Inheritance Of Sugar Content And The Relationship Between Sugar Accumulation And Enzymes Related To Sucrose Metabolism In Fruits Of Watermelon

Parents and progeny: P₁(jingyuandaban, edible seed watermelon), P₂(04-12, high sugar watermelon for flesh), progeny included F₁, F₂ and back cross with parents were used to research inheritance of sugar content of the fruit, characteristics of the accumulation about soluble solids, sucrose, glucose, fructose in fruit development, and relationship between sugar accumulation and enzymes related to sucrose metabolism, the results showed that:1. In early development of P₂, it has high levels of glucose and fructose, but the sucrose content is very low. With the development of fruit, glucose and fructose levels rising until declined later. Sucrose content increases rapidly become the main components of soluble sugar in the end. The content of glucose and fructose of P1 is relative high in young fruit and in the fruit development has a certain degree of elevated, but the sucrose rises significantly smaller, this makes the parents of total sugar gap widening. Thus we could make a conclusion that during the appreciation of total value of P₂ depends more with the sucrose increased range, although glucose and fructose have certain increase. Accumulation characteristics of glucose and fructose content of F₁ between the two parents, but the trend of sucrose was significantly lower than the average values of the mid-parent and similar with microparent.2. Fructose and glucose content of F₂ and backcross have shown a continuous distribution, F₁ close to the average values of the mid-parent. Therefore, the distribution of the soluble solid and glucose content both corresponded to the genetic effect of quantitative character, that fructose and glucose content were quantitative traits controlled by multiple genes. Sucrose content changes are different, and the content distribution of BC1-P2 was corresponded to normal continuity, F₂ also have similar trend, but the distribution is relatively concentrated, the distribution of BC₁-P₁ content focused on 0 to 5 mg.g^-1 .FW. Combining the performance of F₁, we could think that sucrose content may determines of one pair of incomplete dominance epistatic genes or restrained genes determine the content of low levels, there are several pairs of genes determine the sucrose content, this makes the content of soluble solids is relatively concentrated in separation of BC₁-P₁.3. High sugar watermelon in young fruit(after flowering 15-20d), AI and NI activity is higher, SS and SPS activity lower, no obvious increase in sucrose accumulation, with AI and NI activity decline sharply 20d later, SS and SPS activity to rise gradually; AI and NI activity of P₁ have been higher during 15-25d, AI and NI activity began to drop dramatically after 25d, AI and NI activity changes of F₁ also similar with P₂, but did not cause rapid accumulation of sucrose, this may be due to activity of SS and SPS is lower wholely; therefore, accumulation of sucrose is the enzymes aforementioned comprehensive effect results. There is not found obvious relationship between enzymes related to sucrose and accumulation of glucose and fructose.