| Fruit coloration is one of the important indicators to measure the commodity value of the fruit. And the changes of pigment in tomato fruits may affect the color from green to red, mainly due to the decrease of chlorophyll content and the increase of carotenoid content. The composition and content of carotenoid also affect the nutrient value of tomato fruit. The sugar in fruit is an important factor affecting fruit quality, which affects fruit sweetness and also is the based raw materials for the synthesis of carotenoid and endogenous hormone. Endogenous hormone has the capability to regulate carotenoid biosynthesis, chlorophyll biosynthesis and the accumulation of sugar. Plant exogenous hormone has the capability to regulate the metabolism of carotenoid, chlorophyll, sugar and endogenous hormones.In this research, the accumulation patterns of carotenoid were studied in the different tissues of 5 different tomato phenotypes, such as pink (JinGuan 5), orange (ShiYingDaHong), red (Hongz-11), yellow (JinGuan) and green (Lvfanq-05). The effects of exogenous GA3 and ABA were explored on the metabolism of main pigment, accumulation of sugar and the content of endogenous hormone in the different tissues of pink tomato fruit which commonly cultivated in north China. And the relationship between the main pigment and sugar was elucidated, meanwhile, the relationship among the endogenous hormones, the main pigment and sugar also was clarified. Physiological mechanism about the metabolism of main pigment was definited by regulation of exogenous GA3 and ABA. This study provided the theory basis for scientific regulation of tomato fruit quality. The main results were as follows.1. Accumulation and distribution of carotenoids in tomato fruitThe experiment tested many tomato fruits with 5 different tomato phenotypes-pink, orange, red, yellow and green. The content of lycopene in tomato fruit was increased gradually with the fruit becoming rippen, while the highest content of lycopene was in pericarp when it was in red ripening period. The P-carotene and xanthophyll were showed a trend of increasing after decreasing. And the highest contents of ?-carotene and xanthophyll were in pectin.The highest content of lycopene was in the peel tissue of red fruit, then was in the pink fruit, the following was orange fruit, yellow fruit and green fruit. The contents of p-carotene from high to low were in red fruit, orange fruit, pink fruit, green fruit and yellow fruit. The highest content of xanthophyll was in the yellow fruit, and second was in the orange fruit, following was in the red fruit, pink fruit and green fruit.2. Effects of exogenous GA3 and ABA on the main pigment in different parts of tomato fruitThis study chose pink tomato strain Golden Crown No.5, and treated tomato fruit of green maturity with 100 mg ·L-1 GA3 and ABA. The results showed that the contents of total carotenoids and lycopene in the fruits were inhibited by exogenous GA3 treatment. The effect on the content of ?-carotene was inhibited firstly and then facilitated. And the content of xanthophyll in various parts was significantly reduced. And it delayed the degradation of chlorophyll and inhibited the formation of tomato fruit-specific color and luster. After dealing with exogenous ABA, the contents of total carotenoids and P-carotene in tomato fruit were increased, while it inhibited firstly and then facilitated, the growth of lycopene and xanthophyll. The treatment of ABA promoted the degradation of chlorophyll and the formation of tomato fruit color.3. Effects of exogenous GA3 and ABA to sugar related substances of main pigment synthesis in different parts of tomato fruitDuring the ripening of tomato fruit, the variation of sugar content was different, and the sugar accumulation in different parts of fruit was also different. Tomato fruit mainly contained glucose and fructose, in which the glucose content was higher than fructose, and sucrose content of each part was very low. The three sugars had the highest content in mature fruit pericarp tissue. The results showed that exogenous GA3 inhibited the accumulation of glucose and fructose in various parts of tomato fruit, and inhibited the degradation of sucrose by exogenous GA3 to treat tomato fruit with green maturity. Then, the fruits were treated with exogenous ABA, and the results showed that exogenous ABA promoted the accumulation of glucose, fructose and sucrose in all parts of fruits.4. Effects of exogenous GA3 and ABA on endogenous hormones related to main pigment synthesis in different parts of tomato fruits.In this study, the change trend of endogenous hormones was determined in different parts of tomato fruit after green ripening during the fruit ripening process. The content of endogenous GA3 showed a decreasing trend, and the content of endogenous GA3 was the lowest at maturity. The content of endogenous ABA demonstrated a "V"-shaped curve, and reached its minimum at 8 d after green ripening. At 20 d after green ripening, the content of endogenous ABA in peel tissue was the highest, and the content of endogenous ZT showed a trend of increasing first and then descending, and the lowest was at 20 d after green ripening. The trend of endogenous ETH displayed a single peak curve in different parts at different peak time. ABA/GA3 increased gradually. Endogenous GA3/ZT, ABA/ZT and ABA/ETH decreased first and then increased. ETH/GA3 first increased and then decreased, but ETH/ZT no obvious law.Smearing of GA3 to treat tomato fruit with green maturity, the consequence showed that exogenous GA3 could promote the increase of endogenous GA3 and ABA contents. Inhibition of endogenous ZT content decreased, decreased the release of endogenous ETH and delayed the peak value, increased GA3/ZT, ABA/ETH, ABA/ZT. And the ratio of ABA/GA3 was first inhibited and then promoted. ETH/ZT and ETH/GA3 increased and then decreased compared with the control. The results showed that exogenous ABA reduced the content of endogenous GA3 after smearing of exogenous ABA on green ripe tomato fruit. The effect of endogenous ABA content was inhibited-promoted-inhibited, promoted the decrease of endogenous ZT content in tomato fruit. The peak of endogenous ETH appeared earlier, which had little effect on the release of endogenous ETH, promoted the ABA/GA3 to become bigger. And no influence of ETH/GA, ABA/ZT, GA3/ZT, ETH/ZT and ABA/ETH.5. The relationship between main pigment and sugar metabolism of tomato fruitThe accumulation of glucose and fructose was beneficial to the synthesis of carotenoids, lycopene and P-carotene, the main pigment in various parts of tomato fruit, and promoted the degradation of chlorophyll. The accumulation of sucrose was disadvantageous to the carotenoids, lycopene and (3-carotene, and was beneficial to delay the degradation of chlorophyll. The accumulation of xanthophyll in the peel was affected by sugar content higher than other parts.6. The relationship between endogenous hormones and main pigments in tomato fruitThe high content of endogenous GA3 in tomato fruit was beneficial to the accumulation of xanthophyll and chlorophyll in the main pigment of tomato fruit, which was not conducive to the synthesis of ?-carotene. The high content of endogenous ABA was favorable to the synthesis of carotenoid, lycopene and P-carotene, and inhibited the accumulation of chlorophyll. The high content of endogenous ZT was beneficial to the accumulation of xanthophyll and chlorophyll, which was not conducive to the synthesis of carotenoid, lycopene and ?-carotene.There was no significant correlation between the main pigment synthesis and the content of endogenous ETH in tomato fruit.Analysis the relationship of hormone balance and main pigment accumulation, this experiment confirmed that the higher ABA/GA3 and ABA/ZT favored the accumulation of carotenoid, lycopene and P-carotene in the main pigments of tomato fruit, the lower of that inhibited chlorophyll degradation.7. The relationship between endogenous hormone and sugar accumulation in tomato fruitThe high contents of endogenous GA3 and ZT in the ripening process of tomato fruit were beneficial to the accumulation of sucrose and was not beneficial to the accumulation of glucose and fructose.The high content of endogenous ABA was beneficial to the formation of fructose. Based on the analysis of the relationship between hormone balance and sugar accumulation, the results showed that higher ABA/GA3 and ABA/ZT were beneficial to the accumulation of glucose and fructose in various parts of tomato fruit, which was not beneficial to the formation of sucrose.8. Physiological mechanism of exogenous GA3 on main pigment regulation in tomato fruitIn this study, tomato fruit was treated with exogenous GA3. The results showed that the physiological mechanism of exogenous GA3 on main pigment regulation was believed to inhibit the accumulation of carotenoids and lycopene by inhibiting of glucose, fructose accumulation and sucrose degradation. To promote the synthesis of ?-carotene by increasing exogenous ABA, to inhibit the xanthophyll accumulation by increasing the ratio ABA to GA3, to delay chlorophyll degradation by increasing endogenous GA3 content, inhibiting of glucose, fructose accumulation and sucrose degradation.9. Physiological mechanism of exogenous ABA on main pigment regulation in tomato fruitIn this study, the tomato fruit was treated with exogenous ABA. The results showed that the physiological mechanism of exogenous ABA to primary pigments was considered as follows:exogenous ABA treatment reduced the content of endogenous ZT, thus increased ABA/GA3 ratio, and the accumulation of glucose and fructose were enhanced, thereby promoted the accumulation of carotenoid and lycopene. Exogenous ABA increased xanthophyll content by increaing the content of sucrose. exogenous ABA treatment reduced the contents of endogenous GA3 and ZT, thus increased ABA/GA3 ratio, and the accumulation of glucose and fructose were enhanced, thereby promoted the accumulation of ?-carotene, exogenous ABA treatment reduced the contents of endogenous GA3, thus increased ABA/GA3 ratio, and the accumulation of glucose and fructose were enhanced, thereby decreased the chlorophyll. |
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