PpTFDB: A pigeonpea transcription factor database for exploring functional genomics in legumes

Genome-Wide Comparative Analysis of Five Amaranthaceae Species Reveals a Large Amount of Repeat Content

Amaranthus is a genus of C4 dicotyledonous herbaceous plant species that are widely distributed in Asia, Africa, Australia, and Europe and are used as grain, vegetables, forages, and ornamental plants. Amaranth species have gained significant attention nowadays as potential sources of nutritious food and industrial products. In this study, we performed a comparative genome analysis of five amaranth species, namely, Amaranthus hypochondriacus, Amaranthus tuberculatus, Amaranthus hybridus, Amaranthus palmeri, and Amaranthus cruentus. The estimated repeat content ranged from 54.49% to 63.26% and was not correlated with the genome sizes. Out of the predicted repeat classes, the majority of repetitive sequences were Long Terminal Repeat (LTR) elements, which account for about 13.91% to 24.89% of all amaranth genomes. Phylogenetic analysis based on 406 single-copy orthologous genes revealed that A. hypochondriacus is most closely linked to A. hybridus and distantly related to A. cruentus. However, dioecious amaranth species, such as A. tuberculatus and A. palmeri, which belong to the subgenera Amaranthus Acnida, have formed their distinct clade. The comparative analysis of genomic data of amaranth species will be useful to identify and characterize agronomically important genes and their mechanisms of action. This will facilitate genomics-based, evolutionary studies, and breeding strategies to design faster, more precise, and predictable crop improvement programs.

Amaranth Genomic Resource Database: an integrated database resource of Amaranth genes and genomics

Amaranth (Amaranthus L.) is native to Mexico and North America, where it was cultivated thousands of years ago, but now amaranth is grown worldwide. Amaranth is one of the most promising food crops with high nutritional value and belongs to the family Amaranthaceae. The high-quality genome assembly of cultivated amaranth species (A. hypochondriacus, A. cruentus) and wild/weedy species (A. tuberculatus, A. hybridus, and A. palmeri) has already been reported; therefore, we developed an Amaranth Genomic Resource Database (AGRDB) to provide access to all the genomic information such as genes, SSRs, SNPs, TFs, miRNAs, and transporters in one place. The AGRDB database contains functionally annotated gene information with their sequence details, genic as well as genomic SSRs with their three sets of primers, transcription factors classified into different families with their sequence information and annotation details, putative miRNAs with their family, sequences, and targeted gene details, transporter genes with their superfamily, trans-membrane domain details, and details of genic as well as nongenic SNPs with 3' and 5' flanking sequence information of five amaranth species. A database search can be performed using the gene ID, sequence ID, sequence motif, motif repeat, family name, annotation keyword, scaffold or chromosome numbers, etc. This resource also includes some useful tools, including JBrowse for the visualization of genes, SSRs, SNPs, and TFs on the respective amaranth genomes and BLAST search to perform a BLAST search of the user's query sequence against the amaranth genome as well as protein sequences. The AGRDB database will serve as a potential platform for genetic improvement and characterization of this futuristic crop. The AGRDB database will be accessible via the link: http://www.nbpgr.ernet.in:8080/AmaranthGRD/.

TinoTranscriptDB: A Database of Transcripts and Microsatellite Markers of Tinospora cordifolia, an Important Medicinal Plant

Tinospora cordifolia, commonly known as “Giloe” in India, is a shrub belonging to the family Menispermaceae. It is an important medicinal plant known for its antipyretic, anti-inflammatory, antispasmodic, and antidiabetic properties and is used in the treatment of jaundice, gout, and rheumatism. Despite its economic importance, the limited information related to its genomic resources prohibits its judicious exploitation through molecular breeding or biotechnological approaches. In this study, we generated a meta-transcriptome assembly of 43,090 non-redundant transcripts by merging the RNASeq data obtained from Roche 454 GS-FLX, and Illumina platforms, and report the first transcriptome-based database for simple sequence repeats and transcription factors (“TinoTranscriptDB” (Tinospora cordifolia Transcriptome Database)). We annotated 26,716 (62%) of the total transcripts successfully from National Center for Biotechnology Information non-redundant protein (NCBI-NR), gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Swiss-Prot, and Pfam databases. This database contains information of 2620 perfect simple sequence repeats (P-SSRs) with a relative abundance of 340.12 (loci/Mb), and relative density of 6309.29 (bp/Mb). Excluding mono-nucleotides, the most abundant SSR motifs were tri-nucleotides (54.31%), followed by di-nucleotides (37.51%), tetra-nucleotides (4.54%), penta-nucleotides (3.16%) and hexa-nucleotides (0.45%). Additionally, we also identified 4,311 transcription factors (TFs) and categorized them into 55 sub-families. This database is expected to fill the gap in genomic resource availability in T. cordifolia and thus accelerate molecular breeding and related functional and other applied studies aimed towards genetic improvements of T. cordifolia and related species.

Understanding the Effect of Structural Diversity in WRKY Transcription Factors on DNA Binding Efficiency through Molecular Dynamics Simulation

A precise understanding of the molecular mechanism involved in stress conditions has great importance for crop improvement. Biomolecules, such as WRKY proteins, which are the largest transcription factor family that is widely distributed in higher plants, plays a significant role in plant defense response against various biotic and abiotic stressors. In the present study, an extensive homology-based three-dimensional model construction and subsequent interaction study of WRKY DNA-binding domain (DBD) in CcWRKY1 (Type I), CcWRKY51 (Type II), and CcWRKY70 (Type III) belonging to pigeonpea, a highly tolerant crop species, was performed. Evaluation of the generated protein models was done to check their reliability and accuracy based on the quantitative and qualitative parameters. The final model was subjected to investigate the comparative binding analysis of different types of WRKY–DBD with DNA-W-box (a cis-acting element) by protein–DNA docking and molecular dynamics (MD) simulation. The DNA binding specificity with WRKY variants was scrutinized through protein–DNA interaction using the HADDOCK server. The stability, as well as conformational changes of protein–DNA complex, was investigated through molecular dynamics (MD) simulations for 100 ns using GROMACS. Additionally, the comparative stability and dynamic behavior of each residue of the WRKY–DBD type were analyzed in terms of root mean square deviation (RMSD), root mean square fluctuation (RMSF)values of the backbone atoms for each frame taking the minimized structure as a reference. The details of DNA binding activity of three different types of WRKY–DBD provided here will be helpful to better understand the regulation of WRKY gene family members in plants.

Understanding the Role of the WRKY Gene Family under Stress Conditions in Pigeonpea (Cajanus Cajan L.)

Pigeonpea (Cajanus cajan L.), a protein-rich legume, is a major food component of the daily diet for residents in semi-arid tropical regions of the word. Pigeonpea is also known for its high level of tolerance against biotic and abiotic stresses. In this regard, understanding the genes involved in stress tolerance has great importance. In the present study, identification, and characterization of WRKY, a large transcription factor gene family involved in numerous biological processes like seed germination, metabolism, plant growth, biotic and abiotic stress responses was performed in pigeonpea. A total of 94 WRKY genes identified in the pigeonpea genome were extensively characterized for gene-structures, localizations, phylogenetic distribution, conserved motif organizations, and functional annotation. Phylogenetic analysis revealed three major groups (I, II, and III) of pigeonpea WRKY genes. Subsequently, expression profiling of 94 CcWRKY genes across different tissues like root, nodule, stem, petiole, petal, sepal, shoot apical meristem (SAM), mature pod, and mature seed retrieved from the available RNAseq data identified tissue-specific WRKY genes with preferential expression in the vegetative and reproductive stages. Gene co-expression networks identified four WRKY genes at the center of maximum interaction which may play a key role in the entire WRKY regulations. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) expression analysis of WRKY genes in root and leaf tissue samples from plants under drought and salinity stress identified differentially expressed WRKY genes. The study will be helpful to understand the evolution, regulation, and distribution of the WRKY gene family, and additional exploration for the development of stress tolerance cultivars in pigeonpea and other legumes crops.

Towards Exploitation of Adaptive Traits for Climate-Resilient Smart Pulses

Pulses are the main source of protein and minerals in the vegetarian diet. These are primarily cultivated on marginal lands with few inputs in several resource-poor countries of the world, including several in South Asia. Their cultivation in resource-scarce conditions exposes them to various abiotic and biotic stresses, leading to significant yield losses. Furthermore, climate change due to global warming has increased their vulnerability to emerging new insect pests and abiotic stresses that can become even more serious in the coming years. The changing climate scenario has made it more challenging to breed and develop climate-resilient smart pulses. Although pulses are climate smart, as they simultaneously adapt to and mitigate the effects of climate change, their narrow genetic diversity has always been a major constraint to their improvement for adaptability. However, existing genetic diversity still provides opportunities to exploit novel attributes for developing climate-resilient cultivars. The mining and exploitation of adaptive traits imparting tolerance/resistance to climate-smart pulses can be accelerated further by using cutting-edge approaches of biotechnology such as transgenics, genome editing, and epigenetics. This review discusses various classical and molecular approaches and strategies to exploit adaptive traits for breeding climate-smart pulses.

Malaysian Carica papaya L. var. Eksotika: Current Research Strategies Fronting Challenges

Carica papaya L. or commonly known as papaya, is a major tropical crop consumed worldwide either as a vegetable or fresh fruit or processed products. In Malaysia, papaya was initially planted as a smallholder crop throughout the country. Eventually after 15 years of breeding and selection, a new variety, named C. papaya L. var. Eksotika, was released by the Malaysian Agricultural Research and Development Institute (MARDI) in 1987. This event changed the outlook of papaya planting from a smallholder crop to a plantation crop. Despite the blooming papaya business, the industry faced various disease issues that jeopardize its future. The most devastating was the papaya dieback disease, which affected approximately 800 hectares of plantation, destroyed approximately 1 million trees nationwide with total losses estimated at US$ 58 million. Even though Eksotika is a favored commercial variety with good eating and aesthetic quality fruit, its potential for more lucrative distant markets is tarnished with its short-shelf life fruits. Several strategies had been reported to address the challenges faced by Eksotika specifically against the dieback disease and the fruit's short shelf-life. This review focuses on C. papaya L. var. Eksotika particularly on the strategies to address the challenges faced in order to sustain the economic value of this crop plant, which had contributed significantly to the Malaysian economy.