AUTHOR=Shah Faheem Afzal , Ni Jun , Yao Yuanyuan , Hu Hao , Wei Ruyue , Wu Lifang 

TITLE=Overexpression of Karrikins Receptor Gene Sapium sebiferum KAI2 Promotes the Cold Stress Tolerance via Regulating the Redox Homeostasis in Arabidopsis thaliana

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.657960

DOI=10.3389/fpls.2021.657960

ISSN=1664-462X

ABSTRACT=<p><italic>KARRIKINS INSENSITIVE2</italic> (<italic>KAI2</italic>) is the receptor gene for karrikins, recently found to be involved in seed germination, hypocotyl development, and the alleviation of salinity and osmotic stresses. Nevertheless, whether <italic>KAI2</italic> could regulate cold tolerance remains elusive. In the present study, we identified that <italic>Arabidopsis</italic> mutants of <italic>KAI2</italic> had a high mortality rate, while overexpression of, a bioenergy plant, <italic>Sapium sebiferum KAI2</italic> (<italic>SsKAI2</italic>) significantly recovered the plants after cold stress. The results showed that the <italic>SsKAI2</italic> overexpression lines (OEs) had significantly increased levels of proline, total soluble sugars, and total soluble protein. Meanwhile, <italic>SsKAI2</italic> OEs had a much higher expression of cold-stress-acclimation-relate genes, such as <italic>Cold Shock Proteins</italic> and <italic>C-REPEAT BINDING FACTORS</italic> under cold stress. Moreover, the results showed that <italic>SsKAI2</italic> OEs were hypersensitive to abscisic acid (ABA), and ABA signaling genes were w significantly affected in <italic>SsKAI2</italic> OEs under cold stress, suggesting a potential interaction between <italic>SsKAI2</italic> and ABA downstream signaling. In <italic>SsKAI2</italic> OEs, the electrolyte leakage, hydrogen peroxide, and malondialdehyde contents were reduced under cold stress in <italic>Arabidopsis</italic>. <italic>SsKAI2</italic> OEs enhanced the anti-oxidants like ascorbate peroxidase, catalase, peroxidase, superoxide dismutase, and total glutathione level under cold stress. Conclusively, these results provide novel insights into the understanding of karrikins role in the regulation of cold stress adaptation.</p>