Photoinduced synthesis of 2-sulfonylacetonitriles with the insertion of sulfur dioxide under ultraviolet irradiation.

Metal-free insertion of sulfur dioxide with aryl iodides and 3-azido-2-methylbut-3-en-2-ol under ultraviolet irradiation at room temperature is achieved, giving rise to 2-(arylsulfonyl)acetonitriles in moderate to good yields. Alkyl iodide is also workable under these conditions. This transformation proceeds smoothly under mild conditions with a broad substrate scope. Various functional groups are compatible including amino, ester, halo, and trifluoromethyl groups. No metal catalyst or additive is needed during the reaction process. Mechanistic studies show that under ultraviolet irradiation, an aryl radical is generated in situ from aryl iodide, which undergoes subsequent sulfonylation via the insertion of sulfur dioxide leading to arylsulfonyl radical intermediates. Then the arylsulfonyl radical reacts with 3-azido-2-methylbut-3-en-2-ol giving rise to the corresponding 2-(arylsulfonyl)acetonitrile.

Copper(II)-Catalyzed Reaction of 2,3-Allenoic Acids, Sulfur Dioxide, and Aryldiazonium Tetrafluoroborates: Route to 4-Sulfonylated Furan-2(5 H)-ones.

A copper(II)-catalyzed three-component reaction of 2,3-allenoic acids, sulfur dioxide, and aryldiazonium tetrafluoroborates under mild conditions is developed, leading to 4-sulfonylated furan-2(5 H)-ones in good yields. Not only sodium metabisulfite but also 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide (DABCO·(SO2)2) is workable under the conditions. This transformation proceeds through a radical process initiated by the addition of arylsulfonyl radical to the C-central position of 2,3-allenoic acid. A broad substrate scope is demonstrated, and many sensitive functional groups are tolerated.

Recent advances in the sulfonylation of C-H bonds with the insertion of sulfur dioxide.

Recent advances in the sulfonylation of C-H bonds with the insertion of sulfur dioxide are summarized. Usually, a sulfur dioxide surrogate, DABCO·(SO2)2, is used, which avoids the utilization of gaseous sulfur dioxide in the transformation. Inorganic sulfites such as sodium metabisulfite are also effective in C(sp3)-H bond sulfonylation. C-H bond sulfonylation under transition metal catalysis or through a radical process has been developed. In some cases, the sulfonylation can be performed under catalyst- and additive-free conditions, or can be facilitated by visible light irradiation. The efficiency is also investigated by merging the radical process and metal catalysis.

C-H bond sulfonylation of anilines with the insertion of sulfur dioxide under metal-free conditions.

C-H bond sulfonylation of anilines with the insertion of sulfur dioxide under metal-free conditions is described. 2-Sulfonylanilines are generated in moderate to good yields through a three-component reaction of anilines, DABCO·(SO2)2, and aryldiazonium tetrafluoroborates under mild conditions. No metal catalysts or additives are needed for this transformation. This direct C-H functionalization is highly efficient, and broad functional group tolerance is observed. A radical process is believed to be involved. In the reaction process, the arylsulfonyl radical and the tertiary amine radical cation generated in situ from DABCO·(SO2)2, and aryldiazonium tetrafluoroborate are the key intermediates. Additionally, the tertiary amine radical cation acts as the electron carrier through a single electron transfer process.

A new approach for obtaining rapid uniformity in rice (Oryza sativa L.) via a 3x x 2x cross.

A triploid (2n = 3x = 36) rice plant was obtained by screening a twin seedling population in which each seed germinated to two or three sprouts that were then crossed with diploid plants. One diploid plant was chosen among the various F(1) progenies and developed into an F (2) population via self-pollination. Compared with the control variety Shanyou 63, this F (2) population had a stable agronomical performance in field trials, as confirmed by the F-test. The stability of the F (2) population was further substantiated by molecular analysis with simple sequence repeat markers. Specifically, of 160 markers assayed, 37 (covering all 12 chromosomes) were polymorphic between the parental lines. Testing the F (1) hybrid individually with these markers showed that each PCR product had only a single band instead of two bands from each parent. The bands were identical to either maternal (23 markers) or paternal (eight markers) bands or distinct from both parents (six markers). The amplified bands of all 60 randomly selected F (2) plants were uniform and identical to those of the F (1) hybrid. These results suggest that the F (1) plant is a non-segregating hybrid and that a stable F (2) population was obtained. This novel system provides an efficient means for shortening the cycle of hybrid rice seed production.

A new approach for obtaining rapid uniformity in rice (Oryza sativa L. ) via a 3x x 2x cross

A triploid (2n = 3x = 36) rice plant was obtained by screening a twin seedling population in which each seed germinated to two or three sprouts that were then crossed with diploid plants. One diploid plant was chosen among the various F1 progenies and developed into an F2 population via self-pollination. Compared with the control variety Shanyou 63, this F2 population had a stable agronomical performance in field trials, as confirmed by the F-test. The stability of the F2 population was further substantiated by molecular analysis with simple sequence repeat markers. Specifically, of 160 markers assayed, 37 (covering all 12 chromosomes) were polymorphic between the parental lines. Testing the F1 hybrid individually with these markers showed that each PCR product had only a single band instead of two bands from each parent. The bands were identical to either maternal (23 markers) or paternal (eight markers) bands or distinct from both parents (six markers). The amplified bands of all 60 randomly selected F2 plants were uniform and identical to those of the F1 hybrid. These results suggest that the F1 plant is a non-segregating hybrid and that a stable F2 population was obtained. This novel system provides an efficient means for shortening the cycle of hybrid rice seed production.

Identification and fine mapping of a mutant gene for palealess spikelet in rice.

In grass, the evolutionary relationship between lemma and palea, and their relationship to the flower organs in dicots have been variously interpreted and wildely debated. In the present study, we carried out morphological and genetic analysis of a palealess mutant (pal) from rice (Oryza sativa L.), and fine mapping the gene responsible for the mutated trait. Together, our findings indicate that the palea is replaced by two leaf-like structures in the pal flowers, and this trait is controlled by one recessive gene, termed palealess1 (pal1). With a large F2 segregating population, the pal1 gene was finally mapped into a physical region of 35 kb. Our results also suggest that the lemma and palea of rice are not homologous organs, palea is likely evolutionarily equivalent to the eudicot sepal, and the pal1 should be an A function gene for rice floral organ identity.

[Marker-assisted selection and pyramiding for three blast resistance genes, Pi-d(t)1, Pi-b, Pi-ta2, in rice].

G46B is a promising holding line used for three-lines breeding strategy in hybrid rice, but it is susceptible to blast disease caused by Pyricularia grisea. To improve its blast resistance, three rice varieties, Digu, BL-1, and Pi-4, with blast resistance genes, Pi-d(t), Pi-b, and Pi-ta2, respectively, were used to be crossed with G46B, and 15 plants with these three blast resistance genes, Pi-d(t)1, Pi-b, and Pi-ta2, were selected from their F2 and B1C1 populations via a marker-aided crossing procedure. Among them, four plants were heterozygotes in the three resistance genes, with the genotype of Pi-d(t)1 pi-d(t)/Pi-b pi-b/ Pi-ta2 pi-ta2; ten plants were heterozygotes in two of the three resistance genes, of which six with the genotype of Pi-d(t)1 Pi-d(t)1/Pi-b pi-b/Pi-ta2 pi-ta2, three with the genotype of Pi-d(t)1 pi-d(t)1/Pi-b pi-b/Pi-ta2 Pi-ta2, and one with the genotype of Pi-d(t)1pi-d(t)1/Pi-b Pi-b/Pi-ta2 pi-ta2; and only one plant was homozygote in two of the three resistance genes with the genotype of Pi-d(t)1 Pi-d(t)/Pi-b pi-b/Pi-ta2 Pi-ta2. These results demonstrate the capacity of maker-assisted selection (MAS) in gene pyramiding for rice blast resistance and its enhancement for the efficiency in rice resistance breeding.

[Anther culture generated stem borer-resistance DH lines of Minghui 81(Oryza sativa L. subsp. indica) expressing modified cry1Ac gene].

2600 Anthers from T0 modified cry1 Ac-transgenic rice lines of Minghui 81, an elite restoring line of commercial CMS indica hybrid rice, were cultured on SK3 media. 83 green plantlets were recovered, 43 double haploid (DH) and 40 haploid among them. Results of PCR analyzes indicated that 55 plants of 83 were harbored the cry1Ac gene, and the ratio of cry1Ac-positive against cry1Ac-negative was 2:1 (55/28). 36 putative transgenic DH plants were further confirmed by Southern blot. ELISA detection showed that Cry1Ac level in different transgenic rice plants of the same cry1Ac-DH clone was almost equal and the highest one amount to 0.25% of the total soluble protein. Pest insect-resistant bioassay at field trials demonstrated that some of the homozygous cry1Ac-transgenic rice plants not only showed high-level resistance against striped stem borer (Chilo suppressalis) but also retained elite agronomy characters. These results demonstrated that rice anther culture has a great value in rice molecular breeding.

[Genetic analysis and molecular tagging of a gene for non-palea in rice].

The mutants involved in the development of floral organ are good material for understanding the molecular genetic mechanisms of floral development. A rice mutant, that lacks palea in its florets, was derived from a spontaneous mutation in an indica line, SAR III-93-369. Genetic analyses in three F2 populations from the mutant crossed with three rice varieties, Sheng 47, N625 and CDR22, respectively, showed that the mutant trait is controlled by a single recessive gene. In the F2 population from npa-1/Sheng47 the gene for the non-palea trait was mapped between two restriction fragment length polymorphism markers, C498 and RZ450, with distances of 7.5 cM and 2.4 cM, respectively. The tagged recessive non-palea gene is temporarily designated npa-1.

[Obtaining stem borer-resistant homozygous transgenic lines of Minghui 81 harboring novel cry1Ac gene via particle bombardment].

A modified cry1Ac gene was generated by fusing with Lys-Asp-Glu-Lue (KDEL), an endoplasmic reticulum retention signal at the 3'-ends, with signal peptide coding sequence of Soybean kunitz trypsin inhibitor (SKTI) at the 5'-ends. Vector containing the modified cry1Ac gene coding region flanked by the corn ubiquitin 1 promoter and the nopaline synthase gene (nos) terminator with Hygromycin Phosphotransferase (hpt) gene as a plant selection marker was constructed. The modified cry1Ac gene in which toxic protein targeted to endoplasmic retention was successfully transferred into Minghui 81 (Oryza sativa L. subsp. indica), an elite restoring line of commercial CMS indica hybrid rice, through particle bombardment and obtained fertile transformants. Homozygous transgenic rice lines were obtained in the third generation exploiting self-seed set reproduction and HygromycinB selection. These transgenic lines were confirmed with polymerase chain reaction (PCR) amplification, Southern blotting and ELISA detection. Pest insect-resistant bioassay indicated that some of the homozygous cry1Ac-transgenic rice plants of T2 progeny showed high-level resistance against striped stem borer (Chilo suppressalis) at field trials.