Histochemical characterisation of unextractable seed coat pigments and quantification of extractable lignin in the Brassicaceae

Abstract

The differences determined by in situ histochemical staining and thioglycolic lignin analyses provided a new view of seed coat composition in a range of yellow-and brown-seeded germplasm of the Brassicaceae. Unextractable seed coat pigments were composed of proanthocyanidin (condensed tannin) polymers. Anthocyanins were absent in all seed coat tissues. Proanthocyanidin was deposited over the entire seed coat in dark-seeded germplasm and in patches in some yellow-seeded germplasm. The seed coat and hilum of Crambe abyssinica cv Prophet and some yellow-seeded accessions contained an unidentified, unreactive brown pigment. Several new pigmentation patterns, occurring as spots and patches and surrounding the hilum, became apparent from this analysis. Thioglycolic lignin was significantly lower in yellow-seeded samples compared with the dark-seeded accessions, and the majority of the lignin occurred in the seed coat. These discoveries provide new and useful data for plant breeders and indicate the need to use more detailed analytical methods in breeding programmes that have the goal of improving seed meal quality by reducing fibre and phenolics.

Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola qualityBrassica napusYN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductaseThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute.

“…Extensive chemical analysis of other black seeded B. napus lines (Durkee 1971;Leung et al 1979;Mitaru et al 1982;Naczk et al 1998) and elucidation of flavonoid biochemistry in general (Marles et al 2003a;Marles and Gruber 2004) have provided a sound basis to apply metabolite profiling to probe the genetic causes of yellow seed trait. For example, Marles et al (2003b) compared a yellowseeded and a brown-seeded type found in a seed lot of Brassica carinata (BB CC genome) after selfing the lines and showed that the yellow seed had lower levels of DFR expression.…”

The promoter of the Arabidopsis thaliana BAN gene is active in proanthocyanidin-accumulating cells of the Brassica napus seed coat

“…During seed maturation, PAs form oxidized complexes with cell wall polysaccharides, other phenolics and/or proteins, thus imparting a dark colour to the seed tissues (reviewed in Moïse et al 2005). A similar structure and development of the seed coat have been described for other Brassica species (Ren and Bewley 1998;Marles 2001;Zeng et al 2004) and Arabidopsis thaliana (Devic et al 1999;Beeckman et al 2000;Debeaujon et al 2003;Haughn and Chaudhury 2005), except that the number of cell layers per integument and the contribution of the seed coat to the total seed mass differ from one species to the other .…”

Involvement of AtLAC15 in lignin synthesis in seeds and in root elongation of Arabidopsis

“…Also, a recent study demonstrated that thioglycolic lignin was signiWcantly lower in yellow seededsamples compared with the dark-seeded accessions in Brassicaceae (Marles and Gruber 2004). Thus we also examined the extractable lignin content in the mature mutant and wild-type seeds (Campbell and Ellis 1992;Marles and Gruber 2004).…”