Emerging paradigms in Genomics-Based crop improvement

Next generation sequencing platforms and high-throughput genotyping assays have remarkably expedited the pace of development of genomic tools and resources for several crops. Complementing the technological developments, conceptual shifts have also been witnessed in designing experimental populations. Availability of second generation mapping populations encompassing multiple alleles, multiple traits, and extensive recombination events is radically changing the phenomenon of classical QTL mapping. Additionally, the rising molecular breeding approaches like marker assisted recurrent selection (MARS) that are able to harness several QTLs are of particular importance in obtaining a “designed” genotype carrying the most desirable combinations of favourable alleles. Furthermore, rapid generation of genome-wide marker data coupled with easy access to precise and accurate phenotypic screens enable large-scale exploitation of LD not only to discover novel QTLs via whole genome association scans but also to practise genomic estimated breeding value (GEBV)-based selection of genotypes. Given refinements being experienced in analytical methods and software tools, the multiparent populations will be the resource of choice to undertake genome wide association studies (GWAS), multiparent MARS, and genomic selection (GS). With this, it is envisioned that these high-throughput and high-power molecular breeding methods would greatly assist in exploiting the enormous potential underlying breeding by design approach to facilitate accelerated crop improvement

Screening of Rhizobacteria for their plant growth promotion abilities and their interaction with Rhizobium of Mung bean

Phosphorus deficiency is a major constraint for crop production. The beneficial microorganisms in the soil convert insoluble phosphorus into soluble form for plant growth and also prevents their leaching in to water bodies. In present investigation seventy two (72) rhizobacterial isolates were obtained from Mungbean rhizospheric soil on King’s B medium, from various locations near Jodhpur. All the isolates were screened for their ability to solubilize insoluble phosphate on Pikovskaya’s medium, nitrogen fixation and auxin like substance production. Four isolates were able to solubilize phosphate ranging from 42.69 ?g TCP/ml to 90.10 ?g TCP/ml. Total fifty eight (80.55%) isolates out of seventy two rhizobacteria were able to fix atmospheric nitrogen in vitro. Rhizobacterial isolates that were able to fix environmental nitrogen and solubilize phosphate were screened for auxin like substance production. Two isolates were able to produce auxin like substances at lower amount. Among all the rhizobacterial isolates screened for their influence on rhizobial growth in vitro, twenty three (31.94%) isolates stimulated the growth of Mung bean Rhizobium. The diameter of zone of stimulation varied from 6.0 mm (MrbIV 14) to 16.5 mm (MrbII 05 and MrbIII 16) and maximum stimulation was shown by MrbIII 10 (17.5 mm). However, thirty two (44.44%) isolates were neutral to the growth of Mung bean Rhizobium

Breeding, genetics, and genomics approaches for improving Fusarium Wilt resistance in major grain legumes

Fusarium wilt (FW) disease is the key constraint to grain legume production worldwide. The projected climate change is likely to exacerbate the current scenario. Of the various plant protection measures, genetic improvement of the disease resistance of crop cultivars remains the most economic, straightforward and environmental-friendly option to mitigate the risk. We begin with a brief recap of the classical genetic efforts that provided first insights into the genetic determinants controlling plant response to different races of FW pathogen in grain legumes. Subsequent technological breakthroughs like sequencing technologies have enhanced our understanding of the genetic basis of both plant resistance and pathogenicity. We present noteworthy examples of targeted improvement of plant resistance using genomics-assisted approaches. In parallel, modern functional genomic tools like RNA-seq are playing a greater role in illuminating the various aspects of plant-pathogen interaction. Further, proteomics and metabolomics have also been leveraged in recent years to reveal molecular players and various signaling pathways and complex networks participating in host-pathogen interaction. Finally, we present a perspective on the challenges and limitations of high-throughput phenotyping and emerging breeding approaches to expeditiously develop FW-resistant cultivars under the changing climate

Traversable wormholes in bi-metric gravity

The ghost-free bi-metric gravity theory is a viable theory of gravity that explores the interaction between a massless and a massive graviton and can be described in terms of two dynamical metrics. In this paper, we present an exact static, spherically symmetric vacuum solution within this theory. The solution is spatially Schwarzschild-de Sitter, with the value of the cosmological constant determined by the graviton mass and the interaction parameters of the theory. Notably, for specific parameter ranges, the solution represents a traversable Lorentzian wormhole that violates the weak energy condition near its throat. Furthermore, we have investigated the evolution of scalar and electromagnetic fields in this wormhole spacetime and observed the presence of arbitrarily long-lived quasi-resonant modes in the quasinormal spectrum.Comment: 14 pages, 7 figure

Achievements and prospects of grass pea ( Lathyrus sativus L.) improvement for sustainable food production

Grass pea offers an attractive choice for sustainable food production, owing to its intrinsic properties including limited water requirement and drought tolerance. However, low productivity and the presence of a neurotoxin (ODAP) have posed major obstacles to its genetic improvement. Also, biotechnological investments remain limited and the genome is complex and not well understood. Strategies that allow identification of genotypes with reduced ODAP content, coupling of low ODAP content with enhanced yield, and effective seed detoxification methods merit immediate attention. Breeder-friendly genomic tools are being increasingly made available to improve the efficiency of breeding protocols. To this end, the application of next-generation sequencing has provided a means of leveraging the repertoire of genomic resources for this somewhat neglected crop. In this review, we describe progress achieved in Lathyrus genetic improvement. We also explore potential opportunities in Lathyrus research and identify urgent research needs

In vitro multiplication protocol for Curcuma mangga : Studies on carbon, cytokinin source and explant size

Mango ginger (Curcuma mangga Valeton & Zijp.) is an underutilized rhizomatous species that has been valued in tropical Asian countries as a source of vegetable, spice, salad, medicine, and essential oil. This species is hardy and requires less care for obtaining good yields. Rhizomes are the commonly used propagules for the species, which are also the economic part of the crop. Huge quantity of seed rhizomes is required to promote this crop in larger areas. An efficient in vitro multiplication protocol is one of the options to meet the planting material requirement. Effects of carbon source (glucose, fructose and sucrose) and concentration (1 and 3%, w/v), cytokinins (BAP and meta topolin) and concentration (1 mg/L and 2 mg/L), size of explants (one/ two/ three bud) and IBA treatment (0, 250, 500 and 1,000 mg/L) for concurrent ex vitro rooting cum hardening were studied. Results revealed that for facilitating efficient multiplication, the medium should be supplemented with glucose (3%) as a carbon source and meta topolin (1 mg/L) as cytokinin. Two-bud explant should be used for subculture as it promoted superior shoot proliferation. Concurrent ex vitro rooting cum hardening was possible even without auxin treatment. The present protocol could be useful for large-scale production of quality planting material of this underexploited tropical species

Translational genomics and molecular breeding for enhancing precision and efficiency in crop improvement programs: Some examples in legumes

Legumes like chickpea, pigeonpea and groundnut are protein rich, nutrient-dense, and nitrogen fixing crops. Their importance is increasingly recognized in view of the urgent need to address burgeoning malnutrition problem and to impart sustainability to cropping systems. Breeding programs in these crops have achieved great success. However, consistent improvement in genetic gains demands integration of innovative tools and technologies with crop breeding programs. Genomic resources are of paramount significance in context of improving the efficiency and precision of crop breeding schemes. The last decade has witnessed a remarkable success in generating unprecedented genomic resources in these crops, thus transforming these genomic orphans into genomic resource rich crops. These genomic resources include array-based genotyping platforms, high-resolution genetic linkage maps/HapMaps, comprehensive transcriptome assemblies and gene expression atlas, and whole genome sequences etc. Further progression from the training phase (development) to breeding (deployment) phase is marked with the current availability of a variety of molecular breeding products in these legume crops. In the present review, we discuss how deployment of the modern genomic resources such as next-generation gene discovery techniques and “gold standard experimental designs” is furthering our knowledge about the genetic underpinnings of trait variation. Also, key success stories demonstrating the power of molecular breeding in these legume crops are highlighted. It is opined that the breeding populations constantly improved by sequence-based breeding approach will greatly help improving breeding traits and the genetic gains accruable from crop breeding programs

Embracing new-generation 'omics' tools to improve drought tolerance in cereal and food-legume crops

Drought stress presents a considerable threat to the global crop production. As a dominant source of vegetarian diet, cereals and grain-legumes remain crucial to meeting the growing dietary demands worldwide. Therefore, breeding cultivars of these staple crops with enhanced drought tolerance stands to be one of the most sustainable solutions to enhance food production in changing climate. Given the context, a more focused survey of environment-defined germplasm sets is imperative to comprehend such adaptive traits. In parallel, uncovering the genetic architecture and the molecular networks that collectively contribute towards drought tolerance is urgently required through rationally combining large-scale genomics, proteomics, and metabolomics data. Also, attention needs to be directed to reasonably quantify the epistatic as well as environmental influences, thereby warranting deployment of analyses like metaquantitative trait loci (QTL) that encompass multiple environments and diverse genetic backgrounds. Further, innovative techniques like genomic selection (GS) and genome wide association study (GWAS) would help to capture the quantitative variation underlying drought tolerance. Equally importantly, integration of physiological traits-based techniques with ever-evolving 'omics' technologies and the new-generation phenotyping platforms will be of immense importance in advancing our existing knowledge about the genetically-complex and poorly-understood phenomena, such as plant drought response, and a deeper understanding would likely to provide a great impetus to the progress of crop breeding for drought tolerance