Effects of Gellan Oligosaccharide and NaCl Stress on Growth, Photosynthetic Pigments, Mineral Composition, Antioxidant Capacity and Antimicrobial Activity in Red Perilla.

The growing market demand for plant raw materials with improved biological value promotes the extensive search for new elicitors and biostimulants. Gellan gum derivatives may enhance plant growth and development, but have never been used under stress conditions. Perilla (Perilla frutescens, Lamiaceae) is a source of valuable bioproducts for the pharmaceutical, cosmetic, and food industries. However, there is not much information on the use of biostimulators in perilla cultivation. In this work we investigated the effects of oligo-gellan and salt (100 mM NaCl) on the yield and quality of red perilla (P. frutescens var. crispa f. purpurea) leaves. Plants grown under stress showed inhibited growth, smaller biomass, their leaves contained less nitrogen, phosphorus, potassium, total polyphenol and total anthocyanins, and accumulated considerably more sodium than control plants. Treatment with oligo-gellan under non-saline conditions stimulated plant growth and the fresh weight content of the above-ground parts, enhanced the accumulation of nitrogen, potassium, magnesium and total polyphenols, and increased antioxidant activity as assessed by DPPH and ABTS assays. Oligo-gellan applied under saline conditions clearly alleviated the stress effects by limiting the loss of biomass, macronutrients, and total polyphenols. Additionally, plants pretreated with oligo-gellan and then exposed to 100 mM NaCl accumulated less sodium, produced greater amounts of photosynthetic pigments, and had greater antioxidant activity than NaCl-stressed plants. Irrespective of the experimental treatment, 50% extract effectively inhibited growth of Escherichia coli and Staphylococcus aureus. Both microorganisms were the least affected by 25% extract obtained from plants untreated with either NaCl or oligo-gellan. In conclusion, oligo-gellan promoted plant growth and enhanced the quality of red perilla leaves and efficiently alleviated the negative effects of salt stress.

Preliminary analysis on essential oil composition of Perilla L. cultivated in Lithuania.

This study represents the investigation of the essential oil of Perilla frutescens (L.) Britton, Perilla frutescens (L.) Britton var. crispa f. viridis, Perilla ocymoides L. var. bicolorlaciniata leaves collected at full flowering stage in August 2007, in Lithuania. As biogenesis and composition of essential oil depends on geographical location, environmental factors, plants with same chemotypes but growing in different conditions have different composition of major components. Plants have been cultivated in the collection of medicinal plants at Kaunas Botanical Garden of Vytautas Magnus University in Lithuania. Essential oil was analyzed using gas chromatography methods with flame ionization and mass spectrometry detectors. Thirteen constituents of essential oil, representing 96.42% of identified compounds, were indentified in the essential oil of Perilla frutescens (L.) Britton. Essential oil was ascertained to perillaketone chemotype. Principal compounds were found to be perillaketone and egomaketone. In Perilla ocymoides L. var. bicolorlaciniata aerial parts 97.70% of essential oil components were indentified with abundant amounts of perillaldehyde (72.07%) and limonene (13.15%). Essential oil contained two phenylpropanoids elemicin (1.91%) and myristicin (1.41%). In the essential oil of Perilla frutescens (L.) Britton var. crispa f. viridis 83.18% compounds were indentified. Principal compounds were found to be perillaldehyde (49.47%), limonene (11.76%), limonene oxides (9.85%) and caryophyllene oxide (7.21%). beta-Caryophyllene and perillaldehyde were the only compounds identified in all investigated perilla plants. Considering a broad diversity of Perilla L. species and chemotypes, it is important to discriminate cultivated Perilla L. species with identified chemotypes.

Comparison of peptides in the phloem sap of flowering and non-flowering Perilla and lupine plants using microbore HPLC followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Physiological evidence indicates that flower formation is hormonally controlled. The floral stimulus, or florigen, is formed in the leaves as a response to an inductive photoperiod and translocated through the phloem to the apical meristem. However, because of difficulties in obtaining and analyzing phloem sap and the lack of a bioassay, the chemical nature of this stimulus is one of the major unsolved problems in plant biology. A combination of microbore high-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to compare the contents of the phloem sap from flowering and non-flowering plants. Instead of using one- or two-dimensional gel electrophoresis, microbore HPLC separations allowed us to detect proteins/peptides that were very small and present at very low levels. We detected more than 100 components in the phloem sap of Perilla ocymoides L. and Lupinus albusL. Sequences for 16 peptides in a mass range from 1 to 9 kDa were obtained. Two of these could be identified, 11 showed similarity to known or deduced protein sequences, and three showed no similarity to any known protein or translated gene sequence. Four of these peptides were specific to, modified, or increased in plants that were flowering, indicating their possible role in flower induction. The sequences of these peptides showed similarities to two purine permeases, a protein with similarity to protein kinases, and a protein with no similarities to any known protein.