Study On Sucrose Metabolism And Related Enzyme Activities In Branches Of Wine Grape At Different Growth Stages

Grape is a worldwide fruit, and the growth areas of grape are mainly distributed in north of China, whereas its suffers cold damage inevitablely for the high geographical latitude, therefore, it is important premise to improve the hardiness of wine grape for the development of grape wine industry. Researchers put their hand to the molecular mechanism of sucrose metabolism and its regulationg mechanism, and mainly focus on cloning and functional analysis for the transcription factor under stress resistance in grape, which has turned into a new period, there are few reports about changes of sucrose metabolism and cold resistance in grape branches. Our studies carried from May to November in 2014 at Gansu Province Key Lab of Aridland Crop, and selected the fresh branches of the two cold-resistant rootstocks ‘Beta’, ‘SO4’ and two wine grape varieties ‘Merlot’, ‘Pinot Noir’ in the field as materials. We discussed the variation of sucrose metabolism for different wine grape at different growth period(germination and growth, flowering, berries growth, berries mature, early overwintering stage) through studied modification and correlations among contents of water, sugar, starch and the activities of SS, SPS, Inv, Amy and SP in grape branches at different growth periods, which provide important reference for the theory and practice of the cold-resistance research in wine grapes, even fruit yields and qualities.The results indicated that:1.The water content in branches of four wine grapes were closely related to the temperature, its performed low at germination and growth period, the water content increased rapidly with the rise of temperature at flowering period in June, which was about 2.5 twice as much as germination, and maintain a high level in berries growth stage, whereas decreased rapidly at berries mature and early overwintering stage.These indicated that the water content in branches was higher and the growth strong along with the higher temperature compared to low temperature. The water content in branches felled to the lowest when the temperature dropped to 4℃at the beginning of the overwintering covered with soil in November, and the two cold-resistant rootstocks were less than two wine grape varieties, it embodied that the water content of grape branchs were associated with the strength of the frost resistance.2. The sucrose content presented the trends “High-Low-High” from 12 May to 2 November in 2014 in four grape varieties, which was higher at germination, berries mature, early overwintering stage and lowest at flowering and berries growth stage, while the content increased by 3.04 and 2.96 times at early overwintering stage with flowering and berries growth stage, respectively, its showed that the sugar mainly shipped to fruit in growing season,while it began to accumulate at overwintering stage, which provided the key substances and physiological basis on cold-resistance in different grapes branches.The sucrose contents in rootstocks were higher than wine varieties(P<0.05) at germination and early overwintering stage, this is an important physiological characteristics for the frost resistance of rootstocks is better than wine varieties.3. The activities of SS and SPS were significant positive with the change of sucrose content, it seems to have nothing to do with the sucrose content. Which indicated that the sucrose synthesis in grape branches were mainly catalysed by SS and SPS, and had high activities in low temperature.4. The starch content in the grape branches reached a maximum in berries mature, and decreased slightly at early overwintering stage, which was 4.4 times as much as germination significantly(P<0.05). Amy activity had no significant change prior to the berries growth stage and remain low, they had the same trend of variability between Amy and starch in berries mature and early overwintering stages, which showed that Amy was correlated to the starch metabolism. Moreover, the activity of SP in berries growth was 3.75, 7.5, 1.875, 5 times as much as other 4 stages, respectively, its indicated that SP could influence the growth of the berries by regulation of starch content in grape branches.5. The ratio between sugar and starch content were 61.68, 13.03, 11.13, 16.42, 25.44 at five growth stages in grape branchs, respectively, the rate increased first and then decreased. The sucrose content decreased, while starch content continues to rise from germination to berries growing, the sugar mainly destined for the growth of berries at this stage. Sucrose content increased, while the starch content decreased slightly after ripe berries to the early winter, part of the stored starch down into sugar for the winter grape desired at this stage.These changes were variant among different wine grapes. The changes of the sucrose and starch contents and the enzyme activities of the different varieties after berries mature stage were the key substances and physiological basis on cold-resistance during overwintering stage.