甜菜丛根病抗性基因的发现
重要性状的基因挖掘对于作物遗传改良来说至关重要。作物野生种资源是基因挖掘途径。最近，科学家利用野生型甜菜种群发现了甜菜丛根病的抗性基因Rz2。
甜菜丛根病是世界范围分布的一种毁灭性病害，我国内蒙、新疆于1978、1981年先后发现，减产22%～44%。该病基本症状为根毛坏死，次生侧根、根毛异常增生或陆续坏死，大量次生侧根和根毛成团集结，块根、侧根剖面维管束有黄褐色条纹，且地上部症状多变。
研究人员搜集了近200个甜菜野生种群，利用全基因组测序的方法建立了这些野生种的基因组草图。利用高通量测序的基因克隆（Mapping-by-sequencing, MBS）方法，他们克隆到甜菜丛根病的抗性基因Rz2。该基因编码一个CC-NB-LRR蛋白，该蛋白是典型的抗病蛋白包含三个结构域，nucleotide-binding site（NB）结构域、leucine-rich repeat（LRR）结构域和coiled-coil（CC）结构域。该基因的发现对甜菜抗性性状的改良具有重要意义。
Nat Commun, 8: 15708. 2017 Jun 6;
Crop wild relative populations of Beta vulgaris allow direct mapping of agronomically important genes.
Author
Capistrano-Gossmann GG, Ries D, Holtgräwe D……Himmelbauer H, Weisshaar B, Kopisch-Obuch FJ*.
*: Plant Breeding Institute, Kiel University, Germany.
Abstract
Rapid identification of agronomically important genes is of pivotal interest for crop breeding. One source of such genes are crop wild relative (CWR) populations. Here we used a CWR population of <200 wild beets (B. vulgaris ssp. maritima), sampled in their natural habitat, to identify the sugar beet (Beta vulgaris ssp. vulgaris) resistance gene Rz2 with a modified version of mapping-by-sequencing (MBS). For that, we generated a draft genome sequence of the wild beet. Our results show the importance of preserving CWR in situ and demonstrate the great potential of CWR for rapid discovery of causal genes relevant for crop improvement. The candidate gene for Rz2 was identified by MBS and subsequently corroborated via RNA interference (RNAi). Rz2 encodes a CC-NB-LRR protein. Access to the DNA sequence of Rz2 opens the path to improvement of resistance towards rhizomania not only by marker-assisted breeding but also by genome editing.
