Most annexins are calcium-dependent, phospholipid-binding proteins with suggested functions in response to environmental stresses and signaling during plant growth and development. They have previously been identified and characterized in Arabidopsis and rice, and constitute a multigene family in plants. In this study, we performed a comparative analysis of annexin gene families in the sequenced genomes of Viridiplantae ranging from unicellular green algae to multicellular plants, and identified 149 genes. Phylogenetic studies of these deduced annexins classified them into nine different arbitrary groups. The occurrence and distribution of bona fide type II calcium binding sites within the four annexin domains were found to be different in each of these groups. Analysis of chromosomal distribution of annexin genes in rice, Arabidopsis and poplar revealed their localization on various chromosomes with some members also found on duplicated chromosomal segments leading to gene family expansion. Analysis of gene structure suggests sequential or differential loss of introns during the evolution of land plant annexin genes. Intron positions and phases are well conserved in annexin genes from representative genomes ranging from Physcomitrella to higher plants. The occurrence of alternative motifs such as K/R/HGD was found to be overlapping or at the mutated regions of the type II calcium binding sites indicating potential functional divergence in certain plant annexins. This study provides a basis for further functional analysis and characterization of annexin multigene families in the plant lineage.

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Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola quality Brassica napus YN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductase Akhov, Leonid; Ashe, Paula; Tan, Yifang; Datla, Raju; Selvaraj, Gopalan Proanthocyanidin biosynthesis in the seed coat of yellow-seeded, canola quality Brassica napus YN01-429 is constrained at the committed step catalyzed by dihydroflavonol 4-reductase 1 Leonid Akhov, Paula Ashe, Yifang Tan, Raju Datla, and Gopalan Selvaraj Abstract: The yellow seed characteristic in Brassica napus L. is desirable because of its association with higher oil content and better quality of oil-extracted meal. YN01-429 is a yellow-seeded canola-quality germplasm developed in Canada arising from several years of research. Seed-coat pigmentation is due to oxidized proanthocyanidins (PA; condensed tannins) derived from phenylpropanoids and malonyl CoA. We found PA accumulation to be most robust in young seed coats (20 d post anthesis; dpa) of a related black-seeded line N89-53 and only very little PA in YN01-429, which also contained much less extractable phenolics. The flavonol content, however, did not show as great a difference between these two lines. Furthermore, sinapine, a product of the general phenylpropanoid metabolism, was present at comparable levels in the embryos of both lines. Dihydroflavonol reductase (DFR) activity that commits phenolics to PA synthesis was lower in YN01-429 seed coats. The results of Southern blot and in silico analyses were indicative of two copies of the DFR gene in B. napus. Both copies were functional in YN01-429, ruling out homeoallelic repression or silencing, but together they showed very low expression levels (17-fold fewer transcripts) relative to DFR activity in N89-53 seed coats. These results collectively suggest that YN01-429 differs in regulatory circuits that impact the PA synthesis branch much more than the flavonol synthesis branch in the seed coats and such circuits do not impinge upon general phenylpropanoid metabolism in the embryos.Key words: condensed tannin, dihydroflavonol reductase, flavonoids, oilseed rape, rapeseed, transparent testa. Résumé :Le jaune caractéristique des grains du Brassica napus L. est désirable, compte tenu de son association avec une haute teneur en huile et une meilleure qualité de la farine extraite de l'huile. Le YN01-429 constitue un germplasme à graine jaune de qualité canola résultant de plusieurs années de recherches. La pigmentation des téguments est attribuéeà des proanthocyanidines oxydées (PA; tannins condensés) dérivées de phénylpropanoïdes et du CoA du malonyl. Les auteurs ont trouvé une plus forte accumulation de PA chez les jeunes téguments (20 jours après l'anthèse; dpa) d'une lignée apparentéeà grains noirs N89-53 et très peu de PA chez la lignée YN01-429 qui contient à la fois beaucoup moins de phénols extractibles. Cependant, la teneur en flavonols ne montre pas autant de différences entre ces deux lignées. De plus, la sinapine, un produit du métabolisme géné...

The flowers of flax (linseed) are blue-hued, ephemeral and self-pollinating, and the seeds are typically brown. A century-old interest in natural yellow seed variants and a historical model point to recessive alleles in B1, D and G loci being responsible, but the functional aspects had remained unknown. Here, we characterized the “D” locus by quantitative trait loci (QTL) mapping and identified a FLAVONOID 3′5′ HYDROXYLASE (F3′5′H) gene therein. It does not belong to the F3′5′H clade, but resembles biochemically characterized F3′Hs (flavonoid 3′ hydroxylase) but without F3′H activity. The genome lacks other F3′H or F3′H-like genes. The apparent neo-functionalization from F3′H is associated with a Thr498 → Ser498 substitution in a substrate recognition site (SRS). The yellow seed and white flower phenotypes of the classical d mutation was found to be due to one nucleotide deletion that would truncate the deduced product and remove three of the six potential SRS, negatively impacting delphinidin synthesis. Delphinidin is sporadic in angiosperms, and flax has no known pollination syndrome(s) with functional pollinator group(s) that are attracted to blue flowers, raising questions on the acquisition of F3′5′H. The appearance of d allele is suggestive of the beginning of the loss of F3′5′H in this species.