Recent Progress of Basic Studies of Natural Products and Their Dental Application.

The present article reviews the research progress of three major polyphenols (tannins, flavonoids and lignin carbohydrate complexes), chromone (backbone structure of flavonoids) and herbal extracts. Chemical modified chromone derivatives showed highly specific toxicity against human oral squamous cell carcinoma cell lines, with much lower toxicity against human oral keratinocytes, as compared with various anticancer drugs. QSAR analysis suggests the possible correlation between their tumor-specificity and three-dimensional molecular shape. Condensed tannins in the tea extracts inactivated the glucosyltransferase enzymes, involved in the biofilm formation. Lignin-carbohydrate complexes (prepared by alkaline extraction and acid-precipitation) and crude alkaline extract of the leaves of Sasa species (SE, available as an over-the-counter drug) showed much higher anti-HIV activity, than tannins, flavonoids and Japanese traditional medicine (Kampo). Long-term treatment with SE and several Kampo medicines showed an anti-inflammatory and anti-oxidant effects in small size of clinical trials. Although the anti-periodontitis activity of synthetic angiotensin II blockers has been suggested in many papers, natural angiotensin II blockers has not yet been tested for their possible anti-periodontitis activity. There should be still many unknown substances that are useful for treating the oral diseases in the natural kingdom.

Diversity evaluation based on morphological, physiological and isozyme variation in genetic resources of garlic (Allium sativum L.) collected worldwide.

The aim of this study was to obtain primary information about the global diversity of garlic (Allium sativum L.) by evaluating morphological, physiological and isozyme variation. A total of 107 garlic accessions collected worldwide were grown in Yamaguchi, Japan. Five morphological traits (bulb weight, bulb diameter, number of cloves per bulb, number of bulbils and scape length) and one physiological trait (bolting period) of the collected garlic showed wide variation. Meanwhile, a total of 140 garlic accessions, including the 107 mentioned above, were characterized by leucine aminopeptidase (LAP) and phosphoglucoisomerase (PGI) isozyme analyses; they clearly showed polymorphisms in putative isozyme loci (Lap-1, Lap-2 and Pgi-1). Allelic frequencies were estimated in each group of accessions categorized by their geographical origin, and the observed (Ho) and expected (He) heterozygosities were calculated. The allelic frequencies differed between groups. A principal component analysis based on morpho-physiological data indicated a grouping of the garlic accessions into Central Asian and Northern Mediterranean groups as well as others. We discuss the roles of artificial and natural selection that may have caused differentiation in these traits, on the assumption that ancestral domesticated garlic populations have adapted in various regions using standing variation or mutations that accumulated during expansion, and have evolved along with human-preferred traits over a long history of cultivation.

Screening and incorporation of rust resistance from Allium cepa into bunching onion (Allium fistulosum) via alien chromosome addition.

Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum - shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance.

Discovery of a new source of resistance to Fusarium oxysporum, cause of Fusarium wilt in Allium fistulosum, located on chromosome 2 of Allium cepa Aggregatum group.

This study was carried out to evaluate the antifungal effect of Allium cepa Aggregatum group (shallot) metabolites on Fusarium oxysporum and to determine the shallot chromosome(s) related to Fusarium wilt resistance using a complete set of eight Allium fistulosum - shallot monosomic addition lines. The antifungal effects of hexane, butanol, and water extraction fractions from bulbs of shallot on 35 isolates of F. oxysporum were examined using the disc diffusion method. Only hexane and butanol fractions showed high antifungal activity. Shallot showed no symptom of disease after inoculation with F. oxysporum f. sp. cepae. The phenolic content of the roots and the saponin content of root exudates of inoculated shallot increased to much higher levels than those of the control at 3 days after inoculation. Application of freeze-dried shallot root exudates to seeds of A. fistulosum soaked in a spore suspension of F. oxysporum resulted in protection of seedlings against infection. Among eight monosomic addition lines and A. fistulosum, FF+2A showed the highest resistance to Fusarium wilt. This monosomic addition line also showed a specific saponin band derived from shallot on the thin layer chromatography profile of saponins in the eight monosomic addition lines. The chromosome 2A of shallot might possess some of the genes related to Fusarium wilt resistance.

Molecular and biochemical identification of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of bunching onion (A. fistulosum L.).

To develop the bunching onion (Allium fistulosum L.; genomes, FF) chromosome-specific genetic markers for identifying extra chromosomes, eight shallot (A. cepa L. Aggregatum group; genomes, AA)--A. fistulosum monosomic addition plants (AA+nF) and 62 shallot--A. fistulosum single-alien deletion plants (AAF-nF) were analyzed by 23 different chromosome-specific genetic markers of shallot. The eight monosomic addition plants consisted of one AA+2F, two AA+6F, and five AA+8F. Of the 62 single-alien deletion plants, 60 could be identified as six different single-alien deletion lines (AAF-1F, -3F, -4F, -6F, -7F, and -8F) out of the eight possible types. Several single-alien deletion lines were classified on the basis of leaf and bulb characteristics. AAF-8F had the largest number of expanded leaves of five deletion plants. AAF-7F grew most vigorously, as expressed by its long leaf blade and biggest bulb size. AAF-4F had very small bulbs. AAF-7F and AAF-8F had different bulbs from those of shallot as well as other types of single-alien deletion lines in skin and outer scale color. Regarding the sugar content of the bulb tissues, the single-alien deletion lines showed higher fructan content than shallot. Moreover, shallot could not produce fructan with degree of polymerization (DP) 12 or higher, although the single-alien deletion lines showed DP 20 or higher. The content of S-alk(en)yl-L-cysteine sulfoxide (ACSO) in the single-alien deletion lines was significantly lower than that in shallot. These results indicated that chromosomes from A. fistulosum might carry anonymous factors to increase the highly polymerized fructan production and inhibit the synthesis of ACSO in shallot bulbs. Accordingly, alien chromosomes from A. fistulosum in shallot would contribute to modify the quality of shallot bulbs.

Complete assignment of structural genes involved in flavonoid biosynthesis influencing bulb color to individual chromosomes of the shallot (Allium cepa L.).

We analyzed Japanese bunching onion (Allium fistulosum L.) - shallot (Allium cepa L. Aggregatum group) alien chromosome addition lines in order to assign the genes involved in the flavonoid biosynthesis pathway to chromosomes of the shallot. Two complete sets of alien monosomic additions (2n = 2x + 1 = 17) were used for determining the chromosomal locations of several partial sequences of candidate genes, CHS, CHI, F3H, DFR, and ANS via analyses of PCR-based markers. The results of DNA marker analyses showed that the CHS-A, CHS-B, CHI, F3H, DFR, and ANS genes should be assigned to chromosomes 2A, 4A, 3A, 3A, 7A, and 4A, respectively. HPLC analyses of 14 A. fistulosum - shallot multiple alien additions (2n = 2x + 2 - 2x + 7 = 18 - 23) were conducted to identify the anthocyanin compounds produced in the scaly leaves. A direct comparison between the genomic constitution and the anthocyanin compositions of the multiple additions revealed that a 3GT gene for glucosylation of anthocyanidin was located on 4A. Thus, we were able to assign all structural genes involved in flavonoid biosynthesis influencing bulb color to individual chromosomes of A. cepa.

Production and characterization of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of Japanese bunching onion (A. fistulosum L.).

First and second backcrosses of amphidiploid hybrids (2n = 4x = 32, genomes AAFF) between shallot (Allium cepa Aggregatum group) and A. fistulosum were conducted to produce A. cepa - A. fistulosum alien addition lines. When shallot (A. cepa Aggregatum group) was used as a pollinator, the amphidiploids and allotriploids set germinable BC(1) and BC(2) seeds, respectively. The 237 BC(1) plants mainly consisted of 170 allotriploids (2n = 3x = 24, AAF) and 42 hypo-allotriploids possessing 23 chromosomes, i.e., single-alien deletions (2n = 3x-1 = 23, AAF-nF). The single-alien deletions in the BC(1) progeny showed dwarfing characteristics and were discriminated from the allotriploids (2n = 24) and hyper-allotriploids (2n = 25) by means of flow cytometric analysis. The chromosome numbers of 46 BC(2) seedlings varied from 16 to 24. Eight monosomic additions (2n = 2x+1 = 17, AA+nF) and 20 single-alien deletions were found in these BC(2) seedlings. Consequently, six kinds of A. cepa - A. fistulosum alien chromosome additions possessing different chromosome numbers (2n = 17, 18, 20, 21, 22, 23) were recognized in the BC(1) and BC(2) populations. A total of 79 aneuploids, including 62 single-alien deletions, were analyzed by a chromosome 6F-specific isozyme marker (Got-2) in order to recognize its existence in their chromosome complements. This analysis revealed that two out of 62 single-alien deletions did not possess 6F. One (AAF-6F) out of the possible eight single-alien deletions could be identified at first. The present study is a first step toward the development of a useful tool, such as a complete set of eight different single-alien deletions, for the rapid chromosomal assignment of genes and genetic markers in A. fistulosum.