Role of Long Noncoding RNAs ZlMSTRG.11348 and UeMSTRG.02678 in Temperature-Dependent Culm Swelling in Zizania latifolia.

Temperature influences the physiological processes and ecology of both hosts and endophytes; however, it remains unclear how long noncoding RNAs (lncRNAs) modulate the consequences of temperature-dependent changes in host-pathogen interactions. To explore the role of lncRNAs in culm gall formation induced by the smut fungus Ustilago esculenta in Zizania latifolia, we employed RNA sequencing to identify lncRNAs and their potential cis-targets in Z. latifolia and U. esculenta under different temperatures. In Z. latifolia and U. esculenta, we identified 3194 and 173 lncRNAs as well as 126 and four potential target genes for differentially expressed lncRNAs, respectively. Further function and expression analysis revealed that lncRNA ZlMSTRG.11348 regulates amino acid metabolism in Z. latifolia and lncRNA UeMSTRG.02678 regulates amino acid transport in U. esculenta. The plant defence response was also found to be regulated by lncRNAs and suppressed in Z. latifolia infected with U. esculenta grown at 25 °C, which may result from the expression of effector genes in U. esculenta. Moreover, in Z. latifolia infected with U. esculenta, the expression of genes related to phytohormones was altered under different temperatures. Our results demonstrate that lncRNAs are important components of the regulatory networks in plant-microbe-environment interactions, and may play a part in regulating culm swelling in Z. latifolia plants.

Gene expression in the smut fungus Ustilago esculenta governs swollen gall metamorphosis in Zizania latifolia.

Ustilago esculenta, a smut fungus, can induce the formation of culm galls in Zizania latifolia, a vegetable consumed in many Asian countries. Specifically, the mycelia-teliospore (M-T) strain of U. esculenta induces the Jiaobai (JB) type of gall, while the teliospore (T) strain induces the Huijiao (HJ) type. The underlying molecular mechanism responsible for the formation of the two distinct types of gall remains unclear. Our results showed that most differentially expressed genes relevant to effector proteins were up-regulated in the T strain compared to those in the M-T strain during gall formation, and the expression of teliospore formation-related genes was higher in the T strain than the M-T strain. Melanin biosynthesis was also clearly induced in the T strain. The T strain exhibited stronger pathogenicity and greater teliospore production than the M-T strain. We evaluated the implications of the gene regulatory networks in the development of these two type of culm gall in Z. latifolia infected with U. esculenta and suggested potential targets for genetic manipulation to modify the gall type for this crop.

S(N)Ar displacements with 6-(fluoro, chloro, bromo, iodo, and alkylsulfonyl)purine nucleosides: synthesis, kinetics, and mechanism1.

SNAr reactions with 6-(fluoro, chloro, bromo, iodo, and alkylsulfonyl)purine nucleosides and nitrogen, oxygen, and sulfur nucleophiles were studied. Pseudo-first-order kinetics were measured with 6-halopurine compounds, and comparative reactivities were determined versus a 6-(alkylsulfonyl)purine nucleoside. The displacement reactivity order was: F > Br > Cl > I (with BuNH2/MeCN), F > Cl approximately Br > I (with MeOH/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)/MeCN), and F > Br > I > Cl [with K+ -SCOCH3/dimethyl sulfoxide (DMSO)]. The order of reactivity with a weakly basic arylamine (aniline) was: I > Br > Cl > F (with 5 equiv of aniline in MeCN at 70 degrees C). However, those reactions with aniline were autocatalytic and had significant induction periods ( approximately 50 min for the iodo compound and approximately 6 h for the fluoro analogue). Addition of trifluoroacetic acid (TFA) eliminated the induction period, and the order then was F > I > Br > Cl (with 5 equiv of aniline and 2 equiv of TFA in MeCN at 50 degrees C). The 6-(alkylsulfonyl)purine nucleoside analogue was more reactive than the 6-fluoropurine compound with both MeOH/DBU/MeCN and iPentSH/DBU/MeCN and was more reactive than the Cl, Br, and I compounds with BuNH2 and aniline/TFA. Titration of the 6-halopurine nucleosides in CDCl3 with TFA showed progressive downfield 1H NMR chemical shifts for H8 (larger) and H2 (smaller). The major site of protonation as N7 for both the 6-fluoro and 6-bromo analogues was confirmed by large upfield shifts ( approximately 16 ppm) of the 15N NMR signal for N7 upon addition of TFA (1.6 equiv). Mechanistic considerations and resolution of prior conflicting results are presented.

Fluoro, alkylsulfanyl, and alkylsulfonyl leaving groups in suzuki cross-coupling reactions of purine 2'-deoxynucleosides and nucleosides.

[reaction: see text] Protected 2'-deoxynucleoside and nucleoside derivatives of 6-fluoropurine, 6-(3-methylbutyl)sulfanylpurine, and 6-(3-methylbutyl)ylsulfonylpurine undergo nickel- or palladium-mediated C-C cross-coupling with arylboronic acids to give good yields of 6-arylpurine products.

Azoles as Suzuki cross-coupling leaving groups: syntheses of 6-arylpurine 2'-deoxynucleosides and nucleosides from 6-(imidazol-1-yl)- and 6-(1,2,4-triazol-4-yl)purine derivatives.

[reaction: see text] 6-(Imidazol-1-yl)-, 6-(benzimidazol-1-yl)-, and 6-(1,2,4-triazol-4-yl)purine nucleosides undergo a nickel-mediated C-C cross-coupling of azole-substituted purine derivatives with arylboronic acids to give good yields of 6-arylpurine nucleosides.

SNAr iodination of 6-chloropurine nucleosides: aromatic Finkelstein reactions at temperatures below -40 degrees C.

Mesitoyl or toluoyl esters of inosine and 2'-deoxyinosine were deoxychlorinated at C6 to give the crystalline 6-chloropurine nucleoside derivatives, which underwent quantitative conversion to the 6-iodo analogues with NaI/TFA/butanone at -50 to -40 degrees C. The 6-iodo compounds were efficient substrates for SNAr, Sonogashira, and Suzuki-Miyaura reactions, in contrast with the 6-chloro analogues, and gave good to high yields of C-N and C-C coupled products.