Reductive thiocyanolysis of tetraoxorhenate (VII): Synthesis, crystal structure, catalytic oxidation and kinetic studies of (PPh4)2[Re(NCS)6] and (PPh4)2[ReO(NCS)5]

Thiocyanate ions reduce perrhenate in aqueous acidic solution, and on addition of a suitable countercation (PPh₄Cl) afford (PPh₄)₂[Re(NCS)₆] (1) and (PPh₄)₂[ReO(NCS)₅] (2), which have been confirmed by X-ray crystallography. The kinetics of the above reaction has been studied. Both the complexes exhibit efficient and highly selective catalytic epoxidation ability in the presence of NaHCO₃ as a co-catalyst and competent catalytic properties in the selective oxidation of alcohols to the corresponding aldehydes or ketones in the presence of pyrazole as an additive and sulfides to sulfoxides and sulfones. H₂O₂ was used as the terminal oxidant in all the above-mentioned oxidation reactions.     

Screening of a broad range of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) germplasm for <Emphasis Type="Italic">in vitro</Emphasis> rapid plant regeneration and development of an early prediction system

Rice has emerged as a model monocot for studies in agriculture and biotechnology due to its relatively small genome and a ready accessibility to plant material. Tissue culture is one of the tools required for genetic transformation and some breeding programs, and the selection of high-frequency regenerator types is essential for success in these technologies. Thirty-three rice entries with agricultural and biotechnological characteristics of interest were screened with the aim to identify the best regenerators. Entries that exhibited between 50% and 90% regeneration frequencies include ‘Taipei-309,’ ‘Super Dwarf,’ ‘Norin’ (japonica types), PI 312777, ‘Ali Combo’ (indica types), ‘STG-S,’ and ‘LA3’ (red rice types). One third of the entries tested were at least two times better at regeneration than the often-cited regenerator ‘Nipponbare.’ Those entries showing at least 85% frequency of greening or somatic embryo formation at 15 or 30 d on regeneration medium ultimately produced whole plants after 45 d on regeneration medium at high frequency (at least 40%); those entries not reaching the 85% threshold of greening by Days 15 or 30 exhibited moderate (15–40%) to low (less than 10%) frequency of whole plant regeneration. This greening response suggests the means for an early prediction system for identification of useful rice regenerator lines, which would be beneficial for high-throughput screening of germplasm as well as for decreasing the time and cost of in vitro culture.     

Detection and Molecular Characterization of a 16SrII‐A* Phytoplasma in Grapefruit (Citrus paradisi) with Huanglongbing‐like Symptoms in China

In the year 2010, in a survey in Guangxi Province, China, to detect and characterize phytoplasmas in a huanglongbing (HLB)‐infected grapefruit (Citrus paradisi) orchard, 87 leaf samples with symptoms of blotchy mottle were collected from symptomatic grapefruit trees, and 320 leaf samples from symptomless trees adjacent to the symptomatic trees. Nested polymerase chain reaction (PCR) using universal phytoplasma primer set P1/P7 followed by primer set fU5/rU3 identified 7 (8.0%) positive samples from symptomatic samples but none from symptomless samples. Of the 87 symptomatic samples, 77 (88.5%) were positive for ‘Candidatus Liberibacter asiaticus’ and 5 for both phytoplasma and ‘Ca. L. asiaticus’. Sequence analysis indicated that seven 881‐bp amplicons, amplified by nested phytoplasma primer sets P1/P7 and fU5/rU3, shared 100.0% sequence identity with each other. Genome walking was then performed based on the 881 bp known sequences, and 5111 bp of upstream and downstream sequences were obtained. The total 5992 bp sequences contained a complete rRNA operon, composed of a 16S rRNA gene, a tRNA^Ile gene, a 23S rRNA gene and a 5S rRNA gene followed by eight tRNA genes. Phylogenetic analysis and virtual restriction fragment length polymorphism analysis confirmed the phytoplasma was a variant (16SrII‐A*) of phytoplasma subgroup 16SrII‐A. As phytoplasmas were only detected in blotchy‐mottle leaves, the 16SrII‐A* phytoplasma identified was related to HLB‐like symptoms.