Understanding the chapati making attributes of the Indian wheats – I: The physico-chemical basis

The research project was largely built around the tall traditional cultivars of the pre-dwarfing era, which were known to excel for chapati quality. These included C 306, C 518 and C 273. The few cultivars that had emanated from crosses of these superior chapati quality wheats with dwarf wheats formed another important component of this set and included WG 357, PBW 175, PBW 154, PBW 226, Lok 1 among others. Asecond set of materials, three backcross recombinant populations (BC1F5 generation) derived from C 273/PBW 343//PBW 343 (70 lines), C 306/PBW 534//PBW 534 (70 lines) and C 518/PBW 343//PBW 343 (80 lines) were also studied to arrive at some conclusion. Various physico-chemical characters(Grain appearance score,Grain hardness,Test weight,1000-grain weight,Yellow berry,Moisture content,Protein content,Gluten content, Gluten index, Sedimentation value, Phenol Test, Carotenoids, Sugar content, Diastatic activity, Falling Number) and chapati-makingscores were evaluated. Grain hardness seems to have a clear role in chapati quality with a correlation coefficient of 0.34, 0.35 and 0.17 observed in different recombinant populations.More consistent correlation was found for grain appearance ranging from 0.26 to 0.36 in the populations.Consistent high positive correlations have showed up for diastase activity, which ranged from 0.32 to 0.46.This consistent behaviour is a strong evidence for the role of this trait in chapati making quality.Diastase activity emerges as a more consistent and stronger contributor to chapati making quality. Phenol score may not serve as a suitable indicator of chapati quality

Understanding the chapatti making attributes of the Indian wheats – II: The rheological basis

The concept of good chapati varies from individual to individual and depends mainly on the rheological properties of the dough used to prepare the chapaties. The research project was largely built around two type of plant meterials, the tall traditional cultivars of the pre-dwarfing era, and three backcross recombinant populations (BC1F5 generation) C 273/PBW 343//PBW 343 (70 lines), C 306/PBW 534//PBW 534 (70 lines) and C 518/PBW 343//PBW 343 (80 lines). Association of traits studied with chapati score in set of cultivars and genetic stocks Starch pasting characteristics showed mild negative correlation with chapati quality, which is again contrasting, to the requirements of bread making. The correlations were not consistent over years possibly due to environmental factor (temperature, rainfall, fertilizer and irrigations etc.) and due to change in the constitution of the set. Similarly mixographic traits showed negative association chapati making quality. The correlations which prevail in the populations carry much greater weight as these have persisted over several rounds of recombination and are likely to reflect under lying causes of superior chapati quality. As various components of chapati quality would be disassembled, the relative levels of correlations for individual traits would be uncovered. Among the starch pasting characteristics, final viscosity and setback were consistently negatively associated with the chapati making quality. In case of the mixographic traits, mixing tolerance index is negatively associated whereas rate of dough development has consistent positive correlation with chapati quality

Understanding the chapati making attributes of the Indian wheats – I: The physico-chemical basis

The research project was largely built around the tall traditional cultivars of the pre-dwarfing era, which were known to excel for chapati quality. These included C 306, C 518 and C 273. The few cultivars that had emanated from crosses of these superior chapati quality wheats with dwarf wheats formed another important component of this set and included WG 357, PBW 175, PBW 154, PBW 226, Lok 1 among others. Asecond set of materials, three backcross recombinant populations (BC1F5 generation) derived from C 273/PBW 343//PBW 343 (70 lines), C 306/PBW 534//PBW 534 (70 lines) and C 518/PBW 343//PBW 343 (80 lines) were also studied to arrive at some conclusion. Various physico-chemical characters(Grain appearance score,Grain hardness,Test weight,1000-grain weight,Yellow berry,Moisture content,Protein content,Gluten content, Gluten index, Sedimentation value, Phenol Test, Carotenoids, Sugar content, Diastatic activity, Falling Number) and chapati-makingscores were evaluated. Grain hardness seems to have a clear role in chapati quality with a correlation coefficient of 0.34, 0.35 and 0.17 observed in different recombinant populations.More consistent correlation was found for grain appearance ranging from 0.26 to 0.36 in the populations.Consistent high positive correlations have showed up for diastase activity, which ranged from 0.32 to 0.46.This consistent behaviour is a strong evidence for the role of this trait in chapati making quality.Diastase activity emerges as a more consistent and stronger contributor to chapati making quality. Phenol score may not serve as a suitable indicator of chapati quality

Stress Adaptive Plasticity: Aegilops tauschii and Triticum dicoccoides as Potential Donors of Drought Associated Morpho-Physiological Traits in Wheat

The inconsistent prevalence of abiotic stress in most of the agroecosystems can be addressed through deployment of plant material with stress adaptive plasticity. The present study explores water stress induced plasticity for early root-shoot development, proline induction and cell membrane injury in 57 accessions of Aegilops tauschii (DD-genome) and 26 accessions of Triticum dicoccoides (AABB-genome) along with durum and bread wheat cultivars. Thirty three Ae. tauschii accessions and 18 T. dicoccoides accessions showed an increase in root dry weight (ranging from 1.8 to 294.75%) under water stress. Shoot parameters- length and biomass, by and large were suppressed by water stress, but genotypes with stress adaptive plasticity leading to improvement of shoot traits (e.g., Ae tauschii accession 14191 and T. dicoccoides accession 7130) could be identified. Water stress induced active responses, rather than passive repartitioning of biomass was indicated by better shoot growth in seedlings of genotypes with enhanced root growth under stress. Membrane injury seemed to work as a trigger to activate water stress adaptive cellular machinery and was found positively correlated with several root-shoot based adaptive responses in seedlings. Stress induced proline accumulation in leaf tissue showed marked inter- and intra-specific genetic variation but hardly any association with stress adaptive plasticity. Genotypic variation for early stage plasticity traits viz., change in root dry weight, shoot length, shoot fresh weight, shoot dry weight and membrane injury positively correlated with grain weight based stress tolerance index (r = 0.267, r = 0.404, r = 0.299, r = 0.526, and r = 0.359, respectively). In another such trend, adaptive seedling plasticity correlated positively with resistance to early flowering under stress (r = 0.372 with membrane injury, r = 0.286 with change in root length, r = 0.352 with change in shoot length, r = 0.268 with change in shoot dry weight). Overall, Ae. tauschii accessions 9816, 14109, 14128, and T. dicoccoides accessions 5259 and 7130 were identified as potential donors of stress adaptive plasticity. The prospect of the study for molecular marker tagging, cloning of plasticity genes and creation of elite synthetic hexaploid donors is discussed

Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios

Multi-Trait and Multi-Environment QTL Analyses for Resistance to Wheat Diseases

BACKGROUND: Stripe rust, leaf rust, tan spot, and Karnal bunt are economically significant diseases impacting wheat production. The objectives of this study were to identify quantitative trait loci for resistance to these diseases in a recombinant inbred line (RIL) from a cross HD29/WH542, and to evaluate the evidence for the presence loci on chromosome region conferring multiple disease resistance. METHODOLOGY/PRINCIPAL FINDINGS: The RIL population was evaluated for four diseases and genotyped with DNA markers. Multi-trait (MT) analysis revealed thirteen QTLs on nine chromosomes, significantly associated with resistance. Phenotypic variation explained by all significant QTLs for KB, TS, Yr, Lr diseases were 57%, 55%, 38% and 22%, respectively. Marginal trait analysis identified the most significant QTLs for resistance to KB on chromosomes 1BS, 2DS, 3BS, 4BL, 5BL, and 5DL. Chromosomes 3AS and 4BL showed significant association with TS resistance. Significant QTLs for Yr resistance were identified on chromosomes 2AS, 4BL and 5BL, while Lr was significant on 6DS. MT analysis revealed that all the QTLs except 3BL significantly reduce KB and was contributed from parent HD29 while all resistant QTLs for TS except on chromosomes 2DS.1, 2DS.2 and 3BL came from WH542. Five resistant QTLs for Yr and six for Lr were contributed from parents WH542 and HD29 respectively. Chromosome region on 4BL showed significant association to KB, TS, and Yr in the population. The multi environment analysis for KB identified three putative QTLs of which two new QTLs, mapped on chromosomes 3BS and 5DL explained 10 and 20% of the phenotypic variation, respectively. CONCLUSIONS/SIGNIFICANCE: This study revealed that MT analysis is an effective tool for detection of multi-trait QTLs for disease resistance. This approach is a more effective and practical than individual QTL mapping analyses. MT analysis identified RILs that combine resistance to multiple diseases from parents WH542 and/or HD29

Why and how putrescine modulates thermotolerance in wheat?

404-412Effects of putrescine (Put) and high temperature (HT) on the responses of wheat (Triticum aestivum L.) seedlings or developing grains were studied in six wheat cultivars (PBW 343, C 273, C 306, PBW 550, PBW 621 and HD 2967) raised in the laboratory (25°C or 32°C) in Petri dishes for seven days or in the field under normal (November) and late (December) planting conditions. High temperature significantly reduced root/shoot lengths and dry weights of all the six cultivars, whereas Put ameliorated this effect by increasing these attributes. C 306 and C 273 showed higher root/shoot lengths and dry weights over PBW 550, PBW 621. High temperature significantly increased the activities of ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase and catalase in correspondence with an increase in membrane injury index (MII) and thiobarbituric acid reactive substances (TBARs) and H2O2 contents. Application of Put under HT further elevated activities of these enzymes whereas MII and contents of TBARs, H2O2 were reduced. In fact, Put treated seedlings performed better in terms of antioxidant response under HT than seedlings in absence. Various morpho-physiological parameters like plant height, peduncle length, 1000 grain weight and the number of grains per year were decreased in the late sown crop. However, Put application under HT stress increased these parameters. Overall, it appears that upregulation of the antioxidant system by Put in wheat cultivars contributes to the better protection and membrane integrity in the root, shoot and grains against HT through reduced MII and TBARs contents

Genome-Wide Association Study of Grain Architecture in Wild Wheat Aegilops tauschii

Aegilops tauschii, the D-genome progenitor of Triticum aestivum, encompasses huge diversity for various traits of potential economic importance such as yield, biotic and abiotic stress tolerance, quality and nutrition. In the present study, variation for grain size in Ae. tauschii germplasm was studied and its genetic basis dissected using genome-wide association study (GWAS). Grain length, width, and weight evaluated in 177 Ae. tauschii accessions over 3 years showed near normal distribution with 1.74-, 1.75-, and 2.82-fold variation, respectively. These lines were genetically characterized using genotyping-by-sequencing (GBS) protocol that produced 11,489 single nucleotide polymorphic (SNP) markers. Genetic diversity analysis revealed the presence of two distinct subgroups (designated as lineage 1 and 2) in Ae. tauschii. Based on GBS markers, the genetic similarity was calculated between the accessions and GWAS was conducted using 114 non-redundant accessions and 5,249 SNP markers. A total of 17 SNPs associated with grain size traits distributed over all the seven chromosomes were revealed with 6D, 5D, and 2D harboring most significant marker–trait associations. Some of the chromosomal regions such as 6D_66.4–71.1 cM, 1D_143.5–156.7 cM, and 2D_89.9–92.5 cM had associations with multiple traits. Candidate genes associated with cell division and differentiation were identified for some of the associated SNP markers. Further efforts to validate these loci will help to understand their role in determining grain size and allelic diversity in current germplasm and its effect on grain size upon transfer to bread wheat background

First part: Significant QTLs, chromosome, nearest marker, LOD score values (outside brackets, in bold) and their positions (inside brackets, in italics) for multi trait analyses including traits Karnal bunt (KB), tan spot (TS), yellow rust (Yr) and leaf rust (Lr).

<p>Second part: Additive effect of the QTL and R² for each trait. For the individual trait profiles, the LOD values are those found at the maximum individual peak.</p>†<p>: Average threshold for individual trait analysis was 2.5.</p>‡<p>: Threshold for Joint analysis was 3.87.</p

Significant QTLs and their positions in chromosomes for multi-environment analysis of Karnal bunt (KB) in five years (KB01M, KB02M, KB03M, KB04M, and KB05M).

†<p>: Threshold for individual trait analysis is 2.5.</p>‡<p>: Threshold for Joint analysis is 4.27.</p>¥<p>: Threshold for Q×E Interaction for five environments is 2.40.</p><p>Values of the likelihood ratio test, the additive effect of the QTL, and the individual and total R² values. For the individual trait profiles the LOD values are those found at the same position as the peak found for the joint profile.</p