AUTHOR=Wang Zhuhua , Wang Wenpeng , Wu Wentao , Wang Huiling , Zhang Shuai , Ye Chen , Guo Liwei , Wei Zhaoxia , Huang Hongping , Liu Yixiang , Zhu Shusheng , Zhu Youyong , Wang Yang , He Xiahong 

TITLE=Integrated analysis of transcriptome, metabolome, and histochemistry reveals the response mechanisms of different ages Panax notoginseng to root-knot nematode infection

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1258316

DOI=10.3389/fpls.2023.1258316

ISSN=1664-462X

ABSTRACT=<p><italic>Panax notoginseng</italic> (<italic>P. notoginseng</italic>) is an invaluable perennial medicinal herb. However, the roots of <italic>P. notoginseng</italic> are frequently subjected to severe damage caused by root-knot nematode (RKN) infestation. Although we have observed that <italic>P. notoginseng</italic> possessed adult-plant resistance (APR) against RKN disease, the defense response mechanisms against RKN disease in different age groups of <italic>P. notoginseng</italic> remain unexplored. We aimed to elucidate the response mechanisms of <italic>P. notoginseng</italic> at different stages of development to RKN infection by employing transcriptome, metabolome, and histochemistry analyses. Our findings indicated that distinct age groups of <italic>P. notoginseng</italic> may activate the phenylpropanoid and flavonoid biosynthesis pathways in varying ways, leading to the synthesis of phenolics, flavonoids, lignin, and anthocyanin pigments as both the response and defense mechanism against RKN attacks. Specifically, one-year-old <italic>P. notoginseng</italic> exhibited resistance to RKN through the upregulation of 5-O-p-coumaroylquinic acid and key genes involved in monolignol biosynthesis, such as PAL, CCR, CYP73A, CYP98A, POD, and CAD. Moreover, two-year-old <italic>P. notoginseng</italic> enhanced the resistance by depleting chlorogenic acid and downregulating most genes associated with monolignol biosynthesis, while concurrently increasing cyanidin and ANR in flavonoid biosynthesis. Three-year-old <italic>P. notoginseng</italic> reinforced its resistance by significantly increasing five phenolic acids related to monolignol biosynthesis, namely p-coumaric acid, chlorogenic acid, 1-O-sinapoyl-D-glucose, coniferyl alcohol, and ferulic acid. Notably, <italic>P. notoginseng</italic> can establish a lignin barrier that restricted RKN to the infection site. In summary, <italic>P. notoginseng</italic> exhibited a potential ability to impede the further propagation of RKN through the accumulation or depletion of the compounds relevant to resistance within the phenylpropanoid and flavonoid pathways, as well as the induction of lignification in tissue cells.</p>