Carotenogenic gene expression and ultrastructural changes during development in marigold.

Marigold (Tagetes erecta) flowers are a good source of carotenoids and can be used as a model studies on pigmentation during flower development. They show different levels of pigmentation caused by lutein. Here we describe the expression of several genes in the carotenoid biosynthetic pathway: phytoene synthase (Psy), phytoene desaturase (Pds), lycopene beta-cyclase (Lcy-b) and lycopene epsilon-cyclase (Lcy-e). cDNA inserts from isolated clones were 1376-1916bp long. The predicted amino acid sequences showed from 66 to 100% homology with other reported sequences (NCBI gene bank). Northern blot analyses of three varieties of marigold showed that most gene transcripts were expressed during flower development. The ultrastructural changes that occurred during plastid differentiation in flower morphogenesis were analyzed, and pigment accumulation among varieties was evaluated. The pigment deposition in specific structures (lipidic vesicles) during flower development was demonstrated.