Posts Tagged ‘Triticum aestivum’

Quantitative trait loci mapping for adult-plant resistance to powdery mildew in Chinese wheat cultivar Bainong 64

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Published in Phytopathology 99(10): 1121-1126

Quantitative trait loci mapping for adult-plant resistance to powdery mildew in Chinese wheat cultivar Bainong 64

Caixia Lan, Shanshan Liang, Zhulin Wang, Jun Yan, Yong Zhang, Xianchun Xia, and Zhonghu He

Adult-plant resistance (APR) is an effective means of controlling powdery mildew in wheat. In the present study, 406 simple-sequence repeat markers were used to map quantitative trait loci (QTLs) for APR to powdery mildew in a doubled-haploid (DH) population of 181 lines derived from the cross Bainong 64 × Jingshuang 16. The DH lines were planted in a randomized complete block design with three replicates in Beijing and Anyang during the 2005–06 and 2007–08 cropping seasons. Artificial inoculations were carried out in Beijing using the highly virulent Blumeria graminis f. sp. tritici isolate E20. Disease severities on penultimate leaves were scored twice in Beijing whereas, at Anyang, maximum disease severities (MDS) were recorded following natural infection. Broad-sense heritabilities of MDS and areas under the disease progress curve were 0.89 and 0.77, respectively, based on the mean values averaged across environments. Composite interval mapping detected four QTLs for APR to powdery mildew on chromosomes 1A, 4DL, 6BS, and 7A; these were designated QPm.caas-1A, QPm.caas-4DL, QPm.caas-6BS, and QPm.caas-7A, respectively, and explained 6.3 to 22.7% of the phenotypic variance. QTLs QPm.caas-4DL and QPm.caas-6BS were stable across environments with high genetic effects on powdery mildew response, accounting for 15.2 to 22.7% and 9.0 to 13.2% of the phenotypic variance, respectively. These results should be useful for the future improvement of powdery mildew resistance in wheat.

Cloning and phylogenetic analysis of polyphenol oxidase genes in common wheat and related species

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Published in Genetic Resources and Crop Evolution 56(3):311-321

Cloning and phylogenetic analysis of polyphenol oxidase genes in common wheat and related species

X. Y. He, Z. H. He, C. F. Morris and X. C. Xia

Cloning and phylogenetic analysis of polyphenol oxidase (PPO) genes in common wheat and its relatives would greatly advance the understanding of molecular mechanisms of grain PPO activity. In the present study, six wheat relative species, including T. urartu, T. boeoticum, T. monococcum, T. dicoccoides, T. durum and Ae. tauschii, were sampled to isolate new alleles at Ppo-A1 and Ppo-D1 loci corresponding to common wheat PPO genes, and seven new alleles were identified from these species, which were designated as Ppo-A1c (from T. urartu), Ppo-A1d (T. boeoticum), Ppo-A1e (T. monococcum and T. durum), Ppo-A1f (T. dicoccoides), Ppo-A1g (T. durum), Ppo-D1c (Ae. tauschii) and Ppo-D1d (Ae. tauschii), respectively. Five out of the seven alleles detected in the wheat relatives contained an open reading frame (ORF) of 1,731 bp, encoding a polypeptide of 577 residues, which is the same as those of Ppo-A1 and Ppo-D1 genes in common wheat, whereas, the full-length ORF of the allele Ppo-A1g from T. durum was not obtained, and a 73-bp deletion occurred in the third exon of Ppo-D1d, an allele from Ae. tauschii, resulting in a shorter polypeptide of 466 amino acids. The 191-bp insertion in the first intron reported previously in common wheat was also found in T. dicoccoides lines, implying that more than one tetraploid wheat lines may be involved in the origination of common wheat. Phylogenetic trees were constructed using the genomic DNA sequences of the seven alleles, together with four from common wheat and four partial PPO gene sequences deposited in GenBank. The genome tribe A was divided into two clusters, one of which contained Ppo-A1d and Ppo-A1e, and the other included the remaining five alleles at Ppo-A1 locus. The alleles from different clusters showed high sequence divergences, indicated by dozens of SNPs and five to six InDels. The genome tribe D comprised the alleles Ppo-D1a, Ppo-D1c, Ppo-D1d and Ppo-D1b, and the former three were clustered together, showing significant sequence divergence from Ppo-D1b. In addition, the relationships between these allelic variants and grain PPO activities were also discussed.

Characterization of Overexpressed Bx7 Gene (Bx7OE) in Chinese and CIMMYT Wheats by STS Markers

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Published in Acta Agronomica Sinica 35(3): 403-411

Characterization of Overexpressed Bx7 Gene (Bx7OE) in Chinese and CIMMYT Wheats by STS Markers

Ren Yan, Liang Dan2, Zhang Ping-Ping, He Zhong-Hu, Chen Jing, Fu Ti-Hua, and Xia Xian-Chun

Over-expression of the high molecular weight glutenin subunit (HMW-GS) Bx7 is highly associated with dough strength of wheat (Triticum aestivum L.) flour. A total of 163 Chinese and CIMMYT wheat cultivars and advanced lines were tested by two STS markers and RP-HPLC to understand the presence of HMW-GS gene Bx7OE. The results indicated that the markers TaBAC1215C06-F517/R964 and TaBAC1215C06-F24671/R25515 could amplify a 447 bp and a 844 bp PCR fragments, respectively, in the lines with Bx7OE, whereas no PCR products were detected in the lines without Bx7OE. Of the 163 cultivars and lines, specific PCR fragments were amplified in 11 genotypes by the two markers, indicating the presence of Bx7OE in these lines, with a frequency of 6.7%. The results obtained by RP-HPLC were consistent with those revealed by STS markers. These two STS markers could be used to detect the presence of Bx7OE gene in wheat cultivars