Studies on production of resistant variant of Japanese pear 'Osa Nijisseiki' to Alternaria alternata Japanese pear pathotype by means of somatic mutation.

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13660039
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 園芸・造園学
• Research Institution: Akita Prefectural College of Agriculture
• Principal Investigator: TAKAHASHI Harumi Akita Prefectural College of Agriculture, Bioproduction, Professor, 生物生産学科, 教授 (00122929)
• Co-Investigator(Kenkyū-buntansha): IMANISHI Hiroyuki Akita Prefectural College of Agriculture, Experimental Farm, Lecturer, 短期大学部・附属農場, 講師 (10320607) ; MATSUMOTO Tsutomu Akita Prefectural College of Agriculture, Bioproduction, Professor, 短期大学部・生物生産学科, 教授 (70073963)
• Project Period (FY): 2001 – 2003
• Keywords: Japanese pear / tissue culture / black spot

Research Abstract

1.The tissue culture conditions necessary for the establishment of a re-differentiation system with a high rate of multiplication were investigated. The shoot apex, stem, lamina, and petiole of the Japanese pear 'Osa Nijisseiki' were used as a material. Types and concentrations of inorganic nutrients, plant growth regulators, additives, and gelling agents were examined. The shoot apex grew shoots, while other materials developed calli. The culture conditions necessary for the establishment of calliclones were examined by using the callus derived from the shoot apex. The calli proliferated vigorously on the medium composed of WP inorganic nutrients. Although the use of various plant growth regulators and additives was examined, re-differentiation from the callus was not obtained.
The shoot apexes of 'Chojuro' and 'Kosui' in addition to 'Osa Nijisseiki' were used as explants. Many adventitious buds were formed in 'Chojuro' by combining auxin, gibberellin, and cytokinin with the WP medium.
2.As preparation for the selection of a resistance variant, a Alternaria alternata Japanese pear pathotype extracted from 'Osa Nijisseiki' was isolated from a single spore, a strain expressing a high spore formation ability and high toxin producing ability was screened, and the spore was then proliferated. A Alternaria alternata strawberry pathotype which also shows toxicity to the Japanese pear was proliferated after confirmation of its spore formation ability. These spores were freeze preserved in a super-low-temperature freezer.
Much new information regarding the tissue culture of 'Osa Nijisseiki' was gained from this study. However, we did not succeed in producing a black spot tolerance variant since the culture conditions necessary for mass propagation were not established. However, in 'Chojuro', a culture condition sufficient for multiple shoot production was established. This result suggests the possibility of selecting a 'Ose Nijisseiki' pear variant with black spot tolerance by producing multiple shoots using a similar system.