Arvind Kumar Ahlawat

Diversity in quality traits amongst Indian wheat varieties I: flour and protein characteristics.

The relationships of polymeric as well as monomeric proteins (unextractable and extractable) with various flour properties amongst Indian wheat varieties were evaluated. Unextractable polymeric proteins and unextractable monomeric proteins in flours ranged from 23.83% to 51.97% and 48.03% to 76.17%, respectively. Varieties with higher grain hardness index resulted into flours with higher a(∗), ash content and protein content. Unextractable polymeric and monomeric proteins were related to grain hardness index. Unextractable polymeric proteins showed a positive correlation with gluten index and LASRC. Majority of varieties with HMW-GS combinations of 91kDa+80kDa+78kDa+74kDa PPs showed very high grain hardness index (97-100).

Physicochemical and rheological properties of starch and flour from different durum wheat varieties and their relationships with noodle quality.

Starch and flour properties of different Indian durum wheat varieties were evaluated and related to noodle-making properties. Flours were evaluated for pasting properties, protein characteristics (extractable as well as unextractable monomeric and polymeric proteins) and dough rheology (farinographic properties), while starches were evaluated for granule size, thermal, pasting, and rheological properties. Flour peak and final viscosities related negatively to the proportion of monomeric proteins but positively to that of polymeric proteins whereas opposite relations were observed for dough rheological properties (dough-development time and stability). Starches from varieties with higher proportion of large granules showed the presence of less stable amylose-lipids and had more swelling power, peak viscosity and breakdown viscosity than those with greater proportion of small granules. Noodle-cooking time related positively to the proportion of monomeric proteins and starch gelatinization temperatures but negatively to that of polymeric proteins and amylose content. Varieties with more proteins resulted in firmer noodles. Noodle-cohesiveness related positively to the proportion of polymeric proteins and amylose-lipids complexes whereas springiness correlated negatively to amylose content and retrogradation tendency of starches.

Molecular mapping of the grain iron and zinc concentration, protein content and thousand kernel weight in wheat (Triticum aestivum L.)

Genomic regions responsible for accumulation of grain iron concentration (Fe), grain zinc concentration (Zn), grain protein content (PC) and thousand kernel weight (TKW) were investigated in 286 recombinant inbred lines (RILs) derived from a cross between an old Indian wheat variety WH542 and a synthetic derivative (Triticum dicoccon PI94624/Aegilops squarrosa [409]//BCN). RILs were grown in six environments and evaluated for Fe, Zn, PC, and TKW. The population showed the continuous distribution for all the four traits, that for pooled Fe and PC was near normal, whereas, for pooled Zn, RILs exhibited positively skewed distribution. A genetic map spanning 2155.3cM was constructed using microsatellite markers covering the 21 chromosomes and used for QTL analysis. 16 quantitative trait loci (QTL) were identified in this study. Four QTLs (QGFe.iari-2A, QGFe.iari-5A, QGFe.iari-7A and QGFe.iari-7B) for Fe, five QTLs (QGZn.iari-2A, QGZn.iari-4A, QGZn.iari-5A, QGZn.iari-7A and QGZn.iari-7B) for Zn, two QTLs (QGpc.iari-2A and QGpc.iari-3A) for PC, and five QTLs (QTkw.iari-1A, QTkw.iari-2A, QTkw.iari-2B, QTkw.iari-5B and QTkw.iari-7A) for TKW were identified. The QTLs together explained 20.0%, 32.0%, 24.1% and 32.3% phenotypic variation, respectively, for Fe, Zn, PC and TKW. QGpc.iari-2A was consistently expressed in all the six environments, whereas, QGFe.iari-7B and QGZn.iari-2A were identified in two environments each apart from pooled mean. QTkw.iari-2A and QTkw.iari-7A, respectively, were identified in four and three environments apart from pooled mean. A common region in the interval of Xgwm359-Xwmc407 on chromosome 2A was associated with Fe, Zn, and PC. One more QTL for TKW was identified on chromosome 2A but in a different chromosomal region (Xgwm382-Xgwm359). Two more regions on 5A (Xgwm126-Xgwm595) and 7A (Xbarc49-Xwmc525) were found to be associated with both Fe and Zn. A QTL for TKW was identified (Xwmc525-Xbarc222) in a different chromosomal region on the same chromosome (7A). This reflects at least a partly common genetic basis for the four traits. It is concluded that fine mapping of the regions of the three chromosomes of A genome involved in determining the accumulation of Fe, Zn, PC, and TKW in this mapping population may be rewarding.

Extraordinarily soft, medium-hard and hard Indian wheat varieties: Composition, protein profile, dough and baking properties

Hard wheat (HW), medium-hard wheat (MHW) and extraordinarily soft wheat (Ex-SW) varieties with grain hardness index (GHI) of 83 to 95, 72 to 80, 17 to 29 were evaluated for pasting, protein molecular weight (MW) distribution, dough rheology and baking properties. Flours from varieties with higher GHI had more protein content, ash content and paste viscosities. Ex-SW had more glutenins proportion as compared to HW and MHW. Flours from Ex-SW varieties showed lower NaSRC, WA and mixographic parameters as compared to HW and MHW. Dough from flours milled from Ex-SW had higher Intermolecular-β-sheets (IM-β-sheets) than those from MHW and HW. Muffins volume increased with decrease in GHI, Ex-SW varieties had more muffin volume and less air space. The accumulation of polypeptides (PPs) varied significantly in different varieties. Ex-SW variety (QBP12-10) showed accumulation of 98, 90, 81 and 79kDa PPs, which was unique and was different from other varieties.

Early ground cover and other physiological traits as efficient selection criteria for grain yield under moisture deficit stress conditions in wheat (Triticum aestivum L.)

An experiment was conducted to study the phenotypic and genotypic variance, heritability, genetic advance, correlation coefficients and path analysis for yield and physiological traits under rainfed condition. High estimates of heritability were recorded for early ground cover, chlorophyll content, flag leaf area, protein percent, and relative water content. Positive and significant correlation were recorded for early ground cover (0.662**), flag leaf area (0.390*), relative water content (0.589**) and canopy temperature depression (0.698**) with grain yield. The path coefficients were studied for all the traits. Early ground cover, flag leaf area, relative water content, canopy temperature depression had positive direct effects on grain yield per plot. Early ground cover, flag leaf area, relative water content and canopy temperature depression had direct positive effect on yield both at genotypic and phenotypic levels across the two environments. This suggests the possibilities of improvement of these characters through selection.

Genetic diversity for moisture deficit stress adaptive traits in bread wheat (Triticum aestivum L.)

A study was conducted to evaluate the genetic divergence for morphological and phenological traits under rainfed conditions in wheat. Seed material comprised of the 294 wheat genotypes used for this study and grouped into six clusters. Among the six clusters, cluster IV contained 86 and cluster I had 68 genotypes, followed by 12 genotypes in cluster V. Fifty one genotypes were grouped in cluster VI and 52 were included in cluster II, while cluster III was represented by 27 genotypes. Maximum cluster mean for the character grain yield per plot was observed for the cluster III (667.1) followed by cluster V (559.3). The minimum cluster mean under the rainfed conditions was observed for the cluster IV (269.3). Intra cluster distance was maximum for cluster III (3.125). The highest inter cluster distance was noted between cluster II and cluster IV (4.997). Parentage of 294 genotypes revealed that genotypes belonging to different eco-geographical areas were included in the same cluster. This indicated that there was no association between clustering pattern and eco-geographical distribution of genotypes.

Effect of grain hardness, fractionation and cultivars on protein, pasting and dough rheological properties of different wheat flours

Coarse flour fractions (CFFs) and fine flour fractions (FFFs) obtained from flour milled from twelve different wheat cultivars varying in grain hardness index (GHI) were evaluated for particle size distribution, pasting and protein characteristics. Cultivars with greater hardness produce flour with high protein content had more proportion of large size particles. FFF had higher unextractable polymeric protein, solvent retention capacity (SRC), sedimentation value (SV) and dough stability (DS) than their corresponding CFF. Both FFF and CFF from cultivars with lower hardness showed lower sodium SRC. CFF showed higher pasting viscosities than their corresponding FFF, and difference in these properties was greater amongst soft cultivars. DS increased with decrease in grain hardness, but medium hard cultivars showed exceptionally higher value. The concentration of HMW-GS in the CFF was higher than FFF of hard wheat cultivars, whereas the concentration of LMW-GS in the CFF and FFF was not influenced by the fractionation of flour.

Genotype-environment interaction for grain iron and zinc concentration in recombinant inbred lines of a bread wheat (Triticum aestivum L.) cross

A set of 306 recombinant inbred lines (RILs) along with the two parents and hitherto popular wheat variety in India, PBW 343, were evaluated in three environments over two years for grain iron (Fe) and zinc (Zn) concentration. Considerable genetic variation for both grain iron and zinc concentration exists. The environment effect was the most important source of variation for grain Fe and Zn concentration, explaining 37.42% and 57.78% of the total sum of squares respectively. Genotype-environment interaction (G x E) for Fe and Zn accounted for 29.46% and 23.24% of the total sum of squares, respectively. The magnitude of G x E interaction was relatively high. High heritabilities were observed for iron (0.81) and zinc (0.71) concentrations reflecting non-crossover type of interaction. The positive and moderately high correlation (0.677**) between Fe and Zn concentration suggest good prospect of simultaneous improvement of both the micronutrients. Additive main effects and multiplicative interaction biplot and environmental indices indicated the most favorable environment for Fe to be at Delhi, which was the second most favorable environment after Samastipur in Bihar for Zn. A poor environment for grain Fe and Zn accumulation was at Pantnagar. Four stable RILs each for grain Fe and grain Zn concentration were identified.

Assessment of genetic diversity based on quality and morphological characters in spring wheat (Triticum aestivum L em Thell)

Wheat (Triticum aestivum L Em Thell) is the leading staple food crop globally which contribute about 30 % of global cereal production. It is being grown in 218.5 million hectare area with an average productivity of 3.26 tonnes/ ha (FAO, 2014). Wheat has a unique property of having a storage protein called ‘Gluten’, which has viscoelastic nature due to which it can be processed into the large number of end products. Currently, only 15 to 18 per cent of total wheat produced in India is used by roll flour mills. Of the remaining harvested wheat less than 7 per cent goes as seed and for grain export. The remaining 76+ percent is used by the village based unorganized stone roller grinding mills to produce whole grain Atta that is used for Chapati (Nagarajan 2013). When wheat grains are grounded without the aleuron layer and seed embryo the resultant white flour is called Maida. Whole wheat is rich in gluten, a protein conglomerate that increases the elasticity of the dough. From Maida, pan bread, noodles, cakes, biscuit and pizza can be made. For every good quality product specific and adapted wheat flour is required (Nagarajan 2013).

Analysis of genetic diversity among the Indian bread wheat cultivars using microsatellite (SSR) markers

Genetic diversity among 35 wheat cultivars was evaluated using 30 polymorphic microsatellite (SSR) markers. Analysis of molecular diversity revealed moderate levels of polymorphism in the set of genotypes studied. Ninety alleles with an average of three alleles per locus were detected. The allelic polymorphism information content (PIC) value ranged from 0.06 to 0.76 with an average of 0.45. The primers like Xgwm294, Xgwm146, Xgwm455, Xgwm497, Xgwm136 and Xgwm132 could be considered particularly informative, as they revealed four or more alleles per locus and displayed high PIC values.Ten rare and three unique alleles were recorded. The most closely related cultivars were ‘Raj3765’ and ‘HD 2402’ displaying the lowest dissimilarity index, whereas highest genetic distance was observed between ‘Pissi Local’ and ‘HB 208’.The land race ‘Pissi Local’ revealed very high genetic distance with most of the cultivars where the dissimilarity indices ranged from 0.42–0.74. Three major clusters comprising 13, 12 and 10 genotypes were formed. Despite the presence of variability among the different Indian cultivars the varieties developed at various institutes during different time periods clustered together indicating the use of common genotypes in the pedigree.