1 Introduction

Wheat is the staple food for 35% of the world’s population and is grown on 17% of the cultivated area in the world (Kronstad, 1998). In Pakistan it is called Kanak (Punjabi), Ghanum (Pashto), and Gandum (Urdu). Wheat belongs to the triticeae tribe (Dumort; Hordeae, Benth.) and subtribe Triticinae of the grass family Poaceae (Gramineae), one of the largest families of Angiosperm (flowering plants) including 600-700 genera and approximately 10,000 species. According to (Levy and Feldman, 2002), all major types of polyploids (autopolyploids, allopolyploids and segmental polyploids) are the members of this family. Being of great importance nutritionally to many people of the world, wheat grain protein plays a fundamental part in food processing, for instance, in bread making, biscuits, breakfast cereals, and pasta products (Payne and Rhodes, 1982). Vavilov (1926) a geneticist and plant geographer, explored the agricultural flora in many of the less developed and largely mountainous parts of the world, where the indigenous crop varieties had not yet given way to cultivars selected by plant breeders. The amount and the quality of gluten, a large complex of polymeric and monomeric endosperm proteins chiefly determine the quality of wheat flour which plays a fundamental part in food processing i.e. in bread making, biscuits, breakfast cereals, and pasta products (Payne and Rhodes, 1982). A large proportion of man’s essential nutrients are contained in the wheat grain. These are carbohydrates (60 to 80%, mainly as starch); proteins (8 to 15% which contain adequate amounts of all essential amino acids except lysine, tryptophane and methionine); fats (1.5 to 2.0%); minerals (1.5 to 2.0%); and vitamins such as the B complex and vitamin E (Kronstad, 1998). High Molecular Weight (HMW) subunits of wheat glutenin have become the most intensively studied group of wheat proteins (Payne and coworkers, 1979). The subsequent studies have given us the most complete picture of the structure of any family of the seed storage proteins and their genes. For the said research analysis the germplasms were got from the Gene bank of Institute of Agri-Biotechnology & Genetic Resources (IABGR), National Agricultural Research Center (NARC), Islamabad to generate a database and characterizing for quantitative and biochemical traits.

2 Materials and Methods

In the 1^st part of an experiment one hundred accessions of wheat (Triticum Aestivum L.) was conducted during the wheat growing season November, 2004 - 2005 in augmented field design at research area of the Department of Plant Breeding and Genetics, Faculty of Agriculture, Gomal University, Dera Ismail Khan (NWFP), Pakistan. Cultural practices and fertilizer were applied properly. Data were taken for spike length (cm), number of spikelets spike^-1, grain yield plant^-1, 1000-grain weight and yield (Kg/Ha). While, in the 2^nd part of experiment all the said one hundred accessions of wheat (Triticum Aestivum L.) germplasms were grown in the said research area for the season 2005 - 2006 with recommended agronomic cultural practices. Hence a single grain was taken from each 100 wheat accessions and ground into fine powder. 10 mg of seed flour was added with 400 µl of protein extraction buffer, centrifuged at 15,000 rpm for 10 minutes and stored at –20.0℃. The said fine powder was run through slab type SDS-PAGE. The gels were stained and destained for date collection.

Analysis of data: For agro-morphological traits the data were statistically analyzed for frequency percentage and combined correlation by the methods of (Steel and Torrie, 1980) and (Sneath and Sokal, 1973). While, for allelic variation the data were recorded on the basis of catalogue (Payne, 1987).

3 Results

3.1 Spike length (cm)

The magnitude of genetic variability was significant for spike length. The frequency distribution (Figure 1) shows that spike length (cm) ranged from 6.2 to 22.1 cm. There are three accessions [PARC/JICA 003839 (02)], [PARC/MAFF 004273 (01)] and [PARC/MAFF 004310 (01)] which had minimum spike length (cm) 7.9, 8.1 and 6.5 cm respectively. While, only one accession [PARC/MAFF 004775 (01)] had maximum spike length (21.9 cm). The diversity in accessions for spike length varied from 6.50 to 21.90 cm with mean value of 12.23 ± 2.28 cm. While, coefficient of variation for this parameter is 18.63 % (Table 1).

3.2 Spikelets spike^-1

The results of formal analysis depictst that wide variation in spikelets spike^-1 was detected. It varied from 8.50 to 29.80 number of spikelets spike^-1 with the mean value 16.35±3.00 and coefficient of variation 18.32% (Table 1). The frequency distribution for number of spikelets spike^-1 (Figure 2) shows that number of spikelets spike^-1 ranged from 7.1 to 31.00. In which one germplasm [PARC/PGRI 004082 (01)] had minimum (8.5) number of spikelets spike^-1. While, the germplasm [PARC/MAFF 004280 (01)] has maximum (29.8) number of spikelets spike^-1.

3.3 Grain yield plant^-1 (g)

Average grain yield plant^-1 of the wheat germplasms ranged considerably. The diversity for grain yield plant^-1 ranged from 1.26 to 4.58 (g) with mean value 2.36 ± 0.52 and coefficient of variation for this character was 21.89 % (Table 1). Frequency distribution as depicted in (Figure 3) ranged from 1.26 to 3.32 (g).

3.4 1000-Grain weight (g)

The results of analysis depicts that significant variation in 1000-grain weight (g) was noted. It ranged from 15.74 to 46.65 g with mean value 34.20 ± 8.05 g. While, coefficient of variation was 23.55%. The frequency distribution for 1000 - grain weight (g) as represented in (Figure 4) depicts that 1000 - grain weight (g) varied between 15.20 and 47.19 (g).

3.5 Grain yield (kg/ha)

Grain yield (Kg/Ha) is the most desirable trait for the identification and selection among wheat accessions for the development of wheat varieties. From analyses the grain yield of one hundred accessions shows good variability. The variation for grain yield (Table 1) ranged from 2610 to 5058 (Kg/Ha) with mean value 4165±504.45 (Kg/Ha) and coefficient of variation 12.11%. Frequency distribution as depicted in (Figure 5) varied from 2610 to 5065.9 (Kg/Ha). The accession [PARC/MAFF 004353 (03)] intimates lowest grain yield (2610 Kg/Ha). While, the accession [PARC/MAFF 004279 (05)] had a maximum grain yield (5058 Kg/Ha).

Result: Correlation coefficients

To analyse the combination among different plant traits is most important and needful for yield improvement. Correlation among quantitative traits may depict biological process that is of considerable evolutionary interest. The correlation coefficients among five parameters for the year 2004-2005 are shown in (Table 2). Spike length revealed significant and highly positive correlation with number of spikelets spike^-1, grain yields plant^-1 and grain yield (Kg/Ha). While, this trait has negative correlation with 1000-grain weight. Highly significant positive correlation was depicted in number of spikelets spike^-1 with grain yield plant^-1 and grain yield Kg/Ha. While, positive correlation of this trait was noted with 1000-grain weight. Grain yield plant^-1 had highly significant positive correlation with 1000-grain weight and grain yield Kg/Ha. Highly significant positive correlation was observed in 1000-grain weight with grain yield (Kg/Ha).

Result: Allelic variation in bread wheat (Triticum Aestivum L.) through sds-page techniques: The accessions belonging to different areas were partitioned into eighteen different HMW- glutenin subunit combinations (Table 3). Out of these the subunit composition of null, 7+8, 2+12 and 2* were recorded with several other subunits with different unique compositions (Table 3). It has been well established that the variation in HMW glutenin subunits of wheat is correlated with bread making quality. Therefore, it is possible to determine overall quality of a variety in terms of HMW glutenin subunits by adding together the score of the individual subunits (Payne et al., 1987). The frequency of various alleles found in the entire set of germplasm at the locus Glu-A1 the subunit “null” was found in 48% of the accessions. While, the remaining accessions were found to possess the subunit 2* (28%), subunit 2 (3%) and subunit 1 (21%) at the Glu-A1 locus. The most frequent HMW glutenin subunits at Glu-B1 locus were 7+8, which appeared in 54 accessions. The other subunit was 17+18 (23%), subunit 7 (4%), subunit 8 (2%) and subunit 7+9 (17%). At the Glu-D1 only three pairs of subunits 2+12, 4+12 and 5+10 were found in most of accessions with frequency of 79%, 6% and 15%, respectively. It has been well established that the variation in HMW Glutenin Sub-units of wheat was correlated with bread making quality (Payne et al., 1987). Therefore, it is possible to determine overall quality of a variety in terms of HMW Glutenin Sub-units by adding together the score of the individual sub-units adapted by (Payne et al., 1987).

4 Discussion

The genetic diversity is the backbone of crop improvement. A positively significant observation was found satisfactory for Spike length, number of spikelets spike^-1, grain yield plant^-1, 1000-grain weight and yield (Kg/Ha) respectively. These traits can be utilized for further breeding programme to synthesize a new wheat variety for the need of the world. These observations agree with the earlier findings (Gorney et al., 2006; Hu et al., 2006; Mohibullah et al., 2012). Significant genotypic differences were observed for all traits, which are in agreement with the results observed by (Stolt et al., 2006). While, negative correlation in spike length was found with 1000-grain weight, which are at par with the results obtained by (Mohibullah et al., 2013). The parameters showing significant positive correlation can be utilized for further crop improvement program to develop new wheat varieties.

Allelic variation through SDS-PAGE techniques for HMW glutenin sub-units the quality score obtained in these landraces are quite comparable to the scores obtained by earlier researchers (Bhagwat and Bahatia, 1988; Lukow et al., 1989). Glutenins and gliadins are two major groups of the seed storage proteins in hexaploid wheat. The inheritance of protein is well characterized and their high levels of polymorphism, has proved immense value in breeding (Morgunov et al., 1990). The HMW glutenin sub-units encoded by genes at Glu-A1, Glu-B1 and Glu-D1 loci on chromosomes 1A, 1B and 1D respectively have received special attention. The results showed a broad and interesting range of variation for HMW glutenin sub-units genes in the landraces under investigation which are in agreement with several researchers viz. (Tahir et al., 1996; Rodriguez-Quijano et al., 1998; Igrejas et al., 1999), who have reported the higher frequency of 7+8 allele than 17+18 at this locus. The allelic result demonstrated that the pattern of HMW glutenin sub-units in the said landraces was almost similar to those reported by different researchers i.e. (Liu et al., 2007; Ren et al., 2008; Alvina et al., 2012; Naushad et al., 2012).

5 Conclusion

From the observations got through frequency distribution it was decided that genotypes [PARC/MAFF 004775 (01)], 004280 (01) and 004279 (05) has maximum spike length of 21.9, 18.7 and 15.2 (cm), while 20.7, 29.8 and 17.6 spikelets spike^-1 and grain yield plant-1consisting of 3.16, 2.53 and 4.58 (g) respectively. 1000-grain weight for the said genotypes contains 32.2, 25.5 and 45.8 (g). While, grain yield consists of 4761, 4653 and 5058 (Kg/Ha). The observations and evaluation of experimental findings of one hundred germplasms through SDS-PAGE techniques, it was concluded that a considerable variation in total 12 different HMW glutenin subunit compositions was found. The frequency of 7+8 and 2+12 was the highest in the entire set of all germplasms. During the present investigation fifteen germplasms (PARC/MAFF 4272 (01), 4269 (01), 4358 (01), 4355 (02), PARC/JICA 3835 (05), PARC/MAFF 4358 (03), 4292 (01), 4354 (02), 4354 (01), 4264 (03), 4280 (03), 4269 (02), 4279 (01), 4277 (01) and 4277 (02) possessing 5+10 allele, which is a known source for good bread making quality, have been identified. The said information’s could be of immense value for varietal improvements in term of bread making quality. Hence all the said noted accessions have the required potential and recommended for general cultivation for further breeding program.

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