ANALYSIS OF INVIVO AND INVITRO GROWN ENDOSPERMS OF HIGH AND LOW PROTEIN STRAINS OF MAIZE

The aim of this research was to examine the effect of C and N supply on growth and protein composition of maize (Zea mays L.) endosperm. Immature endosperms of the Illinois High and Low Protein (IHP and ILP) strains were grown for 5, 8 and 12 days on a solid medium containing different sucrose to asparagine ratios. A comparison between endosperms of IHP and ILP strains grown to maturity in vitro and in field conditions (in vivo) was also reported. The results showed that the ILP strain cultured in vitro accumulated a greater amount of dry matter per endosperm than the IHP strain; this was also observed in in vivo experiments. The accumulation of total nitrogen per endosperm followed a different trend when the in vivo and the in vitro conditions were compared. In vivo IHP was more efficient than ILP in assimilating nitrogen. The reverse was observed in vitro; there the ILP strain was always capable of accumulating higher amounts of N per endosperm than IHP at all stages of development considered and on all culture media. IHP endosperms, during development in vivo and in vitro, synthesized both the 22 kDa and the 20 kDa fractions of zeins. While ILP endosperms grown in vivo were much less efficient in accumulating the 22 kDa fraction of zeins, these latter endosperms cultured in vitro were capable of restoring normal synthesis of the 22 kDa zein fraction. Our data suggest that the expression of endosperm phenotype was affected by nitrogen substrates supplied to the seed.