马蹄莲远缘杂交PGI障碍白化后代中β-胡萝卜素缺失的分子机制

彩色马蹄莲是观赏价值极高的重要花卉，但软腐细菌Pcc引起的软腐病，对彩色马蹄莲生产造成了极大的威胁。虽然传统栽培的白花马蹄莲Zantedeschia aethiopica具有高抗性，但由于核-质基因不相容（Plastome-genome Incompatibility; PGI）障碍，二者杂交只能得到白化后代。申请者前期研究发现PGI障碍白化后代中β-胡萝卜素缺失，且β-胡萝卜素合成关键酶番茄红素β-环化酶（LCYB）基因表达显著下调、转化代谢关键酶玉米黄质环氧化酶（ZEP）基因表达显著上调。本项目拟采用酵母单杂技术筛选LCYB、ZEP基因上游的调控因子，酶切-PCR和亚硫酸盐测序法分析白化后代中LCYB、ZEP及上游调控因子基因甲基化修饰的变化，解析马蹄莲远缘杂交PGI障碍白化后代中β-胡萝卜素缺失的分子机制，以期为克服马蹄莲远缘杂交障碍，培育抗软腐病等优良性状品种的研究提供理论依据。

The colored Zantedeschia is an important flower with high ornamental value. However, production of the colored Zantedeschia is affected severely with soft rot caused by Pectobacterium carotovora subsp. carotovora (Pcc). Although the traditional species Z. aethiopica has very high resistance to this pathogen, the introgression of R-genes from the Z. aethiopica into the cultivars of colored Zantedeschia is impossible due to Plastome-Genome Incompatibility (PGI). The interspecific hybrids suffer from PGI are albino plants, which blocks the traditional way for resistance breeding. In previous work, we found that β-carotene lost in the albino bybrids and the expression of lycopene β-cyclase (LCYB) was down-regulated significantly and Zeaxanthin epoxidase (ZEP) was up-regulated significantly. In this study, the regulating factors in the upstream of LCYB, ZEP will be screened by the Yeast One-Hybrid System, and the changes of DNA methylation status of LCYB, ZEP and the regulating factors selected in the albino hybrids will be analyzed by Chop-PCR and bisulfite sequencing. The results will be hired to explore the molecular mechanism underlying the loss of β-carotene in the albino hybrids, which will give a powerful support to overcome the obstacles derived from PGI and breed new varieties of the colored Zantedeschia with resistance to soft rot.