Genetic Analysis of Quercetin in Onion (Allium cepa L.) 'Lady Raider'

Abstract

Onion bulbs (Allium cepa L.) uniform in color, size, shape, and maturity were selected from breeding line 97-50 of the Texas Tech University onion improvement program and were designated breeding line ‘Lady Raider’.  Bulbs in this line are pearlized, red in color, grano shaped, and are in the short-day onion class, which matures in Lubbock in early summer.  In a 1999 grow-out, bulbs of this phenotype were analyzed spectrophotometrically for quercetin content, as measured by total flavonol (TF) content.  Quercetin is of interest in the onion industry because of its health-related properties.  There had been no previous selection for TF in this line. Values in this parent population were normally distributed and ranged from 79 - 431 mg/kg.  Bulbs were grouped by TF concentration into high (>232 mg/kg), medium (203-223 mg/kg), or low (<203 mg/kg) populations and designated POH, POM, and POL, respectively.  The populations were caged separately in 2000 and allowed to sib-pollinate, forming three Sib-one (S1) populations.  These populations were designated as Sib-one high (S1H), Sib-one medium (S1M), and Sib-one low (S1L) based upon the parent population from which it was generated. Flavonol concentrations of the PO populations were compared to those of the S1’s. TF frequencies for all populations were normally distributed and TF ranges differed. TF values of the S1 populations ranged from 228 - 675 mg/kg.  The TF mean of each PO population was significantly different from that of each S1 population.  Flavonol content in the S1 generation segregated into classes similar to those of PO populations, indicating that TF’s can be manipulated through selective breeding.