engleski

Extracellular glycoproteins in embryogenic culture of pumpkin (Cucurbita pepo L.)

The extracellular proteins in three distinctly induced embryogenic lines of pumpkin (Cucurbita pepo L.) cultivated on four MS media modified regarding to nitrogen composition or auxin presence/absebnce were analyzed. Extracellular glycoproteins containing α-D-mannose were specifically detected by the lectine concavalin A. During the cultivation of embryogenic tissue on the medium supplemented with reduced nitrogen embryos were mostly arrested to preglobular and globular developmental stages which coincide with absence of protein secretion. Secreted glycoproteins of 76, 68, 37, and 34 kDa were detected only if any of the three lines were cultivated on medium that stimulate embryo development, irrespectively to 2, 4-D or tunicamycin addition. The glycoprotein of 64 kDa was detected in all lines cultivated on hormone-free MS medium with conventional nitrogen sources and appears to be associated with embryo maturation. Tunicamycin treatment did not influence embryogenesis, although it specifically affected glycosilation of proteins in investigated lines. Our results show that beside the auxin, source of nitrate is of great importance for proper protein glycosilation, excretion and developmental transition of pumpkin somatic embryos.

Cucurbita pepo L. ; extracellular glycoproteins ; hormone-free medium ; nitrogen sources ; pumpkin ; somatic embryogenesis

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