Jingya Zhao

Specialized structures in medicinal plants underpin the spatial regulation of secondary metabolism, determining the biosynthesis, accumulation, and storage of pharmacologically active compounds. Specialized structures, such as glandular trichomes, roots, rhizomes, laticifer, heartwood, and so on, have evolved distinct developmental programs and metabolic regulatory networks, enabling efficient synthesis, storage, and secretion of bioactive compounds. Understanding how these tissues originate, differentiate, and coordinate metabolism is essential not only for elucidating the molecular basis of plant chemical diversity but also for decoding the biosynthetic pathways of active ingredients and improving their yields through metabolic engineering. This study summarizes recent advances in elucidating the developmental and regulatory mechanisms underlying the formation and function of specialized structures in medicinal plants, including genetic, hormonal, and environmental controls. Moreover, it also highlights the technologies that have advanced the exploration of tissue‐specific metabolism, development, and differentiation mechanisms. Together, this review summarizes recent progress in elucidating the types of specialized structures responsible for active compound biosynthesis and the underlying developmental mechanisms in medicinal plants, offering new perspectives for precision breeding and metabolic engineering of medicinal plants.

Artemisinin, an antimalarial sesquiterpene lactone, is biosynthesized in glandular trichomes of Artemisia annua . Although numerous transcription factors have been demonstrated to regulate artemisinin biosynthesis, the molecular mechanisms underlying the high expression of artemisinin‐associated biosynthetic enzyme and transcription factor genes in young leaves and their marked decline during leaf maturation remain elusive. Here, we identify a trichome‐enriched bHLH transcription factor, AabHLH93, through yeast two‐hybrid screening using AaWRKY9 as bait. Yeast one‐hybrid and electrophoretic mobility shift assays demonstrate that AabHLH93 directly binds to the AaCYP71AV1 promoter. Furthermore, overexpressing AabHLH93 elevates artemisinin levels, while its RNAi suppresses artemisinin biosynthesis. In young leaves, elevated JA represses AaMYB7 expression and triggers 26S proteasome‐mediated degradation of AaJAZ9. AabHLH93 physically interacts with AaWRKY9 through its C‐terminal domain to form the AaWRKY9–AabHLH93 complex, enhancing the activation of artemisinin biosynthetic genes. Conversely, age‐dependent accumulation of the R2R3‐MYB repressor AaMYB7 in mature trichomes disrupts this synergy. In mature leaves, age‐dependent JA depletion permits AaMYB7 upregulation and AaJAZ9 accumulation. AaMYB7 directly binds to AabHLH93's C‐terminal domain, displacing AaWRKY9 and hindering the formation of the AaWRKY9–AabHLH93 activation complex. These findings elucidate how antagonistic AabHLH93–AaWRKY9 and AabHLH93–AaMYB7 modules, coupled with JA and developmental cues, dynamically control artemisinin biosynthesis.

Artemisinin, an effective antimalarial compound, is isolated from the medicinal plant Artemisia annua L. However, because of the low content of artemisinin in A. annua, the demand of artemisinin exceeds supply. Previous studies show that the artemisinin biosynthesis is promoted by light in A. annua. Cryptochrome1 (CRY1) is involved in many processes in the light response. In this study, AaCRY1 was cloned from A. annua. Overexpressing AaCRY1 in Arabidopsis thaliana cry1 mutant resulted in blue‐light‐dependent short hypocotyl phenotype and short coleoptile under blue light. Yeast two‐hybrid and subcellular colocalization showed that AaCRY1 interacted with AtCOP1 (ubiquitin E3 ligase CONSTITUTIVE PHOTOMORPHOGENIC1). Overexpression of AaCRY1 in transgenic A. annua increased the artemisinin content. When AaCRY1 was overexpressed in A. annua driven by the CYP71AV1 (cytochrome P450 dependent amorpha‐4,11‐diene 12‐hydroxylase) promoter, the artemisinin content was 1.6 times higher than that of the control. Furthermore, we expressed the C terminal of AaCRY1(CCT) involved a GUS‐CCT fusion protein in A. annua. The results showed that the artemisinin content was increased to 1.7‐ to 2.4‐fold in GUS‐CCT transgenic A. annua plants. These results demonstrate that overexpression of GUS‐CCT is an effective strategy to increase artemisinin production in A. annua.

研究青蒿异分支酸合酶的表达模式, 评价其对青蒿素含量的影响。 该研究首次克隆了青蒿异分支酸合酶基因(AaICS1), 并发现AaICS1 影响青蒿素的合成, 为更有效地开发利用青蒿提供了新思路。 根据青蒿转录组数据, 利用聚合酶链式反应(PCR)克隆AaICS1 基因和启动子, 并进行多重序列分析和启动子作用元件预测。通过实时定量PCR( qRT-PCR ) 对AaICS1 进行表达分析, 用So

Phenylalanine ammonia‐lyase (PAL) is the key enzyme in the biosynthetic pathway of salicylic acid (SA). In this study, a full‐length cDNA of PAL gene (named asAaPAL1) was cloned fromArtemisia annua. The gene contains an open reading frame of 2,151 bps encoding 716 amino acids. Comparative and bioinformatics analysis revealed that the polypeptide protein ofAaPAL1was highly homologous to PALs from other plant species. Southern blot analysis revealed that it belonged to a gene family with three members. Quantitative RT‐PCR analysis of various tissues ofA. annuashowed thatAaPAL1transcript levels were highest in the young leaves. A 1160‐bp promoter region was also isolated resulting in identification of distinctcis‐regulatory elements including W‐box, TGACG‐motif, and TC‐rich repeats. Quantitative RT‐PCR indicated thatAaPAL1was upregulated by salinity, drought, wounding, and SA stresses, which were corroborated positively with the identifiedcis‐elements within the promoter region.AaPAL1was successfully expressed inEscherichia. coliand the enzyme activity of the purified AaPAL1 was approximately 287.2 U/mg. These results substantiated the involvement ofAaPAL1in the phenylalanine pathway.