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EN
Kernel hardness is an important agronomic trait that influences end-product properties. In wheat cultivars, this trait is determined by the Puroindoline a (Pina) and Puroindoline b (Pinb) genes, located in the Hardness locus (Ha) on chromosome 5DS of the D genome. Wild type alleles code puroindoline a (PINA) and puroindoline b (PINB) proteins, which form a 15-kDa friabilin present on the surface of water-washed starch granules. Both the proteins are accumulated in the starch endosperm cells and aleurone of the mature kernels. Puroindoline-like genes coding puroindoline-like proteins in the starch endosperm occur in some of the genomes of Triticeae and Aveneae cereals. Orthologs are present in barley, rye and oats. However, some genomes of these diploid and polyploid cereals, like that of Triticum turgidum var. durum (AABB) lack the puroindoline genes, having a very hard kernel texture. The two wild type alleles in opposition (dominant loci) control the soft phenotype. Mutation either in Pina or Pinb or in both leads to a medium-hard or hard kernel texture. The most frequent types of Pin mutations are point mutations within the coding sequence resulting in the substitution of a single amino acid or a null allele. The latter is the result of a frame shift determined by base deletion or insertion or a one-point mutation to the stop codon. The lipid-binding properties of the puroindolines affect not only the dough quality but also the plants' resistance to pathogens. Genetic modification of cereals with Puroindoline genes and/or their promoters enable more detailed functional analyses and the production of plants with the desired characteristics.
EN
The results published in recent years proved that Agrobacterium based system for genetic transformation was also suitable for cereal crops. Several groups were able to obtain transgenic rice, corn, wheat and barley using hipervirulent strains Agl1 and EHA101 (or EHA105) or 'regular' LBA4404 strain with superbinary vector pTOK233. The first phase of our research was designed to establish transformation susceptibility of two wheat, two barley and one triticale cultivars using three different bacterial systems. Two of those systems were based on hipervirulent strains: Agl1 (pDM805) and EHA101 (pGAH). The third one combined strong virulence of pTOK233 vector and commonly-used LBA 4404 strain. Putative transgenic plants (regenerated and rooted under selective pressure of appropriate factor and further confirmed with GUS or PCR) were obtained for barley (cultivar Scarlett), wheat (Torka and Kontesa) and triticale (Wanad) with Agrobacterium strain Agl1. Kontesa's putative transgenics were also obtained with the strain EHA101. The highest rate of selection of putative transgenics was for Agl1 / phosphinothricine and ranged from 9 to15% for wheat cultivars. The lowest rate for the same strain and selection was 0,5% for barley cv. Scarlett.Inoculation of 700 immature embryos of barley cv. Lot with three bacterial systems (strains, vectors and selection factors) failed to produce putative transformants. Also no putative transgenics of barley Scralett, wheat Torka and triticale Wanad were obtained after transformation with EHA101 and selection on higromycine. Selection with kanamycin and hygromycin + kanamycin after transformation with EHA101 and LBA4404 respectively also failed to give positive results.
EN
RNAi technology is based on a natural process of RNA-directed gene regulation. The technique is widely used for gene functional analysis and to obtain plants with modified traits. The main advantage of this system, particularly when applied for polyploid species, is the possibility of simultaneous silencing of homologous, homoeologous or orthologous genes. The article discusses the results of relatively few papers where RNAi has been used for functional analysis of native genes of wheat and barley. The main part of the article presents the research on RNAi based gene silencing in cereals performed by our group. The experimental basis of our work was the elaboration of efficient Agrobacterium-based transformation and plant regeneration systems of different cereal species (wheat, barley, triticale and oat). Currently, the method is applied for modification of two types of traits in wheat, triticale and barley. The first one is a technological trait related to cereal grain hardness. It is genetically controlled by Pina and Pinb genes. We obtained over a hundred transgenic lines with various degrees of Pina and Pinb silencing. Currently, the lines are being analyzed for the amount of PINA and PINB proteins, composition of storage proteins, and the grain texture. The second set of traits depends on CKX genes encoding cytokinin oxidase/dehydrogenase ? the part of the system specifically governing the cytokinin level in different organs and developmental stages. We obtained over forty barley transgenic lines with silenced HvCKX1. This modification was found to be tightly correlated with enhanced plant productivity measured as the higher grain number and higher mass of a thousand kernels. The T1 and T2 transgenic seedlings developed bigger root system.
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