ISHS Acta Horticulturae 637: XXVI International Horticultural Congress: Advances in Vegetable Breeding
RELATIONSHIP OF WHITE ROT RESISTANCE TO PYRUVATE AND S-ALK(EN)YL-L-CYSTEINE SULFOXIDES IN ONION ROOTS |
| Authors: | M.H.Y Hovius, I.L. Goldman |
| Keywords: | Allium cepa, Sclerotium cepivorum, disease screening, onion breeding |
| Abstract:
Sclerotium cepivorum (Berk.) causes white rot and is a serious threat to the onion (Allium cepa L.) industry worldwide. S. cepivorum sclerotia are stimulated to germinate by Allium root organosulfur root exudates. Allium organosulfur compounds are often quantified by a simple method measuring pyruvate. The objective was to determine if differences in white rot resistance levels were due to differing organosulfur profiles found in Allium roots. If so, pyruvate analysis of onion roots could be used as a disease resistance screen for plant breeders. Onion breeding lines (B) and hybrids (H) that were putatively white rot resistant (RBH) and susceptible (SBH) were grown in naturally infested fields in 1999 and 2000 (New Zealand) and in 2000 (Canada). Significant differences in disease incidence at harvest were found. The analysis of root juice from greenhouse grown plants showed that garlic had significantly more pyruvate (20.5 μmoles/mL of juice) than leek (3.5) and the eight H and B onions tested (5.0 to 2.7). The contrast comparing pyruvate concentration of roots between the three SBH and the five putative RBH was not significant. Root juice pyruvate concentration could not be used to distinguish the SBH vs. RBH. The pyruvate data were used as a covariate to predict disease incidence in the field. Similar results were found for both countries. Pyruvate was not a good predictor of disease incidence. HPLC was used to analyze S-alk(en)yl-L-cysteine sulfoxides (ACSOs) in onion roots. Differences in root ACSOs were found between SBH and RBH onions and 1-propenylcysteine sulfoxide was predictive of field disease incidence among SBH vs. RBH onions, and, therefore, can be used to screen for resistance. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
