Photosynthetic features of leaf and silique of 'Qinyou 7' oilseed rape(Brassica napus L.) at reproductive growth stage

Photosynthetic products are mainly produced by leaf and green silique of oil-seed rape （Brassica napus L.） at reproductive growth stage. This study aimed to compare photosynthetic features of leaf and green silique of ‘Qinyou 7’ hybrid oilseed rape variety. Results showed that, during photosynthetic day time, net photosynthetic rate （PN） and sto-matal conductance （gs） of leaf were markedly higher than that of silique. Compared with silique, leaf had signifcant higher PN, gs, light saturated net photosynthetic rate （PNmax）, light saturation point （LSP）, and apparent quantum yield （AQY）, but lower light compensa-tion point （LCP）, CO2 compensation point （Γ） and carboxylation effciency （CE） under var-ious light densities and CO2 concentrations. Carboxylation activities of ribulose-1, 5-bis-phosphate carboxylase/oxygenase （Rubisco）, phosphoenolpyruvate carboxylase （PEPC） and chlorophyll a, b （Chl a, b） of leaf were signifcantly higher than that of silique shell. Our study demonstrated that leaf of oilseed rape at reproductive growth stage had higher photosynthetic capacity than green silique due to its higher carboxylation activity of pho-tosynthetic enzymes as well as higher gs and Chl contents. This study might have good implication in selecting a biological control strategy to enhance seed yield and oil produc-tion of oilseed rape.

Analysis of yield and quality characteristics of winter oilseed rape in China from 2001 to 2015: towards future breeding goals

The exciting outcomes of national regional trials have led to production and industrialization of China oilseed rape to a larger extent. To understand current trends of yield and quality traits of new varieties, data of national winter oilseed rape trials from 2001 to 2015 in 4 districts （upper, middle, lower Yangtze River and Huang-Huai River） was comprehensively analyzed. Results showed that average yield of new varieties of winter oilseed rape increased during the study period. In 2013, average yield of each district reached its highest level. Number of pod per plant reached its peak in 2011 and then declined rapidly in the next 4 years. Average number of seeds per pod did not signif-cantly changed in any districts. Moreover, 1,000 seeds weight increased most obviously in Huang-Huai River district. After 2007, new oilseed rape varieties encountered the dou-ble-low quality （i.e., low erucic acid and low glucosinolate）. In addition, oil content of new oilseed rape varieties increased over 15 years period and average oil content of all tested varieties during 2006-2015 was 42.96%, which was 2.38% higher than in 2005. Future breeding goals should be set to further improve yield, oil content, oil quality （such as high oleic acid and low saturated fatty acids）, achieve full mechanization of oilseed rape pro-duction process and develop ideotypes.

LC-MS based secondary metabolic profile of BraLTP2 overexpressing Brassica napus

BraLTP2 is an important member of lipid transfer protein family, and its molecular biology function in Brassica napus （B. napus） had been explored by prerious study. How-ever, affection of BraLTP2 on secondary metabolites is still not clear. In this study, we inves-tigated difference of leaf secondary metabolite profling between BraLTP2 overexpressing B. napus and wild type. Liquid chromatography tandem mass spectrometry （LC-MS） was utilized. Wide range of secondary metabolites was found in BraLTP2 overexpressing plants. A total of 100 secondary metabolites were determined, 42 of which had signifcant differ-ences, including favonoids, phenylpropanoids and phenolamides. These results were in accordance with signifcant increasing trichomes of overexpressing BraLTP2 plants, which might produce and store secondary metabolites. Partial least squares discriminant anal-ysis （PLS-DA） was performed to identify difference of secondary metabolites. PLS-DA score plots showed high reproducibility of each treatment. Signifcant changes were found between transformed and wild type. Permutation test validates the reliability rigorously. Fur-thermore, overexpressing of BraLTP2 led to seed germination improvement during the frst 48 h under oxidation stress. Increased oxidation resistance of transgenic B. napus was in accordance with the signifcant variations of phenylpropanoids, phenylpropanoids and phe-nolamides.This work was supported by Central Public-interest Scientifc Institution Basal Research Fund, Major Research Project of CAAS Science and National Genetically Modifed Organisms Breeding Major Projects China （2018ZX0801023B）.