Post Germination Research Articles

Metabolome and transcriptome analyses reveal changes of rapeseed in response to ABA signal during early seedling development

Seed germination is an important development process in plant growth. The phytohormone abscisic acid (ABA) plays a critical role during seed germination. However, the mechanism of rapeseed in response to ABA is still elusive. In order to understand changes of rapeseed under exogenous ABA treatment, we explored differentially expressed metabolites (DEMs) and the differentially expressed genes (DEGs) between mock- and ABA-treated seedlings. A widely targeted LC-MS/MS based metabolomics were used to identify and quantify metabolic changes in response to ABA during seed germination, and a total of 186 significantly DEMs were identified. There are many compounds which are involved in ABA stimuli, especially some specific ABA transportation-related metabolites such as starches and lipids were screened out. Meanwhile, a total of 4440 significantly DEGs were identified by transcriptomic analyses. There was a significant enrichment of DEGs related to phenylpropanoid and cell wall organization. It suggests that exogenous ABA mainly affects seed germination by regulating cell wall loosening. Finally, the correlation analysis of the key DEMs and DEGs indicates that many DEGs play a direct or indirect regulatory role in DEMs metabolism. The integrative analysis between DEGs and DEMs suggests that the starch and sucrose pathways were the key pathway in ABA responses. The two metabolites from starch and sucrose pathways, levan and cellobiose, both were found significantly down-regulated in ABA-treated seedlings. These comprehensive metabolic and transcript analyses provide useful information for the subsequent post-transcriptional modification and post germination growth of rapeseed in response to ABA signals and stresses.

Arbuscular mycorrhizal fungi and phosphorus affect Araucaria angustifolia seedling growth

Symbioses between plants and arbuscular mycorrhizal fungi (AMF) provide many advantages, including a reduced need for fertilization. In this study, the effects of AMF inoculation and phosphorus application on the growth and nutritional status of Araucaria angustifolia seedlings were evaluated. The treatments included inoculation with AMF (Gigaspora margarita, Rhizophagus intraradices, Acaulospora colombiana, Acaulospora scrobiculata, or Dentiscutata heterogama), inoculation with a mixture of AMF in 100 g of 50-year-old araucaria forest soil, application of two doses of P2O5 (25 or 100 mg kg-1), and the control. A completely randomized design was used, with seven replicates per treatment. The growth parameters, macronutrient and micro-nutrient contents, root colonization, and mycorrhizal effects on the extracted nutrients were evaluated at 75 and 150 d post germination. Analysis of variance, correlations, and principal component analysis (PCA) were used to evaluate that data. Inoculation with AMF had favorable effects on growth parameters, root colonization, and the extraction of macronutrients and micro-nutrients. In particular, the mixture of AMF from the 50-year-old araucaria forest soil, R. intraradices, and A. colombiana were beneficial. Similarly, the application of 25 mg of P2O5 significantly affected the growth of A. angustifolia seedlings compared to other treatments and increased the efficiency of root colonization.

Efeito da germinação nas propriedades nutricionais de sementes de quatro variedades de melão

ABSTRACT: Fruit seeds, in terms of nutrition, are as wholesome as the grains cultivated exclusively for human consumption. The fruit pulp-processing agroindustry, more often than not, discards these seeds as unprofitable waste. The inclusion of seeds as a consumer product, equal in value to the pulp itself, can be made possible by adopting processes that increase their worth, and ideally at minimal costs. The controlled germination process is suitable for such an endeavor. The strategy presented here, is low in cost and permits the modulation of the constituents of the seeds by breaking the continuity of the process at the precise time, thus enabling the formation of a new product, which possesses bioactive properties. This research was performed with the focus on exploring the ways that the germination time influences the constituents of the seeds in four melon varieties. The Cantaloupe, Gália, Pele-de-Sapo and Orange melon seeds were studied and the water content, ash, proteins, lipids, total and reducing sugars, total phenolic compounds, tannins, flavonoids and anthocyanins were determined in the samples. This was done in natura and post germination specifically at 24, 48, 72 and 96 hours. Germination altered all the parameters, except the ash content. In Pele-de-Sapo, the protein content dropped, while in the others it showed an increase. Germination caused a rise in the values of the total and reducing sugars, as well as the total phenolic compounds, tannins, flavonoids and anthocyanins, showing variations during the intermediate times, based on the variety. Mostly, higher values were achieved at 96 h of the germination process.

Chromatin dynamics associated with seed desiccation tolerance/sensitivity at early germination in Medicago truncatula.

Desiccation tolerance (DT) has contributed greatly to the adaptation of land plants to severe water-deficient conditions. DT is mostly observed in reproductive parts in flowering plants such as seeds. The seed DT is lost at early post germination stage but is temporally re-inducible in 1mm radicles during the so-called DT window following a PEG treatment before being permanently silenced in 5mm radicles of germinating seeds. The molecular mechanisms that activate/reactivate/silence DT in developing and germinating seeds have not yet been elucidated. Here, we analyzed chromatin dynamics related to re-inducibility of DT before and after the DT window at early germination in Medicago truncatula radicles to determine if DT-associated genes were transcriptionally regulated at the chromatin levels. Comparative transcriptome analysis of these radicles identified 948 genes as DT re-induction-related genes, positively correlated with DT re-induction. ATAC-Seq analyses revealed that the chromatin state of genomic regions containing these genes was clearly modulated by PEG treatment and affected by growth stages with opened chromatin in 1mm radicles with PEG (R1P); intermediate openness in 1mm radicles without PEG (R1); and condensed chromatin in 5mm radicles without PEG (R5). In contrast, we also showed that the 103 genes negatively correlated with the re-induction of DT did not show any transcriptional regulation at the chromatin level. Additionally, ChIP-Seq analyses for repressive marks H2AK119ub and H3K27me3 detected a prominent signal of H3K27me3 on the DT re-induction-related gene sequences at R5 but not in R1 and R1P. Moreover, no clear H2AK119ub marks was observed on the DT re-induction-related gene sequences at both developmental radicle stages, suggesting that silencing of DT process after germination will be mainly due to H3K27me3 marks by the action of the PRC2 complex, without involvement of PRC1 complex. The dynamic of chromatin changes associated with H3K27me3 were also confirmed on seed-specific genes encoding potential DT-related proteins such as LEAs, oleosins and transcriptional factors. However, several transcriptional factors did not show a clear link between their decrease of chromatin openness and H3K27me3 levels, suggesting that their accessibility may also be regulated by additional factors, such as other histone modifications. Finally, in order to make these comprehensive genome-wide analyses of transcript and chromatin dynamics useful to the scientific community working on early germination and DT, we generated a dedicated genome browser containing all these data and publicly available at https://iris.angers.inrae.fr/mtseedepiatlas/jbrowse/?data=Mtruncatula.

Phytohormones Ameliorated the Physiological Changes During Post Germination Drought in Maize

A pot experiment was conducted to find out effect of gibberellic acid (GA), salicylic acid (SA) and sodium nitroprusside as nitric oxide donor (NO) separately or in combination to mitigate the deviations in physiological parameters evaluated in maize while drought imposed post germination stage. Maize seeds after soaking in 10-4 M of above mention chemicals were sown in pots filled with soil. The leaves were sampled at post germination stage. Results indicated that under drought stress, carotenoid and anthocyanin contents increased significantly while chlorophyll a and chlorophyll b remained unchanged at 5% level of significance. Pre-treatment of solution comprising SA, GA and interaction of GA+SA enhanced the content of these pigments under drought stress. While sodium nitroprusside slightly increased chlorophyll a and b content under drought. Sugar and protein decreased due to drought stress and sugar enhanced due to effect of NO only but protein content did not increase by any one of applying hormones under drought stress. Likewise GA and SA enhanced accumulation of proline which acts as osmolyte and scavenger of free radical to defend cell injury against drought stress. Similarly activities of oxidative enzymes such as peroxidase and polyphenol oxidase increased under drought stress and responded differentially by GA, SA etc, while ascorbate peroxidase and catalase activities decreased due to drought stress which became increased by effect of NO. Results revealed that pretreatment of seeds with GA, SA, GA+SA and NO are effective to tolerate the effect of drought stress in maize at post germination stage. Keywords: Drought, Enzymes, Maize, osmolyte, Pigments DOI: 10.7176/JBAH/11-15-01 Publication date: August 31 st 2021

Impact of post scarification storage period on seed germination and quality in soapnut (Sapinduas emarginatus)

Soapnut (Sapinduas emarginatus) is one of the most primitive precious useful plants since ancient times. This plant was domesticated due to its multifarious usefulness. The study was conducted in College of Forestry, Sirsi during 2019-20 to know the influence of post scarification storage treatments on seed germination and quality in Sapinduas emarginatus. The seeds were collected from in and around Sirsi area. In soap nut, the basic problem is poor seed germination due to hard seed coat. The seeds were treated with concentrated H2So4 for 12min and stored under laboratory condition for six months. At monthly interval, seed samples were drawn and evaluated for post scarification germination. The germination behaviour remarkably influenced due to scarification and without scarification during experimentation. The untreated seeds recorded the maximum germination (68%) compared to scarified seeds (22.85%).Speed of germination was highest in seed without scarification treatment (2.7) compared to scarified seeds. Mean daily germination was highest in without scarified seeds (1.04) and lowest in the scarified seeds (0.32). Peak value was maximum in without scarified seeds (0.50) compared to scarified seeds (0.22). Seedling vigour index was significantly highest in without scarified seeds (1290) compared to scarified seeds (455). In general, scarified seeds with conc. H2SO4 for 12 min affected seed germination due high conc. H2SO4 because of chemical residues remaining in seed that affects the embryo. As the advancement in storage period the seed coat may lose the integrity so, germination was improved in without scarified seeds.

Seed Priming Significantly Affects Germination and Post Germination Early Seedling Growth in Okra

Abstract Seed priming significantly affects germination and post germination emergence in seedling of plants. Okra is an important vegetable plays significant role in human nutrition. However, little information is available regarding effect of seed priming on germination and post germination early vegetative growth. Therefore, a pot experiment was conducted to find out the effect of seed priming on the emergence and seedling vigor in different okra varieties. Six local Bangladeshi okra varieties were primed in water for 24 hours and evaluated their germination and post germination emergence. The varieties were named as V1-V6 (V1 = Flash power, V2 = Durga, V3 = BARI dheros-2, V4 =Okra pornota, V5 =Dandy all green, V6 = Boishakhi). Post priming evaluation was done based on germination percentage, root-shoot length of seedlings, seedling height, and dry weight of seedlings, germination index and speed of germination at different days after sowing (5-15 DAS). Highest germination was observed in V3 (88.00%) and lowest was in V5 (25.33%). Root length was highest in V3 and V4 (8.77cm) and lowest was observed in V2 (5.15cm). Shoot length of the seedlings was highest in V3 (7.94cm) followed by V1 (7.33). Shoot length of the seedlings was lowest in V5 (5.12cm). Seedling height was highest in V3 (16.71cm) which was followed by V6 (16.26cm). The lowest seedling height was observed in V1 (12.50cm). Dry weight of the seedlings was highest in V3 (2.32g) which was followed in V1 (2.26g). The lowest dry weight was observed in V5 (1.99g). The variety V3 performed better in most of the evaluated parameters and suggested for commercial cultivation.

In vitro conservation strategies for the critically endangered Malabar river lily (Crinum malabaricum Lekhak & Yadav) using somatic embryogenesis and synthetic seed production

Crinum malabaricum Lekhak & Yadav (Malabar river lily of the family Amaryllidaceae) is a critically endangered plant species and a natural source of galanthamine. Synthetic seeds production via somatic embryogenesis was adopted as in vitro conservation strategy and proliferation of Malabar river lily in this study. Murashige and Skoog's (MS) basal medium with 8.0 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D) and additives induced maximum percentage of somatic embryos (98.4%) at various stages with an average of 53.8 somatic embryos per inoculum/tri-scale explant. Histo-anatomical examinations showed that the meristematic cell layers of reduced stem (present between the scales) had the highest embryogenic capacity. The meristematic activity of the globular somatic embryos (SEs) assisted in further differentiation of distinct stages of embryogenesis. Synthetic seeds encapsulated with 2.0% sodium alginate and 100 mM calcium chloride resulted in the development of delicate beads with 92.5% post thawing germination potential after one year cold storage in dark at - 4 °C. The effect of 6-bezylaminopurine (BAP) and indole-3 acetic acid (IAA) on germination of SEs, plantlet retrieval, and shoot and root regeneration was significant as compared with combination of BAP and α-Naphthalene acetic acid (NAA). Highest 12.8 shoots per synthetic seed and 5.6 roots/ shoot were regenerated from encapsulated somatic embryos on MS medium + 2.0 mg L−1 BAP + 0.5 mg L−1 IAA + additives. This report could help in mass propagation of C. malabaricum, and could be applied for enhanced production of galanthamine using elicitors and through genetic transformations.

Alleviation of Salinity Stress in Maize Using Silicon Nutrition

Improving salinity tolerance through mineral nutrition in plants is emerging strategy for sustainable agriculture under limited resources. Silicon (Si) is considered as silver bullet to mitigate biotic and abiotic stresses. Present study was conducted to understand the new mechanisms of Si nutrition against salinity stress in two different maize (Zea mays L.) cultivars (‘Syngenta-8441’ and ‘Pearl’). Three different levels of NaCl (0.67, 8 and 13 dSm-1) were used with and without addition of silicic acid (2 mM). Distilled water was used for irrigation purposes and crop was harvested after 40 days of post germination. Results indicated that plant biomass reduced under saline condition while Si application increased growth parameters. Data regarding chemical analysis showed that Si nutrition reduced Na+ concentration and enhanced K+ levels in root, shoot, new and old leaves of ‘Sygenta 8441’ compared to ‘Pearl’ maize variety. Si application improved both chlorophyll a and b in both maize cultivars compared to NaCl-treated plants. The current findings indicate that Si nutrition can alleviate salinity stress in maize without decreasing growth attributes of crop and ‘Sygenta 8441’ is a salt resistant variety whereas ‘Pearl’ is a salt sensitive variety.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Comprehensive dissection of transcript and metabolite shifts during seed germination and post-germination stages in poplar

BackgroundSeed germination, a complex, physiological–morphogenetic process, is a critical stage in the life cycle of plants. Biological changes in germinating seeds have not been investigated in poplar, a model woody plant.ResultsIn this study, we exploited next-generation sequencing and metabolomics analysis and uncovered a series of significantly different genes and metabolites at various stages of seed germination and post germination. The K-means method was used to identify multiple transcription factors, including AP2/EREBP, DOF, and YABBY, involved in specific seed germination and post-germination stages. A weighted gene coexpression network analysis revealed that cell wall, amino acid metabolism, and transport-related pathways were significantly enriched during stages 3 and 5, with no significant enrichment observed in primary metabolic processes such as glycolysis and the tricarboxylic acid cycle. A metabolomics analysis detected significant changes in intermediate metabolites in these primary metabolic processes, while a targeted correlation network analysis identified the gene family members most relevant to these changing metabolites.ConclusionsTaken together, our results provide important insights into the molecular networks underlying poplar seed germination and post-germination processes. The targeted correlation network analysis approach developed in this study can be applied to search for key candidate genes in specific biochemical reactions and represents a new strategy for joint multiomics analyses.

QUANTITATIVE ASSESSMENT OF ANISOCOTYLY IN HABERLEA RHODOPENSIS AND RAMONDA MYCONI

Anisocotyly, the unequal development of cotyledons post germination, is a unique trait observed only in Old World Gesneriaceae (Lamiales). New World Gesneriaceae have isocotylous seedlings. In both Old and New World Gesneriaceae, cotyledons initially grow equally for a short period just after germination. In the New World species, both cotyledons cease their growth at the same time early on, whereas in Old World species one cotyledon continues to expand to become a macrocotyledon while the other withers away. In this study, cotyledon growth was observed in two European Old World Gesneriaceae: Haberlea rhodopensis and Ramonda myconi. The results were compared with those for the typical anisocotylous species Streptocarpus rexii and the typical isocotylous species Corytoplectus speciosus. We found that the cotyledon growth patterns in Haberlea rhodopensis and Ramonda myconi were intermediate between the typical anisocotylous or isocotylous species. Haberlea rhodopensis and Ramonda myconi showed irregular growth patterns, with some plants being slightly anisocotylous but most being isocotylous. The developmental basis for the residual anisocotyly, the extended basal meristem activity in the macrocotyledon, appeared to be identical in the European species to that in the typical Old World Streptocarpus rexii but weakly expressed, rare and terminated early. In conclusion, European Gesneriaceae retain a reduced anisocotylous growth that may be linked to their early plumule development.

Rice with reduced stomatal density conserves water and has improved drought tolerance under future climate conditions.

Summary Much of humanity relies on rice (Oryza sativa) as a food source, but cultivation is water intensive and the crop is vulnerable to drought and high temperatures. Under climate change, periods of reduced water availability and high temperature are expected to become more frequent, leading to detrimental effects on rice yields.We engineered the high‐yielding rice cultivar ‘IR64’ to produce fewer stomata by manipulating the level of a developmental signal. We overexpressed the rice epidermal patterning factor OsEPF1, creating plants with substantially reduced stomatal density and correspondingly low stomatal conductance.Low stomatal density rice lines were more able to conserve water, using c. 60% of the normal amount between weeks 4 and 5 post germination. When grown at elevated atmospheric CO 2, rice plants with low stomatal density were able to maintain their stomatal conductance and survive drought and high temperature (40°C) for longer than control plants. Low stomatal density rice gave equivalent or even improved yields, despite a reduced rate of photosynthesis in some conditions.Rice plants with fewer stomata are drought tolerant and more conservative in their water use, and they should perform better in the future when climate change is expected to threaten food security.

Expression profiling of the Dolichos lablab lectin during germination and development of the seed

The temporal expression of the field bean (Dolichos lablab) galactose specific lectin, DLL-II, during germination, post-germination and seed development was evaluated using Native-PAGE followed by activity staining, immunodetection and quantitative Real Time PCR (qPCR). A rapid and steep decline in the polyphenol oxidase (PPO) and hemagglutinating activity during the initial stages of germination, which did not correlate with the slow decline in total protein was observed. During post germination period, PPO and hemagglutination activities were negligible, whereas a rapid resorption of the protein was evident. These results suggest that DLL-II is not a storage protein. The presence of mRNA in the quiescent seed and initial stages of germination are indicative of a very stable mRNA. DLL-II was expressed in high copies during seed development and increased dramatically between 10 and 20 days after flowering (DAF), suggesting a switch over stage in DLL-II expression. Transcript levels reached a maximum at the mature stage of seed development. Among the non-seed tissues examined, root showed the highest level. The high affinity binding to kinetin and indole acetic acid, the key hormones that regulate root development and its vascular differentiation add a new dimension to the physiological role of DLL-II in the seed. This finding, coupled with the PPO and hemagglutinating activity makes DLL-II, truly a multifunctional protein.

Improved Salinity Resilience in Black Bean by Seed Elicitation Using Organic Compounds

Core Ideas Black bean cultivars were extremely susceptible to high salinity stress. Seed elicitation improved salinity stress resilience. Chitosan oligosaccharide and marine peptide were used for seed elicitation. Adaptive response to salinity stress varied among black bean cultivars. Seed elicitation induced phenolic‐linked antioxidant enzyme responses. The adaptive responses of plants to abiotic stress include stimulation of secondary metabolites and endogenous antioxidant enzymes through up‐regulation of the pentose phosphate pathway (PPP). Therefore improving abiotic stress resilience in food crops through upregulation of critical redox‐linked anabolic PPP and enhancement of phenolic‐linked antioxidant enzyme responses has merit. This study evaluated the effects of seed elicitor treatments (chitosan oligosaccharide [COS] Kong Poong Bio, Jeju, Korea, and marine hydrolysate [GroPro], Icelandic Bioenhancer, Harrison, NY) to improve salinity stress resilience through up‐regulation of PPP in black bean (Phaseolus vulgaris L.) cultivars. Eclipse and Zenith cultivars were subjected to elicitor treatments (1%) and then 1 wk after germination were transplanted into three soil salinity treatments (no salt, 2–3, and 5–6 dS m−1) in greenhouse. Elicitation resulted in enhanced survival at medium salt stress (2–3 dS m−1), however none survived more than 55 to 60 d post germination under high salt stress (5–6 dS m−1). Stimulation of phenolic biosynthesis through up‐regulation of PPP was confirmed in Eclipse, while Zenith exhibited higher reliance by stimulation of endogenous antioxidant enzyme responses to counter salinity stress. GroPro induced elicitation improved total soluble phenolic content (60 d) and higher glucose‐6‐phosphate dehydrogenase (G6PDH) activity (45 d) in Eclipse. In Zenith, GroPro stimulated antioxidant enzyme responses (superoxide dismutase [SOD] and guaiacol peroxidase [GPX]) during later growth stages, while COS elicitation improved antioxidant response in early stages. Therefore seed elicitation can be a selective strategy to improve salinity stress resilience in black bean.

Establishment strategy of a rare wetland species Sparganium erectum in Korea

BackgroundTo reveal establishment strategy of Sparganium erectum, we tried to find realized niche of adults through field survey and effects of water level on the establishment process through mesocosm experiments.ResultsIn the field survey, the height and coverage of community living in deeper water were greater than those of community living in shallow water. There was no statistically significant difference (p > 0.05) in the means of water and soil properties between the two communities. In mesocosm experiments, we found no correlation between water levels and germination rates, but S. erectum seedlings have characteristics of post germination seedling buoyancy when S. erectum seeds germinated in inundation conditions. Shoot height, total leaf length, and survival rates of sinking seedlings in shallow water levels at −5, 0, and 5 cm were higher than those in deeper water levels at 10 and 20 cm. Floating seedlings established in water levels of 3 and 6 cm only. The seedlings could live up to 6 weeks in floating state but died if they were unable to establish.ConclusionsThe water level around adult S. erectum communities in the field were different from the water level at which S. erectum seedlings can survive in the mesocosm experiments. The findings provided not only understanding of S. erectum habitat characteristics but also evidence to connect historical links between the early seedlings stage and adult habitat conditions. We suggested the logical establishment strategy of S. erectum based on the data.

Adequação do teste de envelhecimento acelerado para avaliação do vigor de sementes de leucena

Leucaena leucocephala (Lam.) de Wit. (Fabaceae) is an arboreal species suitable for the composition of agroforestry systems and animal feeding in semiarid climates. Given its importance, the aim of this study was to adapt the methodology of the accelerated aging test to evaluate the vigor of L. leucocephala seeds. To this end, they proceeded to implementation of accelerated aging at 41 °C for 0, 48, 72 and 96 h in seed lots, with evaluation of the percentage of post aging germination and simple correlation with the variables germination, first count, speed of germination, electrical conductivity and seedling emergence. After 48 h of aging was no difference found on the percentage of germination of the lots, and only the 96 h exposure period showed a significant correlation with the seedling emergence test. The accelerated aging test conducted at 41 °C for 96 h is effective to differentiate lots of L. leucocephala seeds in vigor levels.

Effect of cryopreservation on germination of seeds and zygotic embryos of Calamus shendurunii an endemic rattan of Western Ghats

<p><em>Calamus shendurunii </em>is an endemic rattan of Western Ghats having restricted distribution and limited population. As a prerequisite to device an appropriate method for <em>ex situ </em>conservation of the species, desiccation and cryopreservation of seeds and zygotic embryo has been studied. Seeds extracted from ripened fruits possessed 35 per cent moisture content and exhibited 97 per cent germination. Desiccation to 28 per cent moisture content reduced the germination to 77 per cent. Desiccation below 14 per cent moisture content caused complete loss of seed germinability. Seeds stored under ambient conditions (28±2oC/60% RH) for more than seven days reduced germination to less than 40 per cent. Thus, conventional storage is not effective for their <em>ex situ </em>conservation. As an alternative method, excised zygotic embryos were subjected to desiccation and storage in liquid nitrogen. The embryos tolerated desiccation down to 5 per cent exhibiting 60 to 90 per cent germination upon culture into MS medium. Desiccated embryos subjected to liquid nitrogen exposure showed post freeze recovery and germination (80-90%) equal to that of desiccated control samples. Thus the study proved the extreme recalcitrance of <em>C. shendurunii </em>seeds and embryo cryopreservation as an alternative method of their <em>ex situ </em>conservation in gene banks.</p>

Plant derived smoke stimulation for seed germination and enhancement of crop growth: A review

Smoke is an important factor involved in fire and post fire germination cues. The role of smoke in stimulating germination was first highlighted in South Africa in a study on <italic>Audouinia capitata</italic>, a threatened fynbos species. Farmers throughout the world have traditionally used fire and smoke in grain drying practices. It is thought that these methods improve germination and seedling vigor. Smoke has been applied in agriculture mainly by two ways <italic>viz</italic>., Aerosol method and Smoke water method. In aerosol method, seeds were directly exposed to smoke generated from burning plant material. Smoke-water is one of the most convenient means of application. The biologically active compounds present in smoke readily dissolve in water and when this smoke-extract is used as a diluted solution, treated seeds of many species show a marked improvement in germination. The main active germination compound of smoke-water derived from burned plant materials and cellulose has been identified as butenolide [3-methyl-2H-furo (2, 3-c) pyran-2-one], which is effective at very low concentrations (1 ppb). The compound has recently been referred to as “karrikinolide”. Following the initial isolation of KAR1, a whole new family of plant growth regulators, termed ‘karrikins’, were identified in smoke and several related compounds have been synthesized. It is estimated that between 2 and 5 g of KAR1 is more than sufficient for 1 ha of land application rates that are commercially viable. Application of smoke in various agricultural, horticultural forage and forestry crops had found that smoke acted as a cue for breaking seeds of dormancy, improve seed germination, seedling growth, flowering, plant biomass of different plant families, <italic>Invitro</italic> plantlet regeneration and pathogen control (Anti-microbial properties).

Effect of Plant Derived Smoke on Germination and Post Germination Expression of Wheat (<i>Triticum aestivum</i> L.)

Smoke produced from burning of plant material elicits a striking increase in seed germination in various plant species. In present work, effect of plant derived smoke exposure on wheat (Triticum aestivum L.) seeds germination and post germination response has been studied in laboratory. Plant derived smoke was generated by burning of plant material (leaf, straws etc.) in a special designed furnace. Non-imbibed and imbibed seeds of wheat were exposed to plant derived smoke for 1 hr time duration. Best results were observed in non-imbibed seeds treated with plant derived smoke while imbibed seeds showed poor response to germination percentage, germination index, seedling vigor index and root shoot length. It has been proved from present study that plant derived smoke has stimulatory effect on germination & post germination response of non-imbibed seeds while it may cause inhibitory effect in imbibed seeds of wheat.

Bacteriocins from the rhizosphere microbiome - from an agriculture perspective.

Bacteria produce and excrete a versatile and dynamic suit of compounds to defend against microbial competitors and mediate local population dynamics. These include a wide range of broad-spectrum non-ribosomally synthesized antibiotics, lytic enzymes, metabolic by-products, proteinaceous exotoxins, and ribosomally produced antimicrobial peptides (bacteriocins). Most bacteria produce at least one bacteriocin. Bacteriocins are of interest in the food industry as natural preservatives and in the probiotics industry, leading to extensive studies on lactic acid bacteria (colicin produced by Escherichia coli is a model bacteriocin). Recent studies have projected use of bacteriocins in veterinary medicine and in agriculture, as biostimulants of plant growth and development and as biocontrol agents. For example, bacteriocins such as Cerein 8A, Bac-GM17, putidacin, Bac 14B, amylocyclicin have been studied for their mechanisms of anti-microbial activity. Bac IH7 promotes tomato and musk melon plant growth. Thuricin 17 (Th17) is the only bacteriocin studied extensively for plant growth promotion, including at the molecular level. Th17 functions as a bacterial signal compound, promoting plant growth in legumes and non-legumes. In Arabidopsis thaliana and Glycine max Th17 increased phytohormones IAA and SA at 24 h post treatment. At the proteome level Th17 treatment of 3-week-old A. thaliana rosettes led to >2-fold changes in activation of the carbon and energy metabolism pathway proteins, 24 h post treatment. At 250 mM NaCl stress, the control plants under osmotic-shock shut down most of carbon-metabolism and activated energy-metabolism and antioxidant pathways. Th17 treated plants, at 250 mM NaCl, retained meaningful levels of the light harvesting complex, photosystems I and II proteins and energy and antioxidant pathways were activated, so that rosettes could better withstand the salt stress. In Glycine max, Th17 helped seeds germinate in the presence of NaCl stress, and was most effective at 100 mM NaCl. The 48 h post germination proteome suggested efficient and speedier partitioning of storage proteins, activation of carbon, nitrogen and energy metabolisms in Th17 treated seeds both under optimal and 100 mM NaCl. This review focuses on the bacteriocins produced by plant-rhizosphere colonizers and plant-pathogenic bacteria, that might have uses in agriculture, veterinary, and human medicine.