The results indicate that the genetic architecture of corn in response to MaYMV is complex, and that developing immune cultivars may not be achievable using natural sources of genetic variation, but this study provides a foundation for breeding maize with improved tolerance and advances the understanding of host response to MaYMV infection.
Abstract
Maize yellow mosaic virus (MaYMV) is an emerging polerovirus of corn and other grass species. Due to its broad host range and transmission by multiple aphid species, management strategies such as crop rotations, pesticides, and weed control are likely ineffective. Therefore, resistant cultivars are needed. In this study, we characterized the Goodman 282 maize diversity panel for its response to MaYMV. Leaf reddening symptoms were quantified, and diagnostics were performed to assess infection and obtain a semi-quantitative measure of virus titer. Low titer lines and inbreds representing symptomatic and asymptomatic infected phenotypic classes were characterized further by RT-qPCR. Genome-wide association studies were performed using MLM, FarmCPU, and BLINK models to identify SNPs associated with disease. In total, 64% of lines were asymptomatically infected. Although all lines tested positive for infection by MaYMV in at least one experiment, Ky226 had reduced viral titer compared to other lines. Sixteen quantitative trait nucleotides (QTN) were identified, many of which are linked to genes implicated in flavonoid, carotenoid, and phenolic metabolic pathways as well as antiviral defense. Notably, a QTN associated with a chalcone synthase, a key enzyme in the flavonoid biosynthesis pathway, was detected by even the most conservative, MLM model. These results indicate that the genetic architecture of corn in response to MaYMV is complex, and that developing immune cultivars may not be achievable using natural sources of genetic variation. However, this study provides a foundation for breeding maize with improved tolerance and advances our understanding of host response to MaYMV infection.
Maize streak virus (MSV) is a major constraint on maize production in the dry and hot tropics, where susceptible cultivars suffer complete yield loss. The objective of this study was to assess the response of tropical-environment-adapted maize inbred lines for MSV resistance and major agronomic traits to identify parental lines for resistance breeding.
Seventy-four inbred lines, including six controls, were evaluated under artificial MSV inoculation over two seasons using an 8 × 10 alpha lattice design.
A significant variability (P ≤ 0.05) was detected among genotypes for MSV resistance and yield components. Area under the disease progress curve (AUDPC) ranged from 0.00 to 240.6, disease incidence from 0 to 100%, and grain yield from 0.54 to 4.99 t ha⁻¹. Genotype-by-season interactions were significant for disease incidence and yield-related traits, with most traits showing moderate to high heritability. MSV disease parameters were negatively correlated with grain yield and agronomic traits. Elite parental lines MM05, MM17, MM19, and MM25 were identified as valuable donor parents combining MSV resistance with superior grain yield and favourable agronomic performance. Lines MM10, MM11 and MM72 were identified for hybrid breeding due to their combination of high grain yield and MSV tolerance. Finally, MM36 and MM35 were recognised for their outstanding grain yield performance, attributable to their MSV tolerance.
The identified inbred lines provide complementary sources of MSV resistance and represent valuable donor parents for introgression and developing high-yielding MSV-resistant maize hybrids.
Malven Mushayi, Hussein Shimelis, S. A. Tesfamariam et al.· Frontiers in Agronomy· 0 citations
Yellow Mosaic Virus (YMV), primarily transmitted by the whitefly (Bemisia tabaci), poses a critical threat to blackgram (Vigna mungo) cultivation across tropical and subtropical regions. The virus causes severe yield losses by inducing yellow mosaic symptoms, stunted growth and poor pod development. This review summarizes current advancements in resistance breeding, encompassing conventional selection, marker-assisted selection (MAS), QTL mapping and biotechnological tools such as genome editing and transcriptomics through comprehensive analysis of published literature from 1991 to 2025. Traditional control measures, including vector management, are often ineffective due to environmental and viral variability. Resistance breeding has emerged as a sustainable solution, supported by the identification of resistant germplasm, wild relatives and molecular markers. The paper highlights challenges like pathogen variability, limited genetic diversity and environmental influences. Future perspectives emphasize integrating high-throughput phenotyping, genomic resources and collaborative breeding strategies to develop durable, high-yielding, YMV-resistant blackgram cultivars. These efforts are essential for enhancing productivity, food security and climate resilience in pulse-growing regions.
A. Bharathi, K. S. Vijai Selvaraj, P. Sivakumar et al.· Legume Research An Internati...· 0 citations
Yellow dwarf viruses (YDV), comprising strains of barley yellow dwarf virus (BYDV) and cereal yellow dwarf virus (CYDV), cause economically important diseases in cereal crops in the United States. Although YDV are widespread in Nebraska, information on species distribution and their temporal variability is limited. A statewide survey was conducted during the 2023 and 2024 growing seasons to characterize YDV strain diversity and associated aphid vectors in cereal crops. Total RNA was extracted from symptomatic leaf samples collected from commercial and experimental fields, and viral detection was performed using a multiplex one-step reverse transcription polymerase chain reaction (RT-PCR). Aphid abundance was assessed separately using Berlese funnel from the field-collected plant materials, and species were determined morphologically. In 2023, 68.1% (644/946) of the tested samples were positive for at least one YDV strain, whereas in 2024, only 25.5% (144/564) of the samples tested positive. BYDV-SGV was the predominant strain in 2023, particularly in oats and wheat, whereas SGV+MAV and RPV+SGV strains were the most common coinfections. In contrast, CYDV-RPV and BYDV-MAV predominated in wheat and barley in 2024, whereas PAV was most frequently detected in oats. The bird cherry-oat aphid (Rhopalosiphum padi) was the most abundant aphid species across all crops and locations. These results demonstrate substantial year-to-year variation in the composition of YDV strains in Nebraska cereal crops and confirm the utility of multiplex RT-PCR for field diagnosis. Furthermore, the observed patterns of virus prevalence and aphid abundance emphasize the epidemiological relevance of these findings and support the role of aphid vectors in shaping strain distribution and composition.
M. Barman, Indranil Mukhopadhyay, Gary L. Hein et al.· Plant Disease· 0 citations
Fusarium ear rot (FER), caused by Fusarium verticillioides (F. verticillioides), is a major disease of maize that reduces grain yield and quality globally. However, few major loci for FER have been verified and cloned. Resistance to FER is a quantitative trait influenced by environmental conditions, and maize genotypes completely resistant to the pathogen remain unknown. To gain a comprehensive understanding of the genetic basis of natural variation in FER resistance, a recombinant inbred line (RIL) population consisting of 257 progenies was developed by crossing the resistant line BT with the susceptible line Xi502. This population was genotyped using a set of 6807 high-density single nucleotide polymorphism (SNP) markers developed in this study. As a result, a total of five QTLs were identified by linkage mapping across three years, located on five chromosomes, and explaining 4.38–13.13% of the phenotypic variation. Among these was a major QTL, qFER5-2. Located on chromosome 5 within the interval 185568562–185574073, qFER5-2 explained 13.13% of the total phenotypic variance. The two candidate genes within qFER5-2 exhibited distinct expression profiles between the BT and Xi502 inbred lines, suggesting their potential association with FER resistance. Collectively, these findings provide candidate genetic resources for further investigation and offer potentially useful materials for maize disease resistance breeding.
Peipei Ma, Xinxiang Li, Xin Li et al.· Plants· 0 citations
Tomato spotted wilt virus (TSWV) and late leaf spot (LLS) are among the major constraints to peanut production. Cultivated peanut has narrow genetic bases and lacks strong sources of resistance. Wild species, on the other hand, harbor diverse and strong resistances to multiple pathogens. In this study, we evaluated advanced breeding lines carrying introgressions from multiple wild Arachis species (A. stenosperma, A. batizocoi, A. valida, and A. cardenasii) across three contrasting field environments and experimental designs in Georgia, USA using complementary incidence- and severity-based phenotyping. Genotype effects were highly significant for both diseases. Several wild-derived lines -particularly those from A. stenosperma ancestry- showed strong and stable TSWV resistance across environments. Interestingly, some lines lacking detectable wild segments also showed high resistance to TSWV, suggesting cryptic or undetected introgressions. LLS resistance was primarily associated with the characteristic A. cardenasii segments on A02 and A03, and lines stacking these introgressions consistently outperformed both cultivated parents and Georgia-06G, the most popular cultivar in the USA. Correlations between TSWV and LLS responses were weak, confirming genetic independence and emphasizing the need to screen both traits. A small subset of lines combined resistance to both diseases, and many also retained resistance loci to root-knot nematode (RKN), expanding their value as multi-trait donors. These findings demonstrate the power of wild introgression breeding for enhancing disease resistance and provide a foundation for deploying stacked alleles through marker-assisted and multi-environment selection.
Namrata Maharjan, A. Culbreath, M. Gonzales et al.· Plant Disease· 0 citations