Allelic Diversification of the Wx and ALK Loci in Indica Restorer Lines and Their Utilisation in Hybrid Rice Breeding in China over the Last 50 Years.

Hybrid rice technology has been used for more than 50 years, and eating and cooking quality (ECQ) has been a major focus throughout this period. Waxy (Wx) and alkaline denaturation (ALK) genes have received attention owing to their pivotal roles in determining rice characteristics. However, despite significant effort, the ECQ of restorer lines (RLs) has changed very little. By contrast, obvious changes have been seen in inbred rice varieties (IRVs), and the ECQ of IRVs is influenced by Wx, which reduces the proportion of Wxa and increases the proportion of Wxb, leading to a decrease in amylose content (AC) and an increase in ECQ. Meanwhile, ALK is not selected in the same way. We investigated Wx alleles and AC values of sterile lines of female parents with the main mating combinations in widely used areas. The results show that almost all sterile lines were Wxa-type with a high AC, which may explain the low ECQ of hybrid rice. Analysis of hybrid rice varieties and RLs in the last 5 years revealed serious homogenisation among hybrid rice varieties.

3,4-Dimeth-oxy-4'-nitro-1,1'-biphen-yl.

The title compound, C(14)H(13)NO(4), was prepared through a palladium-catalysed Suzuki-Miyaura coupling reaction. The asymmetric unit comprises two mol-ecules related by pseudo-inversion symmetry. The dihedral angles between the benzene rings in the two mol-ecules are 44.30 (6) and 48.50 (6)° while those between the benzene ring and the nitro group are 6.54 (13) and 5.73 (10)°. The crystal packing is defined only by Van der Waals inter-actions.

3',4'-Dimeth-oxy-biphenyl-4-carbonitrile.

The title compound, C(15)H(13)NO(2), was prepared through a palladium-catalysed Suzuki-Miyaura coupling reaction. The dihedral angle between the biphenyl rings is 40.96 (6)°. The meth-oxy groups are twisted slightly out of the plane of the benzene ring [C-C-C-C torsion angles = -3.61 (18) and 12.6 (2)°]. The packing of the molecules is stabilized by van der Waals inter-actions.

2,9,10-Trimeth-oxy-dibenzo[b,d]oxepin-7(6H)-one.

The title compound, C(17)H(16)O(5), was prepared through a cyclization reaction of 2-(3',4',5-trimeth-oxy-biphenyl-2-yl-oxy)acetyl chloride. The two benzene rings form a dihedral angle of 34.55 (5)°. The crystal structure does not feature any hydrogen bonds.

3a,11b-Dihy-droxy-3a,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline-2(3H)-thione.

The title compound, C(13)H(10)N(4)O(2)S, was prepared through a cyclization reaction of 1,10-phenanthroline-5,6-dione and thio-urea. The dihedral angle between the pyridine rings is 8.22 (2)°. In the crystal, mol-ecules are connected by N-H⋯O, O-H⋯N, N-H⋯S and O-H⋯S hydrogen bonds, forming a three-dimensional network.

Development and high-throughput genotyping of substitution lines carring the chromosome segments of indica 9311 in the background of japonica Nipponbare.

Chromosome segment substitution lines (CSSLs) are useful for the precise mapping of quantitative trait loci (QTLs) and dissection of the genetic basis of complex traits. In this study, two whole-genome sequenced rice cultivars, the japonica Nipponbare and indica 9311 were used as recipient and donor, respectively. A population with 57 CSSLs was developed after crossing and back-crossing assisted by molecular markers, and genotypes were identified using a high-throughput resequencing strategy. Detailed graphical genotypes of 38 lines were constructed based on resequencing data. These CSSLs had a total of 95 substituted segments derived from indica 9311, with an average of about 2.5 segments per CSSL and eight segments per chromosome, and covered about 87.4% of the rice whole genome. A multiple linear regression QTL analysis mapped four QTLs for 1000-grain weight. The largest-effect QTL was located in a region on chromosome 5 that contained a cloned major QTL GW5/qSW5 for grain size in rice. These CSSLs with a background of Nipponbare may provide powerful tools for future whole-genome discovery and functional study of essential genes/QTLs in rice, and offer ideal materials and foundations for japonica breeding.

A major locus qS12, located in a duplicated segment of chromosome 12, causes spikelet sterility in an indica-japonica rice hybrid.

Chromosome segment duplications are integral in genome evolution by providing a source for the origin of new genes. In the rice genome, besides an ancient polyploidy event known in the rice common ancestor, it had been identified that there was a special segmental duplication involving chromosomes 11 and 12, but the biological role of this duplication remains unknown. In this study, by using a set of chromosome segment substitution lines (CSSLs) and near isogenic lines (NILs) derived from the indica cultivar 9311 and japonica cultivar Nipponbare, a major QTL (qS12) resulting in hybrid male sterility was mapped within ~400 kb region adjacent to the special duplicated segment on the short arm of chromosome 12. Compared to the japonica cultivar Nipponbare, the two sides of the qS12 candidate region were inverted in the indica cultivar 9311. Among 47 of the 111 rice genotypes evaluated by molecular markers, the inverted sides were detected, and found completely homologous to indica cultivar 9311. These results suggested that the two inverted sides protect the sequence in the qS12 regions from recombination. On the short-arm of chromosome 12, two QTLs S-e and S25, in addition to qS12, were previously detected as a distinct segregation distortion and pollen semi-sterility loci. We propose these three hybrid sterility loci are the same locus, and the duplicated segment on chromosome 12 may play a prominent role in diversification, i.e., sub-speciation of cultivated rice.

4-Meth-oxy-2-nitro-4'-(trifluoro-meth-yl)biphen-yl.

The title compound, C(14)H(10)F(3)NO(3), was prepared by a palladium-catalysed Suzuki-Miyaura coupling reaction. The dihedral angle between the nitro group and its parent benzene ring is 66.85 (19)° while the dihedral angle between the two benzene rings is 49.98 (9)°. The CF(3) group is disordered over two sets of sites with occupancies of 0.457 (8) and 0.543 (8).

Ethyl N-[3-(N,N-dimethyl-carbamo-yl)pyridin-2-ylsulfon-yl]carbamate.

In the mol-ecular structure of the title compound, C(11)H(15)N(3)O(5)S, the amide group is nearly perpendicular to the pyridine ring, making a dihedral angle of 86.30 (13)°. The terminal ethyl group is disordered over two sites of equal occupancy. Inter-molecular N-H⋯O hydrogen bonding is present in the crystal structure.

Methyl 4-methyl-sulfonyl-2-nitro-benzoate.

The title compound, C(9)H(9)NO(6)S, was prepared by the reaction of methanol and thionyl chloride with 4-methyl-sulfonyl-2-nitro-benzoic acid under mild conditions. The dihedral angle between the nitro group and benzene ring is 21.33 (19)° and that between the carboxyl-ate group and the benzene ring is 72.09 (17)°. The crystal structure is stabilized by weak inter-molecular bifurcated C-H⋯O inter-actions occurring in the (100) plane.

Preliminary kinetic study on the degradation of nitrobenzene by modified ceramic honeycomb-catalytic ozonation in aqueous solution.

The kinetics of degradation of nitrobenzene in aqueous solution was investigated in the processes of ozone alone, ozone/ceramic honeycomb (CH), ozone/modified ceramic honeycomb (MCH). The results indicated that all reactions followed the pseudo-first-order kinetic model, and the degradation rate of nitrobenzene was accelerated in the presence of CH or MCH catalyst, and the more pronounced degradation rate was achieved in O(3)/MCH system. Under the experimental conditions of reaction temperature 293 K and initial pH 6.87, the rate constants were determined to be 5.21 x 10(-2)min(-1) for O(3) alone, 7.99 x 10(-2)min(-1) for O(3)/CH and 15.45 x 10(-2)min(-1) for O(3)/MCH. The influencing factors, such as applied ozone concentration (0.987-2.732 mg L(-1)), initial concentration of nitrobenzene (50-250 microg L(-1)) and amount of catalyst (0-5 blocks) could yield respectively the positive effect on the pseudo-first-order rate constants for degradation of nitrobenzene in the three processes mentioned above. The results suggested that the modification process promoted the catalytic activity of raw CH catalyst, namely the impregnation of metals (Mn, Cu and K) maybe enhance the initiation of hydroxyl radical (OH).

Poly[[[diaqua-cobalt(II)]-bis-[µ(2)-1,1'-(butane-1,4-di-yl)diimidazole-κN:N]] dinitrate].

In the title compound, {[Co(C(10)H(14)N(4))(2)(H(2)O)(2)](NO(3))(2)}(n), the Co(II) ion lies on an inversion center and is six-coordinated in an octa-hedral environment by four N atoms from four different 1,1'-butane-1,4-diyldiimidazole ligands and two O atoms from the two water mol-ecules. The Co(II) atoms are bridged by ligands, generating a two-dimensional (4,4)-network. Adjacent fishnet planes are linked to the nitrate anions via O-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular structure.

Poly[[[diaqua-cobalt(II)]-bis-[µ-1,1'-(butane-1,4-di-yl)diimidazole-κN:N]] dichloride tetra-hydrate].

In the title compound, {[Co(C(10)H(14)N(4))(2)(H(2)O)(2)]Cl(2)·4H(2)O}(n), the Co(II) atom and the mid-point of the 1,1'-butane-1,4-diyl-diimidazole ligands lie on inversion centers. The Co(II) atom is six-coordinated in a slightly distorted octa-hedral environment by four N atoms from four different ligands and by two O atoms from the water mol-ecules. The Co(II) atoms are bridged by the ligands into a (4,4) net. Adjacent nets are linked to the chloride anions and uncoordinated water mol-ecules via O-H⋯Cl and O-H⋯O hydrogen bonds, generating a three-dimensional supra-molecular structure.

[Effect of organic compounds on the degradation of nitrobenzene in aqueous solution by catalytic ozonation].

We investigated the effects of organic compounds on the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation for the degradation of nitrobenzene in aqueous solution, including formaldehyde, methanol, formic acid and dibutyl phthalate. The results indicated that degradation rate of ozonation alone and ceramic honeycomb-catalyzed ozonation decreased by 11.6% and 9.6% with the increase of the concentration of formaldehyde (0-12 mg x L(-1)). The degradation rates of the two processes both increased firstly and decreased subsequently with the increase of the concentration of methanol (0-16 mg x L(-1)). The degradation rate of ozonation alone reached the climax at the concentration of methanol 2 mg x L(-1), and that of ceramic honeycomb-catalyzed ozonation reached the culmination at the concentration of methanol 4 mg x L(-1) under the same experimental condition. With the increase of the concentration of formic acid (0-8 mg x L(-1)), the degradation rates also increased firstly and decreased subsequently, and those of ozonation alone and ceramic honeycomb-catalyzed ozonation reached the vertex, respectively, at the concentration of methanol 0.5 mg x L(-1) and 2 mg x L(-1). At the lower concentration, methanol and formic acid could accelerate the degradation of nitrobenzene, however, the reaction was retarded at higher concentrations of methanol and formic acid. The degradation rates of ozonation alone and ozonation/ceramic honeycomb both declined by 19.7% and 18.6% with the increase of the concentration of dibutyl phthalate (0-10 mg x L(-1)).

[Study on mechanism of ceramic honeycomb-catalytic ozonation for the decomposition of trace nitrobenzene in aqueous solution].

The experiment investigated effects of the presence of hydroxyl radical inhibitor on degradation efficiency of trace nitrobenzene in aqueous solution in the processes of ozonation alone and ceramic honeycomb-catalyzed ozonation, including HCO3-, CO3(2-), HPO4(2-), H2PO4- and tert-butanol, and studied preliminarily on their mechanism. The results indicated that degradation rate of the two processes both increased firstly and decreased subsequently with the increase of the concentration of HCO3- (0 - 200 mg x L(-1)), and reached the climax at the concentration of bicarbonate ion 50 mg x L(-1) under the same experimental condition. The degradation rates of ozonation alone and ozonation/ ceramic honeycomb both declined by 16.57% and 27.52% with the increase of the concentration of CO3(2-) (0 - 20 mg x L(-1)), respectively, and decreased by 13.61% and 17.52% with the addition of the concentration of HPO4(2-) (0 - 12 mg x L(-1)), and reduced by 6.61% and 12.52% with the enhancement of the concentration of H2PO4- (0 - 120 mg x L(-1)), and dropped by 30.06% and 46.09% with the increasing of the concentration of tert-butanol (0 - 10 mg x L(-1)). The experimental results indicated that decomposition of nitrobenzene in both processes all followed the mechanism of oxidization by OH free radical, and tert-butanol is a more suitable indicator for the radical type reaction. The removal rate of ozonation alone rose with the increase of the concentration of pH (3.02 - 10.96), but that of ozonation/ceramic honeycomb process reached the maximum at pH = 9.23.

[Catalytic ozonation by ceramic honeycomb for the degradation of oxalic acid in aqueous solution].

Comparative experiments for the degradation of oxalic acid in aqueous solution were carried out in the three processes of ozonation alone, ceramic honeycomb-catalyzed ozonation and ceramic honeycomb adsorption. The results show that the degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation, ozonation alone and ceramic honeycomb adsorption systems are 37.6%, 2.2% and 0.4%, and the presence of ceramic honeycomb catalyst significantly improves the degradation rate of oxalic acid compared to the results from non-catalytic ozonation and adsorption. With the addition of tert-butanol, the degradation rates of oxalic acid in catalytic ozonation system decrease by 24.1%, 29.0% and 30.1%, respectively, at the concentration of 5, 10 and 15 mg x L(-1). This phenomenon indicates that ceramic honeycomb-catalyzed ozonation for the degradation of oxalic acid in aqueous solution follows the mechanism of *OH oxidation, namely the heterogeneous surface of catalyst enhances the initiation of *OH. The results of TOC analysis demonstrate that the process of ceramic honeycomb-catalyzed ozonation can achieve the complete mineralization level without the formation of intermediary degradation products. The experimental results suggest that the reaction temperature has positive relationship with the degradation rate of oxalic acid. The degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation system are 16.4%, 37.6%, 61.3% and 68.2%, at the respective reaction temperature of 10, 20, 30 and 40 degrees C.

[Effect of inorganic ions on degradation of trace nitrobenzene in aqueous solution by catalytic ozonation].

The experiment investigated the effects of general inorganic ions in natural source water on the three processes of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation for degradation of trace nitrobenzene in aqueous solution. The removal rate of ozonation alone and modified ceramic honeycomb-catalyzed ozonation increased by 5.0% and 8.6% with the increase of the concentration of calcium ion (0-4 mg x L(-1)), and that of ceramic honeycomb-catalyzed ozonation reached the climax at the concentration of calcium ion 0.5 mg x L(-1) under the same experimental condition. The degradation efficiency of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation enhanced by 10.9%, 11.6% and 9.6% with the increase of the concentration of manganese ion (0-4 mg x L(-1)), respectively, and decreased by 8.6%, 11.5% and 8.9% with the increase of the concentration of bicarbonate ion (0-200 mg x L(-1)). The concentration of nitrate and sulfate ion had no remarkable effect on ozonation alone, but the removal rate of other two processes decreased with the increase of the concentration of nitrate and sulfate ion.

[Effect of background constituents on the degradation of trace nitrobenzene in aqueous solution by catalytic ozonation].

Effect of background constituents on the catalytic ozonation of nitrobenzene was investigated. Degradation rates of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation in tap water increased by 4.90%, 2.47% and 5.12% than those in distilled water respectively. The removal rate of ozonation alone increased by 6.25% with the increase of the concentration of magnesium ion (0 to approximately 8 x mg x L(-1)), but those of other two processes decreased by 11.41% and 17.64%, respectively, under the same experimental condition. Degradation efficiency of ozonation alone, ceramic honeycomb and modified ceramic honeycomb-catalyzed ozonation decreased by 4.42%, 9.38% and 12.24%, respectively, with the increase of the concentration of chloride ion (0 to approximately 40 mg x L(-1)). At the lower concentration, humic acid could accelerate the degradation of nitrobenzene, however, the reaction was retarded at higher concentrations of humic acid. The experiment also studied the influences of the applied ozone and initial concentration of nitrobenzene.

Degradation of benzophenone in aqueous solution by Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation.

Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance (EPR) experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.

Degradation of nitrobenzene in aqueous solution by ozone-ceramic honeycomb.

The degradation of nitrobenzene by ceramic-honeycomb catalyzed ozonation was investigated. The results showed that the presence of ceramic honeycombs significantly increased the oxidation rate of nitrobenzene by ozone compared to the case of ozone oxidation alone. In this paper, the effects of various factors on the catalytic oxidation were investigated, such as the amount of catalysts, the ozone dosage, the temperature, the pH value and the presence of tert-butanol. With the addition of tert-butanol the removal of nitrobenzene decreased sharply, which appeared to support that, the degradation of nitrobenzene by ozonation followed a radical type mechanism. The EPR experiments verified that higher nitrobenzene removal rate was attributed to more OH* radicals generated in the catalyzed ozonation than ozonation alone.