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Ma D.,Northwest University, China | Ma D.,Yangtze University | Li Q.,Northwest University, China | Tang M.,Northwest University, China | And 5 more authors.
Molecular Breeding

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive foliar disease of wheat worldwide. Sustainable control of the disease is preferably achieved by deploying stripe rust resistance genes in wheat cultivars. Our previous studies have shown that Baidatou, a Chinese wheat landrace, displayed good adult-plant resistance (APR) to wheat stripe rust in Gansu Province, an epidemic region for stripe rust in China. To elucidate the genetic basis of APR to stripe rust in Baidatou, a cross between Baidatou and Mingxian 169, which is susceptible to all the known Chinese (Pst) races, was performed. Adult plants of F1, F2 and F2:3 generations derived from the cross Mingxian 169/Baidatou were inoculated in the field with the most prevalent Chinese Pst race, CYR33, in Yangling, Shaanxi Province, during 2009–2010 and 2010–2011 crop seasons, respectively. The results showed that the resistance of Baidatou to stripe rust was conferred by a single dominant gene. Six hundred and sixty simple sequence repeat (SSR) markers and 128 sequence-related amplified polymorphism (SRAP) markers were screened for association with the resistance gene to stripe rust using bulked segregant analysis. Four polymorphic SSR markers and two SRAP markers were identified to be linked to the resistance gene. A linkage map was constructed with six molecular markers and the resistance gene. The genetic distance of two flanking SSR markers to the resistance gene, temporarily designated YrBai, was 3.6 and 5.4 cM, respectively. Based on the position of the SSR markers on the wheat chromosome, YrBai was located on chromosome 6DS. According to the rust reaction patterns, SSR marker allele analysis and the pedigree of the Yr genes on chromosome 6D, YrBai is likely to be a novel APR gene against stripe rust. The specificity of the two flanking markers of YrBai was validated in 99 wheat germplasms. The gene and its flanking markers should be useful for developing wheat cultivars with durable resistance. © 2015, Springer Science+Business Media Dordrecht. Source

Ma D.-F.,Northwest University, China | Wang H.-G.,Northwest University, China | Tang M.-S.,Northwest University, China | Yuan X.-L.,Northwest University, China | And 4 more authors.
Acta Agronomica Sinica

Wheat (Triticum aestivum L.) cultivar Zhongliang 21 displays resistance to 7 prevalent Puccinia striiformis f. sp. tritici (Pst) races from China. The resistance gene(s) carried by this cultivar was identified using molecular markers in combination with phenotypic evaluation. Seedlings of the F1, F2, and BC1 generations from the cross between Zhongliang 21 (resistant) and Mingxian 169 (susceptible), as well as the parents, were inoculated with Pst race CYR30 in greenhouse, and the resistance was evaluated 15-16 d after inoculation. The results showed that the stripe rust resistance in Zhongliang 21 was conferred by a single dominant gene, which was designated tentatively Yrzhong21. Based on bulked segregant analysis, 10 simple sequence repeat (SSR) markers located on chromosome 5AL were identified to be linked to Yrzhong21, of which Xgwm186 andXbarc165 were the closest flanking markers with genetic distances of 7.4 and 2.7 cM, respectively. In combination with analyses of chromosomal location, reactions to various pathotypes, and pedigree, Yrzhong21 was deduced as a novel gene resistant to stripe rust. Eighteen wheat cultivars (lines) in Zhongliang series were further screened with markers Xgwm186 andXbarc165. Only 3 cultivars produced identical banding pattern to that of Zhongliang 21. This result primarily indicates that only 17% of Zhongliang cultivars (lines) might carry Yrzhong21. This resistance gene is promising in wheat breeding programs for strip rust resistance. © 2011 Crop Science Society of China and Institute of Crop Sciences, Chinese Academy of Agricultural Sciences. Source

Zhe E S.,Lanzhou University | Gang Li X.,Lanzhou University | Ming Chen Z.,Lanzhou University | Hang Li X.,Lanzhou University | And 2 more authors.
Journal of Plant Nutrition and Soil Science

An essential prerequisite for a sustainable soil use is to maintain a satisfactory soil organic-matter (OM) level. This might be achieved by sound fertilization management, though impacts of fertilization on OM have been rarely investigated with the aid of physical fractionation techniques in semiarid regions. This study aimed at examining changes in organic C (OC) and N concentrations of physically separated soil OM pools after 26 y of fertilization at a site of the semiarid Loess Plateau in China. To separate sensitive OM pools, total macro-OM (> 0.05mm) was obtained from bulk soil by wet-sieving and then separated into light macro-OM (< 1.8 gcm-3) and heavy macro-OM (> 1.8 gcm-3) subfractions; bulk soil was also differentiated into light OM (< 1.8 gcm-3) and mineral-associated OM (> 1.8 gcm-3). Farmyard manure increased concentrations of total macro-OC and N by 19% and 25%, and those of light fraction OC and N by 36% and 46%, compared to no manuring; both light OC and N concentrations but only total macro-OC concentration responded positively to mineral fertilizations compared to no mineral fertilization. This demonstrated that the light-fraction OM was more sensitive to organic or inorganic fertilization than the total macro-OM. Mineral-associated OC and N concentrations also increased by manuring or mineral fertilizations, indicating an increase of stable OM relative to no fertilization treatment, however, their shares on bulk soil OC and N decreased. Mineral fertilizations improved soil OM quality by decreasing C : N ratio in the light OM fraction whereas manuring led to a decline of the C : N ratio in the total macro-OM fraction, with respect to nil treatment. Further fractionation of the total macro-OM according to density clarified that across treatments about 3/4 of total macro-OM was associated with minerals. Thus, by simultaneously applying particle-size and density separation procedures, we clearly demonstrated that the macro-OM differed from the light OM fraction not only in its chemical composition but also in associations with minerals. The proportion of the 0.5-0.25mm water-stable aggregates of soil was higher under organic or inorganic fertilizations than under no manure or no mineral fertilization, and increases in OC and N concentrations of water-stable aggregates as affected by fertilization were greater for 1-0.5 and 0.5-0.25mm classes than for the other classes. Results indicate that OM stocks in different soil pools can be increased and the loose aggregation of these strongly eroded loess soils can be improved by organic or inorganic fertilization. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Wang F.,Institute of Biotechnology of Qinghai Academy of Agriculture and Forestry | Wang F.,The Qinghai Tibet Plateau Biotechnology Key Laboratory of Ministry of Education | Wang F.,Germplasm Innovation and Utilization of Plateau Crop Key Laboratory of Qinghai Province | Li F.-D.,Tianshui Institute of Agricultural science | And 3 more authors.
Potato Research

The genetic diversity of 123 potato clones, consisting of 103 clonal accessions from the International Potato Center (CIP) and 20 Chinese cultivars, was assessed using amplified fragment length polymorphism (AFLP) markers. Ten polymorphic primer combinations were selected to analyse and compare the diversity of the two sources of clones. A total of 521 reproducible bands were amplified, of which 488 were polymorphic. These AFLP markers were analysed to estimate the genetic distance (GD) and genetic similarity (GS) coefficient of all clones. The GD between pairs of clones ranged from 0.03 to 0.48. Nei's gene diversity index was between 0.236 and 0.387, with an average of 0.330. The index of Shannon's information varied from 0.361 to 0.567 with an average of 0.498. A high degree of polymorphism was observed with an average of 93.6% loci found to be polymorphic. Cluster analysis showed that the CIP accessions were grouped together at the GS 0.59 clustering line, whereas most Chinese cultivars grouped at the GS 0.82 clustering line. The diversity in CIP potato resources was found to be higher than that of the Chinese cultivars, indicating that the genetic base of Chinese potato cultivars is narrow and may benefit from broadening. © 2013 EAPR. Source

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