RESUMO: Monochasma savatieri Franch. O ex Maxim é uma erva parasitária aperene usada na medicina tradicional chinesa suas fontes diminuíram acentuadamente nos últimos anos devido à colheita destrutiva e à destruição de habitats e condições de sobrevivência no campo. Neste estudo, investigamos os efeitos da concentração de 2,6-dimetoxi-p-benzoquinona (DMBQ) e densidade de cultivo sobre as características de crescimento, formação de haustório e biomassa de M. savatieri na ausência de uma planta hospedeira. Os resultados mostraram que a concentração de DMBQ e a densidade de cultivo regularam as características de crescimento, a formação de haustório e a biomassa em M. savatieri. O número de haustórios foi significativamente correlacionado positivamente com a altura das plântulas, comprimento máximo das raízes, número de pontas das raízes e peso seco total. Revelou também um aumento geral nas características de crescimento, formação de haustório e biomassa quando M. savatieri foi tratado com 10 μmol • L-1DMBQ e cresceu solitariamente. Esses resultados oferecem uma compreensão do crescimento de M. savatieri influenciado pela concentração de DMBQ e densidade de cultivo, o que pode ajudar no estabelecimento de um sistema abrangente de cultivo para plantas similares de M. savatierior.

ABSTRACT: Monochasma savatieri Franch. ex Maxim is a perennial, parasitic herb used in traditional Chinese medicine and its wild resources have decreased sharply in recent years due to destructively harvesting and habitat destruction. Haustorium formation is a key event of parasites, but the concentrations of haustorium-inducing factors vary with species and cultivation conditions. In this study, we investigated the effects of the 2,6-dimethoxy-p-benzoquinone (DMBQ) concentration and cultivation density on the growth traits, haustorium formation and biomass of M. savatieri in the absence of a host plant. The results showed that both the DMBQ concentration and cultivation density regulated growth traits, haustorium formation and biomass in M. savatieri. The number of haustoria was significantly positively correlated with seedling height, maximum root length, the number of root tips and total dry weight. Membership function analysis revealed an overall greater increase in growth traits, haustorium formation and biomass when M. savatieri was treated with 10 μmol·L-1DMBQ and grew solitarily. These results offer an understanding of growth in M. savatieri influenced by the DMBQ concentration and cultivation density, which may aid in the establishment of a comprehensive cultivation system for M. savatieri or similar plants.

BACKGROUND: Prunella vulgaris L. is a medical plant cultivated in sloping, sun-shaded areas in China. Recently, owing to air-environmental stress, especially drought stress strongly inhibits plant growth and development, the appropriate fertilizer supply can alleviate these effects. However, these is little information about their effects on P. vulgaris growing in arid and semi-arid areas with limited water and fertilizer supply. RESULTS: In this study, water stress decreased the photosynthetic pigment contents, inhibited photosynthetic efficiency, induced photodamage in photosystem 2 (PS2), and decreased leaf instantaneous WUE (WUEi). The decreased net photosynthetic rate (Pn) under medium drought stress compared with the control might result from stomatal limitations. However, fertilizer supply improved photosynthetic capacity by increasing the photosynthetic pigment contents and enhancing photosynthetic efficiency under water deficit. Moreover, medium fertilization also increased WUEi under the two water conditions, but fertilizer supply did little to alleviate the PS2 photodamage caused by drought stress. Hence, drought stress was the primary limitation in the photosynthetic process of P. vulgaris seedlings, while the photosynthetic characteristics of the seedlings exhibited positive responses to fertilizer supply. CONCLUSIONS: Appropriate fertilizer supply is recommended to improve photosynthetic efficiency, enhance WUEi and alleviate photodamage under drought stress.

Prunella vulgaris L. (Labiatae) contains a variety of structurally diverse natural products, primarily rosmarinic acid (RA), ursolic acid (UA) and oleanolic acid (OA), which possess a wide array of biological properties. In the present study, P. vulgaris was harvested at three developmental stages (vegetative, full-flowering and mature-fruiting stages), dissected into stem and leaf tissues and assayed for chemical contents using high performance liquid chromatography. Significant changes in the concentrations of the major secondary metabolites (RA, UA and OA) were observed at the different development stages. The highest concentrations of RA, UA and OA were found at the full-flowering stage (15.83 mg/g dry weight (DW) RA, 1.77 mg/g DW UA and 0.65 mg/g DW OA). Among the different aerial parts of the plant, the concentrations of RA, UA and OA were higher in the leaves than in the stems at the different developmental stages. These results suggest that the full-flowering stage is characterized by the highest concentrations of bioactive compounds. Therefore, this stage may be the optimum point for harvesting P. vulgaris plants. In additional, the leaves of P. vulgaris demonstrated higher RA, UA and OA concentrations than the stems, suggesting higher utilization potential.