This review focuses on investigation in acquisition of embryogenic competence during somatic embryogenesis in the last five decades. In tissue culture, differentiated somatic cells acquire ...embryogenic competence and proliferate as embryogenic cells during the induction phase. These embryogenic cells are important because they differentiate to form somatic embryos at a later time. Various molecular and structural markers for detecting embryogenic cells or enhancing embryogenic competence are summarized and implications of the findings are discussed.
•Agar is a sulfated galactan synthesized in the cell wall matrix of red seaweeds.•The gaps in current knowledges on agar biosynthesis in red seaweeds are reviewed.•Development of molecular markers ...for the selection of seaweeds is also discussed.
Agar is a jelly-like biopolymer synthesized by many red seaweeds as their major cell wall component. Due to its excellent rheological properties, it has been exploited commercially for applications in food, cosmetic, pharmaceutical, biomedical and biotechnology industries. Despite its multiple uses, the biosynthesis of this phycocolloid is not fully understood. The current knowledge on agar biosynthesis is inferred from plant biochemistry and putative pathways for ulvan and alginate biosynthesis in green and brown seaweeds, respectively. In this review, the gaps in our current knowledge on agar biosynthetic pathway are discussed, focusing on the biosynthesis of agar precursors, elongation of agar polysaccharide chain and side chain modification. The development of molecular markers for the screening of desired seaweeds for industrial exploitation is also discussed.
Agar, a gelatinous polysaccharide in the cell wall of many red algal species, is widely used as a gelling, thickening and stabilizing agent. The commercial value of seaweed is judged by their agar ...content and gel quality. Seaweed materials with higher agar yield and better gelling properties are desired due to the growing demand for agar in the global market. Agar biosynthesis in seaweeds is affected by genetic variations, developmental stages and environmental conditions, while different agar extraction techniques can also affect the yield and quality of agar. In this paper, the effects of different physiological states of seaweed, abiotic and biotic factors, seaweed storage and agar extraction techniques on the agar yield and gelling characteristics, are reviewed. This information is important as a guide for marine aquaculture of potential agarophytes and the possible effects of climate change on the stock of this natural resource.
Knowledge of heat-tolerant/sensitive cultivars based on morpho-physiological indicators and an understanding of the action and interaction of different genes in the molecular network are critical for ...genetic improvement. To screen these indicators, the physiological performance of two different varieties of white and red cabbages (
var. capitate
and
, respectively) under heat stress (HS) and non-stress (NS) was evaluated. Cultivars that showed considerable cell membrane thermostability and less reduction in chlorophyll content with better head formation were categorized as the heat-tolerant cultivars (HTC), while those with reduction in stomatal conductance, higher reduction incurred in chlorophyll and damage to thylakoid membranes are categorized as the heat-sensitive cultivars (HSC). Expression profiling of key genes in the HS response network, including
(HEAT SHOCK PROTEIN 70),
(SCARECROW-LIKE 13) and
(transcriptional regulator DNA POLYMERASE II SUBUNIT B3-1 (DPB3-1))/NUCLEAR FACTOR Y SUBUNIT C10 (NF-YC10), were evaluated in all cultivars under HS compared to NS plants, which showed their potential as molecular indicators to differentiate HTC from HSC. Based on the results, the morphophysiological and molecular indicators are applicable to cabbage cultivars for differentiating HTC from HSC, and potential target genes for genome editing were identified for enhancing food security in the warmer regions of the world.
Ganoderma produces lignolytic enzymes that can degrade the lignin component of plant cell walls, causing basal stem rot to oil palms. Nitrogen sources may affect plant tolerance to root pathogens ...while hydrogen peroxide (H2O2), salicylic acid (SA) and jasmonic acid (JA) play important roles in plant defense against pathogens. In this study, we examined the expression of genes encoding manganese peroxidase (MnP) and laccase (Lac) in Ganoderma boninense treated with different nitrogen sources (ammonium nitrate, ammonium sulphate, sodium nitrate and potassium nitrate), JA, SA and H2O2. Transcripts encoding MnP and Lac were cloned from G. boninense. Of the three GbMnP genes, GbMnP_U6011 was up-regulated by all nitrogen sources examined and H2O2 but was down-regulated by JA. The expression of GbMnP_U87 was only up-regulated by JA while GbMnP_35959 was up-regulated by ammonium nitrate but suppressed by sodium nitrate and down-regulated by H2O2. Among the three GbLac genes examined, GbLac_U90667 was up-regulated by ammonium nitrate, JA, SA and H2O2; GbLac_U36023 was up-regulated by JA and H2O2 while GbLac_U30636 was up-regulated by SA but suppressed by ammonium sulphate, sodium nitrate, JA and H2O2. Differential expression of these genes may be required by their different functional roles in G. boninense.
Abiotic stress reduces plant growth and crop productivity. However, the mechanism underlying posttranscriptional regulations of stress response remains elusive. Herein, we report the ...posttranscriptional mechanism of nucleocytoplasmic RNA transport of stress‐responsive transcripts mediated by EgRBP42, a heterogeneous nuclear ribonucleoprotein‐like RNA‐binding protein from oil palm, which could be necessary for rapid protein translation to confer abiotic stress tolerance in plants. Transgenic Arabidopsis overexpressing EgRBP42 showed early flowering through alteration of gene expression of flowering regulators and exhibited tolerance towards heat, cold, drought, flood, and salinity stresses with enhanced poststress recovery response by increasing the expression of its target stress‐responsive genes. EgRBP42 harbours nucleocytoplasmic shuttling activity mediated by the nuclear localization signal and the M9‐like domain of EgRBP42 and interacts directly with regulators in the nucleus, membrane, and the cytoplasm. EgRBP42 regulates the nucleocytoplasmic RNA transport of target stress‐responsive transcripts through direct binding to their AG‐rich motifs. Additionally, EgRBP42 transcript and protein induction by environmental stimuli are regulated at the transcriptional and posttranscriptional levels. Taken together, the posttranscriptional regulation of RNA transport mediated by EgRBP42 may change the stress‐responsive protein profiles under abiotic stress conditions leading to a better adaptation of plants to environmental changes.
This study shows that EgRBP42, an RNA‐binding protein from oil palm, is involved in plant response to abiotic stress. Overexpression of EgRBP42 in Arabidopsis conferred drought, flood, salinity, and cold tolerance with early flowering. EgRBP42 harbours nucleocytoplasmic shuttling activity, and it interacts directly and is colocalized with stress‐responsive mRNAs in response to abiotic stresses, suggesting that EgRBP42 may be involved in intracellular transport of stress‐responsive RNAs in response to abiotic stress.
Vandachostylis
‘Sri-Siam’ is a fragrant orchid, suitable as a potted plant for the floriculture and perfumery industries due to its sweet citrus-like fragrance. Fragrance from the flowers was ...captured using SPME and subjected to GC–MS analysis. A transcriptome library was constructed from the tepals for sequencing using the Illumina MiSeq Desktop Sequencer and for de novo assembly using the CLC Genomic Workbench version 6.0. All de novo assembly sequences were subjected to bioinformatics analyses including BLASTx analysis, functional annotations and mapping of the annotated genes/gene products to the KEGG database using the Blast2go Pro software. GC–MS analysis reveals the fragrance are dominated by 68.73% monoterpenes, 11.26% esters, 4.20% sesquiterpenes and traces of alcohols (1.20%), dissimilar to both its parents. Analysis of the de novo assembly sequences generated 45,585 contigs which identified 14 fragrance-related transcripts. Information on the fragrance constituents and fragrance-related transcripts is deemed important as a reference for current and future work of using this hybrid in the breeding process of commercially valuable fragrant orchids.
The aim of the study was to determine the effect of seed production environment in Sri Lanka on seed development, maturation, and subsequent seed quality. The experiment was conducted at six ...production environments, three locations (Mahailluppalama (M1), Polonnaruwa (POL), and Aluttarama (ALU), over two planting cycles (P1, P2). Seed development and maturation, seed and seedling quality characteristics were evaluated at five reproductive (R6, R7, R8, R8 + 5 and R8 + 10) maturity stages. The study infers that production environment at the late reproductive (LR) stage (R6–R8) was critical in determining the seed quality. If the LR stage coincided with cumulative rainfall (RF) over 100 mm or above 75% relative humidity (RH), categorized as wet environment, around 27.5 days was required for the completion of seed maturation compared with only 17.5 days in dry environment. Seed lots from dry environment during LR stage surpassed the minimum quality standards (75% final germination, germination index of 300, germination rate index of 25% per day, seedling vigor index of 2500 and 15 µmol/min/mg FW catalase activity) at maturity stage R7 onwards, while this only occurred at maturity stage R8 for wet environment. A significant negative correlation (r = −0.50 **) was observed between glucose content, antioxidant enzyme activities and germination percentage. In conclusion, the findings provide useful information for the expansion of areas for seed production in Sri Lanka.
Soybean seed vigour declines with increase in storage duration, due to ageing, which can be alleviated through seed priming. The objective of this study was to investigate the effects of Humic acid ...(HA) priming on germination, vigour and seedling performance under laboratory and greenhouse conditions with two soil moisture level 50% and 80% field capacity (FC). Seeds stored for 12 months having 60% germination were primed either with 0.2 g/L HA solution or distilled water (hydro-primed) at 25 °C for 1, 3, 5 and 7 h. Non-primed dry seeds were used as control, giving nine treatment combinations. Various germination traits mean germination time (MGT), final germination percentage (FG%), germination rate index (GRI), seedling emergence percentage (SEP), mean emergence time (MET), seedling quality traits seedling vigor index (SVI), shoot length, root length, root volume, antioxidant enzyme activities catalase (CAT), peroxidase (POD), lipid peroxidation malondialdehyde (MDA) and electrical conductivity (EC) were determined. A germination test in the laboratory was conducted as single factor (nine priming treatments), while the greenhouse experiment was conducted as two factors 2 soil moisture level (50 and 80% FC) and 9 priming treatments. The results indicated that seeds primed with HA for 5 h was able to reinstate the CAT activities (25%), POD activities (50%) and reduced EC (51%) and MDA content (40%) compared with non-primed seeds, reduced the MET (from 4.3 to 3.5 days), increased FG% (from 62 to 71%), GRI (15.6–21.1) and SEP (from 35 to 54%) and (from 60 to 72%) at 50% FC level and 80% FC level, respectively. A strong negative correlation (r = −0.80 **) was found between MDA content and GRI, while CAT and POD activities had positive correlation with GRI r= 0.67 ** and r = 0.56 **, respectively. Thus, priming with 0.2 g/L HA for 5 h improved the vigour of minimally deteriorated soybean seeds resulting in increased emergence with more uniform field establishment.
Vanda Mimi Palmer (VMP) is commercially valuable for its strong fragrance but little is known regarding the fragrance production and emission sites on the flowers.
Olfactory perception detected ...fragrance only from the petals and sepals. Light and Environmental Scanning Electron microscopy analyses on fresh tissues showed distributions of stomata and trichomes concentrated mostly around the edges. These results paralleled the rich starch deposits and intense neutral red stain, indicating strong fragrance and trichomes as potential main fragrance release sites. Next Generation Sequencing (NGS) transcriptomic data of adaxial and abaxial layers of the tissues showed monoterpene synthase transcripts specifically linalool and ocimene synthases distributed throughout the tissues. qPCR analyses taken at different time points revealed high levels of linalool and ocimene synthases transcripts in the early morning with maximal level at 4.00 am but remained low throughout daylight hours.
Knowledge of the VMP floral anatomy and its fragrance production characteristics, which complemented our previous molecular and biochemical data on VMP, provided additional knowledge on how fragrance and flower morphology are closely intertwined. Further investigation on the mechanisms of fragrance biosynthesis and interaction of potential pollinators would elucidate the evolution of the flower morphology to maximize the reproduction success of this plant.
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