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<i>BvcZR3</i> and <i>BvHs1<sup>pro-1</sup></i> Genes Pyramiding Enhanced Beet Cyst Nematode (<i>Heterodera schachtii</i> Schm.) Resistance in Oilseed Rape (<i>Brassica napus</i> L.)
oleh: Xuanbo Zhong, Qizheng Zhou, Nan Cui, Daguang Cai, Guixiang Tang
Format: | Article |
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Diterbitkan: | MDPI AG 2019-04-01 |
Deskripsi
Beet cyst nematode (<i>Heterodera schachtii</i> Schm.) is one of the most damaging pests in sugar beet growing areas around the world. The <i>Hs1<sup>pro-1</sup></i> and <i>cZR3</i> genes confer resistance to the beet cyst nematode, and both were cloned from sugar beet translocation line (A906001). The translocation line carried the locus from <i>B. procumbens</i> chromosome 1 including <i>Hs1<sup>pro-1</sup></i> gene and resistance gene analogs (RGA), which confer resistance to <i>Heterodera schachtii</i>. In this research, <i>BvHs1<sup>pro-1</sup></i> and <i>BvcZR3</i> genes were transferred into oilseed rape to obtain different transgenic lines by <i>A. tumefaciens</i> mediated transformation method. The <i>cZR3Hs1<sup>pro-1</sup></i> gene was pyramided into the same plants by crossing homozygous <i>cZR3</i> and <i>Hs1<sup>pro-1</sup></i> plants to identify the function and interaction of <i>cZR3</i> and <i>Hs1<sup>pro-1</sup></i> genes. In vitro and in vivo cyst nematode resistance tests showed that <i>cZR3</i> and <i>Hs1<sup>pro-1</sup></i> plants could be infested by beet cyst nematode (BCN) juveniles, however a large fraction of penetrated nematode juveniles was not able to develop normally and stagnated in roots of transgenic plants, consequently resulting in a significant reduction in the number of developed nematode females. A higher efficiency in inhibition of nematode females was observed in plants expressing pyramiding genes than in those only expressing a single gene. Molecular analysis demonstrated that <i>BvHs1<sup>pro-1</sup></i> and <i>BvcZR3</i> gene expressions in oilseed rape constitutively activated transcription of plant-defense related genes such as <i>NPR1</i> (non-expresser of <i>PR1</i>), <i>SGT1b</i> (enhanced disease resistance 1) and <i>RAR1</i> (suppressor of the <i>G2</i> allele of <i>skp1</i>). Transcript of <i>NPR1</i> gene in transgenic <i>cZR3</i> and <i>Hs1<sup>pro-1</sup></i> plants were slightly up-regulated, while its expression was considerably enhanced in <i>cZR3Hs1<sup>pro-1</sup></i> gene pyramiding plants. The expression of <i>EDS1</i> gene did not change significantly among transgenic <i>cZR3</i>, <i>Hs1<sup>pro-1</sup></i> and <i>cZR3Hs1<sup>pro-1</sup></i> gene pyramiding plants and wild type. The expression of <i>SGT1b</i> gene was slightly up-regulated in transgenic <i>cZR3</i> and <i>Hs1<sup>pro-1</sup></i> plants compared with the wild type, however, its expression was not changed in <i>cZR3Hs1<sup>pro-1</sup></i> gene pyramiding plant and had no interaction effect. <i>RAR1</i> gene expression was significantly up-regulated in transgenic <i>cZR3</i> and <i>cZR3Hs1<sup>pro-1</sup></i> genes pyramiding plants, but almost no expression was found in <i>Hs1<sup>pro-1</sup></i> transgenic plants. These results show that nematode resistance genes from sugar beet were functional in oilseed rape and conferred BCN resistance by activation of a CC-NBS-LRR R gene mediated resistance response. The gene pyramiding had enhanced resistance, thus offering a novel approach for the BCN control by preventing the propagation of BCN in oilseed rape. The transgenic oilseed rape could be used as a trap crop to offer an alternative method for beet cyst nematode control.