Person:
Joshi, A.K.

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Joshi
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A.K.
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Joshi, A.K.

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Now showing 1 - 10 of 18
  • New genomic regions identified for resistance to spot blotch and terminal heat stress in an interspecific population of triticum aestivum and T. spelta
    (MDPI, 2022) Sudhir Navathe; Pandey, A.K.; Sandeep Sharma; Chand, R.; Mishra, V.K.; Kumar, D.; Jaiswal, S.K.; Mir Asif Iquebal; Velu, G.; Joshi, A.K.; Singh, P.K.
    Publication
  • Genomic selection for spot blotch in bread wheat breeding panels, full-sibs and half-sibs and index-based selection for spot blotch, heading and plant height
    (Springer, 2022) Juliana, P.; Xinyao He; Poland, J.; Roy, K.K.; Malaker, P.K.; Mishra, V.K.; Chand, R.; Shrestha, S.; Kumar, U.; Roy, C.; Gahtyari, N.C.; Joshi, A.K.; Singh, R.P.; Singh, P.K.
    Publication
  • Expression analysis of hormonal pathways and defense associated genes in gamma-rays mutagenized wheat genotypes against combined stresses of spot blotch and terminal heat
    (Elsevier, 2022) Singh, G.M.; SrinathaReddy S; Sharma, G.; Bakshi, S.; Kumar, U.; Bhati, P.; Jambhulkar, S.J.; Chand, R.; Joshi, A.K.; Mishra, V.K.; Sandeep Sharma
    Publication
  • Dissecting quantitative trait loci for spot blotch resistance in South Asia using two wheat recombinant inbred line populations
    (Frontiers, 2021) Roy, C.; Gahtyari, N.C.; Xinyao He; Mishra, V.K.; Chand, R.; Joshi, A.K.; Singh, P.K.
    Publication
  • Genetic characterization for lesion mimic and other traits in relation to spot blotch resistance in spring wheat
    (Public Library of Science, 2020) Singh, S.; Mishra, V.K.; Kharwar, R.N.; Neeraj Budhlakoti; Ram Narayan Ahirwar; Dwijesh Chandra Mishra; Kumar, S.; Chand, R.; Kumar, U.; Kumar, S.; Joshi, A.K.
    Publication
  • Genetic gain on resistance to spot blotch of wheat by developing lines with near immunity
    (Hapres State Key Laboratory of Hybrid Rice, 2019) Kumar, U.; Kumar, S.; Prasad, R.C.; Roder, M.S.; Kumar, S.; Chand, R.; Mishra, V.K.; Joshi, A.K.
    Publication
  • Variations in straw fodder quality and grain–Straw relationships in a mapping population of 287 diverse spring wheat lines
    (Elsevier, 2019) Joshi, A.K.; Kumar, U.; Mishra, V.K.; Chand, R.; Chatrath, R.; Naik, R.; Suma S. Biradar; Singh, R.P.; Neeraj Budhlakoti; Devulapalli, R.; Blummel, M.
    A wheat association mapping population consisting of 287 diverse spring wheat lines were evaluated for three years in one location (Varanasi) and out of these for one year across three locations (Karnal, Dharwad and Varanasi) in India. Straw fodder quality traits analyzed were nitrogen (N) content, neutral (NDF) and acid (ADF) detergent fiber, acid detergent lignin (ADL), ash (ASH), in vitro organic matter digestibility (IVOMD) and metabolizable energy (ME) content. Grain yield (GY) and straw yield (SY) were also recorded. Highly significant (P < 0.0001) differences among lines were observed for all traits except for ADF and ADL in the three years trials conducted at Varanasi. However, year and location had strong (P < 0.0001) effects on all traits. Compared to line-dependent variations in GY and SY variation in straw fodder quality traits were small. Proportionally greatest variations between lines were observed for straw N where lowest and highest N varied by about 30%. Difference for NDF and ADF between lines were at most 4% units and below 3% units for IVOMD. Grain yield and straw yield were positively correlated (P < 0.0001) with GY accounting for 26% of the variation in SY. Straw N, IVOMD and ME were weakly but significantly (P < 0.05) negatively associated with GY and SY. Straw NDF and ADF were significantly (P < 0.05) positively correlated with GY but the association was again weak. Straw NDF, ADF and ADL were also weakly but significantly positively correlated with SY. Genome-wide association studies (GWAS) were applied to detect significant marker- straw fodder quality trait associations. Five genomic regions contributed for six traits (ADF, ADL, ASH, IVOMD, ME and NDF). ADF and ADL mapped in the common QTL region on chromosome 2B. Similarly, for the IVOMD and ME QTLs on chromosome 5B were associated with SNP marker, wsnp_Ku_c35090_44349517. While some associations were detected for ADF, ALD, ASH, IVOMD, ME and NDF on chromosomes 1A, 2B, 3A, 5A and 5B, the phenotypic variation explained was low to medium by individual QTL. A likely contributing factor was the comparatively small difference in straw fodder quality traits among the lines. It is interesting to note that line dependent variations in GY and SY were about two-fold. In other words, strong genotypic variations of GY and SY do exist. The lack of any similar variations in straw fodder quality traits is intriguing and requires further research.
    Publication
  • Hydrogen peroxide prompted lignification affects pathogenicity of hemi-biotrophic pathogen Bipolaris sorokiniana to wheat
    (Korean Society of Plant Pathology, 2019) Poudel, A.; Sudhir Navathe; Chand, R.; Mishra, V.K.; Singh, P.K.; Joshi, A.K.
    Spot blotch caused by Bipolaris sorokiniana has spread to more than 9 million ha of wheat in the warm, humid areas of the Eastern Gangetic Plains (EGP) of South Asia and is a disease of major concern in other similar wheat growing regions worldwide. Differential lignin content in resistant and susceptible genotypes and its association with free radicals such as hydrogen peroxide (H2O2), superoxide (O2−) and hydroxyl radical (OH−) were studied after inoculation under field conditions for two consecutive years. H2O2 significantly influenced lignin content in flag leaves, whereas there was a negative correlation among lignin and H2O2 to the Area Under Disease Progress Curve (AUDPC). The production of H2O2 was higher in the resistant genotypes than susceptible ones. The O2− and OH− positively correlated with AUDPC but negatively with lignin content. This study illustrates that H2O2 has a vital role in prompting lignification and thereby resistance to spot blotch in wheat. We used cluster analysis to separate the resistant and susceptible genotypes by phenotypic and biochemical traits. H2O2 associated lignin production significantly reduced the number of appressoria and penetration pegs. We visualized the effect of lignin in disease resistance using differential histochemical staining of tissue from resistant and susceptible genotypes, which shows the variable accumulation of hydrogen peroxide and lignin around penetration sites.
    Publication
  • Genome-wide association mapping of spot blotch resistance in wheat association mapping initiative (WAMI) panel of spring wheat (Triticum aestivum L.)
    (Public Library of Science, 2018) Ram Narayan Ahirwar; Mishra, V.K.; Chand, R.; Neeraj Budhlakoti; Dwijesh Chandra Mishra; Kumar, S.; Singh, S.; Joshi, A.K.
    Spot blotch (SB) caused by Bipolaris sorokiniana, is one of the most important diseases of wheat in the eastern part of south Asia causing considerable yield loss to the wheat crop. There is an urgent need to identify genetic loci closely associated with resistance to this pathogen for developing resistant cultivars. Hence, genomic regions responsible for SB resistance were searched using a wheat association mapping initiative (WAMI) panel involving 287 spring wheat genotypes of different origin. Genome-wide association mapping (GWAM) was performed using single nucleotide polymorphism (SNP) markers from a custom 90 K wheat SNP array. A mixed linear model (MLM) was used for assessing the association of SNP markers with spot blotch resistance in three consecutive years. Three traits were measured: incubation period, lesion number and area under the disease progress curve (AUDPC). Significant SNP markers were found linked to five, six and four quantitative trait loci (QTLs) for incubation period, lesion number and AUDPC respectively. They were detected on 11 different chromosomes: 1A, 1B, 1D, 4A, 5A, 5B, 6A, 6B, 6D, 7A, 7B with marker R2 range of 0.083 to 0.11. The greatest number of significant SNP-markers was found for lesion number and AUDPC on chromosome 6B and 5B, respectively, representing a better coverage of B-genome by SNPs. On the other hand, the most significant and largest SNP markers for incubation period were detected on 6A and 4A chromosomes indicating that this trait is associated with the A-genome of wheat. Although, QTLs for spot blotch resistance have been reported in wheat on these same chromosomes, the association of incubation period and lesion number with SB resistance has not been reported in previous studies. The panel exhibits considerable variation for SB resistance and also provides a good scope of marker-assisted selection using the identified SNP markers linked to resistant QTLs.
    Publication
  • Natural variation in elicitation of defense-signaling associates to field resistance against the spot blotch disease in bread wheat (Triticum aestivum L.)
    (Frontiers, 2018) Sharma, S.; Ranabir Sahu; Sudhir Navathe; Mishra, V.K.; Chand, R.; Singh, P.K.; Joshi, A.K.; Pandey, S.P.
    Spot blotch, caused by the hemibiotropic fungus Bipolaris sorokiniana, is amongst the most damaging diseases of wheat. Still, natural variation in expression of biochemical traits that determine field resistance to spot blotch in wheat remain unaddressed. To understand how genotypic variations relate to metabolite profiles of the components of defense-signaling and the plant performance, as well as to discover novel sources of resistance against spot blotch, we have conducted field studies using 968 wheat genotypes at 5 geographical locations in South-Asia in 2 years. 46 genotypes were identified as resistant. Further, in independent confirmatory trials in subsequent 3 years, over 5 geographical locations, we re-characterized 55 genotypes for their resistance (above 46 along with Yangmai#6, a well characterized resistant genotype, and eight susceptible genotypes). We next determined time-dependent spot blotch-induced metabolite profiles of components of defense-signaling as well as levels of enzymatic components of defense pathway (such as salicylic acid (SA), phenolic acids, and redox components), and derived co-variation patterns with respect to resistance in these 55 genotypes. Spot blotch-induced SA accumulation was negatively correlated to disease progression. Amongst phenolic acids, syringic acid was most strongly inversely correlated to disease progression, indicating a defensive function, which was independently confirmed. Thus, exploring natural variation proved extremely useful in determining traits influencing phenotypic plasticity and adaptation to complex environments. Further, by overcoming environmental heterogeneity, our study identifies germplasmand biochemical traits that are deployable for spot blotch resistance in wheat along South-Asia.
    Publication