The application of third-generation sequencing (TGS) technology in genetics and genomics have provided opportunities to categorize and explore the individual genomic landscapes and mutations relevant for diagnosis and therapy using whole genome sequencing and de novo genome assembly. In general, the emerging TGS technology can produce high quality long reads for the determination of overlapping reads and transcript isoforms. However, this technology still faces challenges such as the accuracy for the identification of nucleotide bases and high error rates. Here, we surveyed 39 TGS-related tools for de novo assembly and genome analysis to identify the differences among their characteristics, such as the required input, the interaction with the user, sequencing platforms, type of reads, error models, the possibility of introducing coverage bias, the simulation of genomic variants and outputs provided. The decision trees are summarized to help researchers to find out the most suitable tools to analyze the TGS data. Our comprehensive survey and evaluation of computational features of existing methods for TGS may provide a valuable guideline for researchers.
This chapter discusses current progress and prospects of molecular breeding and strategies for developing better saline-tolerant sorghum (Sorghum bicolor) varieties. Most molecular breeding techniques for salt tolerance have been carried out in controlled environments where the plants were not exposed to any variation of the surrounding environment, producing reliable results. Due to the polygenic nature of salt tolerance, the identified quantitative trait loci (QTLs) could be false QTLs. Therefore, QTL validation is important in different plant populations and field conditions. Subsequently, marker validation is important before utilizing marker-assisted selection for screening salt-tolerant plants. Combining molecular breeding with conventional breeding can hasten the development of salt-tolerant sorghum varieties.
The study was conducted to elucidate the diverse change in the amount of cellular pigment contents of papaya leaves infected with different biological variants of Papaya ring spot virus-Papaya strain (PRSV-P). Among the naturally prevailing PRSV-P strains in Bangladesh 7 different and distinctly defined ailments of symptoms, namely Mild mosaic, mosaic, fern leaf, severe mosaic, vein clearing, leaf distortion and chlorotic leaf spot has been selected to conduct the tests of this experimentation. Different partition of cellular pigments (Chlorophyll-a, Chlorophyll-b and s-carotene) were measured to quantify the alteration of cellular components. For every partition of pigments tested, the highest alteration was found in leaf bearing leaf distortion symptom. In most of the cases the lowest shift in pigment content was determined with the leaf showing Mild Mosaic symptom followed by the mosaic, severe mosaic, vein clearing, chlorotic leaf spot, fern leaf and leaf distortion symptom, respectively. The variability in all the partition of pigments contents alteration was found to be consistently correlated with 7 symptomatic variants of PRSV-P.
Abscisic acid (ABA) is postulated to be a ubiquitous hormone that plays a central role in seed development and responses to environmental stresses of vascular plants. However, in liverworts (Marchantiophyta), which represent the oldest extant lineage of land plants, the role of ABA has been least emphasized; thus, very little information is available on the molecular mechanisms underlying ABA responses. In this study, we isolated and characterized MpABI1, an ortholog of ABSCISIC ACID INSENSITIVE1 (ABI1), from the liverwort Marchantia polymorpha. The MpABI1 cDNA encoded a 568-amino acid protein consisting of the carboxy-terminal protein phosphatase 2C (PP2C) domain and a novel amino-terminal regulatory domain. The MpABI1 transcript was detected in the gametophyte, and its expression level was increased by exogenous ABA treatment in the gemma, whose growth was strongly inhibited by ABA. Experiments using green fluorescent protein fusion constructs indicated that MpABI1 was mainly localized in the nucleus and that its nuclear localization was directed by the amino-terminal domain. Transient overexpression of MpABI1 in M. polymorpha and Physcomitrella patens cells resulted in suppression of ABA-induced expression of the wheat Em promoter fused to the beta -glucuronidase gene. Transgenic P. patens expressing MpABI1 and its mutant construct, MpABI1-d2, lacking the amino-terminal domain, had reduced freezing and osmotic stress tolerance, and associated with reduced accumulation of ABA-induced late embryogenesis abundant-like boiling-soluble proteins. Furthermore, ABA-induced morphological changes leading to brood cells were not prominent in these transgenic plants. These results suggest that MpABI1 is a negative regulator of ABA signaling, providing unequivocal molecular evidence of PP2C-mediated ABA response mechanisms functioning in liverworts.