Sequence analysis of two new members of the major latex protein gene family supports the triploid-hybrid origin of the opium poppy

Latex from the opium poppy ( Papaver somniferum) contains an abundant group of laticifer-specific, low-molecularweight polypeptides called the major latex proteins (MLPs). MLPs are encoded by a family of nine genes which can be divided into two distinct subfamilies based on DNA gel blot analysis. This report describes two new members of the MLP gene family ( MLP146 and MLP149) that are physically linked and separated by approx. 5.5 kb. Comparison of their nucleotide and deduced amino-acid sequences with those of other MLP indicates that both new MLP belong to the MLP15 subfamily. The organization of the MLP family is consistent with the triploid-hybrid origin of the opium poppy.