PubMed · 965749
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J S Agarwal. 1976-04-01. Welcome address.. https://pubmed.ncbi.nlm.nih.gov/965749/
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Stripe rust of wheat caused by Puccinia striiformis f. sp. tritici (Pst) remains a major constraint to wheat production in India due to the rapid evolution and frequent emergence of virulent pathotypes. Rapid and reliable discrimination of Pst pathotypes is essential for effective resistance deployment and surveillance. In the present study, transcriptome-wide simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs) were exploited to develop and validate molecular markers for pathotype-specific detection of Pst pathotypes prevalent in North India (110S119, 238S119, 46S119, 110S84 and 78S84). Microsatellite mining from 6103 core orthologous clusters comprising 51,127 transcripts mined 14,634 SSR loci, from which 93 primer pairs were synthesized. However, only three SSR markers exhibited polymorphism indicating limited discrimination potential of expressed sequence-derived (EST) SSRs for pathotype differentiation. In contrast, SNP discovery through stringent variant calling and filtration yielded 186 pathotype-specific homokaryotic SNPs, of which 56 high-confidence loci were selected for Kompetitive Allele-Specific PCR (KASP) assay development. A total of 48 KASP markers were synthesized and 14 demonstrated clear pathotype- or cluster-specific polymorphism representing substantially higher resolution than SSR markers. The high SNP-to-KASP conversion efficiency (~ 95%) and reproducible fluorescence-based clustering emphasize the robustness of KASP assay. Comparative evaluation revealed that SNP-based KASP markers provide superior discriminatory capacity for closely related Pst pathotypes and represent a promising complementary molecular approach for rapid identification of predominant Indian Pst pathotypes. The validated marker panel developed in this study can complement conventional virulence phenotyping and field pathogenomics approaches for surveillance of currently known pathotypes, while continued refinement may accommodate future changes in pathogen populations.
BACKGROUND: Advanced maternal age (AMA; > = 35 years) is associated with increased fetal chromosomal risk and is an important indication for invasive prenatal diagnosis. This study evaluates karyotyping and chromosomal microarray analysis (CMA) findings among AMA pregnancies in Tamil Nadu, India. METHODS: In this prospective observational study, 2,200 pregnant women aged ≥35 years who underwent amniocentesis between July 2020 and June 2021 were enrolled. Conventional karyotyping was performed in all cases. CMA was performed as a reflex or complementary test when predefined clinical or cytogenetic criteria were present, including ultrasound abnormalities, high-risk screening/NIPT results, abnormal or uncertain karyotype findings, prior adverse pregnancy history suggestive of genetic etiology, parental chromosomal abnormalities, or patient request after counseling. RESULTS: Numerical chromosomal abnormalities were detected in 76/2200 cases (3.5%), and structural abnormalities were detected in 9/2200 cases (0.4%). The total abnormal cytogenetic yield was therefore 85/2200 cases (3.9%) when numerical and structural abnormalities were considered together. Age-stratified analysis showed an increasing trend in chromosomal abnormalities with advancing maternal age, reaching 10.4% in women aged > = 43 years. Cases with additional clinical indications showed higher abnormality rates than simple AMA. CMA was performed in selected cases and contributed to characterization of clinically relevant genomic abnormalities, supporting its role in indicated high-risk AMA pregnancies. CONCLUSION: The Tamil Nadu cohort provides regional evidence on age-stratified cytogenetic risk in AMA pregnancies and supports the use of clearly defined criteria for integrating CMA with conventional karyotyping in prenatal diagnosis.
Radiation-resistant microorganisms that survive high doses of ionising radiation serve as valuable models for understanding stress adaptation; however, the genomic determinants underlying extreme radiation tolerance in bacteria from natural environments with high background radiation remain insufficiently characterised. Bacterial isolates from the Chavara-Neendakara HBRA (Kerala, India) were evaluated for desiccation tolerance, and the desiccation-resistant isolates were subsequently exposed to gamma irradiation (1-10 kGy) using a 60Co source. Isolates were identified through 16S rRNA sequencing, morphologically characterised by FE-SEM, and screened for antibiotic susceptibility. The highly radiation-resistant strain underwent whole-genome sequencing via Oxford Nanopore Technology, with De novo assembly, polishing, and genome annotation. Four bacterial isolates (Micrococcaceae and Paenibacillaceae) exhibited D10 values of 1-7 kGy, including one multidrug-resistant strain; no endospores were observed in the Paenibacillus isolate under the tested conditions. Paenibacillus sp. HBRA004 survived 10 kGy gamma radiation, exceeding all previously reported HBRA isolates by over fourfold. Its 5.0 Mbp genome (GC = 48.27%, ≥ 99% completeness) encodes five mechanistically independent DNA repair pathways; homologous recombination (recA, recN, radA), base excision repair (mutM, mutY, mutT), mismatch repair (mutL, mutS), nucleotide excision repair (uvrA, uvrB, uvrD), and non-homologous end joining (ku, ligD), alongside a redundant antioxidant network comprising triple-copy Fe/Mn-family superoxide dismutases and ahpC peroxiredoxin. A thioredoxin system (trxA, trxB, msrA) and manganese uptake via mntH may contribute to further layers of ROS defence. Their specific contribution to the HBRA004 phenotype remains to be experimentally and comparatively validated. These findings represent the first genomically characterised 10 kGy-resistant bacterial isolate from the Chavara-Neendakara HBRA, establishing a new benchmark for radiation tolerance within this ecologically significant environment. Pathway depth, gene copy amplification, and Mn/Fe homeostasis appear to be candidate mechanisms contributing to high-level radiation tolerance, consistent with patterns in other radiation-resistant taxa, though their contribution requires functional validation.