AUTHOR=Yu Mu-Yao , Hua Zhong-Yi , Liao Pei-Ran , Zheng Han , Jin Yan , Peng Hua-Sheng , Cui Xiu-Ming , Huang Lu-Qi , Yuan Yuan 

TITLE=Increasing Expression of PnGAP and PnEXPA4 Provides Insights Into the Enlargement of Panax notoginseng Root Size From Qing Dynasty to Cultivation Era

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.878796

DOI=10.3389/fpls.2022.878796

ISSN=1664-462X

ABSTRACT=<p>Root size is a key trait in plant cultivation and can be influenced by the cultivation environment. However, physical evidence of root size change in a secular context is scarce due to the difficulty in preserving ancient root samples, and how they were modified during the domestication and cultivation stays unclear. About 100 ancient root samples of <italic>Panax notoginseng</italic>, preserved as tribute in the Palace Museum (A.D. 1636 to 1912, <italic>Qing</italic> dynasty), provided an opportunity to investigate the root size changes during the last 100 years of cultivation. The dry weight of ancient root samples (~120 <italic>tou</italic> samples, <italic>tou</italic> represents number of roots per 500 g dry weight) is 0.22-fold of the modern samples with the biggest size (20 <italic>tou</italic> samples). Transcriptome analysis revealed that <italic>PnGAP</italic> and <italic>PnEXPA4</italic> were highly expressed in 20 <italic>tou</italic> samples, compared with the 120 <italic>tou</italic> samples, which might contribute to the thicker cell wall and a higher content of lignin, cellulose, and callose in 20 <italic>tou</italic> samples. A relatively lower content of dencichine and higher content of ginsenoside Rb<sub>1</sub> in 20 <italic>tou</italic> samples are also consistent with higher expression of ginsenoside biosynthesis-related genes. PnPHL8 was filtrated through transcriptome analysis, which could specifically bind the promoters of <italic>PnGAP, PnCYP716A47</italic>, and <italic>PnGGPPS3</italic>, respectively. The results in this study represent the first physical evidence of root size changes in <italic>P. notoginseng</italic> in the last 100 years of cultivation and contribute to a comprehensive understanding of how the cultivation environment affected root size, chemical composition, and clinical application.</p>