Peggy Ozias-Akins

University of Georgia | UGA · Department of Horticulture

Key message We identified markers associated with GRD resistance after screening an Africa-wide core collection across three seasons in Uganda Abstract Groundnut is cultivated in several African countries where it is a major source of food, feed and income. One of the major constraints to groundnut production in Africa is groundnut rosette disease...

Peanut stem rot (also known as white mold), caused by the fungus Athelia rolfsii, is one of the most damaging soilborne pathogens for U.S. peanut production. The disease is mainly controlled by fungicides and by adopting cultivars with moderate resistance. Field evaluation is the main approach for evaluating plant resistance, but it is costly and l...

Early leaf spot (ELS) and late leaf spot (LLS) diseases are the two most destructive groundnut diseases in Ghana resulting in ≤ 70% yield losses which is controlled largely by chemical method. To develop leaf spot resistant varieties, the present study was undertaken to identify single nucleotide polymorphism (SNP) markers and putative candidate ge...

'Runner' and 'Virginia', the two main market types of Arachis hypogaea subspecies hypogaea , differ in several agricultural and industrial characteristics. One such trait is time to maturation (TTM), contributing to the specific environmental adaptability of each subspecies. However, little is known regarding TTM's genetic and molecular control in...

Modern plant breeding programs rely heavily on the generation of homozygous lines, with the traditional process requiring the inbreeding of a heterozygous cross for five to six generations. Doubled haploid (DH) technology, a process of generating haploid plants from an initial heterozygote, followed by chromosome doubling, reduces the process to tw...

The combination of apomixis and hybrid production is hailed as the holy grail of agriculture for the ability of apomixis to fix heterosis of F1 hybrids in succeeding generations, thereby eliminating the need for repeated crosses to produce F1 hybrids. Apomixis, asexual reproduction through seed, achieves this feat by circumventing two processes tha...

Late leaf spot (LLS) disease is an omnipresent peanut (Arachis hypogaea L.) foliar disease that causes significant yield loss. Integrating host resistance to reduce yield loss and management costs from this disease is highly desirable. In addition to disease resistance, market demand for high‐oleic peanut is on the rise due to its improved oxidativ...

Drought stress is one of the major environmental factors limiting peanut (Arachis hypogea L.) productivity. Peanut response to drought varies depending on genotypic characteristics, crop growth stages, and environmental conditions. The objective of this study was to evaluate the effects of drought stress and rehydration on symbiotic nitrogen fixati...

Plant genetic transformation is a crucial step for applying biotechnology such as genome editing to basic and applied plant science research. Its success primarily relies on the efficiency of gene delivery into plant cells and the ability to regenerate transgenic plants. In this study, we have examined the effect of several developmental regulators...

Key message A major gene controls flowering pattern in peanut, possibly encoding a TFL1-like. It was subjected to gain/loss events of a deletion and changes in mRNA expression levels, partly explaining the evolution of flowering pattern in Arachis. Abstract Flowering pattern (FP) is a major characteristic differentiating the two subspecies of cult...

Crop wild species are increasingly important for crop improvement. Peanut ( Arachis hypogaea L.) wild relatives comprise a diverse genetic pool that is being used to broaden its narrow genetic base. Peanut is an allotetraploid species extremely susceptible to peanut root-knot nematode (PRKN) Meloidogyne arenaria . Current resistant cultivars rely o...

The fatty acid composition of seed oil is a major determinant of the flavor, shelf-life, and nutritional quality of peanuts. Major QTLs controlling high oil content, high oleic content, and low linoleic content have been characterized in several seed oil crop species. Here, we employ genome-wide association approaches on a recently genotyped collec...

Blanchability is an often overlooked, but important trait for peanut breeding. The process of blanching, removing the skin, is an important step in the processing of raw nuts for manufacturing. Under strong genetic control and requiring considerable effort to phenotype, blanchability is conducive for marker-assisted selection. We used QTL sequencin...

Root nodule symbiosis (RNS) is the pillar behind sustainable agriculture and plays a pivotal role in the environmental nitrogen cycle. Most of the genetic, molecular, and cell-biological knowledge on RNS comes from model legumes that exhibit a root-hair mode of bacterial infection, in contrast to the Dalbergoid legumes exhibiting crack-entry of rhi...

Peanut improvement is limited by a narrow genetic base. However, this obstacle can be circumvented by incorporating phenotypic variability from wild, diploid Arachis species through interspecific hybridizations. In this study, four allotetraploid interspecific hybrids IpaCor 4 x ( A. ipaensis × A. correntina ) , IpaDur 4 x ( A. ipaensis × A. durane...

Peanut is an important global food crop with a narrow genetic base due to its domestication bottleneck and the ploidy barrier between it and almost all of its wild diploid relatives. Increasingly, peanut breeders have been introgressing beneficial alleles from its diploid relatives into the cultigen to improve agronomic traits along with its pathog...

Key message Expression of Cre recombinase by AtRps5a pro or AtDD45 pro enabled Cre/ lox -mediated recombination at an early embryonic developmental stage upon crossing, activating transgenes in the hybrid cowpea and tobacco. Abstract Genetic engineering ideally results in precise spatiotemporal control of transgene expression. To activate transgen...

Significance A great challenge for humanity is feeding its growing population while minimizing ecosystem damage and climate change. Here, we uncover the global benefits arising from the introduction of one wild species accession to peanut-breeding programs decades ago. This work emphasizes the importance of biodiversity to crop improvement: peanut...

Peanut rust, caused by Puccinia arachidis Speg., is a foliar disease that plagues peanut production along with early and late leaf spots, Passalora arachidicola (Hori) U. Braun and Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous, respectively. Rust can cause up to 80% yield losses without control and is widesprea...

Cultivated peanut (Arachis hypogaea L.) has a narrow genetic base and is isolated from its wild relatives. This genetic bottleneck results in a lack of strong resistance to biotic and abiotic stress. However, high levels of genetic variation and resistance exist among the wild relatives. In order to enlarge the genetic base of cultivated peanut and...

Wild, diploid Arachis species are a great source of biotic and abiotic stress resistances and tolerances for peanut breeding programs; however, these species also have undesirable characteristics such as small seed size, low yield, and weak peg strength. Peg strength has been shown to have a positive, linear relationship with yield in cultivated pe...

Genetic engineering ideally results in precise spatiotemporal control of transgene expression. To activate transgenes exclusively in a hybrid upon fertilization, we evaluated a Cre/ lox -mediated gene activation system with the Cre recombinase expressed by either AtRps5a or AtDD45 promoters that showed activity in egg cells and young embryos. In cr...

The fatty acid composition of seed oil is a major determinant of the flavor, shelf-life, and nutritional quality of peanuts. Major QTLs controlling high oil content, high oleic content, and low linoleic content have been characterized in several seed oil crop species. Here we employ genome-wide association approaches on a recently genotyped collect...

Apomixis, a type of asexual reproduction in angiosperms, results in progenies that are genetically identical to the mother plant. It is a highly desirable trait in agriculture due to its potential to preserve heterosis of F 1 hybrids through subsequent generations. However, no major crops are apomictic. Deciphering mechanisms underlying apomixis be...

Wild relatives of peanut harbor alleles that confer strong resistance to diseases and pests and adaptation to environmental stresses, traits that frequently cannot be found in Arachis hypogaea. However, most wild species are diploid, while cultivated peanut (A. hypogaea L.) is tetraploid. When crossed, they produce sterile progeny, thus hindering t...

Cultivated peanut ( Arachis hypogaea ) is one of the most widely grown food legumes in the world, being valued for its high protein and unsaturated oil contents. Drought stress is one of the major constraints that limit peanut production. This study’s objective was to identify the drought-responsive genes preferentially expressed under drought stre...

Background Time-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut ( Arachis hypogaea L). Virginia market-type peanut belongs to the late-maturing A. hypogaea subspecies with considerable variation in TTM within this market type. Consequently, planting and harvesting schedule of peanut cultivars, inc...

Flowering pattern is a major taxonomic characteristic differentiating the two main subspecies of cultivated peanut (Arachis hypogaea L.). subsp. fastigiata possessing flowers on the mainstem (MSF) and a sequential flowering pattern, whereas subsp. hypogaea lacks flowers on the mainstem and exhibits an alternate flowering pattern. This character is...

Next Generation sequencing was a step change for molecular genetics and genomics. Illumina sequencing in particular still provides substantial value to animal and plant genomics. A simple yet powerful technique, referred to as QTL sequencing (QTL-seq) is susceptible to high levels of noise due to ambiguity of alignment of short reads in complex reg...

Genome instability in newly synthesized allotetraploids of peanut has breeding implications that have not been fully appreciated. Synthesis of wild species-derived neo-tetraploids offers the opportunity to broaden the gene pool of peanut; however, the dynamics among the newly merged genomes creates predictable and unpredictable variation. Selfed pr...

Peanut root‐knot nematode (PRKN) Meloidogyne arenaria is a very destructive pathogen to which most peanut cultivars are highly susceptible. Current peanut cultivars rely on a single locus for PRKN resistance incorporated from the wild relative Arachis cardenasii, that could be overcome as a result of the emergence of new nematode populations. Thus,...

Background Time-to-maturation (TTM) is an important trait contributing to adaptability, yield and quality in peanut (Arachis hypogaea L). Virginia market-type peanut belongs to the late-maturing A. hypogaea subspecies with considerable variation in TTM within this market type. Consequently, planting and harvesting schedule of peanut cultivars inclu...

Symbiotic nitrogen fixation (SNF) inside root-nodules is a primary and sustainable source of soil nitrogen. Understanding nodule development and metabolism in crop legumes may lead to more effective SNF in agriculture. Peanut (Arachis hypogaea) is an economically important allotetraploid legume with non-canonical nodule developmental features. Rece...

Cowpea is one of the most important legume crops planted worldwide, but despite decades of effort, cowpea transformation is still challenging due to inefficient Agrobacterium‐mediated T‐DNA delivery, transgenic selection and in vitro shoot regeneration. Here, we report a highly efficient transformation system using embryonic axis explants isolated...

Late leaf spot (LLS) disease caused by Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous is prevalent among pathogens encountered in peanut (Arachis hypogaea L.) growing regions. Chemical control is expensive, sometimes inaccessible, and can be difficult to apply. One effective solution to control this disease is t...

The peanut CSSL population represents one of the ways that interspecific hybridization has been used to introduce genetic variation into cultivated peanut. The lines were developed by crossing Fleur 11, a farmer preferred spanish cultivar from West Africa with a synthetic allotetraploid. The latter was developed by crossing A. duranensis to A. ipae...

Fall armyworm (FAW) is an economically devastating, invasive pest in Sub-Saharan Africa and can be a major pest in the Americas. This pest feeds on more than 80 plant species, including peanut, and threatens the food security of millions of people who rely on these crops in Sub-Saharan Africa. An integrated pest management strategy, including resis...

Background: Engineering apomixis in sexually reproducing plants has been long desired because of the potential to fix hybrid vigor. Validating the functionality of genes originated from apomictic species that contribute to apomixis upon transfer to sexually reproducing species is an important step. The PsASGR-BABYBOOM-like (PsASGR-BBML) gene from...

Cultivated peanut (Arachis hypogaea) is an important oil, food, and feed crop worldwide. The USDA peanut germplasm collection currently contains 8,982 accessions. In the 1990s, 812 accessions were selected as a core collection on the basis of phenotype and country of origin. The present study reports genotyping results for the entire available core...

Efforts in genome sequencing in the Aspergillus genus have led to the development of quality reference genomes for several important species including A. nidulans, A. fumigatus, and A. oryzae . However, less progress has been made for A. flavus . As part of the effort of the USDA-ARS Annual Aflatoxin Workshop Fungal Genome Project, the isolate NRRL...

Key message: Two QTLs on ChrB09 significantly associated with both early and late leaf spots were identified by genome-wide association study in the US peanut mini-core collection. Early leaf spot (ELS) and late leaf spot (LLS) are two serious peanut diseases in the USA, causing tens of millions of dollars of annual economic losses. However, the g...

Although seed and pod traits are important for peanut breeding, little is known about the inheritance of these traits. A recombinant inbred line (RIL) population of 156 lines from a cross of Tifrunner x NC 3033 was genotyped with the Axiom_Arachis1 SNP array and SSRs to generate a genetic map composed of 1524 markers in 29 linkage groups (LG). The...

Cultivated peanut (Arachis hypogaea) is an important oil, food, and feed crop worldwide. The USDA peanut germplasm collection currently contains 8,982 accessions. In the 1990s, 812 accessions were selected as a core collection on the basis of phenotype and country of origin. The present study reports genotyping results for the entire available core...

Key message A total of 33 additive stem rot QTLs were identified in peanut genome with nine of them consistently detected in multiple years or locations. And 12 pairs of epistatic QTLs were firstly reported for peanut stem rot disease. Abstract Stem rot in peanut (Arachis hypogaea) is caused by the Sclerotium rolfsii and can result in great econom...

Cultivated peanut (Arachis hypogaea L.) forms root nodules to enable a symbiotic relationship with rhizobia for biological nitrogen fixation. To understand the genetic factors of peanut nodulation, it is fundamental to genetically map and clone the genes involved in nodulation. For genetic mapping, high throughput genotyping with a large number of...

Apomixis or asexual reproduction through seeds, enables the preservation of hybrid vigor. Hybrids are heterozygous and segregate for genotype and phenotype upon sexual reproduction. While apomixis, that is, clonal reproduction, is intuitively antithetical to diversity, it is rarely obligate and actually provides a mechanism to recover and maintain...

Developing markers linked to key traits has been a focus of peanut genomics in the post‐genome era. Multiple disease resistance traits have been found to be qualitative and controlled by major quantitative trait loci (QTL) or even single genes while others are more complex. Southern stem rot (stem rot in short) is a devastating disease of peanut ca...

Pod and seed size are important characteristics for the peanut industry and have been under strong selection pressure since peanut domestication. In order to dissect the genetic control of peanut pod and seed size, a recombinant inbred mapping population from a cross of Florida-07 by GP-NC WS 16 was used to determine the genomic regions associated...

Multi-parental genetic mapping populations such as nested-association mapping (NAM) have great potential for investigating quantitative traits and associated genomics regions leading to rapid discovery of candidate genes and markers. To demonstrate the utility and power of this approach, two NAM populations, NAM_Tifrunner and NAM_Florida-07, were u...

Root-knot nematode is a very destructive pathogen, to which most peanut cultivars are highly susceptible. Strong resistance is present in the wild diploid peanut relatives. Previously, QTLs controlling nematode resistance were identified on chromosomes A02, A04 and A09 of Arachis stenosperma. Here, to study the inheritance of these resistance allel...

Cowpea is one of the most important legume crops planted worldwide, especially in Sub-Saharan Africa and Asia. Despite decades of effort, genetic engineering of cowpea is still challenging due to inefficient in vitro shoot regeneration, Agrobacterium-mediated T-DNA delivery and transgenic selection. Here, we report a rapid and highly efficient cowp...

Although seed and pod traits are important for peanut breeding, little is known about the inheritance of these traits. A recombinant inbred line (RIL) population of 156 lines from a cross of Tifrunner x NC 3033 was genotyped with the Axiom_Arachis1 SNP array and SSRs to generate a genetic map composed of 1524 markers in 29 linkage groups (LG). The...

Early and late leaf spots (LLSs) are the major foliar diseases of peanut responsible for severely decreased yield in the absence of intensive fungicide spray programs. Pyramiding host resistance to leaf spots in elite cultivars is a sustainable solution to mitigate the diseases. In order to determine the genetic control of leaf spot disease resista...

Background Due to the recent domestication of peanut from a single tetraploidization event, relatively little genetic diversity underlies the extensive morphological and agronomic diversity in peanut cultivars today. To broaden the genetic variation in future breeding programs, it is necessary to characterize germplasm accessions for new sources o...

Background Tomato spotted wilt (TSW), early leaf spot (ELS), and late leaf spot (LLS) are three serious peanut diseases in the United States, causing tens of millions of dollars of annual economic losses. However, the genes underlying resistance to those diseases in peanut have not been well studied. We conducted a genome-wide association study (GW...

Like many other crops, the cultivated peanut (Arachis hypogaea L.) is of hybrid origin and has a polyploid genome that contains essentially complete sets of chromosomes from two ancestral species. Here we report the genome sequence of peanut and show that after its polyploid origin, the genome has evolved through mobile-element activity, deletions...

Early and late leaf spots are the major foliar diseases of peanut responsible for severely decreased yield in the absence of intensive fungicide spray programs. Pyramiding host resistance to leaf spots in elite cultivars is a sustainable solution to mitigate the diseases. In order to determine the genetic control of leaf spot disease resistance in...

Cultivated peanut (Arachis hypogaea L.) is an economically important crop grown around the world. Compared with the entire Arachis genus, cultivated peanut germplasm has low levels of genetic diversity for several economically important traits, resulting in the need for alternative sources of favorable alleles. Wild diploid species of Arachis are a...