Biochemical-genetic implications for variation in plant cuticle lipids

All terrestrial plants are covered with a cuticle composed of a cutin polymer and cuticular waxes. Plant cuticles provide protection against both abiotic and biotic stress. In the context of crop plants, protection against water-loss both in the field and during storage is of particular importance. Although there have been many reports on cuticular transpiration, the correlation between water loss and fruit cuticle is still not well understood. The hollow nature of pepper fruit limits its water storage capacity and severely reduces its shelf-life. Since pepper fruit has no stomata, most water is lost through the cuticle making pepper fruit a perfect model for cuticle transpiration studies. Analysis of post-harvest water loss in near isogenic lines of pepper provided evidence of correlations between water loss and pepper cuticle. A larger analysis of different pepper cultivars from a world collection of peppers within the broader Capsicum genera revealed significant changes in both plant cuticle amount and composition. Providing further evidence that natural selection leads to adaptation of the plant cuticle to different environmental stimuli. Glossy1 is the Arabidopsis Wax2 syn. CER3 homologue in corn and was characterized as a wax mutant in its juvenile stage. Both glossy1 and wax2 were shown to have an altered cuticle structure, but neither was characterized as a cutin mutant. We report that both glossy1 and its wax2 homologue are indeed cutin mutants. We also report that a wax mutant in sorghum (bm2) which also has an altered cutin structure is also a cutin mutant. This mutant showed remarkably similar wax and cutin profiles to another cuticle mutant in sorghum: bmlc. We report that bm2 and bmlc are the same mutation based on rough mapping, allelism tests and cutin analysis. Cowpea like all legumes is deficient in the sulfur containing amino acids, cysteine and methionine. In an attempt to improve its nutritive value, we transformed cowpea with a heterologous sunflower seed albumin gene. We report the results of this transformation