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Transposon insertion resulted in the silencing of Wx-B1n in Chinese wheat landraces

点击数:1505发布时间:2017-03-27 14:54:11 来源: 四川农业大学·小麦研究所

Ling-Ling Zhang1 Hu Chen1 Mi Luo1 Xiao-Wei Zhang1 Mei Deng1 Jian Ma1 Peng-Fei Qi1 Ji-Rui Wang1 Guo-Yue Chen1 Ya-Xi Liu1 Zhi-En Pu2 Wei Li2 Xiu-Jin Lan1 Yu-Ming Wei1 You-Liang Zheng1 Qian-Tao Jiang


1.Triticeae Research InstituteSichuan Agricultural UniversityChengduChina

2.College of AgronomySichuan Agricultural UniversityChengduChina
*. Email author


Ling-Ling Zhang and Hu Chen have contributed equally to this paper.


Cite this article as:
Zhang, LL., Chen, H., Luo, M. et al. Theor Appl Genet (2017). doi:10.1007/s00122-017-2878-4

Abstract
Key message
A novelWx-B1allele was characterized; a transposon insertion resulted in the loss of its function, which is different from the previously reported gene silencing mechanisms at theWx-B1locus.

Abstract
The waxy protein composition of 53 Chinese wheat landraces was analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis; of these, 10 did not show the expression of Wx-A1 (four accession) or Wx-B1 (six accessions) protein. The results of molecular marker detection revealed that the Wx-B1 allele (Wx-B1n) showed normal expression, inconsistent with the findings of SDS-PAGE for the Xiaobaipi accession. Further cloning of the 9160-bp region covering the Wx-B1 coding region and 3′-downstream region revealed that a 2178-bp transposon fragment had been inserted at 2462 bp within the tenth exon of Wx-B1n ORF, leading to the absence of Wx-B1 protein. Sequence analysis indicated that the insertion possessed the structural features of invert repeat and target repeat elements, we deduced that it was a transposon. Further PCR analysis revealed that this fragment had moved, but not copied itself, from 3B chromosome to the current location in Wx-B1n. Therefore, the reason for the inactivation of Wx-B1n was considerably different from those for the inactivation of Wx-B1b, Wx-B1k, and Wx-B1m; to our knowledge, this kind of structural mutation has never been reported in Wx-B1 alleles. This novel allele is interesting, because it was not associated with the deletion of other quality-related genes included in the 67 kb region lost with the common null allele Wx-B1b. The null Wx-B1n might be useful for investigating gene inactivation and expression as well as for enriching the genetic resource pool for the modification of the amylose/amylopectin ratio, thereby improving wheat quality.