DNA barcoding is a fast and reliable tool to assess and monitor biodiversity and, via community phylogenetics, to investigate ecological and evolutionary processes that may be responsible for the community structure of forests. In this study, DNA barcodes for the two widely used plastid coding regions rbcL and matK are used to contribute to identification of morphologically undetermined individuals, as well as to investigate phylogenetic structure of tree communities in 70 subplots (10 × 10m) of a 25-ha forest-dynamics plot in Brunei (Borneo, Southeast Asia). The combined matrix (rbcL + matK) comprised 555 haplotypes (from ≥154 genera, 68 families and 25 orders sensu APG, Angiosperm Phylogeny Group, 2016), making a substantial contribution to tree barcode sequences from Southeast Asia. Barcode sequences were used to reconstruct phylogenetic relationships using maximum likelihood, both with and without constraining the topology of taxonomic orders to match that proposed by the Angiosperm Phylogeny Group. A third phylogenetic tree was reconstructed using the program Phylomatic to investigate the influence of phylogenetic resolution on results. Detection of non-random patterns of community assembly was determined by net relatedness index (NRI) and nearest taxon index (NTI). In most cases, community assembly was either random or phylogenetically clustered, which likely indicates the importance to community structure of habitat filtering based on phylogenetically correlated traits in determining community structure. Different phylogenetic trees gave similar overall results, but the Phylomatic tree produced greater variation across plots for NRI and NTI values, presumably due to noise introduced by using an unresolved phylogenetic tree. Our results suggest that using a DNA barcode tree has benefits over the traditionally used Phylomatic approach by increasing precision and accuracy and allowing the incorporation of taxonomically unidentified individuals into analyses.
Co-application of biochar and biosolids to soil has potential to mitigate N leaching due to physical and chemical properties of biochar. Changes in N cycling pathways in soil induced by co-application of biological amendments could further mitigate N loss, but this is largely unexplored. The aim of this study was to determine whether co-application of a biochar and a modified biosolids product to three pasture soils differing in texture could alter the relative abundance of N cycling genes in soil sown with subterranean clover. The biosolids product contained lime and clay and increased subterranean clover shoot biomass in parallel with increases in soil pH and soil nitrate. Its co-application with biochar similarly increased plant growth and soil pH with a marked reduction in nitrate in two coarse textured soils but not in a clayey soil. While application of the biosolids product altered in silico predicted N cycling functional genes, there was no additional change when applied to soil in combination with biochar. This supports the conclusion that co-application of the biochar and biosolids product used here has potential to mitigate loss of N in coarse textured soils due to N adsoption by the biochar and independently of microbial N pathways.
Identification of plant variety and cultivar is pivotal in the agricultural sector due to the abundance of plant varieties and cultivars developed in many crop species. However, plant variety and cultivar identification via basic morphological features is problematic and challenging when differentiating closely related species not only due to their limited differences but also due to technical limitations of the process being time-consuming, labour-intensive and costly, and statistically imprecise information being available due to phenotypic plasticity. Therefore, it is imperative to have rapid and highly efficient techniques to mitigate these limitations. This review provides an overview and summarization of the development and application of molecular markers such as Random Amplified Polymorphic DNA (RAPD), Restriction Fragment Length Polymorphism (RFLP), Simple Sequence Repeats (SSR), Inter-simple sequence repeats (ISSR), Amplified Fragment Length Polymorphism (AFLP), Single nucleotide polymorphism (SNP) and DNA barcoding, High-resolution melting (HRM) and biosensor technology as potential tools in the identification of plant variety and cultivar.
microRNAs (miRNAs) are well known as major players in mammalian and plant genetic systems that act by regulating gene expression at the post-transcriptional level. These tiny molecules can regulate target genes (mRNAs) through either cleavage or translational inhibition. Recently, the discovery of plant-derived miRNAs showing cross-kingdom abilities to regulate mammalian gene expression has prompted exciting discussions among researchers. After being acquired orally through the diet, plant miRNAs can survive in the digestive tract, enter the circulatory system, and regulate endogenous mRNAs. Here, we review current knowledge regarding the cross-kingdom mechanisms of plant miRNAs, related controversies, and potential applications of these miRNAs in dietary therapy, which will provide new insights for plant miRNA investigations related to health issues in humans.
Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.
Plant cells contain a diverse repertoire of RNA-binding proteins (RBPs) that coordinate a network of post-transcriptional regulation. RBPs govern diverse developmental processes by modulating the gene expression of specific transcripts. Recent gene annotation and RNA sequencing clearly showed that heterogeneous nuclear ribonucleoprotein (hnRNP)-like proteins which form a family of RBPs, are also expressed in higher plants and serve specific plant functions. In addition to their involvement in post-transcriptional regulation from mRNA capping to translation, they are also involved in telomere regulation, gene silencing and regulation in chloroplast. Here, we review the involvement of plant hnRNP-like proteins in post-transcription regulation of RNA processes and their functional roles in control of plant developmental processes especially plant-specific functions including flowering, chloroplastic-specific mRNA regulation, long-distance phloem transportation and plant responses to environmental stresses.
Contamination of insect DNA for RAPD-PCR analysis can be a problem because many primers are non-specific and DNA from parasites or gut contents may be simultaneously extracted along with that of the insect. We measured the quantity of food ingested and assimilated by two sympatric populations of brown planthopper (BPH), Nilaparvata lugens, one from rice and the other from Leersia hexandra (Poaceae), a wetland forage grass, and we also investigated whether host plant DNA contaminates that of herbivore insects in extractions of whole insects. Ingestion and assimilation of food were reduced significantly when individuals derived from one host plant were caged on the other species. The bands, OPA3 (1.25), OPD3 (1.10), OPD3 (0.80), OPD3 (0.60), pUC/M13F (0.35), pUC/M13F (0.20), BOXAIR (0.50), peh#3 (0.50), and peh#3 (0.17) were found in both rice-infesting populations of brown planthopper and its host plant (rice). Similarly, the bands, OPA4 (1.00), OPB10 (0.70), OPD3 (0.90), OPD3 (0.80), OPD3 (0.60), pUC/ M13F (0.35), pUC/M13F (0.20), and BOXAIR (0.50) were found in both Leersia-infesting populations of brown planthopper and the host plant. So, it is clear that the DNA bands amplified in the host plants were also found in the extracts from the insects feeding on them.
MicroRNAs (miRNAs) are small RNAs (sRNAs) with approximately 21-24 nucleotides in length. They regulate the expression of target genes through the mechanism of RNA silencing. Conventional isolation and cloning of miRNAs methods are usually technical demanding and inefficient. These limitations include the requirement for high amounts of starting total RNA, inefficient ligation of linkers, high amount of PCR artifacts and bias in the formation of short miRNA-concatamers. Here we describe in detail a method that uses 80 μg of total RNA as the starting material. Enhancement of the ligation of sRNAs and linkers with the use of polyethylene glycol (PEG8000) was described. PCR artifacts from the amplification of reverse-transcribed sRNAs were greatly decreased by using lower concentrations of primers and reducing the number of amplification cycles. Large concatamers with up to 1 kb in size with around 20 sRNAs/concatamer were obtained by using an optimized reaction condition. This protocol provide researchers with a rapid, efficient and cost-effective method for the construction of miRNA profiles from plant tissues containing low amounts of total RNA, such as fruit flesh and senescent leaves.
Briskly evolving phytopathogens are dire threats to our food supplies and threaten global food security. From the recent advances made toward high-throughput sequencing technologies, understanding of pathogenesis and effector biology, and plant innate immunity, translation of these means into new control tools is being introduced to develop durable disease resistance. Effectoromics as a powerful genetic tool for uncovering effector-target genes, both susceptibility genes and executor resistance genes in effector-assisted breeding, open up new avenues to improve resistance. TALENs (Transcription Activator-Like Effector Nucleases), engineered nucleases and CRISPR (Clustered Regulatory Interspaced Short Palindromic Repeats)/Cas9 systems are breakthrough and powerful techniques for genome editing, providing efficient mechanisms for targeted crop protection strategies in disease resistance programs. In this review, major advances in plant disease management to confer durable disease resistance and novel strategies for boosting plant innate immunity are highlighted.
Tropical mountains are hot spots of biodiversity and endemism, but the evolutionary origins of their unique biotas are poorly understood. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and 'evolutionary rescue' in montane biodiversity hot spots under climate change scenarios.
Nine simple sequence repeat (SSR) markers were developed from Shorea curtisii using two different methods. One SSR locus was isolated by the commonly used method of screening by colony hybridization, and the other eight loci were isolated by a vectorette PCR method. Primer pairs were designed based on the sequences of all these SSR loci. Analysis of 40 individuals of S. curtisii from natural forest in Malaysia revealed that all SSR loci were polymorphic. Four SSR markers, Shc01, Shc04, Shc07 and Shc09, were highly polymorphic. We have also tested the applicability of these SSR printers to other species of Dipterocarpaceae using PCR amplification. Because the flanking region sequences of the S. curtisii SSRs were well conserved within this family, the SSR primers for S. curtisii can be applied to almost all species of Dipterocarpaceae.
PHAs (polyhydroxyalkanoates) have emerged as biodegradable plastics more strongly in the 20th century. A wide range of bacterial species along with fungi, plants, oilseed crops and carbon sources have been used extensively to synthesize PHA on large scales. Alteration of PHA monomers in their structures and composition has led to the development of biodegradable and biocompatible polymers with highly specific mechanical properties. This leads to the incorporation of PHA in numerous biomedical applications within the previous decade. PHAs have been fabricated in various forms to perform tissue engineering to repair liver, bone, cartilage, heart tissues, cardiovascular tissues, bone marrow, and to act as drug delivery system and nerve conduits. A large number of animal trials have been carried out to assess the biomedical properties of PHA monomers, which also confirms the high compatibility of PHA family for this field. This review summarizes the synthesis of PHA from different sources, and biosynthetic pathways and biomedical applications of biosynthesized polyhydroxyalkanoates.
The availability of data produced from various sequencing platforms offer the possibility to answer complex questions in plant research. However, drawbacks can arise when there are gaps in the information generated, and complementary platforms are essential to obtain more comprehensive data sets relating to specific biological process, such as responses to environmental perturbations in plant systems. The investigation of transcriptional regulation raises different challenges, particularly in associating differentially expressed transcription factors with their downstream responsive genes. In this paper, we discuss the integration of transcriptional factor studies through RNA sequencing (RNA-seq) and Chromatin Immunoprecipitation sequencing (ChIP-seq). We show how the data from ChIP-seq can strengthen information generated from RNA-seq in elucidating gene regulatory mechanisms. In particular, we discuss how integration of ChIP-seq and RNA-seq data can help to unravel transcriptional regulatory networks. This review discusses recent advances in methods for studying transcriptional regulation using these two methods. It also provides guidelines for making choices in selecting specific protocols in RNA-seq pipelines for genome-wide analysis to achieve more detailed characterization of specific transcription regulatory pathways via ChIP-seq.
Plants produce a wide range of secondary metabolites that play important roles in plant defense and immunity, their interaction with the environment and symbiotic associations. Sulfur-containing compounds (SCCs) are a group of important secondary metabolites produced in members of the Brassicales order. SCCs constitute various groups of phytochemicals, but not much is known about them. Findings from previous studies on SCCs were scattered in published literatures, hence SuCComBase was developed to store all molecular information related to the biosynthesis of SCCs. Information that includes genes, proteins and compounds that are involved in the SCC biosynthetic pathway was manually identified from databases and published scientific literatures. Sets of co-expression data was analyzed to search for other possible (previously unknown) genes that might be involved in the biosynthesis of SCC. These genes were named as potential SCC-related encoding genes. A total of 147 known and 92 putative Arabidopsis thaliana SCC-related genes from literatures were used to identify other potential SCC-related encoding genes. We identified 778 potential SCC-related encoding genes, 4026 homologs to the SCC-related encoding genes and 116 SCCs as shown on SuCComBase homepage. Data entries are searchable from the Main page, Search, Browse and Datasets tabs. Users can easily download all data stored in SuCComBase. All publications related to SCCs are also indexed in SuCComBase, which is currently the first and only database dedicated to plant SCCs. SuCComBase aims to become a manually curated and au fait knowledge-based repository for plant SCCs.
Oil palm, a plantation crop of major economic importance in Southeast Asia, is the predominant source of edible oil worldwide. We report the identification of the virescens (VIR) gene, which controls fruit exocarp colour and is an indicator of ripeness. VIR is a R2R3-MYB transcription factor with homology to Lilium LhMYB12 and similarity to Arabidopsis production of anthocyanin pigment1 (PAP1). We identify five independent mutant alleles of VIR in over 400 accessions from sub-Saharan Africa that account for the dominant-negative virescens phenotype. Each mutation results in premature termination of the carboxy-terminal domain of VIR, resembling McClintock's C1-I allele in maize. The abundance of alleles likely reflects cultural practices, by which fruits were venerated for magical and medicinal properties. The identification of VIR will allow selection of the trait at the seed or early-nursery stage, 3-6 years before fruits are produced, greatly advancing introgression into elite breeding material.
A natural shift is taking place in the approaches being adopted by plant scientists in response to the accessibility of systems-based technology platforms. Metabolomics is one such field, which involves a comprehensive non-biased analysis of metabolites in a given cell at a specific time. This review briefly introduces the emerging field and a range of analytical techniques that are most useful in metabolomics when combined with computational approaches in data analyses. Using cases from Arabidopsis and other selected plant systems, this review highlights how information can be integrated from metabolomics and other functional genomics platforms to obtain a global picture of plant cellular responses. We discuss how metabolomics is enabling large-scale and parallel interrogation of cell states under different stages of development and defined environmental conditions to uncover novel interactions among various pathways. Finally, we discuss selected applications of metabolomics.
Tocotrienols are forms of vitamin E that are present in several important food crops. Compared to tocopherols, less research has been conducted on these compounds because of their low bioavailability and distribution in plant tissues. Both tocotrienols and tocopherols are known for their antioxidant and anticancer activities, which are beneficial for both humans and animals. Moreover, tocotrienols possess certain properties which are not found in tocopherols, such as neuroprotective and cholesterol-lowering activities. The contents of tocotrienols in plants vary. Tocotrienols constitute more than 70% and tocopherols less than 30% of the total vitamin E content in palm oil, which is the best source of vitamin E. Accumulation of tocotrienols also occurs in non-photosynthetic tissues, such as the seeds, fruits and latex of some monocotyledonous and dicotyledonous plant species. The use of biotechnological techniques to increase the tocotrienol content in plants, their biological functions, and benefits to human health are discussed in this review.
Wild relatives of domesticated crop species harbor multiple, diverse, disease resistance (R) genes that could be used to engineer sustainable disease control. However, breeding R genes into crop lines often requires long breeding timelines of 5-15 years to break linkage between R genes and deleterious alleles (linkage drag). Further, when R genes are bred one at a time into crop lines, the protection that they confer is often overcome within a few seasons by pathogen evolution. If several cloned R genes were available, it would be possible to pyramid R genes in a crop, which might provide more durable resistance. We describe a three-step method (MutRenSeq)-that combines chemical mutagenesis with exome capture and sequencing for rapid R gene cloning. We applied MutRenSeq to clone stem rust resistance genes Sr22 and Sr45 from hexaploid bread wheat. MutRenSeq can be applied to other commercially relevant crops and their relatives, including, for example, pea, bean, barley, oat, rye, rice and maize.
The clastogenic and mutagenic effects of the insecticide Dimethoate (Cygon-2E), herbicides Atrazine, Simazine (Princep), Dicamba (Banvel D) and Picloram (Tordon) were studied using the Tradescantia-micronucleus (Trad-MCN) and Tradescantia-stamen hair mutation (Trad-SHM) assays. In clone 4430, dimethoate fumes both significantly increased the pink mutation events and reduced the number of stamen hairs per filament with increasing dosages. The pink mutation events were elevated by the liquid treatment with Picloram at 100 ppm concentration. The result of Trad-MCN test on Dimethoate fumes was not significantly different between the control and treated groups. The herbicide Atrazine showed positive effects at 10-50 ppm dose (liquid) and signs of overdose at 100 and 500 ppm concentrations. Simazine was mildly positive in elevating the MCN frequencies in the dose range of 5 to 200 ppm (liquid doses). Both Dicamba and Picloram induced a dosage-related increase in MCN frequencies in the Trad-MCN tests using Tradescantia clone 03. However, in higher dosages (200 ppm or higher), there were signs of overdose, reduction of MCN frequencies and physical damage of the leaves and buds of plant cuttings.
Four ADP-glucose pyrophosphorylase cDNA clones were isolated from mature leaves and pith of sago palm by the polymerase chain reaction (PCR) technique. Three of them (agpp10, agpp12 and agpl19) encoded the AGP large subunit, while the fourth clone (agpl1) encoded the small subunit. agpp10 and agpp12 were isolated from pith, agpl19 was isolated from mature leaves, while agpl1 from both tissues. In addition, a full-length cDNA of agpl1 was successfully isolated from a cDNA library of mature leaves by a PCR-based screening technique. Semi-quantitative analysis suggests that agpp10 and agpp12 were detectable only in pith, agpl19 only in leaves, while agpl1 was expressed in both leaves and pith tissues.