Inter-species diversity of moisture and drought stress tolerance in wild cowpea (V. unguiculata subsp. dekindtiana)

Research Project

Project/Area Number	17K15219
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Crop production science
Research Institution	Japan International Research Center for Agricultural Sciences
Principal Investigator	Iseki Kohtaro 国立研究開発法人国際農林水産業研究センター, 生物資源・利用領域, 任期付研究員 (80748426)
Project Period (FY)	2017-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000) Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2018: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000) Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	ササゲ / 野生種 / 乾燥ストレス / 湿害 / 遺伝資源 / 乾燥 / ストレス耐性
Outline of Final Research Achievements	Stress tolerances under drought and waterlogged conditions were evaluated for cowpea wild relatives (V. unguiculata subsp. dekindtiana) targeted as promising genetic resources to breed tolerance varieties. The tolerances were phenotyped using different types of physiological and agronomical parameters for plants grown with wood box. Through this method, accessions having tolerance to both drought and waterlogged stresses were selected. Morphological analysis of taproot cross section clarified that, compared with susceptible cultivars, the selected tolerant wild accessions showed higher plasticity of the size of vascular bundle and cortical layer in response to drought and waterlogged conditions. However, under the waterlogged conditions, aerenchyma was less developed in the wild accessions than cultivars suggesting that there would be different mechanisms responsible to the tolerance of the wild accessions.
Academic Significance and Societal Importance of the Research Achievements	西アフリカでは不安定な降雨による土壌の乾燥と過湿がササゲ生産上の問題となっている。土壌の乾燥と過湿に対する植物の応答は相反するため、双方への耐性を同時に獲得することは困難と考えられてきた。しかし、本研究においてササゲの近縁野生種から乾燥と過湿の双方に耐性を示す系統を同定したことで、今後、この材料を用いた品種育成が進むとともに、途上国において同様の手法を使った更なる未利用遺伝資源の評価が進むことが期待される。さらに、選抜した野生種では過湿条件下でのストレス耐性に重要と考えられている通気組織の発達が顕著でなかったことから、これまでに知られていない耐性機構の解明につながる可能性がある。