We tested antheridiogen interactions between representatives of three well-established antheridiogen types and A. ruta-muraria to assess their uniqueness. Furthermore, the effect of potentially antheridiogen-releasing gametophytes of A. ruta-muraria on multiple Asplenium species was examined. Germination in darkness in response to antheridiogens was also tested.Pivotal results. The younger gametophytes of A. ruta-muraria did not respond to the presence of older conspecific gametophytes in a way that could be attributed to antheridiogens. No antheridiogen interactions between A. ruta-muraria and any other species were observed. Nevertheless, the exudates of older A. ruta-muraria gametophytes may affect the development of younger conspecific and interspecific gametophytes.Conclusions. On the basis of its interaction with representatives of known antheridiogen types and the lack of germination in darkness, we conclude that our sample of A. ruta-muraria does not use antheridiogens. This discrepancy between our experiment and the initial publication describing antheridiogens in A. ruta-muraria may have been caused by intraspecific genetic variability within the species. The studied individual of A. ruta-muraria may be able to affect the growth of other gametophytes by other means, possibly via allelopathy, although this aspect of gametophyte interaction is poorly understood.

Effects of salinity on sawgrass (Cladium jamaicense Crantz) seed germination

Sea level rise threatens coastal peatlands globally, as increased salinity can cause peat collapse and formation of brackish ponds, replacing marshes. Sawgrass, Cladium jamaicense Crantz (Cyperaceae), is the charismatic macrophyte that dominates Everglades marshes (Florida, USA). Sawgrass root growth is reduced by salinity pulses of 20 ppt, impacting soil structure and organic input into coastal peats and possibly leading to coastal marsh loss. The potential for regeneration of coastal sawgrass marsh from seeds depends on how salinity affects sawgrass germination. Although adult sawgrass plants can tolerate salinities of 10–20 ppt in the field, the effect of salinity on seed germination is not known. In this study, sawgrass seeds were exposed to salinities of 0, 5, 15, and 25 ppt and observed weekly for germination over seven months (Oct. 2017-Apr. 2018). Twenty-eight percent of seeds in 0 ppt water germinated, while only 4% of seeds in 5 ppt germinated. Seeds in 15 and 25 ppt salt did not germinate. After 3.6 months, four-fifths of the seedling trays at the two higher salinities were transferred to 0 ppt. Beginning 7 weeks after transfer, 6% (15 ppt) and 3% (25 ppt) of transferred seeds germinated, while seeds remaining at the higher salinities did not. These results indicate that sawgrass seeds have greatly reduced or no germination in elevated salinity. If salinities rise in coastal areas, this lack of germination could prevent coastal sawgrass regeneration from seed, negatively affecting coastlines as sea level continues to rise.

Seasonal germination responses of seeds in fruits of the cold desert shrub Zygophyllum xanthoxylon buried in the field

We hypothesized that seeds of the central Asian cold desert shrub Zygophyllum xanthoxylon exhibit dormancy cycling in nature, which would help ensure that germination occurs at a favorable time for seedling survival. Fresh mature fruits of Z. xanthoxylon were placed on the soil surface and buried at a depth of 3–5 cm in soil in a natural habitat in August 2015. At regular intervals until July 2017, fruits/seeds were taken to the laboratory and evaluated for viability and germination. Fresh seeds in fruits germinated to 22–62% over a range of temperatures. After 6 weeks in the field, seeds on the surface germinated to 72–99% and those in soil to 70–100%. From 12 to 98 weeks, seeds on and in soil germinated to 72–100% at low (15/5 and 20/10 °C) temperatures, but germination at high (25/25 and 30/15 °C) temperatures was higher in summer than in spring. Seeds in fruits on the soil surface had higher germination percentages than those in the soil, especially at high temperatures. Although about half the seeds were dormant at maturity, they became nondormant in the field during summer. There was a decrease in ability to germinate at high temperatures in spring, especially for seeds in buried fruits, which indicates conditional dormancy/nondormancy cycling. Lack of germination at high temperatures in spring would help delay germination until the onset of the summer rainy season in the desert. Burial of fruits in the soil enhances the formation of a short-lived persistent seed bank.

The Role of Seed Bank and Germination Dynamics in the Restoration of a Tidal Freshwater Marsh in the Sacramento–San Joaquin Delta

Liberty Island, California, is a historical freshwater tidal wetland that was converted to agricultural fields in the early 1900s. Liberty Island functioned as farmland until an accidental levee break flooded the area in 1997, inadvertently restoring tidal marsh hydrology. Since then, wetland vegetation has naturally recolonized part of the site. We conducted a seed bank assay at the site and found that despite a lack of germination or seedling recruitment at the site, the seed bank contained a diverse plant community, indicating that the site’s continuous flooding was likely suppressing germination. Additionally, the frequency of germinating seeds in the seed bank did not represent the dominant adult plant community. We conducted a cold stratification study to determine if this observed disparity could be explained by seed germination dynamics, and whether germination could be enhanced using a pre-germination cold exposure, particularly for species of concern for wetland restoration. The cold stratification study showed that longer durations of pre-germination cold enhanced germination in Schoenoplectus acutus, but reduced germination in Schoenoplectus californicus, and had no effect on Typha latifolia. Overall, germination of S. californicus and S. acutus was much lower than T. latifolia. Our findings suggest that seeding may not be an effective restoration technique for Schoenoplectus spp., and, to improve restoration techniques, further study is needed to more comprehensively understand the reproduction ecology of important marsh species.

Enhanced germination performance of dormant seeds of <i>Eragrostis tef</i> in the presence of light

Lack of germination or low germination due to seed dormancy prevents successful crop establishment in several important plants. To determine the presence of innate seed dormancy and effects of stress-related plant hormones on germination performance of Teff (Eragrostis tef) seeds, we primed seeds in 1% KNO3 for 24 hours in dark conditions at 21 ± 0.5 ºC along with varying concentrations of chemicals known to influence seed germination, including: acetyl salicylic acid (ASA); methyl jasmonate (JA-Me); giberellic acid (GA3); and indole acetic acid (IAA). Primed seeds were incubated either in constant light (210 µM/m2/s) or in darkness at 21 ± 0.5 ºC. The results indicated that primingsignificantly improved final germination percentage (FGP) in both light (92.5%) and dark (89.4%) conditions compared with untreated seeds. The inclusion of plant hormones in the priming media generally had limited effects, except for 10 mM ASA (94.5%) and 100 mM GA3 (92.5%). ASA generally provided faster seed germination than seeds primed in 1% KNO3 only, while the other plant hormones had no effect on the time required for 50% of FGP in the dark. Priming had no significant effect on time span of germination in either light or dark incubation conditions. The results demonstrate that E. tef has light-inducible seed germination and about half of freshly harvested seeds can be dormant, which can be eliminated to some extent by priming seeds in 1% KNO3.

Temperature Effect on Seed Germination in the Genus Leucocoryne (Amaryllidaceae)

Leucocoryne is a Chilean endemic genus from the Amaryllidaceae family. It is an emerging crop with some registered varieties, currently oriented to a niche ornamental market. In the present work, seed germination in Leucocoryne dimorphopetala, Leucocoryne coquimbensis, Leucocoryne purpurea, Leucocoryne aff. vittata, Leucocoryne aff. violacescens, and Leucocoryne ixioides for seeds stored for 4 months and in L. purpurea, Leucocoryne vittata, L. aff. vittata, and L. ixioides for seeds stored for up to 16 months was analyzed at 10, 15, 20, or 25 °C. Germination data were analyzed by the previously developed time-germination model p = A{1 − exp[−k(t − t0)]}. Each germination curve had a coefficient of determination (R2) higher than 0.89, except when there was lack of germination. Results show that higher germination was better achieved at lower (10 or 15 °C) rather than at the higher temperatures (20 or 25 °C). When comparing germination results at temperatures of 10 and 15 with results at 20 °C, germination decreased by at least 30% and became near zero at 25 °C in seed stored for 4 months. Similarly when seeds were stored for 16 months, germination decreased by ≈20% at 20 °C, and again was near zero for germination at 25 °C. These germination habits of Leucocoryne are interpreted as an adaptive strategy to its natural habitats. In addition, L. dimorphopetala presents a type of dormancy and other species (L. purpurea, L. ixioides, and L. aff. vittata) may be sensitive to after-ripening changes during storage.

Initial Plant Growth in Sand Mine Spoil Amended with Organic Materials

Sand dunes in the Great Lakes Basin are ecologically and economically important. One economic value of sand dunes is sand mining. However, sand mining activities reduce soil quality which represents an impediment to reclamation efforts. Soil quality improvements followed by revegetation may be necessary for successful reclamation. This study evaluates the germination and initial growth of two legume species, wild lupine ( Lupinus perennis ) and Illinois bundleflower ( Desmanthus illinoensis ), and two warm-season grass species, Indian grass ( Sorghastrum nutans ) and little bluestem ( Schizachyrium scoparium ), in the presence of three soil amendments (coco peat, municipal sewage sludge, and sphagnum peat moss) added to spoil from a local sand mine. Species were grown in pots and propagated under greenhouse conditions. Our results indicate that lupine and Illinois bundleflower exhibited the greatest germination and growth and are recommended as potential candidates for the reclamation of sand mines. Indian grass and little bluestem exhibited low rates of germination and growth. Among spoil amendments, we recommend coco peat based on germination and root, shoot, and total biomass results. Peat moss also exhibited increased rates of germination and growth. We did not observe any germination success for seeds sown in sewage sludge amended spoil. The lack of germination in the sewage sludge amendment may be due to a combination of unfavorable abiotic and biotic soil conditions such as electrical conductivity, pH, or soil microbial activity. Our results are helpful in determining which species and amendment combinations are useful candidates for revegetating former sand mines or similar habitats.

Comparative study of the germination of Ulva prolifera gametes on various substrates

Since 2007, massive green tides have occurred every summer in the southern Yellow Sea (YS), China. They have caused severe ecological consequences and huge economic losses. Ulva prolifera originated from Subei Shoal of the YS was confirmed as causative species of the green tides. The Porphyra yezoensis aquaculture rafts in the Subei Shoal have been highly suspected to be the “seed bed” of the green tides, because U. prolifera abundantly fouled the Porphyra yezoensis aquaculture facilities. Besides, various habitats of aquaculture ponds along the Jiangsu coastline and mudflat in the Subei Shoal were proposed to be possible sources of green tides. To understand the “seed” of the green tides in the southern YS and mitigate the original biomass of the green tide, various materials used as substrates for the germination of U. prolifera gametes were tested in this study. Culture experiments showed the following: 1) materials used in the P. yezoensis rafts (plastic, bamboo, jute rope, plastic rope, nylon netting, and plastic netting) displayed a significantly higher germination rate than those associated with mudflats and aquaculture ponds (mud, sand and rock); 2) plastics were the best substrates for the germination of U. prolifera gametes; 3) poor germination was found on old fronds of U. prolifera,, and rubber showed inhibitory effect on germination. The success in germination on P. yezoensis rafts related materials supports the notion that these mariculture structures may be involved in acting as a seed bed for green tide macroalgae. The lack of germination on rubber surfaces may suggest one way to limit the proliferation of early stages of U. prolifera.

Sexual Dimorphism in Cryptically Dioecious Thalictrum macrostylum

Premise of research. Among dioecious angiosperms, occasional species exist in which one sex produces sterile reproductive structures of the opposite sex. These cryptically dioecious systems have the potential to provide significant insights into the selective factors and constraints involved in the evolution to and from dioecy. Thalictrum macrostylum is a morphologically androdioecious species in which the apparently hermaphroditic morph is functionally female.Methodology. I quantified sex ratios, the presence of sexual dimorphism, trait variation, and correlations of floral and vegetative traits in three or four natural populations. Lack of function of pollen from females was also tested. Morphological data were collected in field populations over two or three seasons to calculate the sex ratio and between-sex differences in trait means and to compare traits among populations and between and within morphs. Pollen from greenhouse-grown plants was used for in vitro pollen germination assays.Pivotal results. Thalictrum macrostylum populations consistently have 1∶1 sex ratios and are significantly sexually dimorphic, with males having more stamens per flower and flowers per plant. Pollen collected from females does not germinate. Other vegetative characters generally did not differ consistently between the sexes, though among-population differences were seen for some floral and vegetative characters.Conclusions. Lack of germination in pollen from females and 1∶1 sex ratios strongly suggest that this species is cryptically dioecious. Greater per-flower stamen number and per-plant flower number in males suggest that stamen and pollen production are important to male fitness. Among-population differences in floral and vegetative trait means may indicate differences among environments. Further studies should aim to test hypotheses for the maintenance of stamens in females of T. macrostylum.

Sowing seeds for the future: the need for establishing protocols for the study of seed dormancy

Seed dormancy is a widely misunderstood plant trait. In several research areas, a lack of germination is wrongly assumed to result from seed dormancy. In an attempt to standardize seed dormancy research and improve communication among seed scientists, a straightforward protocol to address the occurrence and causes of seed dormancy is provided. Standardizing communication is not just a theoretical exercise but also has practical implications in agriculture and conservation. Standardization will make studies comparable and hence we will have a deeper understanding of the physiology, ecology and evolution of seed dormancy. A better understanding of the various aspects of seed dormancy will lead to greater appreciation of the biogeographical and phylogenetic distribution of seed dormancy among our flora.

Analysis of Pregerminated Barley Using Hyperspectral Image Analysis

Pregermination is one of many serious degradations to barley when used for malting. A pregerminated barley kernel can under certain conditions not regerminate and is reduced to animal feed of lower quality. Identifying pregermination at an early stage is therefore essential in order to segregate the barley kernels into low or high quality. Current standard methods to quantify pregerminated barley include visual approaches, e.g. to identify the root sprout, or using an embryo staining method, which use a time-consuming procedure. We present an approach using a near-infrared (NIR) hyperspectral imaging system in a mathematical modeling framework to identify pregerminated barley at an early stage of approximately 12 h of pregermination. Our model only assigns pregermination as the cause for a single kernel's lack of germination and is unable to identify dormancy, kernel damage etc. The analysis is based on more than 750 Rosalina barley kernels being pregerminated at 8 different durations between 0 and 60 h based on the BRF method. Regerminating the kernels reveals a grouping of the pregerminated kernels into three categories: normal, delayed and limited germination. Our model employs a supervised classification framework based on a set of extracted features insensitive to the kernel orientation. An out-of-sample classification error of 32% (CI(95%): 29-35%) is obtained for single kernels when grouped into the three categories, and an error of 3% (CI(95%): 0-15%) is achieved on a bulk kernel level. The model provides class probabilities for each kernel, which can assist in achieving homogeneous germination profiles. This research can further be developed to establish an automated and faster procedure as an alternative to the standard procedures for pregerminated barley.

Reproductive ecology of Ochetophila trinervis in Northwest Patagonia.

Native actinorhizal species Ochetophila trinervis (Gillies ex Hook. & Arn.) Poepp. ex Miers, also known as Discaria trinervis (Kellermann et al. 2005), grows along watercourses and distant from them, along a rainfall gradient in north-west Patagonia. We studied the reproductive ecology of this species under different macro- and micro-environmental conditions, in three zones in a rainfall gradient (western, intermediate and eastern) with two sites for each one, near and distant to a watercourse (riparian and dry-land). We performed field studies and germination trials. Plant size, reproductive effort (seed abundance per branch) and seed bank size of O. trinervis, were favoured by the proximity of streams in the drier environments of the gradient. The abundance of seedlings and saplings in the field was very low, which was in agreement with a lack of germination in the field, despite the good germination capacity of seeds. Sexual reproduction of O. trinervis was affected by the low abundance of seedlings. Lower rainfall, higher temperatures and a longer growing season along the gradient favour the potential regeneration of the species. Because of its nitrogen-fixing capacity and other features, O. trinervis has potential for reclamation of eroded lands in Patagonia. Patterns of seed biology and regeneration presented in this study will aid in the use of O. trinervis in the reclamation of disturbed lands.

Effects of temperature and humidity on the survival of urediniospores of gladiolus rust (Uromyces transversalis)

Uromyces transversalis is an autoecious microcyclic rust mainly infecting Gladiolus spp. The pathogen is considered of plant quarantine importance in Europe and the USA. In 2006, the pathogen was found for the first time in the USA in several commercial nurseries in Florida and California. The US Department of Agriculture (USDA) initiated an eradication programme that recommended the immediate removal and destruction of infected plants followed by a host-free period, use of a fungicide treatment schedule, and equipment decontamination. In support of this plan, a study was conducted to determine how long urediniospores of U. transversalis would continue to germinate at temperatures of 2.8, 15.0, 18.8 and 25.0°C under controlled relative humidities (RH) of 11, 23, 43, 75, 93 and 100%. Choice of temperature and humidity parameters were mostly based on historical multi-year climate data from areas where the disease was detected in California and Florida. Analysis of variance (ANOVA) indicated no significant effect of RH on urediniospore germination but a highly significant effect of temperature. No germinating urediniospores were detected after 79 days for any treatment, but the 15°C treatment was more likely to be the result of germination independent of any low or high temperature-induced spore quiescence. Thus, lack of germination after 79 days was probably a good indicator of the lack of viable spores after this time for the 15°C treatment.

Germination Patterns in Naturally Chilled and Nonchilled Seeds of Fierce Thornapple (Datura Ferox) and Velvetleaf (Abutilon Theophrasti)

Seeds from natural populations of fierce thornapple and velvetleaf collected in a corn-growing area in central Spain were incubated at a range of constant temperatures and water potentials to model the progress of germination on the basis of the accumulation of hydrothermal time. Previous to the germination tests, the seeds were treated in two different ways: (1) dark storage under dry conditions (nonchilled seeds), and (2) burying in the original soil at 10-cm depth during 2 mo in winter (naturally chilled seeds). The results indicated different mechanisms inhibiting germination in both weed species. Whereas fierce thornapple displayed some type of embryo dormancy, the lack of germination in velvetleaf appeared to be entirely due to the seed coat. On the other hand, significant differences between nonchilled and naturally chilled seeds in fierce thornapple were observed, mainly due to the decrease in the mean base water potential of the 50th percentile in the latter, which indicated a loss of dormancy by exposure of the seeds to natural conditions. Hydrothermal time appears to be a good description of the germination patterns in both weed species, but in the case of fierce thornapple, only for naturally chilled seeds. Thus, the development of the hydrothermal model in fierce thornapple raises some questions for consideration concerning the influence of the type of seeds (conditions of storage, pretreatments of the seeds before germination tests) on its germination capacity.

High temperature and burial inhibit seed germination of two perennial Mediterranean Euphorbia species

Narbona E., Arista M. and Ortiz P. L. 2007. High temperature and burial inhibit seed germination of two perennial Mediterranean Euphorbia species. Bot. Helv. 117: 169 – 180. Seeds of the Mediterranean Euphorbia boetica and E. nicaeensis are produced in summer but germinate only in autumn; they are actively dispersed by ants, which may cause them to be buried. Here we tested whether the delay in germination is caused by thermodormancy, and whether seedlings are able to emerge after burial. Seeds of the perennial spurges Euphorbia boetica and E. nicaeensis were collected in four populations of southern Spain and were incubated at differing temperatures or after burial at differing soil depths. Most seeds germinated at 18–21 °C, but germination percentages were reduced at 25 °C and nearly zero at 30 °C. In E. boetica, the lack of germination at 30 °C was due to thermoinhibition, as all seeds that had not germinated at 30 °C did germinate when they were subsequently incubated at 18–21 °C. In contrast, about 15% of the viable seeds of E. nicaeensis did not germinate under these conditions, meaning that they had entered secondary dormancy. All viable seeds of E. boetica buried at 1 and 5 cm emerged, but at 10 cm emergence was significantly lower. In contrast, very few buried seeds of E. nicaeensis emerged at all burial depths, and some buried seeds entered secondary dormancy. The different germination strategies of the two species may reflect their different habitats and dispersal modes: E. boetica grows in the lowlands on sandy soils, and its seeds are always buried after ant dispersal, whereas E. nicaeensis lives in montane regions on stony and compact soils, and its seeds may be frequently dispersed at soil surface, reducing the selective pressure for seeds to germinate after burial.

Molecular profiling demonstrates limited diversity amongst geographically separate strains of Ustilago scitaminea

Intraspecies diversity within Ustilago scitaminea isolates from South Africa, Reunion Island, Hawaii and Guadeloupe was assessed by RAPDs, bE mating-type gene detection, rDNA sequence analysis, microscopy and germination and morphological studies. Except for sequence data, the other analyses yielded no differences in the isolates that could be used in a phylogenetic separation. Mycelial DNA of the SA isolate shared 100% sequence identity with that of mycelial DNA cultured from in vitro produced teliospores of the parent cultivar. Overall the ITS1 and ITS2 regions were found to have 96.1% and 96.9% sequence identity with a total of 17 and 21 base changes, respectively, amongst the isolates. The Reunion Island isolate was shown to be most distantly related by 3.6% to the other isolates, indicating a single clonal lineage. The lack of germination in teliospores from Guadeloupe may be attributed to changes in temperature and humidity during transportation.

Demographic and spatial analysis of a population of Juniperus oxycedrus L. in an abandoned grassland

A study of the structural, dynamic, and space occupancy characteristics of a prickly juniper (Juniperus oxycedrus) population developed on an abandoned secondary grassland of the Central Apennines (Italy), is presented here. The data were collected from a permanent plot, limited by mixed deciduous woods dominated by Ostrya carpinifolia Scop. by a plantation of Pinus nigra Arnold, and by a forest road, and consisting of 1744 prickly juniper individuals, as well as other pre-forest and forest species. The age and sex distributions of this population were assessed. With these data, the age pyramid was constructed, within which three developmental phases of the population became apparent, as confirmed by a study of the logistic curve of development of the population. Based on an estimate of the intensity function of the spatial distribution of the prickly juniper individuals, the hypothesis of complete randomness has to be rejected. On the other hand, the correlation between sex and population density was significant. The mode of space occupancy of the prickly juniper population was investigated also with respect to the other populations of shrubs and forest species. It was shown to spread out in all directions, following lines of diffusion that could be randomly determined. Finally, the presence, within the plot, of some pasture areas not occupied by prickly juniper may be derived from lack of germination of the fruits, or development of the seedlings owing to unfavourable micro-environmental conditions.

Seed germination is blocked in Arabidopsis putative vacuolar sorting receptor (atbp80) antisense transformants

The membrane receptor protein from pea, peabp80, has been shown to function by in vitro binding studies, and in vivo in yeast mutant, as a vacuolar sorting receptor (VSR). Families of proteins with homology to peabp80 have been identified in many plants including Arabidopsis. The family of membrane receptors, atbp80a–f (Arabidopsis thaliana binding protein 80 kDa) is highly homologous to peabp80 and may also function as vacuolar sorting receptors. Interactions with vacuolar sorting determinants have been shown only in vitro for atbp80b. In this paper, atbp80b was over‐ and under‐expressed in Arabidopsis. Transgenic plants that over‐expressed atbp80b showed no visible phenotype. However, antisense transformants were defective in germination. In non‐germinating antisense transformants the embryo appeared to be normal, but, using several methods, it was not possible to rescue the non‐germinating seeds, indicating that the mechanisms were probably independent of a seed‐coat‐imposed inhibition. To make a correlation between the lack of germination and gene expression, transcription analysis of all atbp80 genes was performed in the non‐germinating antisense seeds indicating that all the normally transcribed genes were not detected. Then, a gene expression study of atbp80s genes was carried‐out following seed imbibition and in various organs during wild‐type plant development showing that all the genes from the family were transcribed and differentially expressed.

Seed germination is blocked in Arabidopsis putative vacuolar sorting receptor (atbp80) antisense transformants.

The membrane receptor protein from pea, peabp80, has been shown to function by in vitro binding studies, and in vivo in yeast mutant, as a vacuolar sorting receptor (VSR). Families of proteins with homology to peabp80 have been identified in many plants including Arabidopsis: The family of membrane receptors, atbp80a-f (Arabidopsis thaliana binding protein 80 kDa) is highly homologous to peabp80 and may also function as vacuolar sorting receptors. Interactions with vacuolar sorting determinants have been shown only in vitro for atbp80b. In this paper, atbp80b was over- and under-expressed in Arabidopsis. Transgenic plants that over-expressed atbp80b showed no visible phenotype. However, antisense transformants were defective in germination. In non-germinating antisense transformants the embryo appeared to be normal, but, using several methods, it was not possible to rescue the non-germinating seeds, indicating that the mechanisms were probably independent of a seed-coat-imposed inhibition. To make a correlation between the lack of germination and gene expression, transcription analysis of all atbp80 genes was performed in the non-germinating antisense seeds indicating that all the normally transcribed genes were not detected. Then, a gene expression study of atbp80s genes was carried-out following seed imbibition and in various organs during wild-type plant development showing that all the genes from the family were transcribed and differentially expressed.