Identification of Novel QTLs/Defense Genes in Spring Wheat Germplasm Panel for Seedling and Adult Plant Resistance to Stem Rust and Their Validation Through KASP Marker Assays.

Stem rust is one of the major diseases threatening wheat production globally. To identify novel resistance quantitative trait loci (QTLs), we performed 35K Axiom Array SNP genotyping assays on an association mapping panel of 400 germplasm accessions, including Indian landraces, in conjunction with phenotyping for stem rust at seedling and adult plant stages. Association analyses using three genome wide association study (GWAS) models (CMLM, MLMM, and FarmCPU) revealed 20 reliable QTLs for seedling and adult plant resistance. Among these 20 QTLs, five QTLs were found consistent with three models, i.e., four QTLs on chromosome 2AL, 2BL, 2DL, and 3BL for seedling resistance and one QTL on chromosome 7DS for adult plant resistance. Further, we identified a total of 21 potential candidate genes underlying QTLs using gene ontology analysis, including a leucine rich repeat receptor (LRR) and P-loop nucleoside triphosphate hydrolase, which have a role in pathogen recognition and disease resistance. Furthermore, four QTLs (Qsr.nbpgr-3B_11, QSr.nbpgr-6AS_11, QSr.nbpgr-2AL_117-6, and QSr.nbpgr-7BS_APR) were validated through KASP located on chromosomes 3B, 6A, 2A, and 7B. Out of these QTLs, QSr.nbpgr-7BS_APR was identified as a novel QTL for stem rust resistance which has been found effective in both seedling as well as the adult plant stages. Identified novel genomic regions and validated QTLs have the potential to be deployed in wheat improvement programs to develop disease resistant varieties for stem rust and can diversify the genetic basis of resistance.

Multi-locus genome-wide association studies (ML-GWAS) reveal novel genomic regions associated with seedling and adult plant stage leaf rust resistance in bread wheat (Triticum aestivum L.).

Leaf rust is one of the important diseases limiting global wheat production and productivity. To identify quantitative trait nucleotides (QTNs) or genomic regions associated with seedling and adult plant leaf rust resistance, multilocus genome-wide association studies (ML-GWAS) were performed on a panel of 400 diverse wheat genotypes using 35 K single-nucleotide polymorphism (SNP) genotyping assays and trait data of leaf rust resistance. Association analyses using six multi-locus GWAS models revealed a set of 201 significantly associated QTNs for seedling and 65 QTNs for adult plant resistance (APR), explaining 1.98-31.72% of the phenotypic variation for leaf rust. Among these QTNs, 51 reliable QTNs for seedling and 15 QTNs for APR were consistently detected in at least two GWAS models and were considered reliable QTNs. Three genomic regions were pleiotropic, each controlling two to three pathotype-specific seedling resistances to leaf rust. We also identified candidate genes, such as leucine-rich repeat receptor-like (LRR) protein kinases, P-loop containing nucleoside triphosphate hydrolase and serine-threonine/tyrosine-protein kinases (STPK), which have a role in pathogen recognition and disease resistance linked to the significantly associated genomic regions. The QTNs identified in this study can prove useful in wheat molecular breeding programs aimed at enhancing resistance to leaf rust and developing next-generation leaf rust-resistant varieties.

Effect of elicitation and precursor feeding on accumulation of 20-hydroxyecdysone in Achyranthes aspera Linn. cell suspension cultures.

20-Hydroxyecdysone is one of the most common ecdysteroids in plants with potential therapeutic applications. In this study, cell suspension cultures of Achyranthes aspera were raised in shake flasks to investigate the production of 20-hydroxyecdysone. The quantification and characterization of 20-hydroxyecdysone in the cultures were done by High performance liquid chromatography (HPLC) and Liquid Chromatography-quadrupole time-of- flight mass spectrometry (LC-Q-TOF) analyses. For raising the suspension, calli initiated from in vitro grown leaf explants were cultured in liquid Murashige and Skoog (MS) medium augmented with combinations of 2, 4-dichlorophenoxyacetic acid (1 mg L-1) and α-naphthaleneacetic acid (1 mg L-1). Maximum growth index of the cell suspension was 9.9, which was achieved during 20th day of culture (final phase of exponential growth). At this stage, the biomass accumulated was 1.09 ± 0.09 g dry weight (DW) and the 20-hydroxyecdysone concentration was 0.24 mg g-1 DW. Eliciting the cultures with 0.6 mM Methyl jasmonate for 6 days; enhanced the production of 20-hydroxyecdysone production to 0.35 mg g-1 DW. By augmenting the cultures with the precursors namely cholesterol (10 mg L-1) and 7-dehydrocholesterol (10 mg L-1), production of 20-hydroxyecdysone was boosted to 0.31 mg g-1 DW and 0.28 mg g-1 DW respectively.

Genetic identification and phylogenetic relationships of Indian clariids based on mitochondrial COI sequences.

Mitochondrial cytochrome C Oxidase I (COI) sequence variation among the clariid fishes of India (Clarias magur, C. dussumieri and C. gariepinus) and their relationship with other representative clariids was studied in this work. Three species were sampled and together with 23 COI sequences from GenBank were used to reconstruct phylogenetic relationships in the family Clariidae. The study revealed two clades: one consisting of the African species with C. dussumieri, and the other of Asian species suggesting the prevalence of intra-continental diversification of catfishes. This study further revealed that the genus Clarias is monophyletic. For the COI gene, the interspecies genetic divergence ranged from 0.056 to 0.182. The mean genetic difference between C. dussumieri and other selected African species in this study is 12.1%. It was also observed that the morphological similarity of C. dussumieri and C. magur was not replicated in the genetic level. Clarias dussumieri was more close to African catfish C. gariepinus thus indicating the utility of COI phylogeny to identify the well-known African-Asian relationships within catfishes. The results also showed that C. magur and C. batrachus are genetically distinct from each other.

A combined chloroplast atpB-rbcL and trnL-F phylogeny unveils the ancestry of balsams (Impatiens spp.) in the Western Ghats of India.

Only a few Impatiens spp. from South India (one of the five centers of diversity for Impatiens species) were included in the published datum of molecular phylogeny of the family Balsaminaceae. The present investigation is a novel attempt to reveal the phylogenetic association of Impatiens species of South India, by placing them in the global phylogeny of Impatiens based on a combined analysis of two chloroplast genes. Thirty species of genus Impatiens were collected from different locations of South India. Total genomic DNA was extracted from fresh plant leaf, and polymerase chain reaction was carried out using atpB-rbcL and trnL-F intergenic spacer-specific forward and reverse primers. Thirteen sequences of Impatiens species from three centers of diversity were obtained from GenBank for reconstructing the evolutionary relationships within the genus Impatiens. Bayesian inference analysis was carried out in MrBayes v.3.2.2. This analysis supported Southeast Asia as the ancestral place of origin of extant Impatiens species. Molecular phylogeny of South Indian Impatiens spp. based on combined chloroplast sequences showed the same association as that of morphological taxonomy. Sections Scapigerae, Tomentosae, Sub-Umbellatae, and Racemosae showed Southeast Asian relationship, while sections Annuae and Microsepalae showed African affinity.