Preliminary Studies On The Evaluation Resources And Polyploid Breeding Of Perilla L. In China

The monotypic genus Perilla belongs to the family Lamiaceae, subfamily Lamioideae, tribe Saturejeae, subtribe Perillinae. It is self-pollinating and originates in East Asia. As a type of oil and vegetable crop, as well as traditional Chinese medicinal plants, the Perilla plants are wildly cultivated throughout China, Japan, and South Korea. Perilla is in the list of products, which serves as both food and medicine, announced by the China Ministry of Health. It contains many kinds of bio-active substances. These bio-active substances have unique medicinal and nutritional values. Modern pharmacological studies have shown that leaf extracts of perilla plants have antiallergic, anti-inflammatory, and tumor-preventing effects, etc. These health benefits, which also include reduction of cholesterol levels and improvement of age-related learning deficiencies, have been attributed to perilla oil. As such, research on development and utilization of perilla resources in China, has great potential and broad market prospects. In this paper, the morphological features of pollen grains and micromorphological features of leaf epidermis of samples of genus perilla were examined using scanning electron microscopy (SEM) and light microscopy (LM), to determine whether detailed features of the pollen grains and leaf epidermis could be used for classification. The contents and compositions of volatile oil from perilla leaves, oil contents and fatty acid compositions in seeds of the genus Perilla have been determined and evaluated in this study by modern chemical analysis methods. The method that purges and traps extraction with GC-MS determination of volatile oil compositions in leaves of Perilla genus has also been studied. Moreover, the study also focused on the methods of colchicine-induced polyploid breeding of Perilla. The results are as follows:1. According to Pei and Li's taxonomic opinions,34 perilla samples collected across seven provinces in China were classified into five varieties of one species, namely, P. frutescens (Linn.) Britt. var. acuta (Thunb.) Kudo., P. frutescens (Linn.) Britt. var. auriculato-dentata C. Y. Wu et Hsuan ex H. W. Li., P. frutescens (Linn.) Britt. var. frutescens, P. frutescens (Linn.) Britt. var. crispa (Benth.) H. W. Li. and P. frutescens (Linn.) Britt. var. arguta (Benth.) Hand.-Mazz. The size, shape and color of leaves, color of flowers and height of plants samples of the five varieties of one species of genus perilla are diverse. Their growth period, seed color, seeds diameter, average 1000-grain weight, average yield per plant are diverse too.2. Pollen morphology of 21 samples of Perilla L. was examined under scanning electron microscope (SEM). The results showed that the pollen grains are monads, heteropolar, radiosymmetric and suboblate to oblate in shape. Most of the pollen grains were hexacolpate, with a few octocolpate grains in each sample. Based on whether they had continuous tecta on the ornamentations, the pollen grains from the 21 samples were classified into two categories:(i) 14 with irregular reticulates; and (ii) seven with continuous tecta with no perforations. The ornamentation pattern and size of pollen grains jointly provide evidence that it is appropriate to use them to classify the genus Perilla into five varieties of one species.3. Under light microscopy (LM), the leaf epidermal cells of 15 samples of genus perilla are usually irregular or irregular polygonal in shape while their anticlinal wall patterns are often slightly straight, sinuolate, sinuous or sinuate. The stomatal apparatuses are usually diacytic while sometimes anomocytic and usually found on abaxial side. Shapes of stomatal apparatus of 15 perilla samples such as round or elliptic were observed with SEM. Guard cell of stomatal apparatus had a symmetric order, while variation existed in the opening of the stomatal apparatus. These various leaf epidermal cells features and stomatal apparatus shape had little taxonomical significance among five varieties of one species. However, they might be useful in distinguishing cultivars of a particular variety of genus perilla.4. The content of aromatic oil in 8 samples of genus perilla collected from China was also studied using steam distillation. The result shows that the content of aromatic oil in different samples at the stage of peak of accumulative dynamics are variant, the highest one can reach at 0.212 percent and the lowest one is only 0.065 percent. Gas chromatography-mass spectrometry (GC/MS) was used to analyse and compare the chemical components with their contents of volatile oils extracted from same 8 samples of genus perilla by Supercritical CO2 fluid extraction (SFE-CO2). In overall,45 kinds of volatiles were identified from leaves of the eight samples, but only five were common among the eight samples. The results showed that the components of volatile oils in leaves were distinctly different among eight samples, which belong to five varieties of the genus perilla.5. Volatiles from leaves of different varieties in the genus perilla were extracted using the purge and trap technique and analyzed with GC/MS. The results showed that the components and the relative contents of volatiles oils in leaves were distinctly different among four samples belonging to three varieties of the genus Perilla. The experimental data measured by methods mentioned above were compared with the volatile oil components of the same samples but extracted with the method of supercritical CO2 flow and analyzed with GC/MS. The result showed that this method is a rapid and effective one for determining volatile compounds in leaves of genus perilla.6. The oil contents and fatty acid compositions of ten seed samples of five varieties of the genus perilla were studied using methods of chemical extraction and GC/MS analyses. The results show that oil contents of the ten samples ranged from 33.49% to 42.58%. According to the GC/MS analysis results, the fatty acid compositions of the seed oils were simple. In all the 10 samples, only six kinds of fatty acids were detected, namely palmitic, linoleic,α-linolenic, stearic,10-octadecenoic and oleic acids. Among them, the first four were common constituents of the ten samples. It was clear that the relative percentages of a-linolenic acid in ten samples ranged from 71.75% to 80.06%, the content of unsaturated fatty acids in total fatty acids ranged from 88.80% to 92.82%.7. Cotton was dipped into the aqueous solution with different concentrations of colchicine, and then put onto the stem tip of perilla seedling for 24 hours, after which polyploidy variant plants were achieved. Five polyploid lines of perilla have been obtained through five years screening and identification of variant strains. Compared with diploid control, five polyploid lines of perilla had bigger pollen grains, bigger stomatal apparatus and lower density of stomata under SEM or LM. Furthermore, compared to the corresponding diploid controls, polyploid lines had lower plant height, thicker leaves, varied leave color, delayed growth period, bigger seeds, lower fertility, increased 1000-grain weight and lower yield of per plant. Compared with the volatile oil components in leaves of their diploid parents, two polyploid lines of perilla contains some new components or lack of certain ingredients, or changes in relative contents of some common components they both contain. The components and relative contents of volatile oil in the leaves between two polyploid lines of perilla also have great differences.