Biology subjects

Rustgi, S.

Publications and source records attributed to Rustgi, S..

6 recordsLinked to original sources

bioRxiv2026

Transcriptional differences between repeatedly recultured and freshly induced embryogenic calli reveal candidate developmental regulators

Peanut (Arachis hypogaea L.) is an economically important oilseed and food legume, yet genetic transformation remains challenging because of genotype dependence and the lengthy tissue-culture and regeneration process. A better understanding of the molecular mechanisms underlying callus development and proliferation could help identify candidate morphogenic genes and developmental regulators (DRs) for peanut improvement. Here, we used RNA sequencing to compare embryogenic calli from the cultivar Georgia Green that had been maintained for three months (new callus; NC) or repeatedly subcultured for four years (old callus; OC). The two callus types displayed distinct morphologies: NC was pale cream, expanded, and cauliflower-like, whereas OC was more yellow, compact, and nodular. We identified 1,141 genes significantly upregulated in NC and 2,086 in OC (adjusted p < 0.05; log2FC; fold change > 2). Transcription factors were prominent among 13 categories of differentially expressed genes, including members of the AP2/ERF, WOX, GRAS, LBD, and NAC families, several of which are known DRs in other crops. qRT-PCR analysis of seven selected genes strongly corroborated the RNA-seq results (r = 0.944; R2 = 0.891). Highly upregulated candidates included C2H2/BED-type zinc-finger proteins, calreticulin/calnexin, a glycine-rich protein, a late embryogenesis abundant protein, glycoside hydrolases, and SWEET sugar transporters. These findings provide a resource for investigating callus development in peanut and prioritize candidate genes for functional validation and future improvement of transformation and regeneration systems.

plant biology↗

bioRxiv2026

Impacts of Anthropogenic, Environmental, and Genetic Factors on Peanut Seed Protein Content and Composition

Peanut contributes approximately $4 billion annually to the U.S. economy, with 13 peanut producing states generating over 3 mmt, 75 to 80% of which is consumed domestically. Peanut seeds contain 22 to 36% protein and 40 to 56% oil, enriched in unsaturated fatty acids, making them a highly nutritious food source. However, specific seed storage proteins can trigger allergic reactions ranging from mild symptoms to severe anaphylaxis, underscoring the need to better understand factors influencing seed protein composition. Anthropogenic processes such as domestication and modern breeding, environmental stresses including excessive heat during flowering and pod development, and genetic mechanisms such as homoeologous exchanges (HEs) collectively shape seed protein content and composition. Domestication improved harvestability, while breeding enhanced yield and nutritional quality. Current improvement programs increasingly emphasize heat resilience in response to a ~1.5 C rise in global temperatures, with further warming anticipated. Yet limited attention has been given to how these factors affect protein composition, allergenic potential, trait stability under future climates, and genotypic uniformity linked to HEs. Here, we review the impacts of domestication, breeding, environmental stress, and genomic restructuring on peanut seed protein content and composition, highlighting key research gaps to ensure nutritional quality, safety, and stability in a changing climate.

molecular biology↗

bioRxiv2026

Molecular Characterization of Gene-Product Relationships in the Wheat Gluten Complex for Reduced Immunogenicity Wheat Development

Immune-mediated reactions to wheat gliadins, including celiac disease and wheat allergies, affect ~1% of the U.S. population and are prevalent worldwide. Reducing the risk of inadvertent gluten exposure for individuals with celiac disease or wheat allergies requires the development of reduced immunogenicity wheat varieties which are suitable for human consumption. This study was designed with a view to improve our understanding of gene protein relationships at the complex wheat Gli1/Glu3 and Gli2 loci, and to develop genetic and molecular resources for breeding reduced-immunogenicity wheat lines. We conducted comprehensive genomic, biochemical, and immunological analyses of diverse wheat genetic resources, including aneuploid stocks, chromosome deficiency and interstitial deletion lines, Wasko omega null, the landrace San Pastore, Pegaso near isogenic lines lacking Gli1/Glu3/Gli2 loci, and progenies derived from a Wasko mega null X Pegaso(6A/6D) alpha null. Genomic characterization involved the targeted GlutEnSeq approach and PCR based DNA markers while biochemical and immunological analyses employed acid-urea PAGE, SDS PAGE, and ELISA. Integration of these complementary approaches resolved gliadin gene protein relationships at an unprecedented level. Notably, two F2; lines exhibited substantial reductions (both omega and alpha gliadins) due to the successful stacking of parental mutations. The resulting F2; progenies and associated DNA markers represent valuable resources for breeding wheat for reduced immunogenicity

genomics↗

bioRxiv2026

Development of the First Cytochrome Oxidase I Barcode and Evidence for a Single Haplotype Associated with the Recent United States Invasion of the Pasture Mealybug Heliococcus summervillei (Pseudococcidae, Hemiptera)

Heliococcus summervillei is an emerging invasive mealybug that causes severe dieback in grasses in pastures and turfgrass landscapes. It is widespread in Australia and has recently been detected across the Caribbean, Mexico, and the United States. Accurate identification of mealybugs is challenging due to cryptic morphology, overlapping diagnostic characters, and limited taxonomic expertise and literature, which makes molecular tools essential for regulatory diagnostics and management. We developed the first Cytochrome Oxidase I (COI) barcode for H. summervillei and used it to examine mitochondrial variation across available populations. COI sequences reveal approximately a 10.2% mitochondrial split between the Type A and Type B variants. Phylogenetic, haplotype network, and genetic distance analyses show that all invasive range populations share one haplotype associated with a recent invasion in the United States, Australia, Pakistan, and the Caribbean, whereas the Barbados lineage contains two closely related haplotypes that represent a historically stable mitochondrial variant. Together, these results establish the first COI reference library for H. summervillei, clarify mitochondrial lineage structure, and provide a practical barcode tool that enables rapid identification of invasive populations and supports timely regulatory and pest management responses. Recognizing mitochondrial variants also establishes a framework for resolving lineage-specific biological and management traits and strengthens reconstruction of introduction pathways central to regulatory decision-making and limiting further spread.

genetics↗

bioRxiv2025

Global phylogeography of Amrasca biguttula (Hemiptera: Cicadellidae) across eight countries reveals a single-haplotype incursion into the United States beyond its putative native range

Amrasca biguttula is a pest of cotton, ornamentals, and vegetables, and is invading the southeastern United States. We addressed five questions: (1) Are US populations genetically identical to those in the putative native range? (2) Does the southeastern US outbreak extend the recent Puerto Rico and Florida invasion or represent separate introductions? (3) Does the lineage infesting ornamentals match that on other crops? (4) What is the mitochondrial cytochrome oxidase subunit 1 (mtCOI) diversity of A. biguttula? (5) Which regions constitute its native versus invaded range? Adults were collected from Florida, Georgia, South Carolina, Texas, and Puerto Rico. Species identity was confirmed morphologically and by sequencing mtCOI, where possible, from five individuals per site, yielding consensus haplotypes. We analyzed 11 US, 20 Puerto Rican, and 342 sequences originating from publicly available databases (n = 373). Phylogenetic analysis confirmed monophyly of this species. A haplotype network recovered 70 unique haplotypes, including a star-like core of 68 radiating from Hap01 and two divergent singletons. The mainland US and Chinese populations were fixed for Hap01, indicating recent introductions. Puerto Rico exhibited Hap01, Hap52, and Hap70, reflecting multiple introductions, but could also result from haplotype diversity carried within a single introduction involving many individuals. Furthermore, southeastern US sites were fixed for Hap01, indicating extension from Puerto Rico and Florida. No haplotype was host-specific, confirming a lineage across crops. Diversity metrics indicate recent expansion in Iraq, Hong Kong, and Puerto Rico. South Asia, particularly Bangladesh, India, and Pakistan, showed the highest haplotype diversity, supporting its role as the putative native range. In contrast, low diversity in China and the US is consistent with recent invasion. Curation yielded 373 high-quality sequences, providing a unified database to support quarantine and management strategies.

genetics↗

bioRxiv2018

Substrate channeling in oxylipin biosynthesis through a protein complex in the plastid envelope of Arabidopsis thaliana

Oxygenated membrane fatty acid derivatives dubbed oxylipins play important roles in the plants defense against biotic and abiotic cues. Plants challenged by insect pests, for example, synthesize a blend of different defense compounds that, amongst others, comprise volatile aldehydes and jasmonic acid (JA). Because all oxylipins are derived from the same pathway, we asked how their synthesis might be regulated and focused on two closely related, atypical cytochrome P450 enzymes designated CYP74A and CYP74B, i.e., allene oxide synthase (AOS) and hydroperoxide lyase (HPL). Both enzymes compete for the same substrate but give rise to different products. While the final product of the AOS branch is JA, those of the HPL branch comprise volatile aldehydes and alcohols. AOS and HPL are plastid envelope enzymes in Arabidopsis thaliana but accumulate at different locations. Biochemical experiments identified AOS as constituent of complexes also containing lipoxygenase 2 (LOX2) and allene oxide cyclase (AOC), which catalyze consecutive steps in JA precursor biosynthesis, while excluding the concurrent HPL reaction. Based on published X-ray data, the structure of this complex could be modelled and amino acids involved in catalysis and subunit interactions identified. Genetic studies identified the microRNA 319 (miR319)-regulated clade of TCP (TEOSINTE BRANCHED/CYCLOIDEA/PCF) transcription factor genes and CORONATINE INSENSITIVE 1 (COI1) to control JA production through the AOS-LOX2-AOC2 complex. Together, our results define a molecular branch point in oxylipin biosynthesis that allows fine-tuning the plants defense machinery in response to biotic and abiotic stimuli.

cell biology↗