Overexpression of <i>RpKTI2</i> from <i>Robinia pseudoacacia</i> Affects the Photosynthetic Physiology and Endogenous Hormones of Tobacco
2024
Jian Zhou | Pengxiang Die | Songyan Zhang | Xiaoya Han | Chenguang Wang | Peipei Wang
Kunitz trypsin inhibitor genes play important roles in stress resistance. In this study, we investigated <i>RpKTI2</i> cloned from <i>Robinia pseudoacacia</i> and its effect on tobacco. <i>RpKTI2</i> was introduced into the tobacco cultivar NC89 using <i>Agrobacterium</i>-mediated transformation. Six <i>RpKTI2</i>-overexpressing lines were obtained. Transgenic and wild-type tobacco plants were then compared for photosynthetic characteristics and endogenous hormone levels. Transgenic tobacco showed minor changes in chlorophyll content, fluorescence, and photosynthetic functions. However, the maximum photochemical efficiency (<i>F</i><sub>v</sub>/<i>F</i><sub>m</sub>) increased significantly while intercellular CO<sub>2</sub> concentration (<i>C</i><sub>i</sub>) decreased significantly. Stomatal size and hormone content (indole-3-acetic acid, zeatin riboside, gibberellin, and indole-3-propionic acid) were reduced, while brassinosteroid content increased. Random forest regression revealed that <i>RpKTI2</i> overexpression had the biggest impact on carotenoid content, initial fluorescence, <i>C</i><sub>i</sub>, stomatal area, and indole-3-acetic acid. Overall, <i>RpKTI2</i> overexpression minimally affected chlorophyll synthesis and photosynthetic system characteristics but influenced stomatal development and likely enhanced the antioxidant capacity of tobacco. These findings provide a basis for future in-depth research on <i>RpKTI2</i>.
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