Functional Studies of Tomato TDR4 in the Integration of Blue Light and Jasmonate Signaling Pathway
Date Issued
2015
Date
2015
Author(s)
Cheng, Maw-Yeun
Abstract
This thesis involves two parts of discussions. The first part attempts to analyze the function of tomato TDR4 in the integration of blue light and jasmonate signaling pathways. Jasmonates (JAs) are plant hormones with essential roles in plant defense and development. Current studies showed that JA might influence fruit ripening processes. However, the regulatory mechanism is still unknown. Our lab found that blue light contributed to the expression of TDR4 in the pericarp of tomato fruit. By positively regulating the expression of fruit ripening and carotenoid biosynthesis related genes, TDR4 enhances the accumulation of lycopene. Thus, this research uses Jasmonate-resistant 1-like1 (JRL1) overexpressing lines as well as TDR4 transgenic lines generated by 35S and the TDR4 native promoter respectively from previous studies, and treats the seedlings and the fruit under blue light along with methyl jasmonate (MeJA). By observing of the phenotype and analyses of mRNA expression levels, we try to link the regulatory relationship between TDR4 and JRL1. Current data show that TDR4 can be induced by MeJA and regulate the expression of JA responsive genes. JRL1 can also up-regulate the expression of TDR4 under blue light. In addition, TDR4 and JRL1 show an antagonistic effect on the inhibition of tomato hypocotyl elongation, and TDR4 poses an influence on the yield of seeds and the internode length positively and negatively, respectively. Taken together, current results indicate that TDR4 participates in JA-mediated growth and fruit ripening in tomato. The other part of this research attempts to study the effect of infrared light (IR) on plant photosynthesis and growth. Our lab found that IR irradiation contributed to the expression of PEP carboxylase gene in C4 plants. Also, IR can maintain higher chlorophyll content in the leaf discs of both maize and Arabidopsis. Therefore, we hypothesize that IR is able to enhance the efficiency of photosynthesis and to delay senescence. By testing vegetable seedlings and leaves, we found that IR can indeed postpone the loss of chlorophyll content, and increase the time of vegetable storage. As well, IR can enhance the activity of PEP carboxylase and the biomass of seedlings, which suggests that IR plays a vital role in enhancing vegetable fresh and yield.
Subjects
Blue light
Jasmonate
tomato
Infrared Light
Type
thesis