Targeted mutations of BnPAP2 lead to a yellow seed coat in Brassica napus L.

The yellow seed trait is preferred by breeders for its potential to improve the seed quality and commercial value of Brassica napus.In the present study,we produced yellow seed mutants using a CRISPR/Cas9 system when the two BnPAP2 homologs were knocked out.Histochemical staining of the seed coat demonstrated that proanthocyanidin accumulation was significantly reduced in the pap2 double mutants and decreased specifically in the endothelial and palisade layer cells of the seed coat.Transcriptomic and metabolite profiling analysis suggested that disruption of the BnPAP2 genes could reduce the expression of structural and regulated genes in the phenylpropanoid and flavonoid biosynthetic pathways.The broad suppression of these genes might hinder proanthocyanidin accumulation during seed development,and thereby causing the yellow seed trait in B.napus.These results indicate that BnPAP2 might play a vital role in the regulatory network controlling proanthocyanidin accumulation.

Transcriptional proffling between yellow-and black-seeded Brassica napus reveals molecular modulations on flavonoid and fatty acid content

Brassica napus is an important cash crop broadly grown for the vegetable and oil values.Yellow-seeded B.napus is preferred by breeders due to its improved oil and protein quality,less pigments and lignin compared with the blackseeded counterpart.This study compared the differences in flavonoid and fatty acid contents between yellow rapeseed from the progenies of B.napus-Sinapis alba somatic hybrids and the black-seeded counterpart using RNA-seq analysis.Through HPLC-PDA-ESI(-)/MSanalysis,it was found that phenylpropanoids and flavonoids(i.e.,isorhamnetin,epicatechin,kaempferol,and other derivatives)in yellow seed were significantly lower than those in black seed.The fatty acid(FA)content in yellow rapeseed was higher than that in black rapeseed due to the variation of C16:0,C18:0,C18:1,C18:2,and C18:3 contents.RNA-seq analysis of seeds at four and five weeks after flowering(WAF)indicated that differentially expressed genes(DEGs)between black and yellow rapeseeds were enriched in flavonoid and FA biosynthesis,including BnTT3,BnTT4,BnTT18,and BnFAD2.Also,genes related to FA biosynthesis,desaturation and elongation(FAD3,LEC1,FUS3,and LPAT2)in yellow seed were up-regulated compared to those in black seed,while genes involved in beta-oxidation cycle(AIM1 and KAT2)of yellow seed were down-regulated compared to those in black seed.The DEGs related to the variation of flavonoids,phenylpropanoids,and FAs would help improve the knowledge of yellow seed character in B.napus and promote rapeseed improvement.

Phenolic Composition Analysis and Gene Expression in Developing Seeds of Yellow-and Black-seeded Brassica napus

Breeders have focused on yellow-seeded Brassica napus （rapeseed） for its better quality com- pared with the black-seeded variety. Moreover, flavonoids have been associated with this kind of rapeseed. In this study, we applied lipid chromatography-electrospray ionization mass spec- trometry （LC-ESI-MSn ） to compare flavonoids in developing seeds of natural black-seeded B. na- pus and yellow-seeded introgression lines selected from progenies of B. napus–Sinapis alba so- matic hybrids. Aside from the most abundant phenolic compounds （sinapine and sinapic acid） and 1, 2-disinapoylglucose, 16 different flavonoids were identified and quantified, including （-）- epicatechin, five monocharged oligomers of （-）-epicatechin （[DP 2]- , [DP 3]- , [DP 4] [DP 2]- B2 and [DP 2]- B5）, quercetin, kaempferol, isorhamnetin-dihexoside, kaempferol-sinapoyl-trihexoside, isorhamnetin- sinapoyl-trihexoside, isorhamnetin-hexoside-sulfate, and isorhamnetin-3-O-glucoside. Most of the flavonoids accumulated with seed development, whereas some rapidly decreased during maturation. The content of these flavonoids was lower in the yellow-seeded materials than in the black seeds. In addition, variations of insoluble procyanidin oligomers and soluble phenolic acids were observed among both rapeseed varieties. Transcriptome changes of genes participating in the flavonoid pathway were discovered by quantitative reverse transcription polymerase chain reaction analysis. Consistent with flavonoid changes identified by high performance liquid chromatography analysis, the expression of most genes in the flavonoid biosynthetic pathway was also downregulated.

Effects of derived meals from juncea(Brassica juncea),yellow and black seeded canola(Brassica napus)and multicarbohydrase enzymes supplementation on apparent metabolizable energy in broiler chickens

Two experiments were conducted to determine the nitrogen-corrected apparent metabolizable energy(AMEn) of differently processed meals from Juncea(Brassica juncea), yellow and black seeded canola(Brassica napus), with or without supplementation of multi-carbohydrase enzymes(Enz) in diets for broiler chickens. The first experiment was a 3×2×2 factorial arrangement with the main factors being seed type(yellow [Yellow] or black [B1] canola seeds and Juncea seeds), processed at two temperatures(high temperature desolventized-toasted [HTDT] at 95℃ or low temperature desolventized-toasted[LTDT] at 57℃), with or without Enz. In Exp. 1, a total of 384 one-day-old male broiler chicks were randomly assigned to 64 battery cages, with 6 birds/cage. The second experiment was a 2×2×2 factorial arrangement with the main factors being seed type(Yellow or black [B2]), seed source(Scott,Saskatchewan or Truro, Nova Scotia) and Enz(with or without) supplementation. A total of 264 one-dayold male broiler chicks were randomly assigned to 44 battery cages, with 6 birds per cage. In Exp, 1 and 2,all birds were fed a common starter diet from 1 to 14 days of age. From d 15 to 21, the birds were fed one of the test treatments, a basal grower diet or the basal grower diet replaced with 30% test ingredient with celite(0.8%) added as an inert marker. Excreta was collected on d 20 and 21. In Exp. 1, there were no interactions(P > 0.05) among seed type, processing temperature and Enz. Processing temperature and dietary Enz did not affect(P > 0.05) AMEn of different canola meals. The AMEn of prepress solvent extracted canola and juncea meals(PSEM) from Yellow(11.2 MJ/kg) was higher(P < 0.05) than B1(10.2 MJ/kg) and Juncea(10.2 MJ/kg). In Exp. 2, there were no interactions(P > 0.05) among seed color,location and Enz. Supplementation of dietary Enz did not affect(P > 0.05) AMEn of different cold press canola meals. The AMEn of cold press canola meals(CPM) from Yellow(14.7 MJ/kg) was higher(P < 0.05)compared with B2(12.2 MJ/kg). In conclusion, among the different processing methods of oil extraction,meals derived from yellow seeded canola had higher AMEn than B seeded canola and Juncea.