Studies On The Regulation Mechanism Of Tryptophan On Tissue Culture And Growth In Strawberry

Auxin indole-3-acetic acid (IAA) has an effect on regulating the relationship of source and sink during the process of plant growth, promoting quality of water and mineral into the fruit, obviously enlarging the size, and improving the quality of the fruit. Exogenous tryptophan is low at the price and safe to human animals and environment. Although it is well known that tryptophan is the precursor of IAA during the process of biosynthesis. There is no directly evidence that all higher plants can transform exogenous tryptophan to IAA and use it without microorganism. Therefore, to study exogenous tryptophan and auxin on regulating vegetative growth and fruit quality to determine the effect of exogenous tryptophan and the transformational mechanism from tryptophan to IAA, is theoretically meaningful and valuable for producing non-polluted strawberry fruits. Research results are as follows:1. Strawberry tissue culture and regeneration system were established by using exogenous tryptophan. During the process of strawberry culture, exogenous L-tryptophan and DL-tryptophan have the same physiology function as IAA does, promoting formation of callus, inducing organ differentiated and plant regeneration. Therefore exogenous tryptophan can instead of auxin such as IAA, NAA, 2, 4-D andKT or BA and so on. Tryptophan has advantages of low price, high efficiency in inducing organ and safety to human and animals, which will benefit the propagation of non-virus seedling and breeding in factory.2. The variation principium of endogenous hormone indeveloping of strawberry fruit has been determined. The growth of fruit means the increasing of cell number and volume, which is regulated by kinds of endogenous hormone. The developing of strawberry fruit appears as double's' curve. The content of IAA and GA3 increased rapidly, but ABA decreased rapidly in the first period of fast growth. IAA reached the highest; the content of IAA, GA3, and ABA also increased during the period of slow growth. During the second fast growth , the content of IAA increased slowly but maintained in a high level and the variation of the content of ABA is not obvious, while the content of GA3 decreased rapidly.3. Exogenous tryptophan regulated strawberry uegetative growth and promoted fruit quality. L-tryptophan and DL-tryptophan which was sprayed on leaf increased the tree height, stem size, leaf thickness, leaf numbers of per tree, and leaf area of per tree, and enhanced tree growth and leaf photosynthesis and it increased fruit production, the content of soluble solids, dissoluble sugar, dissoluble protein, VC, and also improve fruit color and fruit hardness. The variation of endogenous hormone in strawberry fruit developing shows that the balance of growth promotion (IAA, GA3) and growth inhibition (ABA), especially the content of IAA, ABA and the ratio of GA3 and ABA, are more important to regulate the fruit developing than the relative content of the three regulaters respectively.4. Exogenous tryptophan that it improved strawberry leaf photosynthesis and increase sugar content of fruit. Exogenous tryptophan can change leaf chlorophylls ultraconstract of and particle and increases slices. It increased the content of chlorophyll and carotene as well.Exogenous tryptophan can regulate sugar accumulation in different developing stage of fruit, especially promoting sucrose accumulation in young berry fruit growth stage. Moreover it can accelerate transmission and utilizing of sucrose. The metabolizing mechanism of sugar regulation may be that exogenous tryptophan accelerates unloading of sucrose from phloem then lead to the accumulation of sucrose.5. The relationship of content of CaM,ACC,C2H4 and active of emzyme and senescence of strawberry studied. Tryptophan reduced the content ofO2, promoted the activity of CaM,SOD,POD and CAT, increased the abilityof self-protection and reduced the activity of ACC synthase and ACC oxidase then slowed the process of fruit senescence.