|CAI, HONG - Yunnan Agricultural University|
|WANG, LIANCHUN - Yunnan Agricultural University|
|MU, WANFU - Yunnan Agricultural University|
|WAN, QIONGLIAN - Yunnan Agricultural University|
|CHEN, HAIRU - Yunnan Agricultural University|
Submitted to: Annals of Applied Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2015
Publication Date: 7/1/2016
Citation: Cai, H., Wang, L., Mu, W., Wan, Q., Wei, W., Davis, R.E., Chen, H., Zhao, Y. 2016. Multilocus genotyping of a ‘Candidatus Phytoplasma aurantifolia’-related strain associated with cauliflower phyllody disease in China. Annals of Applied Biology. 169:64-74. doi:10.1111/aab.12281.
Interpretive Summary: Cauliflower is a widely cultivated vegetable crop that has a superb nutritional value. It is low in calories, high in dietary fiber, and rich in vitamins and minerals, indicating its potential health benefits for consumers. Recently, a new disease affecting cauliflower seed production occurred in China. Diseased plants failed to develop normal flowers and rarely produced seeds. In the present study, ARS scientists and researchers in China worked together and determined that the disease was caused by a small bacterium called phytoplasma. Using DNA fingerprinting technology, the research team found that the cauliflower-infecting phytoplasma has a close genetic relationship with a phytoplasma lineage exclusively present in East Asia. The phytoplasma lineage has a broad host range and impacts the health of several agriculturally and environmentally important plant species. The research team identified molecular markers for specific detection and differentiation of the cauliflower-infecting and other closely-related phytoplasmas. The work is important to farmers and extension personnel for disease diagnosis and management, and is critical to regulatory agencies for preventing exotic pathogens from being introduced into the U.S.
Technical Abstract: A new cauliflower disease characterized by formation of leaf-like inflorescences and malformed flowers occurred in a seed production filed located in Yunnan, a southwest province of China. In the diseased plants, floral organs in three inner whorls (petals, carpels, and stamens) were under-developed or abolished. The diseased plants formed very few seed pods and rarely produced seeds. Detection of phytoplasma-characteristic 16S rRNA gene sequences in DNA samples from diseased plants linked the cauliflower disease to phytoplasmal infection. Results from phylogenetic and virtual RFLP analyses of the 16S rRNA gene sequence indicated that the cauliflower-infecting agent is a ‘Candidatus Phytoplasma aurantifolia’-related strain and is a new member of the peanut witches’-broom phytoplasma group, subgroup A (16SrII-A). Multilocus genotyping revealed close genetic relationship between this cauliflower phytoplasma and a broad host range phytoplasma linage found only in East Asia thus far. Molecular markers present in the secY and rp loci distinguished this phytoplasma from other members of the subgroup 16SrII-A.