Genome-Wide Association and Transcriptome Analyses Reveal Candidate Genes Underlying Yield-determining Traits in Brassica napus.

Yield is one of the most important yet complex crop traits. To improve our understanding of the genetic basis of yield establishment, and to identify candidate genes responsible for yield improvement in Brassica napus, we performed genome-wide association studies (GWAS) for seven yield-determining traits [main inflorescence pod number (MIPN), branch pod number (BPN), pod number per plant (PNP), seed number per pod (SPP), thousand seed weight, main inflorescence yield (MIY), and branch yield], using data from 520 diverse B. napus accessions from two different yield environments. In total, we detected 128 significant single nucleotide polymorphisms (SNPs), 93 of which were revealed as novel by integrative analysis. A combination of GWAS and transcriptome sequencing on 21 haplotype blocks from samples pooled by four extremely high-yielding or low-yielding accessions revealed the differential expression of 14 crucial candiate genes (such as Bna.MYB83, Bna.SPL5, and Bna.ROP3) associated with multiple traits or containing multiple SNPs associated with the same trait. Functional annotation and expression pattern analyses further demonstrated that these 14 candiate genes might be important in developmental processes and biomass accumulation, thus affecting the yield establishment of B. napus. These results provide valuable information for understanding the genetic mechanisms underlying the establishment of high yield in B. napus, and lay the foundation for developing high-yielding B. napus varieties.

A combination of genome-wide association and transcriptome analysis reveals candidate genes controlling harvest index-related traits in Brassica napus.

Harvest index (HI), the ratio of seed mass to total biomass of the aboveground plant parts, is an important trait for harvestable yield of crops. Unfortunately, HI of Brassica napus is lower than that of other economically important crops. To identify candidate genes associated with high HI, a genome-wide association study of HI and four HI-related traits was conducted with 520 B. napus accessions cultivated in both Yunnan and Chongqing. We detected 294 single nucleotide polymorphisms significantly associated with the abovementioned traits, including 79 SNPs that affected two or more traits. Differentially expressed genes between extremely high- and low-HI accessions were identified in 8 tissues at two cultivated regions. Combination of linkage disequilibrium and transcriptome analyses revealed 33 functional candidate genes located within the confidence intervals of significant SNPs associated with more than one trait, such as SHOOT GRAVITROPISM 5 (Bna.SGR5), ATP-CITRATE LYASE A-3 (Bna.ACLA-3) and CAROTENOID CLEAVAGE DIOXYGENASE 1 (Bna.CCD1), their orthologs in the Arabidopsis thaliana have been shown to play key roles in photosynthesis, inflorescence, and silique development. Our results provide insight into the molecular mechanisms underlying establishment of high-HI B. napus and lay a foundation for characterization of candidate genes aimed at developing high-HI B. napus varieties.

[Research on the modification of Kevlar fiber by polypropylene glycol and cis-2-butene-1,4-diol].

The mechanism of the modification of Kevlar fiber by polypropylene glycol(PPG) and cis-2-butene-1, 4-diol was studied in the paper, the authors learned the esterification of toluene-2, 4-diisocyanate (TDI) onto Kevlar fiber by infrared spectrum. In the mean time, the infrared spectrograms of the productions which steadily disposed by PPG and butendiol were analysed respectively, the result showed that the intensity of the bands was reinforced at about 1700-1720 cm(-1) after the samples were steadily disposed, that is to say, the group of --NCO has been stabilized into --NHCO group, the effect of steady disposal was obvious; but the disposal effect of butendiol was apparently better than PPG's at the same condition. Finally, the authors compared the influence of different mol rates between TDI and butendiol on the productions. Based onthe consequence, excessive butendiol would prevent the Kevlar fiber from farther reaction, therefore, the mol rate between TDI and butendiol should approach 1:1.

[Preparation and properties of organobentonites].

The chemistry organobentonites were synthesized by means of the ionexchange reaction between single-octadecyl trimethyl ammonium chloride(SOAC), di-octadecyl dimethyl ammonium chloride (DOAC) , tri-octadecyl methylammonium chloride (TOAC) quaternary ammonium salts and sodium base bentonies, respectively. The authors used FTIR, X-ray diffraction diagram and DSC thermograms to characterate the structure of the modified bentonites, and discussed the effect of different quaternary ammonium salt on the properties of organobentonites. The results showed that ion of the surfactants had entered into the chip layer of the bentonites, and changed the hydrophilic environment of the chip layer into hydrophobic environment and increased the distance among the chip layer, all of these had laid a base for the preparation of the nanometer composite material of high polymer/bentonite.

[Study on the modification of short chain phoshate ammonium salt of bentonites].

The Organobentonites were synthesized by means of the ionexchange reaction of Na+ between tetramethylammonium chloride and tetrabutylammonium chloride quaternary ammonium salts, and sodium base bentonites. The authors used FTIR, X-ray diffraction diagram and DSC thermograms to characterize the structure of the modified bentonites, and discussed the effect of different quaternary ammonium salt on the properties of organobentonites. The results showed that ions of the surfactants had entered into the chip layer of the bentonites, changed the hydrophilic environment of the chip layer into a hydrophobic environment, increased the distance among the chip layers, and improved the compatibility between montmorillonite andthe organic phases. All of these have laid a base for the preparation of nanometer composite material of high polymer/bentonite.

[Surface grafting modification and stabilization of Kevlar fiber].

Chemical disposal was used to bring the activity group onto the surface of Kevlar fiber for the purpose of surface grafting modification. The interfacial constitution of the grafting of toluene-2,4-diisocyanate (TDI) onto Kevlar fiber was determined by Fourier transform infrared spectroscopy. In the mean time, hexyl-lactam stabilization and poly-glycol (400, PEG) stabilization on the grafted product were also studied. The effects of different nTDI:nPEG ratios on the production's interfacial constitution was analysed. It is concluded that the stabilization took place on the surface. The intensity of the bands relented at about 3300 cm(-1) and was reinforced at about 1700-1720 cm(-1) when the ratio of nTDI:nPEG = 1:3, but when the ratio is 1:1 and 1:2, the bands at about 3 300 and 1700-1720 cm(-1) are almost the same.

[Research of FTIR and XRD study on the organic modification of bentonites].

Organobentonites were prepared to improve the compatibility between bentonites and organic phase. The change of lamellar structure after organic modification was observed. Na+ -bentonites and octadecylamine were used to exchange the Na+ which is in the layers of bentonites, and the organobentonites were obtained. Both FTIR and DTA-TG proved that octadecylamine entered the layers of bentonites, and XRD showed that the lamellar distance increased from 1.4 nm to 4.3 nm. Based on the experiment, most of the properties of Na+ -bentonites such as the ethylene blue adsorbed by bentonites, cation exchange capacity and the like are better than Ca2+ -bentonites'. The bentonites modified by octadecylamine improved the hydrophobic ability and widened the lamellar distance of bentonites, which contributes to enhancing the whole properties of composites.

[Structural characterization of rare-earth stearate and its thermal stability mechanism for PVC].

Structural characterization of rare-earth stearate was conducted by FTIR and XRD. The results show that the bonds between the stearate and rare-earth metal ions in rare-earth stearate are main ionic character and have the stratified crystalline structure with the crystal layer formed from a plane layer of rare-earth ions combined with two layers of fully extended zigzag chains of stearic acid radicals arranged parallell to each other on its both sides, and the rare-earth ions axes are inclined to the crystal layer planes in it. Congo red test showed that the stabilizing time increased when the stabilizers' concentration increased. The order of stability of this four rare-earth stearates is Last>Ndst>Yst>Dyst. Furthermore, the thermal stability mechanism of rare earth stearate for PVC has been presumed by FTIR. The results indicate that Last and Ndst can bate the chain reaction and exchange the labile functional groups in the backbone chains for other more stable substituents derived from the stabilizer and change the framework, while Yst and Dyst's effect is not clear.

[The research on the surfacial modification of organic high-performance Kevlar fiber].

In the paper the authors tried to use chemical disposal to bring the activity mass onto the surface of Kevlar fiber with the purpose of surface graft modification. In the paper the authors used the FTIR spectra to discuss the graft of toluene-2, 4-diisocyanate onto Kevlar fiber. The authors studied and analysed the effect of hydrolytic time on the content of -O-H group of the production, and the effect of hydrolyzation and hexyl-lactam steadily disposing on the graft reaction. The result showed that the content of -O-H group increased after hydrolyzation, it's helpful for the graft reaction, and hexyl-lactam steadily disposing made the graf product more stable. Through the research the authors came to the conclusion that by bringing some activity masses onto the fiber surface the authors can improve the interface of fiber/resin effectively.