36E-1

E. Mercado-Silva¹, E. MERCADO-PAULINO², H. Bohnert³, and V. Poroyko³. (1) Programa de Posgrado en Alimentos del Centro de la República, Univ. Autónoma de Querétaro, Centro Universitario S/N, Cerro de las Campanas, Querétaro, 76010, Mexico, (2) Posgrado en Ciencia y Tecnología de Alimentos, Univ. Autónoma de Querétaro, Primavera 167 Col. La Era., Queretaro, Mexico, (3) Plant Biology/Crop Sciences, Univ. of Illinois, Urbana-Champaign, IL 61801

Breaking dormancy of garlic, is initiated by gibberellin activity and its signaling pathway controlled by temperature. Bioactive gibberellins act over the cells producing some responses like 26S proteasome activity expression, which is responsible for DELLA proteins degradation, which are related with suppression of gibberellin signaling. We hypothesize that storage temperature of garlic could regulate 26S proteasome expression and then the sprouting process. Our objective was to determine the expression rate of garlic 26S proteasome under three different storage temperatures and relate it with the Sprouting Index (SI). Garlic bulbs were stored at 0, 15 and 30^o C. Every 15 days during 3 months, sprouting index (sprout length/clove length) was measured and the sprouts were separated and lyophilized. 150 mg were taken for expression analysis. 26S proteasome primers were designed to apply RT-PCR method. Temperature of 15º C was a strong sprouting activator (SI=93%, 90 days); whereas at 0 and 30º C was inhibited. At 15^o C, 26S proteasome expression was not affected during the storage period (delta C=2), at 0^o C, expression increased two fold after 45 days; and at 30º C the expression was low. It seems that at 15º C the 26S proteasome is active and functioning degrading DELLA proteins and stimulating the sprouting process. At 0º C the 26S proteasome expression rate was the highest but it was not related with SI suggesting that at this temperature there were not bioactive gibberellins that could activate gibberellin signaling factors. At 30º C the expression rate and sprouting were inhibited. The 26S proteosome is an important element in the signaling process during the breaking dormancy but the mechanism of action depends on temperature.

Session 36E, Fruit & Vegetable Products: General
8:30 AM - 12:00 PM, Monday AM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana