| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 102 === Phosphorous (P), one of the essential mineral nutrients for plant growth and development, is involved in the regulation of several physiological and biochemical processes in plants. In our study, it was found that, in the tobacco and tomato plants at vegetative growth stage under phosphorus deficiency treatment, the phosphate (Pi) concentration in shoot and root decreased rapidly, the chlorophyll fluorescence (Fv/Fm), chlorophyll content and shoot fresh weight decreased relatively slowly, while the root/shoot fresh weight ratio increased gradually. Furthermore, in tomato plants at reproductive growth stage under Pi starvation, the Pi concentration in fruit decreased rapidly, and then the fruit yield and total soluble solids decreased. Accordingly, it is shown that the vegetative growth of tobacco and tomato plants as well as the final yield and quality of tomato depend on whether phosphorus fertilizer is supplied sufficiently. It was further found that, while temporary phosphorus deficiency may immediately lead to the decrease of the Pi concentration in shoot or fruit, the shoot fresh weight or the fruit yield and quality may not be adversely impacted thereby so long as phosphorus fertilizer is timely supplemented to rapidly increase the Pi concentration in shoot or fruit. This indicates that the yield and quality of crops can be ensured by monitoring the nutritional status of the crops and supplying fertilizer as appropriate. By Agroinfiltration and Agroinjection, this study demonstrated that the expression of GUS reporter gene driven by tomato TPSI1 promoter can rapidly and truly reflect the phosphorus deficiency stress in tobacco leaf and tomato fruit. This indicates that the employed Agroinfiltration/Agroinjection transient expression system is useful in monitoring the Pi status in plants. Further, the aforesaid expression of GUS reporter gene is independent of the deficiency of the mineral nutrients other than phosphorus, indicating the specificity of the employed Agroinfiltration transient expression system. Because the application of the aforesaid system is convenient and leads to rapid and accurate reflection of phosphorus status in plants, the aforesaid system should be applicable to other crops or to monitor other mineral nutrient status if the tomato TPSI1 promoter is replaced by other appropriate promoters.
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