Tetraploid wheats

Okinawa and Morioka, Japan A durum (tetraploid) wheat Aldura was crossed with Kanto 107 (hexaploid with double null for Wx-A1 and Wx-B1 proteins) to produce the first waxy tetraploid wheat Chinese Bai Huo wheat (null for Wx-D1 protein) was crossed with Japanese Kanto 107 and Saikai 173 (null for Wx-A1 andWx-B1 proteins) to obtain waxy hexaploid wheat 258-260... 

Work on DNA fingerprinting and genetic diversity analysis of tetraploid wheat in relation to evaluation of glutenin and gliadin polymorphism in durum, evaluation of /1-carotene, and development of mapping populations is also underway [2,27]. 

The study clearly indicates the possibility of an enhanced efficiency of chlorophyll synthetic gene in the background of different genotypes. Consequently, it would be worthwhile to incorporate the chlorophyll synthetic genes from diploid and tetraploid wheat species with high rate of photosynthesis to the modern cultivars. 

Of interest, recently a tetraploid wheat, cv. Trin kria, has been found inhibiting the production of B-dicarbonyl compounds. This line and the crosses with B-diketones producing wheat varieties would be suitable material for studying the manner of action of biosynthetic and inhibitor biosynthetic genes responsible for the production of B-diketones and alkan-2-ol esters. 

This is a tetraploid wheat with generally yellow vitreous endosperm used for the industrial production of long and short pastas. It contains from 10%-17% of protein. 

Diploid wheat has 2 normal sets of chromosomes (2n=14), tetraploid wheat has 4 sets of chromo-... 

The most common wheat species used in food production is ordinary wheat, also called bread wheat (Triticum aestivum). It is an allohexaploid (AABBDD), in which the genomes were obtained by spontaneous hybridization of T. turgidum (AABB) and Aegilops tauschii (DD) about 10,000 years ago (Vasil, 2007). Other grown wheat species are tetraploidal durum wheat T. durum, used in pasta production and small amounts of hexaploidal spelt T. spelta and tetraploidal T. polonicum (Curtis et al. 2002). 

Figure 8. SDS—PAGE patterns of reduced glutenin of hexaploid wheats and their extracted AABB tetraploids (A) Chinese Spring (B) Prelude (C) Tetra-prelude (D) Rescue (E) Tetrarescue (F) Stewart 63 (durum) (G) Thatcher (H)...

Wheat, barley, and rye are classified in the same subfamily (Festucoideae) and tribe (Triticeae) of the grass family (Gramineae), and this close relationship is reflected in the structures of their prolamin storage proteins. Only in wheat, however, do these proteins form a cohesive mass (gluten). Barley and rye are diploids, each with seven pairs of chromosomes, while wheat species are diploid, tetraploid, or hexaploid (Figure 3.14). 

The total number of chromosomes is 42 for hexaploids (used for bread making), 28 for tetraploids (durum wheat used for pasta), and 14 for diploids (primitive wheat). 

In a relatively young allopolyploid like vulgare wheat the genetic control of mechanisms essential to life is duplicated in an autopolyploid manner, e.g., chlorophyll mutation frequencies will be low in Xg (Mac Key, 1967 Swaminathan et aL, 1962). In contrast, peripheral morphological characteristics are inherited in a diploid fashion. In the much older tetraploid emmer wheats, evolution has had time to provoke a diploidization, and chlorophyll mutations again become as common as they are in diploids (Mac Key, 1967). 

Table 11.3 Protein Composition and Mixograph Dough Development Times for Near-Isogenic Lines (NILs) of Tetraploid (Durum) Wheat Cultivar Svevo...

The wild diploid and tetraploid species of wheat possess much higher rates of flag leaf photosynthesis than the cultivated hexaploids (1) The high rates of photosynthesis per unit leaf area have been correlated with several morphological and anatomical traits (2>3). Attempts have also been made to correlate the in vitro electron-transport rates with leaf photosynthesis. Zelenskii et al (4) found that the chloroplasts of wild diploid species had 42 per cent higher rates of uncoupled Hill reaction as compared with cultivated hexaploid. This was later confirmed by Miginiac-Maslow et al (5). However,... 

The plants of different species of wheat viz. T.monococcum, T.boeoticum, T.urartu, T.searsii, Ae.speltoides, Ae.squarrosa Tdiploid), T. dicoccoides ( tetraploid) and T. zhukowaskyi,... 

Both the stage of the microspore when collected for pretreatment and the pathway of nuclear development have also been considered to influence the frequency of doubling. He concluded that microspores collected at uninucleate stages 1-3 (early, mid and late, respectively) resulted in mostly haploid and doubled haploid plants while those collected at later stages (4-6, mitosis and binucleate) resulted in mostly doubled haploids as well as some triploid and tetraploid plants. It has also been demonstrated in wheat that the pretreatment method will influence the pathway alongwhich the nuclei will develop. 

On the other hand, colchicine s ability to induce polyploidy can solve many important problems of plant breeding. Colchicine renders infertile hybrids fertile. For example, the maximum Fuchsia species are diploid or tetraploid. The cross between diploid and tetraploid results often in a triploid, which is mostly sterile because the process of meiosis requires the pairing of similar chromosomes and due to lack of mechanism to allow the alignment of three similar chromosomes. However, colchicine treatment produces fertile hexaploid plants. Breeding of triticale from wheat and rye shows similar problem wheat is typically tetraploid and rye is diploid, with the triploid hybrid being infertile. Here also, treatment with colchicine results in fertile hexaploid triticale. 

This is produced by crossing tetraploid durum wheat with diploid lye and treating seedlings of the sterile FI plants so that their chromosome number is doubled and they become reasonably fertile. It is bearded and intermediate between wheat and rye in most of its characteristics. Mainly winter varieties are being grown in the UK. There is no EU support. Triticale is in direct competition with other feed grains. The area grown in the UK is small, only approximately 20 000 ha. 

In the works of A. Konarev (Konarev et al. 1999 Konarev et al., 2004) shows in detail the variability of inhibitors of trypsin-like proteinases in cereals due to resistance to various grain pests. So in wheat trypsin inhibitors are represented by several genetically independent systems of proteins controlled by the genome and B chromosomes ID (endosperm), 3Dp (aleurone layer), IDS and 3Ap (leaf). Trypsin inhibitors of rye are controlled chromosome 3R and barley 3H. The most complex structure of inhibitors was wheat leaves, with the genomic formula AABBDD. In general, it is the sum of the spectra of trypsin inhibitors from several tetraploid (T. turgidum) (AABB) and (Aegilops tauschii Coss.) (DD) (Konarev, 1986 Konarev et al., 2004). 

Tetraploid ancient wheat (Triticum dicoccoides or dicoccum). 

A mutant tetraploid durum wheat that reduces amylose content has lead to the discovery of full and partial durum wheats. According to Vignaux et al. (2004), the waxy mutation did not affect grain yield, kernel size, or hardness. However, waxy cultivars contained more alpha amylase activity and lower semolina yield. The commercial growth of high yielding waxy durum wheats will bring new beneficial applications and probably new markets to the industry. 

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