Novel resistance loci for quantitative resistance to Septoria tritici blotch in Asian wheat (Triticum aestivum) via genome-wide association study.

BACKGROUND: Septoria tritici blotch (STB) disease causes yield losses of up to 50 per cent in susceptible wheat cultivars and can reduce wheat production. In this study, genomic architecture for adult-plant STB resistance in a Septoria Association Mapping Panel (SAMP) having 181 accessions and genomic regions governing STB resistance in a South Asian wheat panel were looked for. RESULTS: Field experiments during the period from 2019 to 2021 revealed those certain accessions, namely BGD52 (CHIR7/ANB//CHIR1), BGD54 (CHIR7/ANB//CHIR1), IND92 (WH 1218), IND8 (DBW 168), and IND75 (PBW 800), exhibited a high level of resistance. Genetic analysis revealed the presence of 21 stable quantitative trait nucleotides (QTNs) associated with resistance to STB (Septoria tritici blotch) on all wheat chromosomes, except for 2D, 3A, 3D, 4A, 4D, 5D, 6B, 6D, and 7A. These QTNs were predominantly located in chromosome regions previously identified as associated with STB resistance. Three Quantitative Trait Loci (QTNs) were found to have significant phenotypic effects in field evaluations. These QTNs are Q.STB.5A.1, Q.STB.5B.1, and Q.STB.5B.3. Furthermore, it is possible that the QTNs located on chromosomes 1A (Q.STB.1A.1), 2A (Q.STB_DH.2A.1, Q.STB.2A.3), 2B (Q.STB.2B.4), 5A (Q.STB.5A.1, Q.STB.5A.2), and 7B (Q.STB.7B.2) could potentially be new genetic regions associated with resistance. CONCLUSION: Our findings demonstrate the importance of Asian bread wheat as a source of STB resistance alleles and novel stable QTNs for wheat breeding programs aiming to develop long-lasting and wide-ranging resistance to Zymoseptoria tritici in wheat cultivars.

Genome-wide association mapping for field spot blotch resistance in South Asian spring wheat genotypes.

Spot blotch caused by Bipolaris sorokiniana ((Sacc.) Shoemaker) (teleomorph: Cochliobolus sativus [Ito and Kuribayashi] Drechsler ex Dastur) is an economically important disease of warm and humid regions. The present study focused on identifying resistant genotypes and single-nucleotide polymorphism (SNP) markers associated with spot blotch resistance in a panel of 174 bread spring wheat lines using field screening and genome-wide association mapping strategies. Field experiments were conducted in Agua Fria, Mexico, during the 2019-2020 and 2020-2021 cropping seasons. A wide range of phenotypic variation was observed among genotypes tested during both years. Twenty SNP markers showed significant association with spot blotch resistance on 15 chromosomes, namely, 1A, 1B, 2A, 2B, 2D, 3A, 3B, 4B, 4D, 5A, 5B, 6A, 6B, 7A, and 7B. Of these, two consistently significant SNPs on 5A, TA003225-0566 and TA003225-1427, may represent a new resistance quantitative trait loci. Further, in the proximity of Tsn1 on 5B, AX-94435238 was the most stable and consistent in both years. The identified genomic regions could be deployed to develop spot blotch-resistant genotypes, particularly in the spot blotch-vulnerable wheat growing areas.

Assessment of Indian wheat germplasm for Septoria nodorum blotch and tan spot reveals new QTLs conferring resistance along with recessive alleles of Tsn1 and Snn3.

The leaf blight diseases, Septoria nodorum blotch (SNB), and tan spot (TS) are emerging due to changing climatic conditions in the northern parts of India. We screened 296 bread wheat cultivars released in India over the past 20 years for seedling resistance against SNB (three experiments) and TS (two experiments). According to a genome-wide association study, six QTLs on chromosome arms 1BL, 2AS, 5BL, and 6BL were particularly significant for SNB across all three years, of which Q.CIM.snb.1BL, Q.CIM.snb.2AS1, Q.CIM.snb.2AS.2, and Q.CIM.snb.6BL appeared novel. In contrast, those on 5BS and 5BL may correspond to Snn3 and Tsn1, respectively. The allelic combination of tsn1/snn3 conferred resistance to SNB, whereas that of Tsn1/Snn3 conferred high susceptibility. As for TS, Tsn1 was the only stably significant locus identified in this panel. Several varieties like PBW 771, DBW 277, and HD 3319, were identified as highly resistant to both diseases that can be used in future wheat improvement programs as resistant donors.

Interference of Nanoparticulates in seed invigoration of Green gram.

In the present study, the impact of four metal/metal oxide nanoparticles (NPs) viz.Ag, ZnO),ZVI and TiO2 on physiological seed quality attributes of green gram (Vigna radiata) were evaluated. The synthesized NPs characterized and evaluated the germination percentage, vigour indices and physiological responses like catalase and peroxidase activities (seed quality parameters) of fresh, naturally aged and fresh accelerated aged seed lots of green gram. In naturally aged seeds, zinc oxide-NPs (1000 mg kg-1) treated seeds showed 14.96% higher germination percentage, 24.81% higher vigour index I and (3696) and 33.33% higher vigour index II than the controls. The treated seeds with ZnO-NPs (1000 mg kg-1) under fresh accelerated aged conditions resulted in higher than 15.15% of germination percentage, 23.61% of vigour index I and 24.11% of vigour index II over controls. Moreover, ZnO-NPs treated naturally aged seeds showed lower electrical conductivity (EC) of 20.10 µ S cm-1g-1 than the control (26.60 µ S cm-1 g-1). Pertinent to catalase enzyme activity, ZnO-NPs (1000 mg kg-1) treated naturally aged seed lots resulted in 356.89 µmol H2O2 mg-1 min-1 activity, 216.05 µmol H2O2 mg-1 min-1 activity in fresh accelerated aged seed lots.. Similarly, ZnO-NPs (1000 mg kg-1) enhanced peroxidase enzyme activity in naturally aged seed lots (3.21 µg/FW/10 min) than control (0.72 µg/FW/10 min) that depicts 63.35% of increased enzyme activity. The present results showcases the ZnO-NPs as potent nano-priming agents in maintaining the seed quality parameters that ultimately establish better crop stand and field performance.

Ensuring Nutritional Security in India through Wheat Biofortification: A Review.

Undernourishment of nutrients, also known as hidden hunger, affects over 2 billion populace globally. Even though stunting among children below five years of age has decreased in India in the last ten years, India is home to roughly thirty percent of the world's population of stunted pre-schoolers. A significant improvement has been witnessed in the targeted development and deployment of biofortified crops; approximately 20 million farm households from developing counties benefit from cultivating and consuming biofortified crops. There is ample scope for including biofortified varieties in the seed chain, ensuring nutritional security. Wheat is a dietary staple in India, typically consumed as wholemeal flour in the form of flatbreads such as chapatti and roti. Wheat contributes to nearly one fifth of global energy requirements and can also provide better amounts of iron (Fe) and zinc (Zn). As a result, biofortified wheat can serve as a medium for delivery of essential micronutrients such as Fe and Zn to end users. This review discusses wheat biofortification components such as Fe and Zn dynamics, its uptake and movement in plants, the genetics of their buildup, and the inclusion of biofortified wheat varieties in the seed multiplication chain concerning India.

Delineation of mechanistic approaches of rhizosphere microorganisms facilitated plant health and resilience under challenging conditions.

Sustainable agriculture demands the balanced use of inorganic, organic, and microbial biofertilizers for enhanced plant productivity and soil fertility. Plant growth-enhancing rhizospheric bacteria can be an excellent biotechnological tool to augment plant productivity in different agricultural setups. We present an overview of microbial mechanisms which directly or indirectly contribute to plant growth, health, and development under highly variable environmental conditions. The rhizosphere microbiomes promote plant growth, suppress pathogens and nematodes, prime plants immunity, and alleviate abiotic stress. The prospective of beneficial rhizobacteria to facilitate plant growth is of primary importance, particularly under abiotic and biotic stresses. Such microbe can promote plant health, tolerate stress, even remediate soil pollutants, and suppress phytopathogens. Providing extra facts and a superior understanding of microbial traits underlying plant growth promotion can stir the development of microbial-based innovative solutions for the betterment of agriculture. Furthermore, the application of novel scientific approaches for facilitating the design of crop-specific microbial biofertilizers is discussed. In this context, we have highlighted the exercise of "multi-omics" methods for assessing the microbiome's impact on plant growth, health, and overall fitness via analyzing biochemical, physiological, and molecular facets. Furthermore, the role of clustered regularly interspaced short palindromic repeats (CRISPR) based genome alteration and nanotechnology for improving the agronomic performance and rhizosphere microbiome is also briefed. In a nutshell, the paper summarizes the recent vital molecular processes that underlie the different beneficial plant-microbe interactions imperative for enhancing plant fitness and resilience under-challenged agriculture.