カテゴリー: Latest-Research

Yu Sugihara, Kwabena Darkwa, Hiroki Yaegashi, Satoshi Natsume, Motoki Shimizu, Akira Abe, Akiko Hirabuchi, Kazue Ito, Kaori Oikawa, Muluneh Tamiru-Oli, Atsushi Ohta, Ryo Matsumoto, Agre Paterne, David De Koeyer, Babil Pachakkil, Shinsuke Yamanaka, Satoru Muranaka, Hiroko Takagi, Ben White, Robert Asiedu, Hideki Innan, Asrat Asfaw, Patrick Adebola, Ryohei Terauchi (2020). Genome Analyses Reveal the Hybrid Origin of the Staple Crop White Guinea Yam (Dioscorea rotundata). PNAS, 117 (50) 31987-31992; DOI: 10.1073/pnas.2015830117.

Abstract

White Guinea yam (Dioscorea rotundata) is an important staple tuber crop in West Africa. However, its origin remains unclear. In this study, we resequenced 336 accessions of white Guinea yam and compared them with the sequences of wild Dioscorea species using an improved reference genome sequence of D. rotundata. In contrast to a previous study suggesting that D. rotundata originated from a subgroup of Dioscorea praehensilis, our results suggest a hybrid origin of white Guinea yam from crosses between the wild rainforest species D. praehensilis and the savannah-adapted species Dioscorea abyssinica. We identified a greater genomic contribution from D. abyssinica in the sex chromosome of Guinea yam and extensive introgression around the SWEETIE gene. Our findings point to a complex domestication scenario for Guinea yam and highlight the importance of wild species as gene donors for improving this crop through molecular breeding.

Kato, H., Onai, K., Abe, A., Shimizu, M., Takagi, H., Tateda, C., Utsushi, H., Singkarabanit-Ogawa, S., Kitakura, S., Ono, E., Zipfel, C., Takano, Y., Ishiura, M., Terauchi, R. (2020). Lumi-Map, a real-time luciferase bioluminescence screen of mutants combined with MutMap, reveals Arabidopsis genes involved in PAMP-triggered immunity. Molecular Plant-Microbe Interactions, https://doi.org/10.1094/MPMI-05-20-0118-TA.

Abstract

Plants recognize pathogen-associated molecular patterns (PAMPs) to activate PAMP-triggered immunity (PTI). However, our knowledge of PTI signaling remains limited. In this report, we introduce Lumi-Map, a high-throughput platform for identifying causative single-nucleotide polymorphisms (SNPs) for studying PTI signaling components. In Lumi-Map, a transgenic reporter plant line is produced that contains a firefly luciferase (LUC) gene driven by a defense gene promoter, which generates luminescence upon PAMP treatment. The line is mutagenized and the mutants with altered luminescence patterns are screened by a high-throughput real-time bioluminescence monitoring system. Selected mutants are subjected to MutMap analysis, a whole-genome sequencing-based method of rapid mutation identification, to identify the causative SNP responsible for the luminescence pattern change. We generated nine transgenic Arabidopsis reporter lines expressing the LUC gene fused to multiple promoter sequences of defense-related genes. These lines generate luminescence upon activation of FLAGELLIN-SENSING 2 (FLS2) by flg22, a PAMP derived from bacterial flagellin. We selected the WRKY29-promoter reporter line to identify mutants in the signaling pathway downstream of FLS2. After screening 24,000 ethylmethanesulfonate-induced mutants of the reporter line, we isolated 22 mutants with altered WRKY29 expression upon flg22 treatment (abbreviated as awf mutants). Although five flg22-insensitive awf mutants harbored mutations in FLS2 itself, Lumi-Map revealed three genes not previously associated with PTI. Lumi-Map has the potential to identify novel PAMPs and their receptors as well as signaling components downstream of the receptors.