The Yr26 gene, conferring resistance to all currently important races of Puccinia striiformis f. sp. tritici (Pst) in China, was previously mapped to wheat chromosome deletion bin C-1BL-6-0.32 with low-density markers. In this study, collinearity of wheat to Brachypodium distachyon and rice was used to develop markers to saturate the chromosomal region containing the Yr26 locus, and a total of 2,341 F2 plants and 551 F2∶3 progenies derived from Avocet S×92R137 were used to develop a fine map of Yr26. Wheat expressed sequence tags (ESTs) located in deletion bin C-1BL-6-0.32 were used to develop sequence tagged site (STS) markers. The EST-STS markers flanking Yr26 were used to identify collinear regions of the rice and B. distachyon genomes. Wheat ESTs with significant similarities in the two collinear regions were selected to develop conserved markers for fine mapping of Yr26. Thirty-one markers were mapped to the Yr26 region, and six of them cosegregated with the resistance gene. Marker orders were highly conserved between rice and B. distachyon, but some rearrangements were observed between rice and wheat. Two flanking markers (CON-4 and CON-12) further narrowed the genomic region containing Yr26 to a 1.92 Mb region in B. distachyon chromosome 3 and a 1.17 Mb region in rice chromosome 10, and two putative resistance gene analogs were identified in the collinear region of B. distachyon. The markers developed in this study provide a potential target site for further map-based cloning of Yr26 and should be useful in marker assisted selection for pyramiding the gene with other resistance genes.

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Heat release of coal combustion in an oxygen-lean and multi-gas environment is a common phenomenon, coalfield fires caused by it can lead to serious environmental destruction and loss of coal resources. Simultaneous thermal analysis experiments for Bulianta (BLT, high-volatile bituminous coal) and Yuwu coal (YW, anthracite) in 21vol.%O2/79vol.%N2 and 15vol.%O2/5vol.%CO2/80vol.%N2 were carried out to study the law of heat release. Based on the TG-DTG-DSC curves, the combustion characteristic parameters were analyzed. Decreasing O2 concentration caused a significant reduction of local reactivity and further the decreasing maximum heat release rate for low-rank coal, while increasing CO2 concentration caused a significant thermal lag effect and further the increasing maximum heat release rate for high-rank coal. The relationship between the heat release rate and the reaction rate constant was quantitatively analyzed. At the increasing stage of the heat release rate, the heat release rate of the two coals increased conforming to ExpGro1 exponential model. At the decreasing stage of the heat release rate, the heat release rate of YW coal decreased exponentially with the reaction rate constant, while the heat release rate of BLT coal decreased linearly. Regardless of the atmospheres, the conversion rates corresponding to maximum heat release rate of BLT and YW coal were about 0.80 and 0.50, respectively, indicating that the coal rank played a dominant role. The results are helpful to understand the heat release process of coal oxygen-lean combustion in O2/CO2/N2.

This study aims at achieving the generation laws of the iconic gas compositions produced during the process of the cotton smoldering. A mini tube furnace was used to heat a long-staple cotton sample from Xinjiang, China, and a gas chromatography-mass spectrometer (GC/MS) was applied to analyze the produced organic and inorganic gas composition at different low temperatures ranging from 95 °C to 185 °C. Besides, a thermogravimetric experiment under air atmosphere was done in order to verify the correctness of the inferences. The pathways of product generation by heating cotton were set forth, including the depolymerization of the cotton cellulose, the sequential generation of coke, low molecular weight products, long chain carboxylic acids, levoglucosenone, and acetone at 125 °C, and the generation of hydrogen at 95 °C, carbon dioxide, carbon monoxide at 145 °C, and methane during the heating process. The results showed that the alkanes, furans, alkenes, aldehydes, hydrazines, and acids could not be regarded as the iconic gas compositions because of their little proportion, the joint detection of the methane and hydrogen could be used to predicate the smoldering, and the acetone and carbon monoxide could be used to confirm the smoldering stage. The results of the thermogravimetric experiment are consistent with theoretical analysis, indicating that analyses are reliable. This work will provide significant practice foundation for the early warning and prevention of cotton fires.