Biology subjects

Baniya, A.

Publications and source records attributed to Baniya, A..

3 recordsLinked to original sources

bioRxiv2026

Novel quantitative trait loci conferring broad-based resistance to root-knot nematodes in lima bean (Phaseolus lunatus)

Lima bean (Phaseolus lunatus) is a broadly adapted, economically important leguminous crop and a susceptible host of root-knot nematodes (Meloidogyne spp.; RKN), which are a devastating plant pathogen in agricultural systems worldwide. To date, there have been few studies to elucidate the genetic determinants of RKN resistance in lima beans. Understanding the genetic mechanisms underlying resistance is essential for improving resistance traits and incorporating them into lima bean breeding programs. To assist in marker-assisted selection, we aimed to identify and map quantitative trait loci (QTLs) conferring RKN resistance-related traits. Three recombinant inbred line (RIL) populations were used in this study. Three populations were derived by crossing two RKN-resistant parents with the same RKN-susceptible parent and with each other. All populations were genotyped using genome-wide single-nucleotide polymorphism (SNP) markers. Each population was screened for root galling (RG) and RKN egg reproduction (ER) in response to M. incognita and M. javanica in greenhouse experiments. Three major QTLs were detected and mapped on chromosome Pl04 (QRk-pl04.1), Pl05 (QRk-pl05.1) and Pl10 (QRk-pl10.1) across populations. Among them, QRk-pl05.1 and QRk-pl10.1 affected levels of RG and ER of both RKN species, while QRk-pl04.1 suppressed root galling and reproduction responses of M. incognita but not of M. javanica. These chromosomal regions defined by flanking markers will help guide marker-assisted breeding and gene discovery for broad-based RKN resistance in lima beans.

plant biology↗

bioRxiv2025

Epistasis between Na+/K+-ATPase Substitutions May Influence Salinity Tolerance in Steinernema Entomopathogenic Nematodes

Soil salinity varies widely across geographies both due to natural factors and human activities, including agriculture, road salt application, sea level rise, and desertification. Increases in soil salinity may affect organisms widely and particularly impact soil foodwebs. As parasites, entomopathogenic nematodes (EPNs) occupy crucial links in soil foodwebs and are important for agriculture as biological control agents of insect pests. Previous research found that the EPN Steinernema carpocapsae may exhibit higher salt tolerance than several of its congeners. We recently identified that S. carpocapsae uniquely evolved two amino acid substitutions in the first extracellular loop of the sodium pump (Na{square}/K{square}-ATPase). Here, we tested if these substitutions explain S. carpocapsaes reported lower sensitivity to salt. Our results confirm that S. carpocapsae exhibits higher salt tolerance and show it can more effectively locate and infect insect hosts than its congeners S. feltiae and S. hermaphroditum in highly saline environments. We then retraced the evolution of the two amino acid substitutions in S. carpocapsae by introducing them alone and in combination in Caenorhabditis elegans using CRISPR genome engineering. We found that C. elegans mutants with single substitutions showed improved salt tolerance. However, this improvement disappeared in the double mutant, whose sodium pump mimicked that of S. carpocapsae. This pattern of negative epistasis between the amino acid substitutions suggests they are not responsible for variation in salt tolerance between Steinernema species. Sodium pump evolution in S. carpocapsae might instead be driven by encounters with cardiac glycosides, which are released into soil by several clades of plants including milkweeds, sequestered by some of this EPNs herbivorous insect hosts, and known to target the first extracellular loop of the sodium pump. Our findings provide valuable insights into EPN adaptation to changes in environmental sodium levels and may have implications for their use in biological control.

ecology↗

bioRxiv2025

Genomes of the entomopathogenic nematode Steinernema hermaphroditum and its associated bacteria

As an entomopathogenic nematode (EPN), Steinernema hermaphroditum parasitizes insect hosts and harbors symbiotic Xenorhabdus griffinae bacteria. In contrast to other Steinernematids, S. hermaphroditum has hermaphroditic genetics, offering the experimental scope found in Caenorhabditis elegans. To enable biological analysis of S. hermaphroditum, we have assembled and analyzed its reference genome. This genome assembly has five chromosomal scaffolds and 83 unassigned scaffolds totaling 90.7 Mb, with 19,426 protein-coding genes having a BUSCO completeness of 88.0%. Its autosomes show higher densities of strongly conserved genes in their centers, as in C. elegans, but repetitive elements are evenly distributed along all chromosomes, rather than with higher arm densities as in C. elegans. Either when comparing protein motif frequencies between nematode species or when analyzing gene family expansions during nematode evolution, we observed two categories of genes preferentially associated with the origin of Steinernema or S. hermaphroditum: orthologs of venom genes in S. carpocapsae or S. feltiae; and some types of chemosensory G protein-coupled receptors, despite the tendency of parasitic nematodes to have reduced numbers of chemosensory genes. Three-quarters of venom orthologs occurred in gene clusters, with the larger clusters comprising functionally diverse pathogenicity islands rather than paralogous repeats of a single venom gene. While assembling the genome of S. hermaphroditum, we coassembled bacterial genomes, finding sequence data for not only the known symbiont, X. griffinae, but also for eight other bacterial genera. All eight genera have previously been observed to be associated with Steinernema species or the EPN Heterorhabditis, and may constitute a "second bacterial circle" of EPNs. The genome assemblies of S. hermaphroditum and its associated bacteria will enable use of these organisms as a model system for both entomopathogenicity and symbiosis.

genomics↗