Identification of Yr59 conferring high-temperature adult-plant resistance to stripe rust in wheat germplasm PI 178759.

KEY MESSAGE: This manuscript reports a new gene for non-race-specific resistance to stripe rust and molecular markers for incorporating it into wheat cultivars for control of the disease with durable resistance. Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive wheat diseases worldwide. The spring wheat germplasm 'PI 178759' originating from Iraq showed effective resistance to stripe rust in field evaluations over 8 years in Washington state, USA. To map the resistance gene(s), PI 178759 was crossed with 'Avocet Susceptible', and the parents and 176 F2:3 lines were phenotyped in the fields under natural infection and in a greenhouse with selected races of P. striiformis f. sp. tritici. PI 178759 was identified to have high-temperature adult-plant (HTAP) resistance. Resistance gene analog polymorphism and simple sequence repeat techniques were used to identify molecular markers linked to the resistance gene and a chromosome region was mapped using a quantitative trait locus approach. One major gene was mapped to the long arm of chromosome 7B. Flanked by Xwgp5175 and Xbarc32 in a 2.1 cM region, the gene explained 31.8 and 54.7 % of the phenotypic variation in rAUDPC and IT, respectively. Based on genetic distances among markers and allelism tests, the HTAP resistance gene in PI 178759 is different from the previously reported Yr39, Yr52, YrZH84, and YrC591, also located on chromosome 7BL, and is therefore designated as Yr59. The gene and its flanking markers should be useful for developing wheat cultivars with durable resistance.

Yr45, a new wheat gene for stripe rust resistance on the long arm of chromosome 3D.

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat worldwide. Growing resistant cultivars is the most effective approach to control the disease, but only a few genes confer effective all-stage resistance against the current populations of the pathogen worldwide. It is urgent to identify new genes for diversifying sources of resistance genes and for pyramiding genes for different types of resistance in order to achieve high levels of durable resistance for sustainable control of stripe rust. The common spring wheat genotype 'PI 181434', originally from Afghanistan, was resistant in all greenhouse and field tests in our previous studies. To identify the resistance gene(s) PI 181434 was crossed with susceptible genotype 'Avocet Susceptible'. Adult plants of 103 F(2) progeny were tested in the field under the natural infection of P. striiformis f. sp. tritici. Seedlings of the parents, F(2) and F(3) were tested with races PST-100 and PST-127 of the pathogen under controlled greenhouse conditions. The genetic study showed that PI 181434 has a single dominant gene conferring all-stage resistance. Resistance gene analog polymorphism (RGAP) and simple sequence repeat (SSR) techniques were used to identify molecular markers linked to the gene. A linkage map of 8 RGAP and 2 SSR markers was constructed for the gene using data from the 103 F(2) plants and their derived F(3) lines tested in the greenhouse. Amplification of the complete set of nulli-tetrasomic lines and selected ditelosomic lines of Chinese Spring with an RGAP marker and the two SSR markers mapped the gene on the long arm of chromosome 3D. Because it is the first gene for stripe rust resistance mapped on chromosome 3DL and different from all previously named Yr genes, the gene in PI 181434 was designated Yr45. Polymorphism rates of the two closest flanking markers, Xwgp115 and Xwgp118, in 45 wheat genotypes were 73.3 and 82.2%, respectively. Single nucleotide polymorphisms (SNPs) were identified in the eight wheat genotypes sharing both flanking markers. The RGAP markers and potential SNP markers should be useful in incorporating the gene into wheat cultivars and in pyramiding it with other genes for durable resistance.

Genetics and molecular mapping of genes for high-temperature resistance to stripe rust in wheat cultivar Xiaoyan 54.

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most widespread and destructive wheat diseases worldwide. Growing resistant cultivars is the preferred means of control of the disease. The winter wheat cultivar Xiaoyan 54 has high-temperature resistance to stripe rust. To identify genes for stripe rust resistance, Xiaoyan 54 was crossed with Mingxian 169, a winter wheat genotype susceptible to all Chinese races of the pathogen. Seedlings and adult plants of the parents and F(1), F(2), F(3) and F(4) progeny were tested with Chinese race CYR32 under controlled greenhouse conditions and in the field. Xiaoyan 54 has two recessive resistance genes, designated as Yrxy1 and Yrxy2, conferring high-temperature resistance. Simple sequence repeat (SSR) primers were used to identify molecular markers flanking Yrxy2 using 181 plants from one segregating F(3) line. A total of nine markers, two of which flanked the locus at genetic distances of 4.0 and 6.4 cM on the long arm of chromosome 2A were identified. Resistance gene analog polymorphism (RGAP) and SSR techniques were used to identify molecular markers linked to Yrxy1. A linkage group of nine RGAP and two SSR markers was constructed for Yrxy1 using 177 plants of another segregating F(3) line. Two RGAP markers were closely linked to the locus with genetic distances of 2.3 and 3.5 cM. Amplification of a set of nulli-tetrasomic Chinese Spring lines with RGAP markers M8 and M9 and the two SSR markers located Yrxy1 on the short arm of chromosome 7A. The SSR markers Xbarc49 and Xwmc422 were 15.8 and 26.1 cM, respectively, from the gene. The closely linked molecular markers should be useful for incorporating the resistance genes into commercial cultivars and combining them with other genes for stripe rust resistance.

[Advances in the research of BRAF(V600E) gene mutation correlated with papillary thyroid carcinoma].

The increase in the incidence of papillary thyroid carcinoma (PTC) is a serious threat to public health. V-raf murine sarcoma viral oncogene homolog B(BRAF)(V600E) gene mutation is not only the common genetics factors, but also is the early event in process of thyroid carcinogenesis. We mainly illustrate the mechanism of BRAF(V600E) gene in genesis and development of PTC and the correlation of BRAF(V600E) gene mutation and the clinicopathological characteristics of PTC. Finally, we briefly summarize some scientific achievements about tyrosine kinase inhibitors targeted for BRAF(V600E) gene and their clinical prospect in terms of translation medicine concept. In summary, BRAF(V600E) gene is expected to be a new molecular marker of PTC, which will take a new hope for individualized precise treatment for patients with PTC.

[RET pro-oncogene and medullary thyroid carcinoma].

Medullary thyroid carcinoma (MTC) originats from the parafollicular C cells of the thyroid, which is one of the most aggressive forms of thyroid malignancy with the poor prognosis. Hereditary MTC has multiple endocrine neoplasia types 1, 2A and 2B. The mutation of RET proto-oncogene has been identified as the main cause of MTC, and all mutations locate among the exons 5, 8, 10, 11, 13, 14, 15, and 16. Mutation analysis of the RET may provide a theoretical basis for the prevention, diagnosis and treatment of MTC.

[A study on the relationship between malignant tumour mortality and environmental pollution in Beicun countryside of Datong City].

The paper reports investigations on malignant tumor mortality in Beicun countryside of Datong city, with Hua yuan tun countryside as the control group. The result showed that malignant tumor mortality (117.04/10(5)) in Beicun countryside was significantly higher than that in the control group (61.06/10(5)). The nitrate and nitrite in drinking water and five kinds of vegetables in Beicun countryside were significantly higher than those in the control group (P < 0.05 - P < 0.001). Serum Cu and Cu/Zu levels in the inhabitants of Beicun countryside were significantly higher than those in the control group (P < 0.001 and P < 0.01). The benzo (a) pyrene and airborne particulates in Beicun countryside area were higher than those in the control group area. The results showed that the malignant tumor mortality was strongly correlated with severe pollution of vegetables, drinking water and air.

[Study of environmental pollution and damage of cytogenetic materials in urban residents].

Recently, epidemiologic data have indicated that the number of deaths caused by malignant tumor presented a significantly rise in Beicun countryside of Datong city. In order to understand the causes of high incidence of cancer, factors were investigated and analysed related to air, river water, drinking water, vegetables and human serum. Results showed that Benzo (a)-pyrene (Bap), total suspended particulates (TSP) in air, nitrate, nitrite in drinking water and vegetables were all significantly higher in Beicun countryside region than those in controlled countryside region, respectively (P < 0.01-P < 0.001). The micronuclei (MN) and berration nucleus (AN) rates of cultured lymphocytes were significantly higher while cpm value of unscheduled DNA synthesis (UDS) test were significantly lower than those in controlled region among residents in Beicun countryside region, respectively (P < 0.01-P < 0.001). The micronuclei, abrerration nucleus rates and cpm value of cultured lymphocytes among residents in Beicun countryside were strongly correlated with Bap, TSP, nitrite and nitrate contents in determination samples. Our results suggest that the air and water source under serious pollution may serve as an important factor causing cytogenetic damage among residents and cancer death rise in Beicun countryside.