Analysis of Isoquinoline Alkaloid Composition and Wound-Induced Variation in Nelumbo Using HPLC-MS/MS.

Alkaloids are the most relevant bioactive components in lotus, a traditional herb in Asia, but little is known about their qualitative and quantitative distributions. Here, we report on the alkaloid composition in various lotus organs. Lotus laminae and embryos are rich in isoquinoline alkaloids, whereas petioles and rhizomes contain trace amounts of alkaloids. Wide variation of alkaloid accumulation in lamina and embryo was observed among screened genotypes. In laminae, alkaloid accumulation increases during early developmental stages, reaches the highest level at full size stage, and then decreases slightly during senescence. Vegetative and embryogenic tissues accumulate mainly aporphine-type and bisbenzylisoquinoline-type alkaloids, respectively. Bisbenzylisoquinoline-type alkaloids may be synthesized mainly in lamina and then transported into embryo via latex through phloem translocation. In addition, mechanical wounding was shown to induce significant accumulation of specific alkaloids in lotus leaves.

Comparative analysis of antioxidant activity and functional components of the ethanol extract of lotus (Nelumbo nucifera) from various growing regions.

The variations in antioxidant activity and concentration of functional components in the ethanol extracts of lotus seeds and rhizomes based on the growing region and dryness were investigated. Free radical scavenging activity, total phenolic and flavonoid content, and concentration of several specific flavonoids and alkaloids in the ethanol extracts of lotus were measured. Antioxidant activity and its correlative total phenolic content varied characteristically depending on the growing region and dryness. High-perfomance liquid chromatography analysis showed that the ethanol extracts of lotus seeds from Vietnam (Ho Chi Minh City), raw rhizomes from Korea (Siheung), and dried rhizomes from Japan (Nigata) had the greatest specific flavonoid content. The ethanol extracts of seeds from China (Hubei), raw rhizomes from Japan (Nigata), and dried rhizomes from Korea (Siheung) had the greatest specific alkaloid content. Astragaline, rutin, isoquercetin, nuciferine, dauricine, isoliensinine, and neferine were identified in lotus rhizomes for the first time in this study.

Proteomic and functional analyses of Nelumbo nucifera annexins involved in seed thermotolerance and germination vigor.

Annexins are multifunctional proteins characterized by their capacity to bind calcium ions and negatively charged lipids. Although there is increasing evidence implicating their importance in plant stress responses, their functions in seeds remain to be further studied. In this study, we identified a heat-induced annexin, NnANN1, from the embryonic axes of sacred lotus (Nelumbo nucifera Gaertn.) using comparative proteomics approach. Moreover, the expression of NnANN1 increased considerably in response to high-temperature treatment. Quantitative real-time PCR (qRT-PCR) revealed that the transcripts of NnANN1 were detected predominantly during seed development and germination in sacred lotus, implicating a role for NnANN1 in plant seeds. Ectopic expression of NnANN1 in Arabidopsis resulted in enhanced tolerance to heat stress in transgenic seeds. In addition, compared to the wild-type seeds, transgenic seeds ectopically expressing NnANN1 exhibited improved resistance to accelerated aging treatment used for assessing seed vigor. Furthermore, transgenic seeds showed enhanced peroxidase activities, accompanied with reduced lipid peroxidation and reduced ROS release levels compared to the wild-type seeds. Taken together, these results indicate that NnANN1 plays an important role in seed thermotolerance and germination vigor.