75 research outputs found

    Leaf litter, a critical habitat for juvenile Japanese giant salamander, Andrias japonicus (Amphibia: Caudata)

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    東広島市椋梨川水系にはオオサンショウウオが生息している。2011 年から,生息状況や産卵,幼生の離散などの生態学的な調査が行われている。この過程で幼生が巣穴から離散した直後の隠れ家や餌となる水生昆虫の生息場所として流水中の落ち葉・落枝が重要な役割を担う可能性が示唆されている。本研究では流水中の落ち葉・落枝の詳細を明らかにするため,河畔林のフロラを調査するとともに,幼生が発見された場所の落ち葉との比較を行った。その結果,流水中の落ち葉・落枝として29種の維管束植物が同定できた。流水中の落ち葉・落枝の大半がコナラやスギなどの木本で,離散後の幼生や餌となる水生昆虫の生息場所として周辺の植生が強い影響を与える可能性が示唆された。Japanese giant salamanders Andrias japonicus inhabit the Mukunashi River around Higashi-Hiroshima City in Hiroshima Prefecture, southwestern Japan; researchers and local people have collaborated to investigate the species’ behavior, particularly its oviposition and the movement of larvae after leaving the nest. In this research we focused on leaf litter in the stream as habitat in which salamander larvae and the aquatic insects which are its critical food cohabit. We studied the flora of the riparian forest to identify the species of leaf litter in the stream among which salamander larvae were found. Leaf litter and branches belonging to 29 species of vascular plants were identified, and most leaves were from the deciduous oak Quercus serrata and the conifer Cryptomeria japonica. It is suggested that the surrounding flora has an important influence on the survival of Japanese giant salamander larvae that have left the nest

    Genome analyses reveal the hybrid origin of the staple crop white Guinea yam (Dioscorea rotundata)

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    西アフリカの主食作物ギニアヤムの起源を解明 --ギニアヤムはサバンナと熱帯雨林に生育する野生種の雑種起源--. 京都大学プレスリリース. 2020-12-11.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

    Disentangling the complex gene interaction networks between rice and the blast fungus identifies a new pathogen effector

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    Studies focused solely on single organisms can fail to identify the networks underlying host–pathogen gene-for-gene interactions. Here, we integrate genetic analyses of rice (Oryza sativa, host) and rice blast fungus (Magnaporthe oryzae, pathogen) and uncover a new pathogen recognition specificity of the rice nucleotide-binding domain and leucine-rich repeat protein (NLR) immune receptor Pik, which mediates resistance to M. oryzae expressing the avirulence effector gene AVR-Pik. Rice Piks-1, encoded by an allele of Pik-1, recognizes a previously unidentified effector encoded by the M. oryzae avirulence gene AVR-Mgk1, which is found on a mini-chromosome. AVR-Mgk1 has no sequence similarity to known AVR-Pik effectors and is prone to deletion from the mini-chromosome mediated by repeated Inago2 retrotransposon sequences. AVR-Mgk1 is detected by Piks-1 and by other Pik-1 alleles known to recognize AVR-Pik effectors; recognition is mediated by AVR-Mgk1 binding to the integrated heavy metal-associated (HMA) domain of Piks-1 and other Pik-1 alleles. Our findings highlight how complex gene-for-gene interaction networks can be disentangled by applying forward genetics approaches simultaneously to the host and pathogen. We demonstrate dynamic coevolution between an NLR integrated domain and multiple families of effector proteins
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