2018 ASHS Annual Conference

Blossom-end rot (BER) is a common physiological disorder in peppers that occurs during early stages of rapid fruit growth. It is characterized by a dry, sunken, brown rot to the distal part of fruit resulting in huge economic losses. Occurrence of BER has been related to insufficient calcium uptake during the cell expansion phase of fruit growth leading to cell wall disintegration. Expansins (EXP) play an important role in facilitating cell expansion by loosening the cell wall in response to cell internal turgor. The main objectives of this study are to identify fruit-specific EXP during cell expansion phase and to determine cell elongation rates during fruit development and BER occurrence. Currently we have identified 29 EXP genes in bell pepper using database resources available from NCBI GenBank and the Sol genomics network. To determine the expression of EXP, bell pepper cultivar ‘Aristotle’ was grown under greenhouse conditions. Samples were harvested from seedlings, leaves, flowers and fruit at various days after anthesis (DAA; 7DAA, 14DAA, 21DAA, 28 DAA) including ripening. Gene expression is being performed using quantitative RT-PCR analysis. Fruit samples from the above stages are being analyzed for cell elongation rates using microscopy. In addition calcium accumulation during fruit growth phase will be determined. The expression of EXP and its role in cell expansion and calcium accumulation rates will be compared using BER resistant and susceptible bell pepper varieties. Collectively, this study will help to determine the importance of EXP in cell expansion and development of BER in peppers.