Abhishek Bohra

The significance of a range legume Stylosanthes spp. is long established in grassland ecosystems. However, its potential for the nutritional security of livestock remains underexploited. A better understanding of floral behavior will assist in its improvement through improved hybridization techniques, seed production and breeding schemes. Only limited studies have been conducted on the floral biology of Stylosanthes spp. The current study focused on floral morphology, anthesis, longevity and pollen viability of four Stylosanthes spp. viz., S. hamata, S. seabrana, S. viscosa and S. scabra. The anthesis time varied among the Stylosanthes species studied here and the maximum anthesis occurred during Indian Standard Time (IST) from 8.00 AM to 10.00 AM. The flower longevity of Stylosanthes spp., lasted for a day after the anthesis. All the species were found to be protandrous, as pollen dehiscence occurred 1 to 2 hours before anthesis. The time of the highest pollen viability (85.08 +/- 2.16%) coincided with stigma receptivity. After two hours of anthesis, higher receptivity and maximum activity of stigma was observed in S. hamata compared to other Stylosanthes species. Furthermore, S. scabra showed the maximum pollen count while estimating a number of pollen per anther and flower.

Wheat is among the most produced grain crops of the world and alone provides a fifth of the world’s calories and protein. Wheat has played a key role in food security since the crop served as a Neolithic founder crop for the establishment of world agriculture. Projections showing a decline in global wheat yields in changing climates imply that food security targets could be jeopardized. Increased frequency and intensity of drought occurrence is evident in major wheat-producing regions worldwide, and notably, the wheat-producing area under drought is projected to swell globally by 60% by the end of the 21st century. Wheat yields are significantly reduced due to changes in plant morphological, physiological, biochemical, and molecular activities in response to drought stress. Advances in wheat genetics, multi-omics technologies and plant phenotyping have enhanced the understanding of crop responses to drought conditions. Research has elucidated key genomic regions, candidate genes, signalling molecules and associated networks that orchestrate tolerance mechanisms under drought stress. Robust and low-cost selection tools are now available in wheat for screening genetic variations for drought tolerance traits. New breeding techniques and selection tools open a unique opportunity to tailor future wheat crop with optimal trait combinations that help withstand extreme drought. Adoption of the new wheat varieties will increase crop diversity in rain-fed agriculture and ensure sustainable improvements in crop yields to safeguard the world’s food security in drier environments.

Adzuki bean (Vigna angularis) is an important legume crop cultivated in over 30 countries worldwide. We developed a high-quality chromosome-level reference genome of adzuki bean cultivar Jingnong6 by combining PacBio Sequel long-read sequencing with short-read and Hi-C technologies. The assembled genome covers 97.8% of the adzuki bean genome with a contig N50 of approximately 16 Mb and a total of 32 738 protein-coding genes. We also generated a comprehensive genome variation map of adzuki bean by whole-genome resequencing (WGRS) of 322 diverse adzuki beans accessions including both wild and cultivated. Furthermore, we have conducted comparative genomics and a genome-wide association study (GWAS) on key agricultural traits to investigate the evolution and domestication. GWAS identified several candidate genes, including VaCycA3;1, VaHB15, VaANR1 and VaBm, that exhibited significant associations with domestication traits. Furthermore, we conducted functional analyses on the roles of VaANR1 and VaBm in regulating seed coat colour. We provided evidence for the highest genetic diversity of wild adzuki (Vigna angularis var. nipponensis) in China with the presence of the most original wild adzuki bean, and the occurrence of domestication process facilitating transition from wild to cultigen. The present study elucidates the genetic basis of adzuki bean domestication traits and provides crucial genomic resources to support future breeding efforts in adzuki bean.

This contributed volume explores the latest breakthroughs in genetic and genomic resources for enhancing biotic stress responses in grain legumes – including minor ones. It covers the advances made to date, including gene identification, transcriptomics, proteomics, transgenics, genome editing, genomic selection, epigenetic breeding, and speed breeding related to different biotic stresses. Authored by crop-specific experts, the chapters in this book are essential resources for those directly involved in improving grain legume crops.

Legumes play a vital role in ensuring food and nutritional security, enhancing soil quality, and promoting environmental sustainability. Rich in protein, they are essential in preventing hunger and malnutrition while adding to dietary diversity. However, as these crops are commonly grown in marginal lands with poor inputs, they are highly susceptible to biotic stresses such as diseases and pests, which can cause significant yield losses. This book consolidates all available knowledge about genetic and genomic aspects of biotic stress responses in various grain legumes.

It is a must-have resource for all stakeholders involved in grain legume improvement. Whether you are a breeder, pathologist, biotechnologist, seed production specialist, market manager, graduate or post-graduate student, or any other industry professional, this book serves as an excellent guide to help you stay at the forefront of grain legume improvement.

Biotic stresses compromise grain legume production worldwide. Deployment of the resistant varieties of grain legume crops that can withstand high disease/pest pressures is the straightforward and sustainable approach for stress management. A high resistance level of crop plants not only reduces the overall production costs but also poses no or little risk to the environment. Modern genomic technologies have deepened our understanding of the genetic determinants governing a plant’s resistance to diseases and pests and plant–pathogen/pest interactions. In-depth knowledge of the plant stress response would help devise sustainable strategies for management of biotic stresses in legume crops. The growing DNA sequence information on large germplasm collections and experimental populations of legume crops expands our capacity to characterize and utilize the untapped diversity of plant traits that confer resistance to major biotic stresses. Advanced systems have helped relieve the long-standing “phenotyping bottleneck” through imparting precision, accuracy, high throughput, and cost-effectiveness to the plant phenotyping procedures. The wealth of genetic sequence information, large-scale screening data, and multi-omics datasets available opens new avenues for identification and validation of target genomic regions and associated superior haplotypes for introgression breeding and gene editing. Successful application of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) system in model legumes (e.g., Medicago truncatula, Lotus japonicus, soybean) holds great promise for further extending the modern gene editing technology to other grain legume crops for improving stress responses, with emergence of new ways to overcome their transformation recalcitrance. The haplotype catalogues and trait packages for biotic stress tolerance derived from growing genetic sequence and plant phenotyping data, when integrated with refined introgression approaches, provide breeders with an unprecedented resource for rapidly modifying plant traits to overcome stressful conditions.

Contiguous genome sequence assemblies will help us to realize the full potential of crop translational genomics. Recent advances in sequencing technologies, especially long-read sequencing strategies, have made it possible to construct gapless telomere-to-telomere (T2T) assemblies, thus offering novel insights into genome organization and function. Plant genomes pose unique challenges, such as a continuum of ancient to recent polyploidy and abundant highly similar and long repetitive elements. Owing to progress in sequencing approaches, for most crop plants, chromosome-scale reference genome assemblies are available, but T2T assembly construction remains challenging. Here we describe methods for haplotype-resolved, gapless T2T assembly construction in plants, including various crop species. We outline the impact of T2T assemblies in elucidating the roles of repetitive elements in gene regulation, as well as in pangenomics, functional genomics, genome-assisted breeding and targeted genome manipulation. In conjunction with sequence-enriched germplasm repositories, T2T assemblies thus hold great promise for basic and applied plant sciences.Contiguous genome sequence assemblies will help us to realize the full potential of crop translational genomics. Recent advances in sequencing technologies, especially long-read sequencing strategies, have made it possible to construct gapless telomere-to-telomere (T2T) assemblies, thus offering novel insights into genome organization and function. Plant genomes pose unique challenges, such as a continuum of ancient to recent polyploidy and abundant highly similar and long repetitive elements. Owing to progress in sequencing approaches, for most crop plants, chromosome-scale reference genome assemblies are available, but T2T assembly construction remains challenging. Here we describe methods for haplotype-resolved, gapless T2T assembly construction in plants, including various crop species. We outline the impact of T2T assemblies in elucidating the roles of repetitive elements in gene regulation, as well as in pangenomics, functional genomics, genome-assisted breeding and targeted genome manipulation. In conjunction with sequence-enriched germplasm repositories, T2T assemblies thus hold great promise for basic and applied plant sciences.

Chickpea (Cicer arietinum L.)-an important legume crop cultivated in arid and semiarid regions-has limited genetic diversity. Efforts are being undertaken to broaden its diversity by utilizing its wild relatives, which remain largely unexplored. Here, we present the Cicer super-pangenome based on the de novo genome assemblies of eight annual Cicer wild species. We identified 24,827 gene families, including 14,748 core, 2,958 softcore, 6,212 dispensable and 909 species-specific gene families. The dispensable genome was enriched for genes related to key agronomic traits. Structural variations between cultivated and wild genomes were used to construct a graph-based genome, revealing variations in genes affecting traits such as flowering time, vernalization and disease resistance. These variations will facilitate the transfer of valuable traits from wild Cicer species into elite chickpea varieties through marker-assisted selection or gene-editing. This study offers valuable insights into the genetic diversity and potential avenues for crop improvement in chickpea.

Professor Rajeev K. Varshney's transformative impact on crop genomics, genetics, and agriculture is the result of his passion, dedication, and unyielding commitment to harnessing the potential of genomics to address the most pressing challenges faced by the global agricultural community. Starting from a small town in India and reaching the global stage, Professor Varshney's academic and professional trajectory has inspired many scientists active in research today. His ground-breaking work, especially his effort to list orphan tropical crops to genomic resource-rich entities, has been transformative. Beyond his scientific achievements, Professor Varshney is recognized by his colleagues as an exemplary mentor, fostering the growth of future researchers, building institutional capacity, and strengthening scientific capability. His focus on translational genomics and strengthening seed system in developing countries for the improvement of agriculture has made a tangible impact on farmers' lives. His skills have been best utilized in roles at leading research centres where he has applied his expertise to deliver a new vision for crop improvement. These efforts have now been recognized by the Royal Society with the award of the Fellowship (FRS). As we mark this significant milestone in his career, we not only celebrate Professor Varshney's accomplishments but also his wider contributions that continue to transform the agricultural landscape.