Current hypotheses concerning the role of polar auxin transport in embryo development are entirely based on studies of angiosperms, while little is known about how auxin regulates pattern formation ...in gymnosperms. In this study, different developmental stages of somatic embryos of Norway spruce (Picea abies) were treated with the polar auxin transport inhibitor 1-N-naphtylphthalamic acid (NPA). Effects of the treatments on auxin content, embryo differentiation and programmed cell death (PCD) were analysed. During early embryo development, NPA-treatment led to increased indole-3-acetic acid (IAA) content, abnormal cell divisions and decreased PCD, resulting in aberrant development of embryonal tube cells and suspensors. Mature embryos that had been treated with NPA showed both apical and basal abnormalities. Typically the embryos had abnormal cotyledon formation and irregular cell divisions in the area of the root meristem. Our results show that polar auxin transport is essential for the correct patterning of both apical and basal parts of conifer embryos throughout the whole developmental process. Furthermore, the aberrant morhologies of NPA-treated spruce embryos are comparable with several auxin response and transport mutants in Arabidopsis. This suggests that the role of polar auxin transport is conserved between angiosperms and gymnosperms.
The aim of this study was to evaluate the variability, partition, and correlation of Fe, Mn, and Zn in the leaves and fruit components (pod husk, pulp, tegument, and cotyledons) of cacao trees. These ...contents were also correlated with chemical attributes of the soils in regions classified as humid (H), humid to sub-humid (SH), and sub-humid to dry (SD) in the South Bahia, Brazil. Soils samples were collected, along with leaves and fruits from the PH16 clone of the cacao tree, for analysis of Fe, Mn, and Zn. Descriptive statistics and Pearson's correlation were applied, as well as Shapiro Wilk's normality test and Tukey's test for comparison of the climate regions. The accumulation order for Fe and Zn in the fruit components was tegument > pod husk > leaf > cotyledons; and for Mn the order was pod husk > leaf > tegument > cotyledons. The increase in hydric restriction, from the most humid region to the driest, causes natural bioconcentration of Fe, Mn, and Zn in the fruit components used to produce food (cotyledons and pulp). The Mn contents in the leaf can be used as indicators of its accumulation in the cotyledon and cacao pulp.
Blackleg is a major fungal disease of canola caused by Leptosphaeria maculans. Due to the breakdown of current host resistance, having an effective fungicide to avoid seedling infection is important ...to avoid disease. Pydiflumetofen is a newly developed broad‐spectrum seed treatment fungicide in the succinate dehydrogenase inhibitor (SDHI) group. We evaluated the separate and combined application of pydiflumetofen and Vibrance Flexi on early‐season control of blackleg using moderately resistant canola cultivar SY4135 and susceptible cultivar Westar. In the greenhouse, seedlings inoculated with green fluorescent protein (GFP)‐tagged L. maculans showed lesion development and apoplastic mycelial growth in cotyledons in control and Vibrance Flexi treatments but no lesion development or in planta mycelial growth was observed in pydiflumetofen‐treated seedlings, in Westar or SY4135, 14 days postinoculation. SY4135 and Westar plants with pydiflumetofen‐treated seeds inoculated with L. maculans isolate D3 had significantly lower disease severity. Both host genotypes treated with pydiflumetofen showed lower disease severity estimates than the other treatments. Statistically significant disease severity reduction was cultivar dependent in the field. Canola is most susceptible to blackleg as a seedling, from the cotyledon to two‐ to four‐leaf stage. Pydiflumetofen protects the plant at the critical window for infection. Therefore, pydiflumetofen could be a potential tool that farmers can add to their blackleg management toolbox.
Blackleg disease severity reduction in plants raised from seeds treated with pydiflumetofen confirmed the ability of the fungicide to protect the plant at the critical window for infection under controlled and field conditions.
BACKGROUND AND AIMS: Imbibition of Japanese soybean (Glycine max) cultivars was studied using micro-magnetic resonance imaging (MRI) in order to elucidate the mechanism of soaking injury and the ...protective role of the seed coat. METHODS: Time-lapse images during water uptake were acquired by the single-point imaging (SPI) method at 15-min intervals, for 20 h in the dry seed with seed coat, and for 2 h in seeds with the seed coat removed. The technique visualized water migration within the testa and demonstrated the distortion associated with cotyledon swelling during the very early stages of water uptake. KEY RESULTS: Water soon appeared in the testa and went around the dorsal surface of the seed from near the raphe, then migrated to the hilum region. An obvious protrusion was noted when water reached the hypocotyl and the radicle, followed by swelling of the cotyledons. A convex area was observed around the raphe with the enlargement of the seed. Water was always incorporated into the cotyledons from the abaxial surfaces, leading to swelling and generating a large air space between the adaxial surfaces. Water uptake greatly slowed, and the internal structures, veins and oil-accumulating tissues in the cotyledons developed after the seed stopped expanding. When the testa was removed from the dry seeds before imbibition, the cotyledons were severely damaged within 1·5 h of water uptake. CONCLUSIONS: The activation of the water channel seemed unnecessary for water entry into soybean seeds, and the testa rapidly swelled with steeping in water. However, the testa did not regulate the water incorporation in itself, but rather the rate at which water encountered the hypocotyl, the radicle, and the cotyledons through the inner layer of the seed coat, and thus prevented the destruction of the seed tissues at the beginning of imbibition.
1 To survive in forest understoreys, seedlings must depend on carbohydrate reserves when they experience negative carbon balance imposed by occasional light reduction and tissue loss to herbivores ...and diseases. We present the first experimental evidence in support of this hypothesis, using seven woody neotropical species. 2 We transplanted seedlings that had recently expanded their first photosynthetic cotyledon or leaf to the forest understorey (1% of full sun) and quantified initial biomass and total non-structural carbohydrate (TNC) in stems, roots and storage cotyledons. We then randomly assigned seedlings to control and two stress treatments: light reduction (0.08% of full sun for 8 weeks) and complete defoliation. 3 First-year survival of control seedlings, a comparative measure of shade tolerance, differed widely among species. The two stress treatments reduced survival and relative growth rates (RGR) of all species. Shade-tolerant species were little impacted by the stress treatments, whereas the two least shade-tolerant species experienced 100% mortality. 4 In all treatments, 8-week and first-year survival was positively correlated with initial TNC pool size in stems and roots. By contrast, survival was generally not correlated with initial TNC concentration in any organ, TNC pools in cotyledons, seed mass or seedling biomass. 5 TNC in stems and roots, but not in cotyledons, decreased in response to light reduction and defoliation over 8 weeks. Leaf area recovery of defoliated seedlings was positively correlated with initial TNC pools in stems and roots. 6 First-year survival in each treatment was negatively correlated with 0-8 week RGR of control seedlings, suggesting higher stress tolerance of species with inherently slow growth rates in shade. RGR of control seedlings from 0 to 8 weeks was negatively correlated with initial TNC pools, but not concentrations, in stems and roots. After 8 weeks, RGR was positive for all species, without clear relationships with survival or TNC. 7 We conclude that carbohydrate storage in stems and roots enhances long-term survival in shade by enabling seedlings to cope with periods of biotic and abiotic stress. Carbohydrate storage is a key functional trait that can explain species differences in growth and survival that lead to species coexistence through niche assembly processes and life-history trade-offs.
The aim of this study was to determine the effect of the pre-mating weight and placental characteristics on birth weight. Data were collected from 62 Karayaka ewes and 70 Karayaka lambs. The ...placental characteristics considered were placental weight, placental area and the number of cotyledons. The Pearson correlation coefficient was used for statistical comparison and the determination of relationships between variables. In addition, correlation coefficients between live weights and placental characteristics were determined. The average birth weight (BW), pre-mating weight (PMW), placental weight (PW), placental area (PA) and cotyledon number (CN) values were 4.37
0.70 kg, 50.22
5.63 kg, 362.51
118.42 g, 994.18
312.76 cm
and 56.93
8.06, respectively. BW had positive correlations with PMW (0.147), birth type (BT) (0.643), PW (0.604), PA (0.323) and CN (0.161) (
0.05). BW had negative correlations with maternal age (MA) (
) (
0.05). PMW had positive correlations with maternal age (MA) (0.237) (
0.05). PMW had negative correlations with S (sex) (
), PW (
), PA (
) and CN (
) (
0.05).
The present investigation aims to study the potential protective role of exogenous applications of gibberellin, auxin, citric acid and calcium on the growth and cellular redox state of pea (Pisum ...sativum L.) germinating seeds exposed to copper stress. All tested treatments alleviated the adverse effects of Cu-induced toxicity on the growth, cell viability and mobilization of nutrients from the cotyledons. This alleviation of Cu toxicity occurred by limiting heavy metal biosorption and maintaining cellular redox homeostasis. Redox balance, examined through the study of the redox state of nicotinamide couples NAD
+
/NADH and NADP
+
/NADPH appeared to be protected by the treatments. This correction was correlated to a modulation of NAD(P)H-oxidase and dehydrogenase activities, such as glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and malate dehydrogenase. The present research provides evidence that supplementation of plants with gibberellin, auxin, citric acid and calcium was an effective approach for enhancing Cu tolerance in pea seedlings.
Sugar-induced anthocyanin accumulation has been observed in many plant species. We observed that sucrose (Suc) is the most effective inducer of anthocyanin biosynthesis in Arabidopsis (Arabidopsis ...thaliana) seedlings. Other sugars and osmotic controls are either less effective or ineffective. Analysis of Suc-induced anthocyanin accumulation in 43 Arabidopsis accessions shows that considerable natural variation exists for this trait. The Cape Verde Islands (Cvi) accession essentially does not respond to Suc, whereas Landsberg erecta is an intermediate responder. The existing Landsberg erecta/Cvi recombinant inbred line population was used in a quantitative trait loci analysis for Suc-induced anthocyanin accumulation (SIAA). A total of four quantitative trait loci for SIAA were identified in this way. The locus with the largest contribution to the trait, SIAA1, was fine mapped and using a candidate gene approach, it was shown that the MYB75/PAP1 gene encodes SIAA1. Genetic complementation studies and analysis of a laboratory-generated knockout mutation in this gene confirmed this conclusion. Suc, in a concentration-dependent way, induces MYB75/PAP1 mRNA accumulation. Moreover, MYB75/PAP1 is essential for the Suc-mediated expression of the dihydroflavonol reductase gene. The SIAA1 locus in Cvi probably is a weak or loss-of-function MYB75/PAP1 allele. The C24 accession similarly shows a very weak response to Suc-induced anthocyanin accumulation encoded by the same locus. Sequence analysis showed that the Cvi and C24 accessions harbor mutations both inside and downstream of the DNA-binding domain of the MYB75/PAP1 protein, which most likely result in loss of activity.
•Zornia latifolia is a subshrubby legume species of the tribe Dalbergieae.•This species has the phanerocotylar, hypogeal, foliaceous (PHF) seedling type.•In Z. latifolia, root crowns developed from ...axillary buds at the cotyledonary node.•Resprouting from a bud bank is a common characteristic of taxa with PHF seedlings.•PHF seedlings couple the benefits of leafy cotyledons with hypogeal germination.
Seedling functional types have been studied at lower intensity in savanna forbs because most studies are biased toward woody species in forests. In this study, we investigated the seedling morphology and early morphological development of the basal bud bank structures of Zornia latifolia, which is a widely distributed neotropical legume species (Papilionoideae, Dalbergieae) and a relevant component of the forb legume guild from the Rio Branco savannas, northern Brazil. The unusual combination of phanerocotylar and foliaceous cotyledons with a noticeably short hypocotyl allows to assign the seedlings of Z. latifolia to the phanerocotylar hypogeal foliaceous (PHF) functional type, which is the first reference to the genus. Resprouting capacity from a bud bank is a common characteristic of taxa with PHF seedlings in savannas and depends on the formation and protection of bud bank organs. In Z. latifolia, root crowns are generated early from the seedling stage as a result of the ontogenetic development of axillary buds and their accessory buds at the cotyledonary node. We examined the ecological role of PHF seedlings in savannas, where this functional seedling type appears to combine the benefits of the photosynthetic efficiency of foliaceous cotyledons with the higher protection offered by hypogeal germination.
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