| 1. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(författare)
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Identifying potential molecular factors involved in Bacillus amyloliquefaciens 5113 mediated abiotic stress tolerance in wheat
- 2018
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 20, s. 271-279
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Tidskriftsartikel (refereegranskat)abstract
- Abiotic stressors are main limiting factors for agricultural production around the world. Plant growth-promoting bacteria have been successfully used to improve abiotic stress tolerance in several crops including wheat. However, the molecular changes involved in the improvement of stress management are poorly understood. The present investigation addressed some molecular factors involved in bacterially induced plant abiotic stress responses by identifying differentially expressed genes in wheat (Triticum aestivum) seedlings treated with the beneficial bacterium Bacillus amyloliquefaciens subsp. plantarum UCMB5113 prior to challenge with abiotic stress conditions such as heat, cold or drought. cDNA-AFLP analysis revealed differential expression of more than 200 transcript-derived fragments (TDFs) in wheat leaves. Expression of selected TDFs was confirmed using RT-PCR. DNA sequencing of 31 differentially expressed TDFs revealed significant homology with both known and unknown genes in database searches. Virus-induced gene silencing of two abscisic acid-related TDFs showed different effects upon heat and drought stress. We conclude that treatment with B.amyloliquefaciens 5113 caused molecular modifications in wheat in order to induce tolerance against heat, cold and drought stress. Bacillus treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.
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| 2. |
- Aguirre, A., et al.
(författare)
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Morphological variation in the flowers of Jacaratia mexicana A. DC. (Caricaceae), a subdioecious tree
- 2009
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Ingår i: Plant Biology. - 1435-8603 .- 1438-8677. ; 11:3, s. 417-424
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Tidskriftsartikel (refereegranskat)abstract
- The Caricaceae is a small family of tropical trees and herbs in which most species are dioecious. In the present study, we extend our previous work on dioecy in the Caricaceae, characterising the morphological variation in sexual expression in flowers of the dioecious tree Jacaratia mexicana. We found that, in J. mexicana, female plants produce only pistillate flowers, while male plants are sexually variable and can bear three different types of flowers: staminate, pistillate and perfect. To characterise the distinct types of flowers, we measured 26 morphological variables. Our results indicate that: (i) pistillate flowers from male trees carry healthy-looking ovules and are morphologically similar, although smaller than, pistillate flowers on female plants; (ii) staminate flowers have a rudimentary, non-functional pistil and are the only flowers capable of producing nectar; and (iii) perfect flowers produce healthy-looking ovules and pollen, but have smaller ovaries than pistillate flowers and fewer anthers than staminate flowers, and do not produce nectar. The restriction of sexual variation to male trees is consistent with the evolutionary path of dioecy from hermaphrodite ancestors through the initial invasion of male-sterile plants and a subsequent gradual reduction in female fertility in cosexual individuals (gynodioecy pathway), but further work is needed to confirm this hypothesis.
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| 3. |
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| 4. |
- Berg, H, et al.
(författare)
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Offspring performance in Oxalis acetosella, a cleistogamous perennial herb
- 2000
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 2:6, s. 638-645
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Tidskriftsartikel (refereegranskat)abstract
- Seed weight, seed germination, seedling survival, and juvenile/adult fitness in chasmogamously (CH) and cleistogamously (CL) derived offspring of Oxalis acetosella were compared during three growing seasons, to test hypotheses of fitness differences between the offspring types accounting for the maintenance of cleistogamy. In plots at three field sites, CH and CL seeds originating from all sites were sown to compare the performance of offspring growing in their habitat of origin and offspring growing in new habitats. Seeds were also sown in pots in a common garden, to test for effects of sibling competition. CL seeds had significantly lower germination than CH seeds in the field, possibly because of lower mean seed weight due to later flowering. Since the outcrossing rate in the CH flowers of O. acetosella is not known, it is uncertain whether the lower CL germination is a consequence of inbreeding depression. CH seeds had higher germination if sown at their home sites than at new sites, while for CL seeds this made no difference; this contradicts the local adaptation hypothesis for cleistogamy. No other fitness differences were found between the offspring types, and the findings did not support the sibling competition or local adaptation hypotheses. We suggest that the maintenance of the dimorphic reproductive system in O. acetosella is not explained by offspring characteristics, but rather by the two flowering phases complementing each other in maximizing annual seed production in the face of environmental variability. It is, therefore, important to include temporal and spatial variation in studies of reproductive strategies.
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| 5. |
- Bohman, Björn
(författare)
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Pollination by nectar-foraging pompilid wasps: a new specialized pollination strategy for the Australian flora
- 2021
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 23, s. 702-710
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Tidskriftsartikel (refereegranskat)abstract
- The Pompilidae is a cosmopolitan and diverse group of wasps, which commonly feed on nectar. However, pollination systems specialized on pompilids have not been documented in detail outside of southern Africa. Here, we studied Caladenia drummondii (Orchidaceae) where, based on floral traits and preliminary field observations, we predicted pollination by sexual deception of male pompilid wasps. Detailed pollinator observations were undertaken using floral baiting experiments at sites spanning 375 km. Following evidence for nectar on some flowers of C. drummondii, the sugar content on the labellum was analysed by GC-MS. Floral spectral reflectance was measured and compared with Caladenia using other pollination strategies. Males of a single species of pompilid wasp (Calopompilus sp.) were the only visitors capable of pollinating C. drummondii. Attempts to feed from the surface of the labellum were frequent and were associated with removal and deposition of pollinia. GC-MS analysis revealed larger quantities of sugar on the labellum than reported in other Caladenia species. While no sexual or courtship behaviour was observed, the zig-zag and circling flight on approach to the flower is suggestive of odour-based attraction. Floral spectral reflectance was similar to sexually deceptive Caladenia. This study represents the first confirmation of a specialized pompilid pollination system outside of Africa. Although pollination occurs during nectar-foraging, long-distance sexual attraction cannot be ruled out as an explanation for the exclusive male visitation. The similarity in floral spectral reflectance to other Caladenia indicates colour may not impose a constraint on the evolution of pollination by pompilids.
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| 6. |
- Burra, Dharani, et al.
(författare)
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Salicylic and jasmonic acid pathways are necessary for defence against Dickeya solani as revealed by a novel method for Blackleg disease screening of invitro grown potato
- 2015
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 17, s. 1030-1038
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Tidskriftsartikel (refereegranskat)abstract
- Potato is major crop ensuring food security in Europe, and blackleg disease is increasingly causing losses in yield and during storage. Recently, one blackleg pathogen, Dickeya solani has been shown to be spreading in Northern Europe that causes aggressive disease development. Currently, identification of tolerant commercial potato varieties has been unsuccessful; this is confounded by the complicated etiology of the disease and a strong environmental influence on disease development. There is currently a lack of efficient testing systems. Here, we describe a system for quantification of blackleg symptoms on shoots of sterile invitro potato plants, which saves time and space compared to greenhouse and existing field assays. We found no evidence for differences in infection between the described invitro-based screening method and existing greenhouse assays. This system facilitates efficient screening of blackleg disease response of potato plants independent of other microorganisms and variable environmental conditions. We therefore used the invitro screening method to increase understanding of plant mechanisms involved in blackleg disease development by analysing disease response of hormone- related (salicylic and jasmonic acid) transgenic potato plants. We show that both jasmonic (JA) and salicylic (SA) acid pathways regulate tolerance to blackleg disease in potato, a result unlike previous findings in Arabidopsis defence response to necrotrophic bacteria. We confirm this by showing induction of a SA marker, pathogenesis-related protein 1 (StPR1), and a JA marker, lipoxygenase (StLOX), in Dickeya solani infected invitro potato plants. We also observed that tubers of transgenic potato plants were more susceptible to soft rot compared to wild type, suggesting a role for SA and JA pathways in general tolerance to Dickeya.
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| 7. |
- Caron, M. M., et al.
(författare)
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Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides
- 2015
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 17:1, s. 52-62
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Tidskriftsartikel (refereegranskat)abstract
- Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A.platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A.platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A.platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A.pseudoplatanus in the face of climate change.
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| 8. |
- De Frenne, P., et al.
(författare)
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A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa
- 2011
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 13:3, s. 493-501
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Tidskriftsartikel (refereegranskat)abstract
- The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours > 5 degrees C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.
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| 9. |
- De Frenne, P., et al.
(författare)
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Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa
- 2018
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 20:3, s. 619-626
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Tidskriftsartikel (refereegranskat)abstract
- Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A.nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A.nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.
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| 10. |
- Demchenko, K., et al.
(författare)
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Analysis of the subcellular localisation of lipoxygenase in legume and actinorhizal nodules
- 2012
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 14:1, s. 56-63
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Tidskriftsartikel (refereegranskat)abstract
- Plant lipoxygenases (LOXs; EC 1.13.11.12) catalyse the oxygenation of polyunsaturated fatty acids, linoleic (18:2) and a-linolenic acid (18:3(n-3)) and are involved in processes such as stress responses and development. Depending on the regio-specificity of a LOX, the incorporation of molecular oxygen leads to formation of 9- or 13-fatty acid hydroperoxides, which are used by LOX itself as well as by members of at least six different enzyme families to form a series of biologically active molecules, collectively called oxylipins. The best characterised oxylipins are the jasmonates: jasmonic acid (JA) and its isoleucine conjugate that are signalling compounds in vegetative and propagative plant development. In several types of nitrogen-fixing root nodules, LOX expression and/or activity is induced during nodule development. Allene oxide cyclase (AOC), a committed enzyme of the JA biosynthetic pathway, has been shown to localise to plastids of nodules of one legume and two actinorhizal plants, Medicago truncatula, Datisca glomerata and Casuarina glauca, respectively. Using an antibody that recognises several types of LOX interspecifically, LOX protein levels were compared in roots and nodules of these plants, showing no significant differences and no obvious nodule-specific isoforms. A comparison of the cell-specific localisation of LOXs and AOC led to the conclusion that (i) only cytosolic LOXs were detected although it is generally assumed that the (13S)-hydroperoxy a-linolenic acid for JA biosynthesis is produced in the plastids, and (ii) in cells of the nodule vascular tissue that contain AOC, no LOX protein could be detected.
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