Plant Life Stages Research Articles

Plant cytokinin signalling

Cytokinin is an essential plant hormone that is involved in a wide range of plant growth and developmental processes which are controlled through its signalling pathway. Cytokinins are a class of molecules that are N(6)-substituted adenine derivatives, such as isopentenyl adenine, and trans- and cis-zeatin, which are common in most plants. The ability to perceive and respond to cytokinin occurs through a modified bacterial two-component pathway that functions via a multi-step phosphorelay. This cytokinin signalling process is a crucial part of almost all stages of plant life, from embryo patterning to apical meristem regulation, organ development and eventually senescence. The cytokinin signalling pathway involves the co-ordination of three types of proteins: histidine kinase receptors to perceive the signal, histidine phosphotransfer proteins to relay the signal, and response regulators to provide signal output. This pathway contains both positive and negative elements that function in a complex co-ordinated manner to control cytokinin-regulated plant responses. Although much is known about how this cytokinin signal is perceived and initially regulated, there are still many avenues that need to be explored before the role of cytokinin in the control of plant processes is fully understood.

Life stage influences the resistance and resilience of black mangrove forests to winter climate extremes

In subtropical coastal wetlands on multiple continents, climate change‐induced reductions in the frequency and intensity of freezing temperatures are expected to lead to the expansion of woody plants (i.e., mangrove forests) at the expense of tidal grasslands (i.e., salt marshes). Since some ecosystem goods and services would be affected by mangrove range expansion, there is a need to better understand mangrove sensitivity to freezing temperatures as well as the implications of changing winter climate extremes for mangrove‐salt marsh interactions. In this study, we investigated the following questions: (1) how does plant life stage (i.e., ontogeny) influence the resistance and resilience of black mangrove (Avicennia germinans) forests to freezing temperatures; and (2) how might differential life stage responses to freeze events affect the rate of mangrove expansion and salt marsh displacement due to climate change? To address these questions, we quantified freeze damage and recovery for different life stages (seedling, short tree, and tall tree) following extreme winter air temperature events that occurred near the northern range limit of A. germinans in North America. We found that life stage affects black mangrove forest resistance and resilience to winter climate extremes in a nonlinear fashion. Resistance to winter climate extremes was high for tall A. germinans trees and seedlings, but lowest for short trees. Resilience was highest for tall A. germinans trees. These results suggest the presence of positive feedbacks and indicate that climate‐change induced decreases in the frequency and intensity of extreme minimum air temperatures could lead to a nonlinear increase in mangrove forest resistance and resilience. This feedback could accelerate future mangrove expansion and salt marsh loss at rates beyond what would be predicted from climate change alone. In general terms, our study highlights the importance of accounting for differential life stage responses and positive feedbacks when evaluating the ecological effects of changes in the frequency and magnitude of climate extremes.

Intraspecific variation in flowering phenology affects seed germinability in the forest herb Primula elatior

Background and aims – Phenological responses to environmental cues are known to be phylogenetically conserved across species, but the adaptive nature of phenological responses to the local environment within the populations of individual species needs further exploration. In temperate forests, the canopy green up timing is expected to act selectively upon the growth and flowering phenology of understorey plants. Methods – Here we quantified the variation in the flowering phenology of a forest herb growing in the understorey of early versus late leafing tree species and explored the effect of this variation on the germinability of its seeds. The flowering of individual plants was recorded in six populations at twelve time points in early spring. Germinability was tested in a lab germination experiment. The individual plants were visited again in a second growing season to quantify the variation in phenology between years. Key results – Variability between plants was found within populations rather than between populations or forest stands. Phenology was consistent across growing seasons with individuals flowering either early or late in both studied years (which was not simply due to differences in plant size). Early flowering individuals had a fitness advantage in the sense that they produced higher proportions of germinable seeds. Conclusions – We quantified phenological variation between the individuals of an understorey plant species relative to the canopy phenology and related this variation to fitness. While some interesting patterns emerged, fitness components other than seed germinability and the plant life stages following germination should be studied as well to understand the evolutionary significance of phenology in forest understorey plants.

Plant-soil feedbacks from 30-year family-specific soil cultures: phylogeny, soil chemistry and plant life stage.

Intraspecific negative feedback effects, where performance is reduced on soils conditioned by conspecifics, are widely documented in plant communities. However, interspecific feedbacks are less well studied, and their direction, strength, causes, and consequences are poorly understood. If more closely related species share pathogens, or have similar soil resource requirements, plants may perform better on soils conditioned by more distant phylogenetic relatives. There have been few empirical tests of this prediction across plant life stages, and none of which attempt to account for soil chemistry. Here, we test the utility of phylogeny for predicting soil feedback effects on plant survival and performance (germination, seedling survival, growth rate, biomass). We implement a full factorial experiment growing species representing five families on five plant family-specific soil sources. Our experiments exploit soils that have been cultured for over 30 years in plant family-specific beds at Oxford University Botanic Gardens. Plant responses to soil source were idiosyncratic, and species did not perform better on soils cultured by phylogenetically more distant relatives. The magnitude and sign of feedback effects could, however, be explained by differences in the chemical properties of “home” and “away” soils. Furthermore, the direction of soil chemistry-related plant-soil feedbacks was dependent on plant life stage, with the effects of soil chemistry on germination success and accumulation of biomass inversely related. Our results (1) suggest that the phylogenetic distance between plant families cannot predict plant–soil feedbacks across multiple life stages, and (2) highlight the need to consider changes in soil chemistry as an important driver of population responses. The contrasting responses at plant life stages suggest that studies focusing on brief phases in plant demography (e.g., germination success) may not give a full picture of plant–soil feedback effects.

Niche partitioning in arbuscular mycorrhizal communities in temperate grasslands: a lesson from adjacent serpentine and nonserpentine habitats.

Arbuscular mycorrhizal fungi (AMF) represent an important soil microbial group playing a fundamental role in many terrestrial ecosystems. We explored the effects of deterministic (soil characteristics, host plant life stage, neighbouring plant communities) and stochastic processes on AMF colonization, richness and community composition in roots of Knautia arvensis (Dipsacaceae) plants from three serpentine grasslands and adjacent nonserpentine sites. Methodically, the study was based on 454-sequencing of the ITS region of rDNA. In total, we detected 81 molecular taxonomical operational units (MOTUs) belonging to the Glomeromycota. Serpentine character of the site negatively influenced AMF root colonization, similarly as higher Fe concentration. AMF MOTUs richness linearly increased along a pH gradient from 3.5 to 5.8. Contrary, K and Cr soil concentration had a negative influence on AMF MOTUs richness. We also detected a strong relation between neighbouring plant community composition and AMF MOTUs richness. Although spatial distance between the sampled sites (c. 0.3-3 km) contributed to structuring AMF communities in K. arvensis roots, environmental parameters were key factors in this respect. In particular, the composition of AMF communities was shaped by the complex of serpentine conditions, pH and available soil Ni concentration. The composition of AMF communities was also dependent on host plant life stage (vegetative vs. generative). Our study supports the dominance of deterministic factors in structuring AMF communities in heterogeneous environment composed of an edaphic mosaic of serpentine and nonserpentine soils.

Contrasting taxonomic and phylogenetic diversity responses to forest modifications: comparisons of taxa and successive plant life stages in South African scarp forest.

The degradation of natural forests to modified forests threatens subtropical and tropical biodiversity worldwide. Yet, species responses to forest modification vary considerably. Furthermore, effects of forest modification can differ, whether with respect to diversity components (taxonomic or phylogenetic) or to local (α-diversity) and regional (β-diversity) spatial scales. This real-world complexity has so far hampered our understanding of subtropical and tropical biodiversity patterns in human-modified forest landscapes. In a subtropical South African forest landscape, we studied the responses of three successive plant life stages (adult trees, saplings, seedlings) and of birds to five different types of forest modification distinguished by the degree of within-forest disturbance and forest loss. Responses of the two taxa differed markedly. Thus, the taxonomic α-diversity of birds was negatively correlated with the diversity of all plant life stages and, contrary to plant diversity, increased with forest disturbance. Conversely, forest disturbance reduced the phylogenetic α-diversity of all plant life stages but not that of birds. Forest loss neither affected taxonomic nor phylogenetic diversity of any taxon. On the regional scale, taxonomic but not phylogenetic β-diversity of both taxa was well predicted by variation in forest disturbance and forest loss. In contrast to adult trees, the phylogenetic diversity of saplings and seedlings showed signs of contemporary environmental filtering. In conclusion, forest modification in this subtropical landscape strongly shaped both local and regional biodiversity but with contrasting outcomes. Phylogenetic diversity of plants may be more threatened than that of mobile species such as birds. The reduced phylogenetic diversity of saplings and seedlings suggests losses in biodiversity that are not visible in adult trees, potentially indicating time-lags and contemporary shifts in forest regeneration. The different responses of taxonomic and phylogenetic diversity to forest modifications imply that biodiversity conservation in this subtropical landscape requires the preservation of natural and modified forests.

Species Turnover across Different Life Stages from Seedlings to Canopy Trees in Swamp Forests of Central Brazil

Processes driving the assembly of swamp forest communities have been poorly explored. We analyzed natural regeneration and adult tree communities data of a swamp gallery forest in Central Brazil to discuss the role of ecological filters in shaping plant species turnover in a successional gradient. Species data of 120 plots were used to assess species turnover between natural regeneration and adult tree communities. Our analyses were based on 4995 individuals belonging to 72 species. Community patterns were discerned using ordination analyses. A clear floristic turnover among plant life stages was distinguished. Regeneration community of swamp forests was richer in species composition than the adult community. Tree species commonly found in nonflooded gallery forests were present in the regeneration plots but not in the adult community. Differences in the floristic composition of these two strata suggest that not all species in the seedling stage can stand permanent flooding conditions and only a few tolerant species survive to become adult trees. We propose that natural disturbances play an important role by altering limiting resources, allowing seeds of nonflooded forest species to germinate. This paper elucidates the turnover between plant life stages in swamp forests and suggests mechanisms that may shape these communities.

Comparative Studies of Drought, Salinity and their Combinations on Germination and Seedling Growth Parameters of Indian Mustard (Brassica juncea) cv.

The seeds of Brassica juncea species were screened for tolerance and susceptibility to salt (NaCl), drought (PEG) and their combination using germination marker. Present research was carried out in order to observe the effects of salinity, drought and their combinations at very critical stages of plant life, i.e., seed germination and early seedling growth. The salinity stress was imposed using, 50 mM, 100 mM and 150 mM Sodium Chloride (NaCl) solutions, drought by 5%, 10% and 15% polyethylene glycol (PEG 6000)Solutions and combinations were as follows: (1) (2.5% PEG + 25 mM NaCl), (2) (5% PEG + 50 mM NaCl) and (3) (7.5% PEG + 75 mM NaCl). All the results obtained for radicle length and plant height of PUSA-AGRANI were highly significantly (P < 0.01) than other varieties under combination levels. Similarly, the germination percentage of CS-52 and RH-30 were more affected under combination levels. Results reveal that cultivar PUSA-AGRANI might be the tolerant variety and CS-52 might be sensitive towards both stress and their combinations.

Time is of the essence: direct and indirect effects of plant ontogenetic trajectories on higher trophic levels

Physiological and morphological constraints during plant ontogeny affect the expression of numerous plant traits relevant to higher trophic levels, such as nutritional content and physical and chemical defenses. Yet we know little about how temporal variation in these traits can directly and/or indirectly mediate tri‐trophic interactions, such as those between plants, their herbivores, and herbivore natural enemies. Using four distinct ontogenetic stages of Plantago lanceolata (Plantaginaceae) and the specialist herbivore Junonia coenia (Lepidoptera, Nymphalidae), we evaluated how ontogenetic changes in plant quality can: (1) directly alter plant–herbivore interactions through butterfly oviposition choice and caterpillar performance assays, and (2) indirectly alter herbivores' susceptibility to higher trophic levels through caterpillars' iridoid glycoside sequestration and immune defenses. Results showed that plant defensive traits increased over P. lanceolata development, with leaf tissues becoming tougher and plant allelochemicals (iridoid glycosides) occurring in higher amounts. Conversely, plant nutritional quality (water and nitrogen content) decreased as plants aged. These ontogenetic trajectories strongly altered both direct and indirect interactions between plants and higher trophic levels. Buckeye butterflies showed a stronger oviposition preference for younger developmental stages of P. lanceolata, laying on average 60% more eggs on juvenile than on reproductive plants. Feeding experiments with caterpillars showed that larvae feeding on juvenile plants showed faster relative growth rate and increased digestive efficiency compared with those feeding on plants in the reproductive stage. These individuals, however, acquired lower levels of sequestered chemical defenses than did those feeding on older P. lanceolata plants, potentially rendering them more susceptible to predation. Finally, host plant age altered the ability of a caterpillar to mount an immune response against simulated parasitoid eggs. Specifically, caterpillars reared on older plant life stages, and thus with higher levels of sequestered iridoid glycosides, showed a compromised immune response compared to those feeding on younger plant age classes. This study exemplifies how ontogenetic trajectories in plant traits can scale up to directly or indirectly alter tri‐trophic interactions, which may have key implications for understanding temporal shifts in herbivore population and community structure.

Functional diversity versus species diversity: relationships with habitat heterogeneity at multiple scales in a subtropical evergreen broad‐leaved forest

AbstractUnderstanding the relationship between functional and species diversity as well as their association with habitat heterogeneity can help reveal the mechanisms of species coexistence in ecological communities. However, these interactions have been poorly studied in subtropical forests. In this paper, we evaluated functional diversity (as measured by Rao's Q) and traditional species diversity (based on Simpson's index) in a 24 ha forest plot in a subtropical evergreen broad‐leaved forest (EBLF) in China. We compared the sensitivities of functional and species diversity to topographic variables (elevation, convexity, slope and aspect) at multiple spatial scales based on 10 × 10, 20 × 20, 40 × 40 and 50 × 50 m quadrats. Functional and species diversity were found to have different distribution patterns along a topographical gradient, with functional diversity better explained by topography than was species diversity using a spatial autocorrelation regression error model. Furthermore, functional diversity had a significantly greater association with topographic variables than species diversity in both adult and young trees; in both cases, the strength of the diversity‐habitat association increased with quadrat size. We conclude that functional diversity reflects a greater diversity‐habitat association in EBLF than does species diversity, and that the association depends on the spatial scale and life stages of the woody plants under evaluation.

Some like it hot and some like it cold, but not too much: plant responses to climate extremes

Current climatic models predict increasing frequency and magnitude of extreme climatic events (ECEs). Ecological studies recognize the importance of these extremes as drivers of plant growth and mortality, as well as drivers of ecological and evolutionary processes. Here we review observational and experimental studies on ECEs on herbaceous plants and shrubs. Extreme events considered were heat waves, drought, advanced or delayed snowmelt, heavy rainfalls, frosts, pulsed watering and flooding. We analysed 39 studies dealing with direct response of plant to ECEs in different ecosystems, with a particular focus on cold ecosystems (alpine and arctic). Although the number of studies increases every year, the understanding of ecological consequences of ECEs is fragmentary. In general, ECEs affected negatively on physiological processes (efficiency of photosystem II, stomatal conductance and leaf water potential), productivity and reproduction, and had consequences on population demography and recruitment several years after ECE. Indeed, the plant responses to ECEs were species specific and depended on the plant life stage and the timing of ECE. In fact, the magnitude of the effect of ECEs decreased over the growing season. Drought had the most severe effect on plants, while heat waves had minor effect if water was available. The overlap of different ECEs had an additive effect (e.g. drought associated to heat-waves). In general, both neutral or positive plant responses were found and acclimation is possible. In some cases, ECEs exert a strong selective pressure on plant species.

Individual- and population-level effects of Odocoileus virginianus herbivory on the rare forest herb Scutellaria montana

Odocoileus virginianus (white-tailed deer) grazing can impact rare plant species dramatically given their risk for local extirpation and extinction. To determine if O. virginianus management could aid conservation of federally threatened Scutellaria montana (large-flowered skullcap), we conducted an exclosure experiment across a large occurrence of this rare species in Catoosa County, Georgia, USA. We aimed to: (1) quantify the effects of O. virginianus grazing on S. montana individuals, and (2) evaluate the potential of O. virginianus to influence S. montana populations. A lesser percentage of S. montana individuals protected from O. virginianus were grazed than plants accessible to grazers and additional protection from smaller grazers did not reduce grazing, suggesting that O. virginianus primarily do graze S. montana. But grazing did not significantly influence S. montana individuals as evidenced by changes in stem height or the number of leaves per plant assessed during two single growing seasons or across those growing seasons. At the population-level, grazing impacts were buffered by a lack of grazer preferences for specific plant life stages. Although mostly not significant, our findings are biologically interesting given the numerous ecological concerns associated with O. virginianus abundance, including their demonstrated and proposed impact on rare plants.

Context-dependent patterns, determinants and demographic consequences of herbivory in an invasive species

Non-native invasive plants often lose many of their specialist herbivores in their invaded ranges, but new enemies may be recruited from the local generalist fauna, or from enemies themselves introduced to the same region. As a result, few invaders are free of herbivore damage; however, the incidence of this herbivory and its consequences for plant demography may depend on an array of biotic and abiotic factors. In Alliaria petiolata, a non-native invasive forb in Canada, we quantified the incidence of leaf herbivory, rosette survival and seed production along with conspecific plant density and environmental site conditions in wild populations in mesic forest understory and moist grasslands. We complemented the field survey by a laboratory experiment with Trichoplusia to test whether the palatability of leaf tissue of A. petiolata varies with plant life stage and habitat type. Incidence of herbivory was significantly higher in adults than in rosettes, and significantly higher in grasslands than in forest understory. The palatability experiment confirmed that leaves of adults were more palatable to a generalist herbivore than leaves of rosettes. Path analysis revealed negative plant density-dependent herbivory of adults in forest understory but positive density-dependent herbivory in grasslands. Incidence of herbivory in rosettes was positively associated with soil moisture in grasslands, but not in forest understory. Seed production was significantly positively associated with herbivory in adults and soil moisture, whereas rosette survival was significantly negatively associated with conspecific plant density. We conclude that the patterns, determinants and demographic consequences of herbivory in invasive Alliaria may strongly depend on a plant’s life stage and plant density and may further be confounded by landscape heterogeneity.

Temperature-dependent differential transcriptomes during formation of an epigenetic memory in Norway spruce embryogenesis

Embryogenesis is the initial stage of plant life, when the basics of body plan and the post-embryonic development are laid down. Epigenetic memory formed in the Norway spruce embryos permanently affect the timing of bud burst and bud set in progenies, vitally important adaptive traits in this long-lived forest species. The epigenetic memory marks are established in response to the temperature conditions prevailing during zygotic and somatic embryogenesis; the epitype is fixed by the time the embryo is fully developed and is mitotically propagated throughout the tree’s life span. Somatic embryogenesis closely mimics the natural zygotic embryo formation and results in epigenetically different plants in a predictable temperature-dependent manner with respect to altered phenology. Using Illumina-based Massive Analysis of cDNA Ends, the transcriptome changes were monitored in somatic embryos during morphogenesis stage under two different temperatures (18 vs. 30 °C). We found distinct differences in transcriptomes between the genetically identical embryogenic tissues grown under the two epitype-inducing temperatures suggesting temperature-dependent canalizing of gene expression during embryo formation, putatively based on chromatin modifications. From 448 transcripts of genes coding for proteins involved in epigenetic machinery, we found 35 of these to be differentially expressed at high level under the epitype-inducing conditions. Therefore, temperature conditions during embryogenesis significantly alter transcriptional profiles including numerous orthologs of transcriptional regulators, epigenetic-related genes, and large sets of unknown and uncharacterized transcripts.

Estrogenicity of soybeans (Glycine max) varies by plant organ and developmental stage

Phytoestrogens are a broad group of environmentally labile plant molecules that can influence development and reproduction of animals by binding estrogen and ecdysone receptors. In plants, phytoestrogens regulate physiological mechanisms such as auxin transport and mediate ecological interactions including attraction of symbionts. Most analytical phytoestrogen studies focus on quantifying particular phytoestrogen compounds (e.g., genistein) rather than measuring the accompanying biological estrogenic activity, and studies that evaluate temporal or spatial estrogenic variation in plants are rare. Therefore, in the present study, variation in estrogenic activity of field-grown soybeans (Glycine max cv Shirofumi) was examined across plant parts and life stages. Ethanolic organ extracts were analyzed for estrogenicity in a yeast reporter assay expressing human estrogen receptors α (ERα) or β (ERβ). All tissues were significantly more active with ERβ than ERα. The estrogenicity of roots, leaves, and shoots var...

Synergistic exposure of rice seeds to different doses of γ-ray and salinity stress resulted in increased antioxidant enzyme activities and gene-specific modulation of TC-NER pathway.

Recent reports have underlined the potential of gamma (γ)-rays as tools for seed priming, a process used in seed industry to increase seed vigor and to enhance plant tolerance to biotic/abiotic stresses. However, the impact of γ-rays on key aspects of plant metabolism still needs to be carefully evaluated. In the present study, rice seeds were challenged with different doses of γ-rays and grown in absence/presence of NaCl to assess the impact of these treatments on the early stages of plant life. Enhanced germination efficiency associated with increase in radicle and hypocotyl length was observed, while at later stages no increase in plant tolerance to salinity stress was evident. APX, CAT, and GR were enhanced at transcriptional level and in terms of enzyme activity, indicating the activation of antioxidant defence. The profiles of DNA damage accumulation were obtained using SCGE and the implication of TC-NER pathway in DNA damage sensing and repair mechanisms is discussed. OsXPB2, OsXPD, OsTFIIS, and OsTFIIS-like genes showed differential modulation in seedlings and plantlets in response to γ-irradiation and salinity stress. Altogether, the synergistic exposure to γ-rays and NaCl resulted in enhanced oxidative stress and proper activation of antioxidant mechanisms, thus being compatible with plant survival.

The effect of habitat filtering on tree seedling distribution in a subtropical evergreen broadleaf forest in China

Niche theory hypothesized that habitat specialization would contribute to the high species diversity of tropical forests and adult tree patterns. However, the effect of habitat selection during early life stages on plant communities and the influence on seedling regeneration remains unresolved. We studied seedling distribution patterns in four habitat types of GTS 24 hm² forest dynamic plots. (1) The torus-translation test was used to detect the species-habitat associations. Out of 24 seedling species, 11 species were significantly associated with a certain habitat, with seven species showing positive associations. (2) Indicator species analysis was used to investigate the strength of seedling species habitat specialization. We found eight representative indicator species and eight pairs of species combinations of particular habitat types. (3) Compared with early studies based on trees with d.b.h.≥1 cm (non-seedling trees), we found habitat associations differed across plant-life stages. We conclude that habitat filtering influences the distribution and regeneration patterns at very early life stages, affecting the diversity of the whole community in this subtropical evergreen broadleaf forest in China.

Differentiating the effects of pot size and nutrient availability on plant biomass and allocation

L. Hess and H. de Kroon (2007. J. Ecol. 95: 241–251) hypothesize that apparent plant responses to neighbour presence could be artifacts of pot-size manipulations. They posit that root size increases with pot size, regardless of nutrient concentration, while plant size increases with nutrient amount in the pot. Simple manipulations of pot size do not test this hypothesis, because larger pots contain more nutrients when nutrients are applied in solution at constant rate. We tested the effects of pot size on growth and allocation in two life stages of Cakile edentula (Bigel.) Hook. subsp. edentula var. lacustris while manipulating nutrient amount and concentration. Although pot size did affect growth and allocation, the patterns were not those predicted by the Hess and de Kroon hypotheses. In several treatments, total plant mass decreased with pot size. Root mass did not increase with pot volume independently of nutrients. Root mass increased with pot volume only when plants were given soluble fertilizer, and to a much greater extent in older plants. Contrary to predictions, root mass increased with pot size only in the treatment with high water-soluble fertilizer where plant size increased greatly with pot size. Root allocation showed a complex pattern of responses with plant life stage and nutrient treatments that were not predicted by the Hess and de Kroon hypotheses.

Microgravity effects on different stages of higher plant life cycle and completion of the seed‐to‐seed cycle

Human inhabitation of Space requires the efficient realisation of crop cultivation in bioregenerative life-support systems (BLSS). It is well known that plants can grow under Space conditions; however, perturbations of many biological phenomena have been highlighted due to the effect of altered gravity and its possible interactions with other factors. The mechanisms priming plant responses to Space factors, as well as the consequences of such alterations on crop productivity, have not been completely elucidated. These perturbations can occur at different stages of plant life and are potentially responsible for failure of the completion of the seed-to-seed cycle. After brief consideration of the main constraints found in the most recent experiments aiming to produce seeds in Space, we focus on two developmental phases in which the plant life cycle can be interrupted more easily than in others also on Earth. The first regards seedling development and establishment; we discuss reasons for slow development at the seedling stage that often occurs under microgravity conditions and can reduce successful establishment. The second stage comprises gametogenesis and pollination; we focus on male gamete formation, also identifying potential constraints to subsequent fertilisation. We finally highlight how similar alterations at cytological level can not only be common to different processes occurring at different life stages, but can be primed by different stress factors; such alterations can be interpreted within the model of 'stress-induced morphogenic response' (SIMR). We conclude by suggesting that a systematic analysis of all growth and reproductive phases during the plant life cycle is needed to optimise resource use in plant-based BLSS.

Changes in the protein patterns in pea (Pisum sativum L.) roots under the influence of long- and short-term chilling stress and post-stress recovery.

Amongst many factors restricting geographical distribution of plants and crop productivity, low temperature is one of the most important. To gain better understanding of the molecular response of germinating pea (Pisum sativum L.) to low temperature, we investigated the influence of long and short chilling stress as well as post-stress recovery on the alterations in the root proteomes. The impact of long stress was examined on the pea seeds germinating in the continuous chilling conditions of 10 °C for 8 days (LS). To examine the impact of short stress, pea seeds germinating for 72 h in the optimal temperature of 20 °C were subjected to 24-h chilling (SS). Additionally, both stress treatments were followed by 24 h of recovery in the optimal conditions (accordingly LSR and SR). Using the 2D gel electrophoresis and MALDI-TOF MS protein identification, it was revealed, that most of the proteins undergoing regulation under the applied conditions were implicated in metabolism, protection against stress, cell cycle regulation, cell structure maintenance and hormone synthesis, which altogether may influence root growth and development in the early stages of plant life. The obtained results have shown that most of detected alterations in the proteome patterns of pea roots are dependent on stress duration. However, there are some analogical response pathways which are triggered regardless of stress length. The functions of proteins which accumulation has been changed by chilling stress and post-stress recovery are discussed here in relation to their impact on pea roots development.