Higher plant biosynthetic mutants

The development of PA-defident mutants in prokaryotes and primitive eukaryotes has demonstrated that PAs are essential for thdr growth, and has corroborated the PA metabolic pathways in these cells. In higher plants, such mutants have not yet been isolated. Therefore, at the present time, the only possible way to block the synthesis of PAs, and at least partly to deplete cells of their PAs, is by using specific inhibitors of their biosynthetic enzymes. 

III. Rationale for Identifying and Studying Carotenoid Biosynthetic Mutants in Higher Plants... 

Among natural BRs, brassinolide is the most potent BR and, together with biosynthetic precursors of brassinolide such as castasterone, frequently found in higher plants. Recently, rapid progress has been made in our understanding of the biosynthetic pathways of brassinolide [2,6,15]. Furthermore, discoveries of several biosynthetic mutants of Arabidopsis and pea have demonstrated that the biosynthesis of BRs is prerequisite to the growth of plants. 

The latter three compounds are esterified to the y-carbon of the monolignols. These compounds are found in higher quantities in certain mutants or genetically engineered plants in which the expression of specific lignin biosynthetic genes has been altered (Sederoff et al., 1999 Boeijan... 

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