AUTHOR=Yin Hang , Wang Zhaoyu , Li Han , Zhang Yu , Yang Mei , Cui Guowen , Zhang Pan 

TITLE=MsTHI1 overexpression improves drought tolerance in transgenic alfalfa (Medicago sativa L.)

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.992024

DOI=10.3389/fpls.2022.992024

ISSN=1664-462X

ABSTRACT=<p>In recent years, drought stress caused by global warming has become a major constraint on agriculture. The thiamine thiazole synthase (THI1) is responsible for controlling thiamine production in plants displaying a response to various abiotic stresses. Nonetheless, most of the THI1 activities in plants remain largely unknown. In this study, we extracted <italic>MsTHI1</italic> from alfalfa and demonstrated its beneficial impact on improving the resistance of plants to stress conditions. The highest levels of <italic>MsTHI1</italic> expression were identified in alfalfa leaves, triggered by exposure to cold, drought, salt, or alkaline conditions. The upregulation of <italic>MsTHI1</italic> in drought-stressed transgenic plants resulted in enhanced accumulation of vitamin B1 (VB1), chlorophyll <italic>a</italic> (Chl <italic>a</italic>), chlorophyll <italic>b</italic> (Chl <italic>b</italic>), soluble protein, higher soil and plant analyzer development (SPAD) value, and the activity of peroxidase (POD), maintained Fv/Fm, and decreased lipid peroxidation. Moreover, overexpression of <italic>MsTHI1</italic> upregulated the transcription of <italic>THI4, TPK1, RbcX2, Cu/Zn-SOD, CPK13</italic>, and <italic>CPK32</italic> and downregulated the transcription of <italic>TH1</italic> and <italic>CPK17</italic> in transgenic alfalfa under drought stress. These results suggested that <italic>MsTHI1</italic> enhances drought tolerance by strengthening photosynthesis, regulating the antioxidant defense system, maintaining osmotic homeostasis, and mediating plant signal transduction.</p>