Protocols were developed to fractionate each of the five protein components present in the PSII reaction centre complex, isolated from the thylakoid membrane of pea plants. The precise molecular weights of all the purified components were then successfully determined, for the first time by electrospray and fast atom bombardment mass spectrometry. Discrepancies between the molecular weights assigned and those calculated from the respective cDNA sequences were observed for all of the reaction centre component proteins. Application of novel mapping and sequencing strategies on these proteins has assured the elucidation of full primary structures of and subunits of cytochrome b559 and the majority of the structures of the D1 and D2 proteins. In the case of the subunit to cytochrome b559 an N-terminal processing event, involving the removal of the initiating formyl-methionine residue was found. The transformations on the subunit of cytochrome b559 were characterised as a N-terminal modification, entailing the processing of the formyl-methionine residue followed by an acetylation of the amino terminus of the mature protein, and a sequence change at residue twenty six, were a serine has been replaced by a phenylalanine residue. This was presumed to be due to an error in the gene sequence, but is more probably a result of the recently described phenomenon of mRNA editing. Currently, the nucleotide sequence of the pshI gene from pea plants is not available. Using a combination of mass spectrometric techniques and automated gas phase sequencing the primary structure of this component has been obtained in these studies. In contrast to the smaller subunits, data obtained on the D1 and D2 proteins indicated that both these components exist in heterogeneous forms. Mapping studies on these subunits have identified phosphorylation and oxidation, as at least two sources of this microheterogeneity.

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The antibiotic, 2,4-diacetylphloroglucinol (Phl), is produced by a range of naturally isolated fluorescent pseudomonads, found in disease suppressive soils. The natural isolate, P. fluorescens F113, protects pea plants from the pathogenic fungus, Pythium ultimum, by reducing the number of pathogenic lesions on the plant's roots. This beneficial effect was however, outweighed by the F113 causing an overall reduction in the emergence of the pea plants in the infected soil. The gene locus responsible for the Phl production was shown to be functionally conserved between the P. fluorescens F113 and another Phl producing organism, P. fluorescens Q2-87. Following identification of this functional sequence homology, the genes were isolated from F113, by optimised, long PCR. The 6.7-kb gene cluster was inserted into the chromosome of a non-pathogenic P. fluorescens, SBW25, which can effect biological control against the plant pathogen, Pythium ultimum through competitive exclusion of the fungus, by means of its strong colonising competence. The insertion was a targeted, homologous recombination designed to insert the Phl coding genes, from the F113, into a non-essential, lacZY coding region of the SBW25 chromosome. The transformed strains of SBW25 assumed two different morphological appearances. The morphological changes were noted at a ratio of 1:1 of normal morphology and altered morphology. Transformation of SBW25 with the Phl locus without this repressor element led to transformants with only normal morphology. All transformants were able to suppress P. ultimum through antibiotic production following the Phl transformation. However, the fitness of the transformants was reduced in flask culture, at 30°C, against the un-transformed SBW25. The organisms transformed with the entire Phl locus were seen to clump together in the culture media. The strain transformed with the Phl locus lacking the repressor element behaved normally. When inoculated on pea seedlings, the strain containing no repressor element behaved similarly to the F113, causing lower pea seed emergence. A transformant containing the entire Phl genetic locus had not lost its environmental competence on the pea roots, maintaining a high population, but was unable to maintain a high population in the surrounding soil.

Ultravioletinės B spinduliuotės intensyvumo didėjimas ir rūgštėjantys dirvožemiai veikia daugelį augalų fiziologinių ir morfologinių procesų. Yra nemažai atliktų tyrimų apie pavienį šių veiksnių poveikį, tačiau kompleksinis UV-B spinduliuotės ir rūgštaus substrato poveikis augalams kol kas tyrinėtas mažai. Tyrimų tikslas – ištirti pavienį bei kompleksinį 1 ir 3 kJ m-2 d-1 UV–B spinduliuotės dozių ir rūgštaus substrato (pH 4,8) poveikį skirtingų vystymosi tarpsnių sėjamiesiems žirniams (Pisum sativum L.). Tyrimai vykdyti dviem etapais: pirmame etape tirtas pavienis UV-B spinduliuotės ir rūgštaus substrato poveikis sėjamiesiems žirniams priklausomai nuo vystymosi tarpsnio; antrame - kompleksinis UV-B spinduliuotės ir rūgštaus substrato poveikis augalams priklausomai nuo vystymosi tarpsnio. Žirniai pasėti į vegetacinius indus su paruoštu neutralaus rūgštumo durpių substratu, o praėjus 10 ir 17 dienų po sudygimo, t.y. lapų vystymosi (BBCH 14-16) ir šoninių ūglių formavimosi (BBCH 21-23) tarpsniais, veikti pasirinktais stresoriais. Penktą poveikio dieną išmatuoti fiziologiniai ir morfologiniai rodikliai: fotosintezės intensyvumas, vandens naudojimo efektyvumas, pigmentų kiekis, žalioji bei sausoji augalų biomasė ir kt. Nustatyta, jog 1 ir 3 kJ m-2 d-1 UV–B spinduliuotė neigiamai veikė tiek fiziologinius, tiek morfologinius sėjamųjų žirnių rodiklius. Lapų vystymosi (BBCH 14-16) tarpsnio žirniai buvo mažiau atsparūs UV-B poveikiui negu šoninių ūglių formavimosi (BBCH 21-23)... [toliau žr. visą tekstą] / UV-B radiation and acidic soils could pose many direct and indirect effects on plants including the alteration in transpiration and photosynthesis, and the change in growth, development and morphology. The single impact of UV-B radiation and acid substrate on plants has been studied by several research groups. However, integrated UV-B radiation and substrate acidity impact on plants are still little studied. The aim of the study was to investigate the single and integrated 1 and 3 kJ m-2 d-1 UV-B radiation and substrate acidity (pH 4,8) impact on different development stages pea plants (Pisum sativum L.). Researches were performed in two stages: in the first stage the single UV-B radiation and acid substrate effect on sown pea plants was analysed depending on the development stage. In the second stage the integrated UV-B radiation and acid substrate effect on sown pea plants was analysed depending on the development stage. Peas were sown in vegetative pots with prepared a neutral acidity peat substrate. 10 and 17 days after germination, i.e. at leaf development (BBCH 14-16) stage and lateral shoot formation (BBCH 21-23) stage pea plants were exposed to different stressors. On the fifth day of effect the physiological and morphological indices were measured: photosynthetic rate, water use efficiency, the content of chlorophylls and carotenoids, fresh and dry biomass, and others. Investigated that 1 and 3 kJ m-2 d-1 UV-B doses had negative affects on both, physiological and... [to full text]