Wheat science at the Sixth International Triticeae Symposium
Nikolay P. Goncharov
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 10 Lavrentyev ave., Novosibirsk 630090, Russia
Corresponding author: Nikolay P. Goncharov
E-mail: gonch@bionet.nsc.ru
The Sixth International Triticeae Symposium was held at the Kyoto University (Kyoto, Japan) from May 31 to June 5, 2009. Earlier, Helsinborg, Logan, Aleppo, Cordoba, Prague hosted the Symposium. The main goal of International Triticeae Symposiums is the tribe Triticeae Dum. It includes the most important cereal crops (wheat, barley, rye) and some fodder grasses (Dasypyrum, Elymus, Agropyron and so on). A wild annual grass Brachypodium distachyon (L.) Beauv. is a good model for molecular-genetic (genomic) investigation in the tribe. Mary Barkworth (1992) believes that the history of botanic studies of the Triticeae is repleted with changes in generic concepts, caused by taxonomists' struggle with the task of representing its highly reticulated history within the hierarchical classification system demanded by scientific nomenclature.
The 118 participants from 20 countries took part in the symposium. There were near 50 oral presentations and 49 posters. They were grouped in 4 sections, namely Systematics and Phylogeny, Domestication and Evolution, Biodiversity and Genetic Resources, Genomics and Breeding. The presented reports allowed to receive more information about the researches in systematics, genetics, plant physiology and breeding and preservation of wheat’s biodiversity in different gene banks. Like its predecessors, the 6th Symposium raised great interest in wheats and their relatives. The 20 oral presentations and 30 posters were connected with studies of them. Wheat species are not good models for molecular-genetic investigations. Common wheat (Triticum aestivum L.) has long genome near 17,000 Mbp, which makes its molecular and genetic study rather difficult, because most of wheat’s studies are connected with its agronomic characters. Despite this research there has been little commercialisation.
A key challenge facing biologists in the twenty-first century is the preservation of biodiversity. Review of K. Tsunewaki “Plasmon analysis in the Triticum-Aegilops complex” [1-46, presentation numbers, hereafter, see Kawahara (2009)] deal with classification and characterization of the wheat and goat grass plasmon, which they classified into 16 groups. Author analyzed genetic effects of 47 Triticum-Aegilops plasmons on wheat alloplasmic line traits, in which they were combined. Chloroplast DNA polymorphism was investigated to clarify the intraspecific variation in plasmon donor of B and G wheat genomes Aegilops speltoides Tausch by N. Mori, H. Watatani, T. Ishii, Y. Kondo, T. Kawahara, C. Nakamura (2-9). The 80 plastotypes found in Ae. speltoides were further grouped into two subgroups, suggesting an intraspecific differentiation.
M. Garg, H. Tanaka, H. Tsujimoto (1-27) believe that wild species of wheat are useful source of genetic variability for crop improvement. Their gene pool has been utilized for improving the tolerance of wheat to different biotic and abiotic stresses. M. Muramatsu (1-6) reviewed studies of wild Triticeae species indigenous to Japan, their features and results of hybridization with wheat and barley cultivars. Much attention was given to introgression from three species, Elymus tsukushiensis, E. humidus, and E. ciliaris.
Aegilops species bearing the D genome can be used as sources of alleles to be incorporated into cultivated hexaploid wheats. Biodiversity and population structure of the D-genome species Aegilops tauschii Coss. (syn. Ae. squarrosa L.) in Iran and central Eurasian was studied by H. Saeidi, M. R. Rahiminejad, J. S. Heslop-Harrison (1-24) and N. Mizuno, M. Yamasaki, Y. Matsuoka, T. Kawahara, S. Takumi (2-47), respectively. Ae. tauschii is the D genome donor of hexaploid wheats and has high importance for introducing new characteristics and alleles from its gene-pool into common wheat. S. Takumi, H. Morihiro, E. Nishioka, T. Kawahara, Y. Matsuoka (1-19) also checked natural variation in morphological traits in central Eurasian wild wheat progenitor Ae. tauschii. Diversity and relationships of the D genome species of Aegilops-Triticum from Iran also was studied by F. Bordbar, M.R. Rahiminejad, H. Saeidi, F.R. Blattner (2-19).
Artificial man-made species are very suitable for introgression of useful genes and their alleles into cultivated wheat species. The synthetic hexaploids obtained by crossing durum wheat (BA-genomes) and the wild relative Ae. tauschii allowed a significant increase of cultivated wheat D-genome genetic diversity. M. Kishii, A. Mujeeb-Kazi (1-26) and M. Zaharieva, S. Dreisigacker, J. Crossa, T. Payne, S. Misra, R. R. Hanchinal, M. Y. Mujahid, R. Trethowan (2-28) carried out the investigation for understanding the genetic structure of the synthetic species. A subset of genetically diverse accessions was created to be further used for development of new pre-breeding wheat germplasm with enhanced drought and heat tolerance. In CIMMYT since 1980s, more than 1,200 have been produced by randomly crossing the wild D genome diploid donor species (Ae. tauschii) of various ecological origins and 51 durum wheat lines.
Spontaneous amphidiploidization via unreduced gametes is a universal phenomenon for Triticum turgidum - Aegilops tauschii hybrids, which was described by L. Q. Zhang, D. C. Liu, Y. L. Zheng, Y. Yen (2-46). The wide spread of spontaneous amphidiploidization in the T. turgidum - Ae. tauschii F1hybrids was found in hexaploid wheat.
N. P. Goncharov, K. A. Golovnina, E. Y. Kondratenko (1-5) reviewed taxonomy and molecular phylogeny of natural and artificial (synthetic) wheat species. The using of classifications of genus Triticum L. including synthetic wheats is important for molecular-biological, genetic and phylogenetic investigations, for collecting and identifying wheat accessions and breeding practice.
Crossability of common wheat with alien species, e. g., rye, wild and cultivated barley, is known to be controlled by Kr gene family. K. Mishina, A. Manickavelu, H. Sato, M. Katsumata, H. Sassa, T. Koba (2-40) produced molecular mapping of these genes.
Mutual interchange of genetic variation and genomic information between wild and cultivated species in Triticeae was viewed by H. Tsujimoto (1-40). The increase of wheat yield by breeding will help to solve the food crisis which we are facing today without another green revolution. Wild species of the tribe Triticeae grow in a wide range of environments around the world and have large genetic variation.
Breeding properties of a single artificial cultivated species Triticale (x Triticosecale Wittmack) for improved bread-making quality was observed by P. Martinek (2-38). The perspective of newly developed translocations in practical breeding is discussed.
M. Tomita, T. Noguchi, T. Kawahara (1-23) discussed evolutional relationships between Revolver and LARD element in synthetic and natural wheat species and Aegilops squarrosa.
Three presentations were connected with genetic engineering and producing transgenic plants in cereals. They were made by D. Miroshnichenko, G. Poroshin, S. Dolgov (2-39), by A. Binka-Wyrwa, W. Orczyk, A. Nadolska-Orczyk (2-31) and by J. Kumlehn (1-34). Basing upon these technologies authors established a numerous transgenic lines with improved performance.
A lot of presentations were connected with wheat protein quality. The seed storage proteins of common wheat, responsible for the ability of flour to form cohesive dough, are required to make strong dough such as bread. However, the narrow genetic base of hexaploid wheat has limited the allelic combinations that are available for the improvement of bread-making quality. The presented results could be implemented in a local breeding program for the improvement of wheat grain quality using marker-assisted selection. The study is the further contribution to our understanding of regions of the wheat genome that contribute to the control of GPC in common wheat. J. Taguchi, C. Kiribuchi-Otobe, H. Matsunaka, T. Ban (2-18) analysed 96 accessions of tetraploid wheat including Triticum timopheevii, T. durum, T. turgidum, T. dicoccum, T. orientale, T. pyramidale and T. carthlicum and D genome chromosome substitution lines of Langdon durum. They examined genetic diversity for several traits associated with pasta making qualities among tetraploid wheat germplasms conserved in KIBR collection. This study showed valuable diversity of the pasta making traits to improve durum wheat with tolerance to biotic and abiotic stresses from the tetraploid wheat gene pool. D. Mihalik, Z. Sramkova, E. Medvecka, V. Horevaj, S. Slikova (2-21) investigated a genetic variability in Triticum aestivum of Slovakia based on polymorphism for high molecular weight glutenin subunits. The HMW glutenin subunits were classified in 44 cultivars. E. Gregova, E. Medvecka, Z. Sramkova, D. Mihalik (2-20) and S. Slikova, Z. Sramkova, E. Gregova, D. Mihalik (2-27) estimated quality of Triticum durum on the basis of gliadin and glutenin characterization and high-molecular-weight glutenin subunits in European wheats respectively.
X. F. Zhang, D. C. Liu, W. L. Yang, J. Z. Sun, D. W. Wang, H. Q. Ling and A. M. Zhang (2-48) investigated molecular markers for systematic characterization of low molecular weight glutenin subunits in common wheat. The specificity of these markers, validated in a large collection of wheat varieties from China, was discussed. M. Nishinaka, Y .Okumoto, K. Kato, T. Kawahara, T. Tanisaka (2-49) studied genetic diversity of high molecular weight glutenines in 297 wheat landraces originated from the Caspian Sea regions.
Alien glutenin subunits expressed in common wheat endosperm effect on the composition was studied by H. Tanaka, T. Arakawa, H. Tsujimoto (2-43). Identification and mapping of QTLs for grain protein content in common wheat was produced by S. Abugalieva, A. Abugalieva, S. Quarrie, V. Turuspekov (2-29). Based on isolation and molecular characterization of three novel HMW glutenin subunits from Aegilops tauschii, the origin and evolution of 1Dx5 subunit in common wheat were discussed by X. An, D. Wang, Y. Yan (2-17).
Four presentations were connected with origin of elemental genomes and related species. Based on the allelic diversity at chloroplast microsatellite loci among polyploid wheat species the process and geography of wheat domestication was discussed by N. Mori (1-13).
Genetic relationships of 55 genotypes belonging to 8 Triticum of A genome bearing species (T. monococcum, T. boeoticum, T. urartu, T. durum, T. turgidum, T. dicoccum, T. dicocoides and T. aestivum) collected from Iran and some accessions from other areas were studied by M. H. Ehtemam, M. R. Rahiminejad, H. Saeidi, B. E. Sayed Tabatabaei, S. Krattinger, B. Keller (1-11).
Sequence variation of the 20th exon within PolA1 gene among Triticeae species was produced by R. Buwan, H. Takahashi, K. Kato, Y-I. Sato, T. Komatsuda, I. Nakamura (2-32). Phylogenetic analysis of the sequences showed that Triticum and Hordeum species were distinctly separated into two major clades, except those SS genome species of Triticum clustered with Hordeum species.
Diploid wheat (Triticum boeoticum, T. monococcum, T. urartu) phylogeny issues are discussed by F. A. Konovalov, S. V. Goryunova, A. S. Shaturova, A. V. Fisenko, N. V. Melnikova, A. M. Kudryavtsev, N. P. Goncharov (1-37).
Adaptation of flowering-time in tetra- and hexaploid wheat was viewed in two presentation. K. Murai (1-14) discussed the molecular mechanism of adaptation of flowering-time in tetraploid wheats on the basis of the VRN1-VRN3-VRN2 triangle model and focused on selection of flowering-time genes under domestication. H. Nishida, T. Yoshida, Y. Akashi, K. Kato (1-16) studied structural variation in 5’ upstream region of photoperiodic response genes, Ppd-A1 and Ppd-B1 in Japanese cultivars of common wheat. Therefore, it was strongly suggested that these structural variations explain the difference between day length-sensitive and day length-insensitive alleles.
Disease resistance also was popular subject of investigation. Fusarium graminearum attacks spike of Triticeae species. QTL to reduce Fusarium mycotoxin accumulation among hexaploid wheats and multiplex quantitative analysis for trichothecene genes expression of Fusarium graminearum presented by S. Niwa, R. Kikuchi, H. Handa, T. Ban (2-42) and by T. Miyazaki, T. Ban (2-22) respectively. The potential of Hordeum chilense cytoplasm in the development of CMS systems in Triticeae crops was discussed by A. C. Martin (2-36). Investigations on yellow rust disease resistance by useful genes and markers in gene-rich regions on wheat chromosomes was produced by Y. Aydin, E. Cabuk, Z. Mert, K. Akan, N. Bolat, M. Cakmak, A. A. Uncuoglu (2-30). The presence of polymorphic markers that is associated with yellow rust resistance may significantly enhance the success of selection for yellow rust resistant genotypes in wheat breeding programs.
One of reports “Development and cytogenetic analysis of Hordeum chilense chromosome 4 introgression lines into durum wheat” presented by P. Prieto, M. C. Ramirez, A. Martin (1-41) was connected with pest resistance, namely the resistance to the root-knot nematode Meloidogyne naas, just like to Septoria.
Three presentations were connected with studies of spike morphology and one with leaf shape-related traits. First of them “Morphological variations of spike and the geographical distribution of subsection Emarginata species of Aegilops” was presented by A. Ohta, T. Kawahara, K. Yamane (2-10). Second (2-16) was connected with novel source of germplasm for the development of branched ear wheat and third titled “Agronomic traits and genetic determination of common winter wheat lines with multirow spike” was presented by P. Martinek, O. Dobrovolskaya, M. S. Roder, A. Borner (2-37).
H. Morihiro, S. Takumi (2-13) presented results of studies of intraspecific variation in leaf shape-related traits in a wild einkorn wheat species Triticum urartu.
The mechanism of abiotic stress resistance was demonstrated in two presentations. Soil salinity is one of the environmental abiotic stress factors limiting agricultural productivity in many regions of the world. Salinity tolerance and sodium exclusion in genus Triticum was presented by Y. Shavrukov, P. Langridge, M. Tester (1-43). Introgression of new genes from different relatives of Triticum that cope better with salt stress can significantly improve salinity tolerance in both cultivated durum and bread wheats. The producing transgenic crops with salt tolerance was discussed in presentation of D. Miroshnichenko, G. Poroshin, S. Dolgov (2-34) titled “Characterization of growth and yield of transgenic wheat plants overexpressing vacuolar Na+/H+antiporter genes”.
Conservation ex situ and in situ of wheat collections, their study, replenishment and maintenance is still in existence as a source of pre-breeding material. It is of fundamental importance for preserving our food resources and security therefore. The conservation and use of plant genetic resources has a history dating back to the first domestication of plants by humans. A strategy to enhance the effective and efficient conservation and use of ex situ plant genetic resources was presented by M. C. Mackay, L. Guarino, K. A. Street (1-7). This presentation showed how the jigsaw puzzle of this global system is being put together.
Genetic resources of Triticeae - cultivated species and genebank collections was reviewed by H. Knupffer (1-21). An overview of these species and their main uses is given. The presentation aims at providing background information for plant breeders and crop plant researchers about the germplasm available in ex situ genebank collections, tending to make this wealth of material more easily accessible.
Annual wild Triticeae Gene Bank collection was demonstrated by V. Holubec (1-22). The Prague Gene Bank wild Triticeae collection consist of 1800 accessions, belonging to 23 genera, and 133 species including genus Aegilops. Biodiversity of Georgian wheat species was presented by M. Mosulishvili, I. Maisaia, T. Shanshiashvili, M. Akhalkatsi (2-24). Georgia is one of the centers of evolution for many cereal crops such as T. timopheevii, T. zhukovskyi and T. carthlicum, which were characterized according to their reaction to diseases, growing period and resistance to abiotic stress. Moreover, existing germplasm collections are not being effectively used in agricultural science and development programs.
Nowadays progress of wheat studies is connected not only with molecular and genetic investigation, but also with good modern taxonomy that will be suitable for use by geneticists, botanists and breeders. New molecular breeding system and MAS need to be developed to introduce chromosomes, chromosome segments, genes and alleles into wheat from related species. This investigations should have been efficiently used for wheat improvement.
The symposium was nice organized under the joint auspices of the Local Organizing Committee, International Organizing Committee and the National Institute of Agrobiological Sciences (Tsukuba, Japan). It was supported by the Kyoto University Foundation and the Japanese Society of Breeding.
References
Barkworth ME (1992) Taxonomy of the Triticeae: a historical perspective. Hereditas 116: 1-14.
Kawahara T (2009) The 6th International Triticeae Symposium (6th ITS). eWIS-2009-0011.