The existing resistance genes against white rust disease are often ineffective due to racial variation of the causal fungal pathogen, Albugo candida. Therefore, new sources of resistance effective against multiple races are needed for durable resistance. Large-scale phenotyping of advanced introgressed (ILs), mutant, and resynthesized (RBJ) lines of Brassica juncea L., under artificial inoculation at cotyledonary and true leaf stages, against thirteen diverse isolates of Albugo candida and simultaneously at the adult plant stage under multi-location field evaluation from 2019–2022, revealed significant differences in white rust reactions. Amongst 194 introgressed lines, three lines, namely ERJ 39, ERJ 12, and ERJ 15, and three lines among 90 resynthesized and 9 mutant lines, including RBJ 18, DRMR 18-36-12, and DRMR 18-37-13, were identified as potential sources of resistance against multiple isolates at all three developmental stages of the plant. Furthermore, correlation and principal component analysis revealed a positive correlation between white rust resistance at true leaf and adult plant stages for ILs as well as mutant and RBJ lines. These novel sources of host resistance will play vital roles are required for the mustard improvement program and to establish a strong genetic and molecular foundation for identifying white rust resistance linked marker(s), QTLs, or gene(s) for sustainable disease management in India.

A high-quality genome sequence from an Indian isolate of Blumeria graminis f. sp. tritici Wtn1, a persistent threat in wheat farming, was obtained using a hybrid method. The assembly of over 9.24 million DNA-sequence reads resulted in 93 contigs, totaling a 140.61 Mb genome size, potentially encoding 8480 genes. Notably, more than 73.80% of the genome, spanning approximately 102.14 Mb, comprises retro-elements, LTR elements, and P elements, influencing evolution and adaptation significantly. The phylogenomic analysis placed B. graminis f. sp. tritici Wtn1 in a distinct monocot-infecting clade. A total of 583 tRNA anticodon sequences were identified from the whole genome of the native virulent strain B. graminis f. sp. tritici, which comprises distinct genome features with high counts of tRNA anticodons for leucine (70), cysteine (61), alanine (58), and arginine (45), with only two stop codons (Opal and Ochre) present and the absence of the Amber stop codon. Comparative InterProScan analysis unveiled “shared and unique” proteins in B. graminis f. sp. tritici Wtn1. Identified were 7707 protein-encoding genes, annotated to different categories such as 805 effectors, 156 CAZymes, 6102 orthologous proteins, and 3180 distinct protein families (PFAMs). Among the effectors, genes like Avra10, Avrk1, Bcg-7, BEC1005, CSEP0105, CSEP0162, BEC1016, BEC1040, and HopI1 closely linked to pathogenesis and virulence were recognized. Transcriptome analysis highlighted abundant proteins associated with RNA processing and modification, post-translational modification, protein turnover, chaperones, and signal transduction. Examining the Environmental Information Processing Pathways in B. graminis f. sp. tritici Wtn1 revealed 393 genes across 33 signal transduction pathways. The key pathways included yeast MAPK signaling (53 genes), mTOR signaling (38 genes), PI3K-Akt signaling (23 genes), and AMPK signaling (21 genes). Additionally, pathways like FoxO, Phosphatidylinositol, the two-component system, and Ras signaling showed significant gene representation, each with 15–16 genes, key SNPs, and Indels in specific chromosomes highlighting their relevance to environmental responses and pathotype evolution. The SNP and InDel analysis resulted in about 3.56 million variants, including 3.45 million SNPs, 5050 insertions, and 5651 deletions within the whole genome of B. graminis f. sp. tritici Wtn1. These comprehensive genome and transcriptome datasets serve as crucial resources for understanding the pathogenicity, virulence effectors, retro-elements, and evolutionary origins of B. graminis f. sp. tritici Wtn1, aiding in developing robust strategies for the effective management of wheat powdery mildew.

Rice false smut [Ustilaginoidea virens (Cooke) Takahashi] is an upcoming major disease in India. The chlamydospores of test pathogen associated with paddy seeds as concomitant contamination drastically reduce seed quality parameters. Physical methods of seed health testing are not successful to identify inoculums with seeds and hence the rapid and reliable techniques are essentially required for detection of U. virens in paddy seeds to formulate better management strategies. Presently, the light microscopy demonstrated distortion of lemma and seed coat but results were inconsistent with different samples. Therefore, we standardized an advanced microscopy (SEM) and simple PCR techniques. These two methods could detect the U. virens associated with apparently healthy seeds having very few chlamydospores. Further analysis with seeds of susceptible variety (Pusa 44) confirmed reliability of SEM, displaying proliferation and penetration of infective hyphae from single spore into seed coat/glumes. The low level of pathogen inoculums (100 spores-seed) was detected (109 bp) by amplifying two μl of total genomic (16srDNA) of this pathogen by using ITS and specific (Uvr1497F and Uvr1586R) primers. We confirmed by using pure inoculums as positive control and with healthy seed coat from susceptible variety as negative control during amplification of 16srDNA of the pathogen. The partial genome sequencing of U. virens was positive for apparently healthy seeds with U. virens. Sequences of two representative isolates (U.v-H and U.v-K) were deposited (KJ195461 and KJ195462) in GenBank database. Therefore, both advanced methods could be useful for rapid and reliable detection of rice false smut pathogen (U. virens).