Paris polyphylla (P. polyphylla) is recognized as an important traditional medicinal plant in China. While there has been a surge in research examining the growth and bioactive compound biosynthesis of P. polyphylla, the plant's physiological adaptions to environmental factors such as soil moisture are not yet fully understood.

In a study published in Industrial Crops & Products, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences revealed how the valuable medicinal plant P. polyphylla (Chong Lou) adaptively enhances the production of its potent anti-cancer and anti-inflammatory compounds, known as polyphyllins, in response to drought stress.

Researchers investigated the impact of soil water stress on the growth and polyphenol biosynthesis of P. polyphylla. An examination of growth and polyphenol accumulation under three distinct soil moisture levels (40%, 55%, and 70%) revealed that a lower water content (SWC40) notably retarded the germination of seedlings and leaf expansion, but concurrently amplified the accumulation of polyphenols in rhizomes.

By studying all active genes through advanced transcriptomic analysis, researchers identified 40 key genes directly involved in polyphyllin production. Most of them showed dramatically higher activity levels specifically in the rhizomes under drought stress (SWC40), perfectly aligning with the measured spike in polyphyllin content.

Through co-expression network analysis, researchers identified certain drought-responsive transcription factors (TFs), i.e., basic leucine zipper (bZIP), basic helix-loop-helix (bHLH), and APETALA2 (AP2), which function as key regulators in activating the production genes of polyphyllin under conditions of drought stress.

By employing the sophisticated Random Walk with Restart (RWR) algorithm, researchers prioritized 98 high-confidence candidate genes likely playing key roles in both polyphyllin biosynthesis and drought response. Among these, genes coding for enzymes like UDP-glycosyltransferases and 2-oxoglutarate-dependent dioxygenases were prominent.

"Our study provides computational predictions of expressed sequence tag-simple sequence repeat markers associated with key regulatory and biosynthetic genes identified in P. polyphylla. It aims to expedite development of new P. polyphylla varieties that are optimized for both high medicinal compound yield and enhanced drought tolerance," said LIU Changning from XTBG.