Changes in patterns of protein synthesis during haustorial development ofStriga hermonthica(Del.) Benth. seedlings

Abstract

This study focuses upon the developmental transition of the parasitic plant Striga hermonthica from its freeliving state (germinated seedling) to its parasitic state after development of an infection organ: the haustorium. A new method has been developed that allows the production of gram quantities of germinated and haustorially-induced Striga seedlings, thereby facilitating biochemical and molecular analysis of haustorial induction. Water-soluble proteins have been extracted from germinated seeds (stage A) and seedlings treated with 2,6-dimethoxy-p-benzoquinone (2,6-DMBQ) to induce haustorium (stage B). Samples were analysed by two-dimension al polyacrylamid e gel electrophoresis and quantitative as well as qualitative differences could be observed. In particular a group of four highly abundant acidic proteins (molecular weight 39 kDa, pi 5.1, 5.3, 5.3, 5.6) and three other proteins (molecular weight 12 kDa, pi 6.9; 17 kDa, pi 4.4; 17 kDa, pi 4.45) were seen in stage A while at least four proteins (molecular weight 21.5 kDa, pi 6.4; 21.5 kDa, pi 6.3; 31 kDa, pi 5.1; 34 kDa, pi 6.2) were present in greater abundance in stage B. In order to compare watersoluble protein with newly synthesized protein patterns, mRNAs from the two stages of development were isolated and cell-free translation products analysed by 2-D PAGE. Two-D gels of cell-free translation products showed the appearance of six proteins in stage B (molecular weight ranging from 10 to 35 kDa) and the presence of three acidic proteins in stage A with one protein (molecular weight 40 kDa) very similar in size to the triplet of proteins in the water-soluble protein 2-D gels.