Kamal Uddin

Abiotic stress severely restricts plant growth, necessitating swift and, at times, heritable reprogramming of gene expression. To regulate chromatin states and fine-tune stress-responsive pathways, plants rely on four key epigenetic mechanisms: DNA methylation, histone modifications, small RNA-mediated silencing, and chromatin remodeling. Cytosine methylation in CG, CHG, and CHH contexts, mediated by Methyltransferase 1 ( MET1 ), Chromomethylase 3 ( CMT3 ), and Domains Rearranged Methyltransferase 2 ( DRM2 ), controls promoter accessibility, transposable-element activity, and stress-induced transcription at loci such as High-Affinity K⁺ Transporter 1 ( HKT1 ), Nine-cis-epoxycarotenoid dioxygenase 3 ( NCED3 ), and Chromatin Remodeling 12 ( CBF ). Histone acetylation and methylation are catalyzed by General Control Non-Repressed 5 ( GCN5 ), Arabidopsis Trithorax 1/SET Domain Group ( ATX/SDG ) methyltransferases, and reversed by Histone Deacetylase/HISTONE DEACETYLASE2C ( HDA6/19/HD2C ) or Jumonji-C Domain-Containing Protein ( JMJ ) demethylases. Small RNAs, produced via the RdDM pathway (Pol IV/V, RDR2, DCLs), direct non-CG methylation, enabling rapid and reversible modulation of transcription in ion transporters, ABA signaling genes, and stress-related transcription factors. Chromatin remodelers like Chromatin Remodeling 12 ( CHR12 ) and Pickle Chromatin Remodeler ( PKL ), alongside epitranscriptomic modifications, such as m ⁶ A and m ⁵ C (written by MTA/MTB and NSUN2 , and erased by ALKBH demethylases), further influence transcript stability, translation, and heat-responsive transposable-element activation. These interconnected processes also generate stress memory, marked by sustained H3K4me3, persistent CHH hypomethylation, and siRNA loss at transposable-element loci, enabling faster reactivation during recurrent stress or, in some cases, transgenerational inheritance. This review offers an integrated framework that links molecular epigenetic mechanisms with adaptive stress physiology and highlights emerging opportunities for epigenetic priming, targeted epigenome editing, and trait engineering to develop climate-resilient crops.

Pigeon pea is an important leguminous crop widely cultivated in tropical and subtropical regions for its protein-rich seeds and soil-enriching properties. The present investigation was conducted in an augmented block design during Kharif 2020 at the Research Farm of Banda University of Agriculture and Technology, Banda, Uttar Pradesh, India. The experimental material consisted of 73 genotypes of pigeon pea, including three checks, NDA-1, Bahar and Pant Arhar-291 to examine genetic diversity among these genotypes. Analysis of variance revealed significant genotypic variation for most of the traits among the genotypes, suggesting that the variation may be exploited through selection for the development of a variety with high-yield genetic potential. Cluster analysis grouped the genotypes into five distinct, non-overlapping clusters. Cluster I contained the highest number of genotypes (25), followed by Cluster III (19), Cluster II (14), Cluster V (9) and Cluster IV (6). Clusters II and IV had the greatest inter-cluster distance, which indicated that crossing genotypes between these clusters would result in high-quality recombinants. Principal component analysis (PCA) extracted five components that contributed 67.89 % variance to the total variation among the tested genotypes. The genotypes which showed the highest genetic diversity can be used as a parent in a hybridization program. Early flowering was observed with the genotypes IPA-10W-8-1 (74.09 days), IPA-12W-16 (78.09 days) and genotypes IPA-12W-3 (202.37 g), IPAB-10-13 (199.70 g), IPA-17W-218 (195.72 g), IPA-12W-38 (192.80 g), Local-4 (191.83 g), IPA-10W-5-8 (190.83 g) had the highest seed yield per plant. These germplasm lines can be used as potential parents for the development of high-yielding and early maturing cultivars.

Finger millet blast caused by Pyricularia grisea hinders crop’s growth and is a serious threat to economic yield. It can lead to massive yield losses i.e. up to 80%, which is a cause of major concern. In this study, we evaluated 200 accessions of finger millet at Banda University of Agriculture & Technology in Banda, India, under natural conditions to determine their resistance against leaf, neck, & finger blast diseases. Nine accessions displayed strong resistance against all forms of blast. The genetic variability analysis revealed high phenotypic & genotypic coefficients of variation. This was especially true for seed yield, plant height, & days to flowering. Most traits had heritability estimates exceeding 80%. Such results indicate a significant potential for effective selection in breeding programs. Leaf blast ratings had a significant but weaker correlation to both neck blast (r = 0.31) and finger blast (r = 0.31) whereas neck and finger blast ratings were very highly correlated and significant (r = 0.97). All types of blast had negative correlation with various agronomic traits studied. Furthermore, DNA fingerprinting of resistant genotypes with SSR markers displayed 10 polymorphic markers with an average of 2.6 alleles per locus. This points to the genetic diversity present within the germplasm. In summary, these findings provide vital insights for breeding initiatives focused on enhancing blast resistance in finger millet. Such efforts are crucial for maintaining the sustainability of this important crop for global food security.

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Eight field pea parental lines and their twenty-eight F₁s resulting from diallel design (excluding reciprocal) were analyzed for their combining ability and heterosis for yield and associated traits. ANOVA revealed significant variation among parents and among hybrids for days to 50% flowering, plant height, total number of pods, effective pods, seeds per pod, 100-seed weight, biological yield and seed yield; pod length also revealed significant differences among hybrids, suggesting the occurrence of considerable variability for studied traits. Crosses P-1541-16 × P-92-97-11 and P-1541-16 × P-1297-97 displayed significant heterosis over better-parent and control varieties for seed yield and associated traits. Combining ability analysis showedthat SCAvariance was considerably higher than corresponding GCAvariance for all traits. Genotype Aman and P-1297-97 were identified as good general combiners for seed yield, while cross P-1541-16 × P-1297-97, Aman × EC-564817, P-1541-16 × P-92-97-11 and P-1297-97 × P-92-97-11 were identified as specific cross-combiners for most of the studied traits. Consequently, these crosses might be exploited in future breeding programs to find desired segregants. PCA explained 81.68% and 83.34% variability in parents and crosses, respectively, for yield component. Furthermore, trait association between GCA effects and SCA effects demonstrates that biological yield, total number of pods, and effective pods exhibit additive gene action, but 100-seed weight exhibits non-additive gene action.

Field pea is one of the important short-duration cool season pulse crops which contributes significantly towards food and nutritional security. Two heat-susceptible (HS) and two heat-tolerant (HT) genotypes were selected from the previous study for further characterization. A significant variation was observed for morpho-physiological traits studied. Principal component analysis explained that first two principal components, i.e., PC1 and PC2 showed 76.5% of the total variance in optimal condition, whereas 91.2% of the total variance was covered by the first two PCs in heat stress environment. The seed yield per plant determined significant and positive association with superoxide dismutase and number of seeds per pod under optimal conditions, whereas under heat stress condition, it was positively associated with number of effective pods per plant, biological yield per plant, proline, pod length, number of seeds per pod, superoxide dismutase, and peroxidase. The significant reduction was noticed in the susceptible genotypes, whereas tolerant genotypes showed stable and non-significant reduction in chlorophyll content. Further, minimum cell damage and higher hydrogen peroxide production was noticed in the susceptible genotypes. In addition, the biochemical characterization of HS and HT genotypes revealed that the higher expression of peroxidase, superoxide dismutase, and catalase modulates the tolerant responses in HT genotypes. These genotypes were further used in developing heat-tolerant field pea genotypes.

Globally, abiotic stresses, such as temperature (heat or cold), water (drought and flooding), and salinity, cause significant losses in crop production and have adverse effects on plant growth and development. A variety of DNA-based molecular markers, such as SSRs, RFLPs, AFLPs, SNPs, etc., have been used to screen germplasms for stress tolerance and the QTL mapping of stress-related genes. Such molecular-marker-assisted selection strategies can quicken the development of tolerant/resistant cultivars to withstand abiotic stresses. Oilseeds such as rapeseed, mustard, peanuts, soybeans, sunflower, safflower, sesame, flaxseed, and castor are the most important source of edible oil worldwide. Although oilseed crops are known for their capacity to withstand abiotic challenges, there is a significant difference between actual and potential yields due to the adaptation and tolerance to severe abiotic pressures. This review summarizes the applications of molecular markers to date to achieve abiotic stress tolerance in major oilseed crops. The molecular markers that have been reported for genetic diversity studies and the mapping and tagging of genes/QTLs for drought, heavy metal stress, salinity, flooding, cold and heat stress, and their application in the MAS are presented.