Anju M. Singh

Diversity in amylopectin structure, thermal and pasting properties of starches from wheat varieties/lines

Structural, thermal and pasting diversity of starches from Indian and exotic lines of wheat was studied. Majority of the starches showed amylose content ranging between 22% and 28%. Endotherm temperatures (T(o), T(p) and T(c)) of the starches showed a range between 56-57, 60 -61 and 65.5-66.5 degrees C, respectively. Exotherms with T(p) between 87.0 and 88.2 degrees C were observed during cooling of heated starches, indicating the presence of amylose-lipid complexes. Exotherm temperatures were negatively correlated to swelling power. Amylopectin unit chains with different degree of polymerization (DP) were observed to be associated with pasting temperature, setback and thermal (endothermic T(o), T(p), and T(c)) parameters. Amylopectin unit chains of DP 13-24 showed positive relationship with endothermic T(o), T(p) and T(c). Pasting temperature showed positive correlation with short chains (DP 6-12) while negative correlation with medium chain (DP 13-24) amylopectins. Setback was positively correlated to DP 16-18 and negatively to DSC amylose-lipid parameters.

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.

Identification of kernel iron- and zinc-rich maize inbreds and analysis of genetic diversity using microsatellite markers

Development of micronutrient enriched staple foods is an important breeding goal in view of the extensive problem of ‘hidden hunger’ caused by micronutrient malnutrition. In the present study, kernel iron (Fe) and zinc (Zn) concentrations were evaluated in a set of 31 diverse maize inbred lines in three trials at two locations – Delhi (Kharif 2007 & 2008) and Hyderabad (Rabi 2007–08). The ranges of kernel Fe and Zn concentrations were 13.95–39.31 mg/kg and 21.85–40.91 mg/kg, respectively, across the three environments. Pooled analysis revealed significant genotype × environment (G × E) interaction in the expression of both the micronutrient traits, although kernel Fe was found to be more sensitive to G × E as compared to kernel Zn. Seven inbred lines, viz., BAJIM-06-03, DQPM-6, CM212, BAJIM-06-12, DQPM-7, DQPM-2 and CM129, were found to be the most stable and promising inbred lines for kernel Zn concentration, while for kernel Fe concentration, no promising and stable genotypes could be identified. Analysis of molecular diversity in 24 selected inbred lines with phenotypic contrast for the two kernel micronutrient traits, using 50 SSR markers covering the maize genome, revealed high levels of polymorphisms (214 SSR alleles; mean PIC value = 0.62). The phenotypically contrasting and genetically diverse maize inbred lines identified in this study could be potentially utilized in further studies on QTL analysis of kernel micronutrient traits in maize, and the stable and most promising kernel micronutrient-rich maize genotypes provide a good foundation for developing micronutrient-enriched maize varieties suitable for the Indian context.

Stability Performance of Inductively Coupled Plasma Mass Spectrometry-Phenotyped Kernel Minerals Concentration and Grain Yield in Maize in Different Agro-Climatic Zones.

Deficiency of iron and zinc causes micronutrient malnutrition or hidden hunger, which severely affects ~25% of global population. Genetic biofortification of maize has emerged as cost effective and sustainable approach in addressing malnourishment of iron and zinc deficiency. Therefore, understanding the genetic variation and stability of kernel micronutrients and grain yield of the maize inbreds is a prerequisite in breeding micronutrient-rich high yielding hybrids to alleviate micronutrient malnutrition. We report here, the genetic variability and stability of the kernel micronutrients concentration and grain yield in a set of 50 maize inbred panel selected from the national and the international centres that were raised at six different maize growing regions of India. Phenotyping of kernels using inductively coupled plasma mass spectrometry (ICP-MS) revealed considerable variability for kernel minerals concentration (iron: 18.88 to 47.65 mg kg–1; zinc: 5.41 to 30.85 mg kg–1; manganese: 3.30 to17.73 mg kg–1; copper: 0.53 to 5.48 mg kg–1) and grain yield (826.6 to 5413 kg ha–1). Significant positive correlation was observed between kernel iron and zinc within (r = 0.37 to r = 0.52, p < 0.05) and across locations (r = 0.44, p < 0.01). Variance components of the additive main effects and multiplicative interactions (AMMI) model showed significant genotype and genotype × environment interaction for kernel minerals concentration and grain yield. Most of the variation was contributed by genotype main effect for kernel iron (39.6%), manganese (41.34%) and copper (41.12%), and environment main effects for both kernel zinc (40.5%) and grain yield (37.0%). Genotype main effect plus genotype-by-environment interaction (GGE) biplot identified several mega environments for kernel minerals and grain yield. Comparison of stability parameters revealed AMMI stability value (ASV) as the better representative of the AMMI stability parameters. Dynamic stability parameter GGE distance (GGED) showed strong and positive correlation with both mean kernel concentrations and grain yield. Inbreds (CM-501, SKV-775, HUZM-185) identified from the present investigation will be useful in developing micronutrient-rich as well as stable maize hybrids without compromising grain yield.

Genetic variability and correlation of kernel micronutrients among exotic quality protein maize inbreds and their utility in breeding programme

Micronutrient malnutrition is a widespread problem known to affect millions of children and women. However, the adverse effects of micronutrient deficiency can be overcome through self-targeting, cost-effective and sustainable genetic biofortification approach, which is mainly based on staple food crops. Since maize has emerged as a prominent future crop especially for India, developing maize hybrids that are rich in kernel micronutrients will help in reducing the problems of micronutrient malnutrition. Here, we report variability of kernel Fe and Zn in 120 exotic Quality Protein Maize (QPM) inbreds and kernel Mn and Cu in a representative subset of 68 lines. A wide range of genetic variation was found among genotypes for all the kernel micronutrients: Fe (16.6–83.4 ppm), Zn (16.4–53.2 ppm), Mn (1.7–34.8 ppm) and Cu (0.5–9.5 ppm). Higher mean for kernel Fe and Zn in QPM inbreds suggests possible influence of opaque2 gene and/or modifiers present in them. Significant and positive correlation was observed among kernel Fe, Zn, Mn and Cu. Genetic diversity based on all four micronutrients grouped 68 lines into three major clusters with a mean coefficient of genetic dissimilarity of 2.46. Parental combinations were selected from different heterotic pools and maturity groups to develop high-yielding hybrids enriched with micronutrients.

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.