Polyacylated Anthocyanins in Bluish-Purple Petals of Chinese Bellflower, Platycodon grandiflorum.

The bluish-purple petals of Chinese bellflower, Platycodon grandiflorum (kikyo in Japanese), contain platyconin (1) as the major anthocyanin. Platyconin (1) is a polyacylated anthocyanin with two caffeoyl residues at the 7-position, and its color is stable in a diluted, weakly acidic aqueous solutions. HPLC analysis of the fresh petal extract showed the presence of several minor pigments. Photo-diode array detection of minor pigments suggested that some of these were polyacylated anthocyanins. To establish the relationship between structure and stability of the acylated anthocyanins and to obtain information on their biosynthetic pathways, minor pigments were isolated from the petals, and their structures were determined by MS and NMR analyses. Four known (2-5) and three new anthocyanins (6-8) were identified, which contained a delphinidin chromophore, and four of these (5-8) were diacylated anthocyanins, in which the acyl-glucosyl-acyl-glucosyl chain was attached at the 7-O-position of the delphinidin chromophore. These diacylated anthocyanins exhibited a bluish-purple color at pH 6, which was stable for more than a week.

Field assessment of a major QTL associated with tolerance to cold-induced seed coat discoloration in soybean.

In Hokkaido, the northernmost region of Japan, soybean [Glycine max (L.) Merr.] crops are damaged by cold weather. Chilling temperatures negatively affect seed appearance by causing seed coat discoloration around the hilum region, which is called cold-induced discoloration (CD). An assay for CD tolerance using a phytotron was developed, and two quantitative trait loci (QTLs) associated with CD tolerance were identified. The major QTL was located in the proximal region of the I locus, and structural variation of this locus can serve as a useful DNA marker, called the Ic marker. To use this marker in breeding programs, the effects need to be assessed under field conditions because the Ic marker has been developed solely under phytotron conditions. The aim of this study was thus to assess the effect of the Ic marker under a cool field environment. We confirmed that the Ic allele was highly effective using 27 cultivars and breeding lines including a near-isogenic line grown in the field where severe cold-weather damage occurred. This allele had no negative influence on the agronomic traits in the near-isogenic line. Our results suggest that marker-assisted selection for the Ic allele is effective for improving CD tolerance in breeding programs.

Method for selection of soybeans tolerant to seed cracking under chilling temperatures.

In Hokkaido, northern Japan, soybean [Glycine max (L.) Merr.] crops are damaged by cold weather. Chilling temperatures result in the appearance of cracking seeds (CS) in soybean crops, especially those grown in eastern and northern Hokkaido. Seed coats of CS are severely split on the dorsal side, and the cotyledons are exposed and frequently separated. CS occurrence causes unstable production because these seeds have no commodity value. However, little is known about the CS phenomenon. The aims of this study were to identify the cold-sensitive stage associated with CS occurrence and to develop a method to select CS-tolerant lines. First, we examined the relationship between chilling temperatures after flowering and CS occurrence in field tests. The average temperature 14 to 21 days after flowering was negatively correlated with the rate of CS. Second, we evaluated differences in CS tolerance among soybean cultivars and breeding lines in field tests. 'Toyohomare' and 'Toiku-238' were more CS-tolerant than 'Yukihomare' and 'Toyomusume'. Third, we developed a selection method in which plants were subjected to 21-day chilling-temperature treatment from 10 days after flowering in a phytotron. This enabled comparisons of CS tolerance among cultivars. This selection method will be useful for breeding CS-tolerant soybeans.

Mapping and use of QTLs controlling pod dehiscence in soybean.

While the cultivated soybean, Glycine max (L.) Merr., is more recalcitrant to pod dehiscence (shattering-resistant) than wild soybean, Glycine soja Sieb. & Zucc., there is also significant genetic variation in shattering resistance among cultivated soybean cultivars. To reveal the genetic basis and develop DNA markers for pod dehiscence, several research groups have conducted quantitative trait locus (QTL) analysis using segregated populations derived from crosses between G. max accessions or between a G. max and G. soja accession. In the populations of G. max, a major QTL was repeatedly identified near SSR marker Sat_366 on linkage group J (chromosome 16). Minor QTLs were also detected in several studies, although less commonality was found for the magnitudes of effect and location. In G. max × G. soja populations, only QTLs with a relatively small effect were detected. The major QTL found in G. max was further fine-mapped, leading to the development of specific markers for the shattering resistance allele at this locus. The markers were used in a breeding program, resulting in the production of near-isogenic lines with shattering resistance and genetic backgrounds of Japanese elite cultivars. The markers and lines developed will hopefully contribute to the rapid production of a variety of shattering-resistant soybean cultivars.