Influence of mitochondrial genome rearrangement on cucumber leaf carbon and nitrogen metabolism

The MSC16 cucumber (Cucumis sativus L.) mitochondrial mutant was used to study the effect of mitochondrial dysfunction and disturbed subcellular redox state on leaf day/night carbon and nitrogen metabolism. We have shown that the mitochondrial dysfunction in MSC16 plants had no effect on photosynthetic CO2 assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants. Impaired mitochondrial respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation rate. Mitochondrial dysfunction in MSC16 plants had different influence on leaf cell metabolism under dark or light conditions. In the dark, when the main mitochondrial function is the energy production, the altered activity of TCA cycle in mutated plants was connected with the accumulation of pyruvate and TCA cycle intermediates (citrate and 2-OG). In the light, when TCA activity is needed for synthesis of carbon skeletons required as the acceptors for NH4+ assimilation, the concentration of pyruvate and TCA intermediates was tightly coupled with nitrate metabolism. Enhanced incorporation of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and accumulation of Glu

Agrobiotechnology and reality

W pracy omówiono najważniejsze sprawy związane z wprowadzaniem do rolnictwa odmian transgenicznych, których światowa powierzchnia uprawy przekroczyła 50 min ha. Odmiany te są uprawiane prawie wyłącznie na obu kontynentach amerykańskich, natomiast w Unii Europejskiej nie wprowadzono ich do obrotu. Wskazuje się na debatę toczoną wokół odmian transgenicznych, jej uwarunkowania oraz najważniejsze informacje związane z oddziaływaniem tych odmian na rolnictwo i środowisko. Pokazywana jest również sytuacja agrobiotechnologii w Polsce i jej najważniejsze charakterystyki oraz prawdopodobne kierunki rozwoju.This article discussed the most important questions concerning the introduction of transgenic plant varieties into agricultural practice. The area of GM crops exceeds 50 million hectares, however they are almost exclusively used in North and South America. The GM plants were not introduced in European Union. The main concerns related to GM varieties and their environmental impact are discussed. Also the situation of agrobiotechnology in Poland, its most important characteristics and perspective were also presented

Characterization of a cucumber [Cucumis sativus L.] somaclonal variant with paternal inheritance

Regeneration of cucumber plants from leaf explants resulted in a new species phenotype designated mosaic (msc). It is characterized by two types of spots on the leaves (zucchini-like and chlorophyllous) and has many altered morphological and physiological properties including slower growth, smaller organs, poorly germinating or empty seeds and a smaller number of flowers per node. In msc plants the shape of the first leaf is always altered, and in about 76% of the flowers the crown is reduced and distorted to a varying degree. Chloroplasts of the zucchini-like sectors are filled with large starch grains, and some of the embryos die at various stages of development. The msc phenotype is transmitted uniparentally only by the male plant and no segregation is observed in the F2 and subsequent generations. Possible mechanisms responsible for the msc phenotype and its transmission are discussed

Sequential fluorescent staining with CMA and DAPI for somatic chromosome identification in cucumber [Cucumis sativus L.]

Each of the seven chromosomes in cucumber (Cucumis sativus L.) was identified using sequential staining with Chromomycin A₃ (CMA) and 4-6-diamidino-2-phenylindole (DAPI) as DNA base-specific fluorescent dyes. The present method using enzymatic digestion produced a high level of well-spread early-metaphase chromosome complements. After CMA and DAPI staining, reproducible fluorescence bands were obtained in mitotic prometaphase chromosomes. The CMA staining method made it possible to characterize whole chromosomes from prometaphase to mid-metaphase. Chromosome 1 had the largest and widest CMA-positive (CMA⁺) band from the proximal region to the interstitial region on the long arm in prometaphase. A large gap separating of the short arm from the long arm was always observed in chromosome 2 during prometaphase. The banding pattern of the short arm was similar to that of the long arm in chromosome 2. Chromosomes 1 and 2 in early metaphase had sharp and large CMA-positive and DAPI-negative (CMA⁺DAPI⁻) bands at the pericentromeric regions. In early metaphase, chromosome 3 was characterized by having a narrow CMA⁺DAPI⁻ band on the pericentromeric region of the short arm. Chromosomes 4 and 5 showed similar chromosome length and had a large CMA⁺ band at the distal region of the long arm. Chromosome 4 did not show any clear band in the short arm, while chromosome 5 showed a telomeric CMA⁺ band at the short arm and a clear CMA⁺DAPI⁻ band at the pericentromeric region. Chromosome 6 had a CMA⁺ band at the distal region and a weak CMA⁺ band at the proximal region in each of the arms. Chromosome 7 had an evident CMA⁺ band in the long arm and a CMA⁺ DAPI⁻ band in the pericentromeric region