Impact of development and environment on Capsicum fruit quality

A quality trait in chile (Capsicum spp.) fruit is pungency, due to the accumulation of capsaicin and its analogs (capsaicinoids) in vesicles or blisters on the epidermis of the chile placenta. Although many of the structural genes for the capsaicinoid pathway have been cloned, little is known about the regulation of this pathway. This study tested several candidate genes for a wide range of transcription factors. Four candidate genes, Erf, Jerf3, Scarecrow and bZip, appeared likely to regulate capsaicinoid biosynthesis based on their transcription pattern. Among the four transcription factors tested, Erf was identified as a strong candidate for capsaicinoid pathway regulation at the transcriptional level since its transcripts were very abundant in pungent varieties compared to non-pungent varieties and transcripts accumulated to higher levels at the beginning of fruit development; allelic variability at the amino acid level showed that three polymorphisms were found in Erf gene products which could be associated with pungency.;Six jalapeno lines bred for different heat levels were used to determine fruit-specific capsaicinoid content of the fruit on a single plant. Fruit at different places at the same developmental stage exhibited different pungency levels. Erf best fit our model for a regulatory transcription factor among these six lines. The expression of this gene was much lower in PX211 fruit, the intermediate pungency line and the non-pungent line, P105. Results from these studies demonstrated that among transcription factor genes tested, Erf is a good candidate to be a regulatory transcription factor for the capsaicinoid pathway.;The carotenoid content of Capsicum fruit is important for human health as these compounds serve as anti-oxidants and pro-Vitamin A precursors. We investigated the relationship between light and the carotenoid levels that accumulated in mature fruit and leaves of three chile cultivars. Leaf carotenoids accumulated to higher levels in plants grown under higher light intensity. Carotenoid levels in fruit from these same plants showed the opposite trend; higher carotenoid levels with lower light intensity level. This study showed that greenhouse production is a good method to improve carotenoid content in chile fruits.