Effect of Oligogalacturonides on Seed Germination and Disease Resistance of Sugar Beet Seedling and Root

Abstract

Oligogalacturonides (OGs) are a bioactive carbohydrate derived from homogalacturonan. The OGs synthesized in this study significantly inhibited the mycelial growth of Rhizoctonia solani AG-4HGI in vitro, even at a low concentration (10 mg/L). The seed vigor test demonstrated that the application of 50 mg/L OGs to sugar beet seeds significantly increased average germination percentage, germination energy, germination index, and seedling vigor index. The same concentration of OGs also improved the seedling emergence percentage of sugar beet when seeds were sown in soil inoculated with D2 and D31 isolates, respectively. The lesion diameter on mature sugar beet roots caused by R. solani AG-4HGI isolates D2 and D31 also decreased by 40.60% and 39.86%, respectively, in sugar beets roots first treated with 50 mg/mL OGs in the wound site, relative to lesion size in untreated/pathogen inoculated wounds. Sugar beet roots treated with 50 mg/mL OGs prior to inoculation with the D2 isolate exhibited up-regulation of the defense-related genes glutathione peroxidase (GPX) and superoxide dismutase (SOD) by 2.4- and 1.6-fold, respectively, relative to control roots. Sugar beet roots treated with 50 mg/mL OGs prior to inoculation with D31 exhibited a 2.0- and 1.6-fold up-regulation of GPX and SOD, respectively, relative to the control. Our results indicate that OGs have the potential to be used for the protection of sugar beet against R. solani AG-4HGI.

Recent advances in the production of oligogalacturonides and their biological properties

“…During the last few years, several raw materials (mainly fruits, agroindustrial byproducts and pectins derived from them) have been used for production of OGalA, including haw, 12,19–22,31 apple pectin, 7,9,10 artichoke, 13 mango peel wastes, 24 lemon peels, 27 mandarin peels, 11,32 finger citron pomace, 15 pomelo peels, 29 sugar beet pulp, 33,34 citrus pectin, 8,23,25 sunflower plate pectin 35,36 and Lonicera japonica Thunb. 14 With the same purpose, commercial polygalacturonic acid (PGalA) was also tested.…”