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Current Research

Light is an important envrionmental signal for optimal plant growth and development, and plants have evloved several photoreceptors to sense and respond to their light environment in different ways. Multiple photoreceptors, the red (R) / far-red (FR) light-sensing phytochromes (PHY), blue/UV-A light-sensing cryptochromes (CRY), and phototropins (PHOT), and and UV-B light-sensing UVR8 (UV resistance locus 8) play central roles in photomorphogenic processes, such as in seed germination and dormancy, shade avoidance, flowering time, defense against herbivory and in establishing circadian rhythms. Main goal of the project is characterizing the fucntions of photoreceptors in growth and development of Nicotiana attenuata plants.

1. Understanding the roles of root-expressed phytochromes and cryptochrome in N. attenuata’s growth and development

Interestingly, plant photoreceptors are expressed not only in the light-exposed shoots, but also in the roots which grow deep into soil where light can not reach. In the roots of N. attenuata plants, we identified multiple members of the photoreceptors, and most were highly expressed in the root-to-shoot junctions, suggesting that the junction might be a key place for light signaling from shoots to roots. In addition, NaPhyA , NaPhyB2, and NaCryp2 showed similar or even higher transcript levels in the roots compared to the shoot levels. Based on the transcript data, our working hypothesis is that light signaling in the roots contributes to the ecological intelligence of plants. To test the hypothesis, we generated photoreceptor-silenced transgenic plants by RNAi technique (Molecular biology platform) and created chimeric plants with normal “sighted” shoots (EV plants) and “blind” roots (photoreceptor-silenced plants) by a micrografting procedure (Molecular biology platform), and released the chimeric plants into their native habitat, the Greate Basin Desert, Utah, USA (Ecology platform), 1) monitor their growth and development; 2) analyze photosynthesis rates, primary and secondary metabolites, and growth-related phytohormone such as giberellic acid, auxin, and cytokinine using analytical instruments, such as LI-6400XT, Bruker GC-QQQ MS, Bruker UPLC ESI/APCI MicrOToF-Q/MS, Bruker Evo LC-QQQ MS (Analytical platform). In addition, we manipulate light in both above and below ground tissues using LEDs and optical fibers.

2. Understanding the roles of NaUVR8 in protection stratagy of N. attenuata plants against high UVB light in nature

Plants use sunlight as an energy source to photosynthesis, but at the same time have to defend against the harmful effect of UVB light in nature. Especially, N. attenuata plants naturally grow in high UVB environment (maxium 400 µW/cm2), and need efficienct stratagy to defend themselves against high UVB light. To investigate how N. attenuata plant defend against high UVB light, we generaged UVB receptor, UVR8(UV resistance locus 8)-silenced transgenic plants by RNAi technique (Molecular biology platform) and released these transgenic plants to their native habitat, the Great Basin Desert, Utah, USA (Ecology platform). In the field, we 1) compare plant growth and development of EV (control) and irUVR8 plants under different levels of UVB using UV filter; 2) examine the efficiency of photosynthesis rates of EV and irUVR8 plants, especially efficiency of PSII using LI-6400XT (Analytical platform); 3) collect sample to analyze the secondary metabolites including phenolic compounds of EV and irUVR8 plants using Aligent HPLC-UV-ELSD and Bruker UPLC ESI/APCI MicrOToF-Q/MS (Analytical platform).
last updated on 2014-10-21