Abstract: The present invention relates to a method of expressing a foreign protein in the plastid of a host cell and secreting said protein into the cytoplasm of the host cell comprising the steps of making a construct of vector linked to a coding sequence of the fusion protein comprising of signal peptide sequence followed by in-frame fusion to a foreign gene; and stably integrating said construct into the plastid genome. The present invention also relates to a method of targeting the expressed and secreted proteins from the plastids to the nucleus of the host cell. The present invention further relates to the method where the host cell is of any higher plant or any organism including single cell algae.

Abstract: The present invention relates to a method of expressing a foreign protein in the plastid of a host cell and secreting said protein into the cytoplasm of the host cell comprising the steps of making a construct of vector linked to a coding sequence of the fusion protein comprising of signal peptide sequence followed by in-frame fusion to a foreign gene; and stably integrating said construct into the plastid genome. The present invention also relates to a method of targeting the expressed and secreted proteins from the plastids to the nucleus of the host cell. The present invention further relates to the method where the host cell is of any higher plant or any organism including single cell algae.

Abstract: The invention provides a process of obtaining a xylanase, said process comprising: providing a protein-containing extract of a transplastomic plant tissue comprising plastids transformed with a polynucleotide encoding said xylanase, said extract having been subjected to heat treatment that has denatured at least some of the protein content of said tissue but under which the xylanase has remained stable; and recovering said xylanase from said extract.