Shubhada Tamhankar

Relationship of HMW, LMW Glutenin Subunits and γ-gliadins with Gluten Strength in Indian Durum Wheats

Twenty-four durum wheat genotypes were evaluated for two years to assess the relationship between HMWglutenin subunits, LMWB glutenin patterns, gammagliadins and gluten strength as measured by SDS-sedimentation volume. Indian durum genotypes assessed in this study represented a diverse set of Glu-1, GH-B1 and Glu-3 alleles. Considerable variability was detected for protein content and gluten strength. All the locals and released varieties derived from locals showed significantly higher protein content. Specific alleles at Glu-1, Glu-3 and Gli-B1 loci showed different effects on gluten strength. HMW glutenin subunits 2* and 14+15 showed association with high gluten strength. Genotypes having LMW-f (linked γ-43.5) showed significantly higher gluten strength than other three LMW-B patterns, i.e. LMW-b and c (linked γ-45) and LMW-e(linked γ-44). While genotypes with γ-44 and linked LMW-e patterns were found to have lowest gluten strength. The Gli-A2 locus did not show any significant association with gluten strength.

Molecular genetic diversity analysis in emmer wheat ( Triticum dicoccon Schrank) from India

Emmer wheat (Triticum dicoccon Schrank) is still largely cultivated in India, and highly appreciated for the preparation of traditional dishes. Moreover, its nutritional characteristics could justify a development of its cultivation. The perspective of genetic improvement however requires a good knowledge of the genetic diversity existing within the eco-geographic group of Indian emmer wheats. A set of 48 emmer wheat accessions from India including 28 from a local collection and 20 Indian accessions obtained from CIMMYT, Mexico, was assessed for genetic variability using 47 microsatellite (SSR) markers, distributed over all the 14 chromosomes. The number of alleles per locus ranged from 2 to 9, with an average of 3.87 alleles per locus. A total of 201 alleles were detected at 52 loci with average polymorphic information content of 0.35 per locus and a mean resolving power of 1. The pair-wise similarity coefficients calculated from binary data matrix based on presence or absence of alleles varied from 0.15 to 0.98, but was greater than 0.5 for most accessions, indicating a high level of similarity. A cluster analysis based on the similarity matrix identified nine distinct accessions and three clusters. All the recently developed commercial varieties were distinctly different from the clusters. Based on the analysis, it appears that Indian emmer wheats are not very diverse. Consequently, there is a need to increase the diversity within the Indian emmer wheat eco-geographic group, by introducing diversity from other eco-geographic groups, or even from other wheat species.

Note: Diversity Analysis of Indian Tetraploid Wheat Using Intersimple Sequence Repeat Markers Reveals Their Superiority over Random Amplified Polymorphic DNA Markers

Intersimple sequence repeat polymorphism (ISSR, Zietkiewicz et al., 1994) has emerged as a relatively new, reliable, and speedy marker system for germplasm evaluation and has been used in wheat for detection of polymorphism (Nagaoka and Ogihara, 1997), genetic mapping (Kojima et al., 1998) and tagging of quantitative traits (Ammirajuet al., in press) and in various other plants such as conifers (Tsumuraet al., 1996), citrus (Fanget al., 1997), grapevine (Moreno et al., 1998), and rice (Joshi et al., 2000) for assessment of variability in germplasm. In the present work, we have employed ISSR markers to characterize the variability in a set of Indian tetraploid wheat germplasm, which had been analyzed using RAPD markers in an earlier work by us (Pujar et al., 1999), and have compared the two marker systems for their suitability in the evaluation of tetraploid wheats.

Molecular phylogenetics and systematics of Trigonella L. (Fabaceae) based on nuclear ribosomal ITS and chloroplast trnL intron sequences

The genus Trigonella includes the widely cultivated T. foenum-graecum and a number of other medicinal and aromatic plant species distributed around the Mediterranean region. Sectional delimitation of Trigonella species is still based on morphology and interspecific relationships within the genus are not yet sufficiently resolved. Phylogenetic relationships in 22 species representing 11 of the 12 sections recognized within the genus Trigonella were analyzed using nuclear ITS and plastid trnL-F DNA sequences. Within nuclear ITS region, ITS-II was found to evolve faster compared to ITS-I. Maximal phylogenetic resolution and support was obtained in the combined analysis of the two selected regions. Trees resulting from maximum parsimony as well as Bayesian inference of combined data provided evidence for Trigonella being monophyletic with high support but did not agree with the traditional subgeneric division. Phylogenetic reconstructions indicated three major lineages supported by apomorphies in inflorescence and stipule. The phylogram supported the sectional delimitation of sections Cylindricae, Vérae, Samaroideae, Pectinatae,Erosae and Callicerates. There is strong support to combine monotypic sections Pectinatae and Erosae into one. However, species belonging to section Foenum-graecum and Falcatulae clustered in different subclades, contrary to their current classification. Inflorescence type appears to be a useful character with taxonomic potential for phenetic implications at subgeneric and sectional level within the genus. Moreover, some legume and seed characteristics, considered important in existing taxonomy, appear to have arisen more than once in Trigonella and are homoplastic.

DNA Profiling and Assessment of Genetic Relationships Among Important Seedless Grape (Vitis vinifera) Varieties in India Using ISSR Markers

In the present work, 43 seedless grape (Vitis vinifera) varieties were evaluated using 14 informative ISSR primers. A total of 119 bands were scored, out of which 79% were polymorphic. The level of polymorphism varied according to the primers which was evident also from different Resolving Power values of the individual primers. Based on the DNA fingerprint data of only three primers (UBC 857, 888 and 890), all the varieties except one could be identified. UPGMA cluster analysis revealed high degree of similarity among the varieties. Distinct subgroups based on the berry colour were observed. No intravarietal differences were detected. Overall grouping was in accordance with morphological characters and pedigree, proving usefulness of ISSR markers to assess genetic relationships among grape varieties.

Identification of Gluten Protein Subunits and Their PCR Amplified Products Related to Sedimentation Volume in Durum Wheat

Protein content and gluten strength are the major parameters, which decide the firmness, stickiness and cooking loss of pasta. In the present study, a population of 140 F2:7 recombinant inbred lines derived from a durum wheat cross was analyzed for the association of protein and PCR based markers with gluten strength as estimated by sodium dodecyl sulfate-sedimentation (SDSS) volume. The regression analysis showed strong association of Glu-B3a, Glu-B2a and one ω-gliadin band coded by Gli-B3 locus with the SDSS volume. The association between gluten strength and Glu-B2/Gli-B3 loci is new observation. Glu-B1b was also found to be associated with gluten strength, while no association of Glu-A3 locus was observed. All these markers collectively explained 51.9% to 59.1% variation in SDSS volume at three diverse environments.

1BL/1RS translocation in durum wheat and its effect on end use quality traits

The gluten proteins document the genotypic identity of a wheat variety, in addition to providing valuable clues about its ancestry and technological properties. In this study, an Indian durum wheat genotype B662 was identified to carry 1BL/1RS translocation and characterized further for its effect on end use quality traits. Comparison of the end use quality traits of B662 with five other durum cultivars without 1BL/1RS, showed decreased gluten content, lower swelling index of glutenins and low MSDS-SV indicating that, B662 with 1BL/1RS is not good for pasta making. In F2:3 seeds from a durum wheat cross between the 1BL/1RS cultivar B662 and HI8498 without the translocation, the secalin Sec-1 loci segregated in theoretically expected 3:1 proportion and were inherited as a block of the rye chromosome arm. The analysis of F2:3 harvests for the two most important durum wheat quality tests showed that the presence of 1BL/1RS translocation did not alter the grain protein content values, but was associated with significant reduction of micro SDS-sedimentation volume indicating inferior quality, thus limiting the commercial exploitation of durum wheat genotypes with 1BL/1RS translocation. The cautious use of rye translocation in Indian durum wheat breeding is suggested.