A spontaneous eggplant (Solanum melongena L.) color mutant conditions anthocyanin-free fruit pigmentation

Authors: Stommel, John; Dumm, Judith; GISBERT-DOMENECH, CARMINA - Polytechnic University Of Valencia (UPV); PROHENS, JAIME - Polytechnic University Of Valencia (UPV)

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2016
Publication Date: 8/1/2016
Citation: Stommel, J.R., Dumm, J.M., Gisbert-Domenech, C., Prohens, J. 2016. A spontaneous eggplant (Solanum melongena L.) color mutant conditions anthocyanin-free fruit pigmentation. HortScience. 51(7):792-798.

Interpretive Summary: In plants and other organisms, spontaneously occurring mutants provide valuable tools for scientists to understand the traits that are affected by the mutant. We identified a naturally occuring eggplant mutant that produced green fruit instead of black fruit. In order to understand what genes are important for fruit color, we evaluated the activity of genes believed to be involved in production of the pigments. We found varying levels of gene activity and determined which genes were active in black fruit and which genes were active in green fruit, thus determining which genes were important for black fruit color. This information on eggplant fruit color will be useful to scientists studying biosynthetic pathways responsible for production of plant pigments and facilitate development of novel pigmented eggplant varieties.

Technical Abstract: Induced or spontaneously occuring color mutants in plants provide valuable tools for elucidating the genetic and developmental regulation of genes that influence pigmentation. We identified a single plant of the eggplant (Solanum melongena) cultivar Black Beauty bearing green fruit. Black Beauty normally produces black pigmented fruit attributed to anthocyanin accumulation. Anthocyanin biosynthesis occurs through coordinated structural gene transcription that requires the expression of at least one member of each of three transcription factor families - MYC, MYB and WD40. Observation of fruit pigmentation in populations developed from crosses between Black Beauty and the green-fruited mutant, together with real-time PCR expression analysis of anthocyanin biosynthetic (Chs, Dfr, Ans) and regulatory (Myc, Myb, Wd) genes in black pigmented (Black Beauty) and green pigmented (Black Beauty mutant) fruit were utilized to determine the genetic nature of this color mutant. Gene expression was evaluated in fruit at various stages of development ranging from small post-anthesis fruit to full-size marketable fruit. Biosynthetic gene transcript levels were significantly higher in black tissue from Black Beauty fruit relative to levels in green tissue from the Black Beauty color mutant. Ans expression was very low or non-detectable throughout fruit developement as was Dfr expression during latter stages of fruit development. Myb and Myc transcript levels were also higher in black pigmented tissue during early stages of fruit development with black fruit exhibiting greater black fruit:green fruit expression ratios. Wd expression was notably higher in black tissue relative to green tissue during latter stages of fruit development.