hrvatski

RAST, POTROŠNJA GLUKOZE I EKSKRECIJA PROTEINA U TRI EMBRIOGENE LINJE BUNDEVE (Cucurbita pepo L.)

The effects of medium composition on the growth, metabolism and protein excretion of three embryogenic lines grown in liquid medium were studied as a step towards elucidating the role of nitrogen supply in the regulation of developmental transition of pumpkin somatic embryos. All parameters were measured over a 15-day culture period on days 0, 4, 8, 11 and 15. Fresh and dry weights were compared with the glucose uptake and pH of the culture media in order to assess growth kinetics. Ammonium, used as the sole source of nitrogen, negatively influenced embryogenic tissue growth and morphogenesis and caused a significant decrease in the media pH. Buffering ammonium-only medium with MES stabilized the pH, enhanced tissue proliferation and facilitated protein excretion. Globular embryos were formed at a low frequency and no further differentiation into late-stage embryos was observed. Maturation of embryos proceeded only when a combination of reduced (NH4+) and unreduced (NO3-) forms of nitrogen was provided in the medium. A noticeable effect of NO3- re-supply of cultures previously maintained on the NH4+- containing medium reflected through increased growth, glucose uptake and protein excretion in the culture medium. A comparative analysis of extracellular proteins in pumpkin embryogenic tissue lines was performed with the intention to detect some nutrient-dependent changes related to the stage of development.

dušik; pH; izlučivanje proteina; somatska embriogeneza

nije evidentirano

engleski

GROWTH PARAMETERS, GLUCOSE UPTAKE AND PROTEIN EXCRETION OF THREE EMBRYOGENIC LINES OF PUMPKIN (Cucurbita pepo L.)

The effects of medium composition on the growth, metabolism and protein excretion of three embryogenic lines grown in liquid medium were studied as a step towards elucidating the role of nitrogen supply in the regulation of developmental transition of pumpkin somatic embryos. All parameters were measured over a 15-day culture period on days 0, 4, 8, 11 and 15. Fresh and dry weights were compared with the glucose uptake and pH of the culture media in order to assess growth kinetics. Ammonium, used as the sole source of nitrogen, negatively influenced embryogenic tissue growth and morphogenesis and caused a significant decrease in the media pH. Buffering ammonium-only medium with MES stabilized the pH, enhanced tissue proliferation and facilitated protein excretion. Globular embryos were formed at a low frequency and no further differentiation into late-stage embryos was observed. Maturation of embryos proceeded only when a combination of reduced (NH4+) and unreduced (NO3-) forms of nitrogen was provided in the medium. A noticeable effect of NO3- re-supply of cultures previously maintained on the NH4+- containing medium reflected through increased growth, glucose uptake and protein excretion in the culture medium. A comparative analysis of extracellular proteins in pumpkin embryogenic tissue lines was performed with the intention to detect some nutrient-dependent changes related to the stage of development.

nitrogen; pH; protein excretion; somatic embryogenesis

nije evidentirano