Genome Sequence of Striga asiatica Provides Insight into the Evolution of Plant Parasitism

First author: Satoko Yoshida; Affiliations: RIKEN Center for Sustainable Resource Science (日本理化研究所可持续资源科学中心): Yokohama, Japan

Corresponding author: Ken Shirasu

Parasitic plants in the genus Striga, commonly known as witchweeds (巫婆草), cause major crop losses in sub-Saharan Africa (撒哈拉以南非洲) and pose a threat to agriculture worldwide. An understanding of Striga parasite biology, which could lead to agricultural solutions, has been hampered by the lack of genome information. Here, we report the draft genome sequence of Striga asiatica with 34,577 predicted protein-coding genes, which reflects gene family contractions and expansions that are consistent with a three-phase model of parasitic plant genome evolution. Striga seeds germinate in response to host-derived strigolactones (SLs) and then develop a specialized penetration structure, the haustorium (吸根), to invade the host root. A family of SL receptors has undergone a striking expansion, suggesting a molecular basis for the evolution of broad host range among Striga spp. We found that genes involved in lateral root development in non-parasitic model species are coordinately induced during haustorium development in Striga, suggesting a pathway that was partly co-opted during the evolution of the haustorium. In addition, we found evidence for horizontal transfer of host genes as well as retrotransposons, indicating gene flow to S. asiatica from hosts. Our results provide valuable insights into the evolution of parasitism and a key resource for the future development of Striga control strategies.

独脚金属中的寄生植物通常称为独脚金或巫婆草，其在撒哈拉以南非洲地区造成了巨大的作物损失，对全球的农业构成了威胁。对于独脚金属植物寄生生物学特性的理解将有助于解决农业上的面临的一些问题，但由于缺乏这些植物的基因组信息，这一过程进展十分缓慢。本文中，作者报道了独脚金的参考基因组，共预测34577个蛋白编码基因，并且基因家族的收缩和扩展符合寄生植物基因组进化的三相模型。独角金的种子会响应于来自寄主的独脚金内酯而萌发，接着会发育出一个特化的穿刺结构吸根，用来侵入寄主植物的根。独脚金中一个独角金内酯受体家族经历了显著扩张，可能作用于独脚金属植物演化出广泛的寄主范围的分子基础。作者发现在非寄生模式植物中参与侧根发育的基因在独脚金的吸根发育时会诱导表，说明这是寄生植物吸根演化过程中受到共同选择的通路。另外，作者发现了来自寄主植物的水平转移基因和逆转座子，说明寄主植物的基因会流向独脚金。本文的研究结果为寄生植物的演化提供了可贵的视野，并且为未来农业中控制独脚金的策略开发提供关键资源。

通讯：Ken Shirasu (http://plantimmunity.riken.jp/CV_E.html)

个人简介：1988年，日本东京大学，学士；1993年，美国加州大学戴维斯分校，博士；1993-1996年，美国索尔克研究所，博士后。

研究方向：植物与其他生物之间的互作。

doi: https://doi.org/10.1016/j.cub.2019.07.086

Journal: Current Biology

Published online: September 12, 2019