This study was conducted to select cultivars and determine the harvest period suited for the availability of biological activities in unripen apple. To analyze effective the components in the apple (Malus domestica), three cultivars, 'Summerking', 'Hongro', 'Fuji' were harvested from 40~50 days after full bloom to harvest time. Soluble solid content increased gradually by ripening but titratable acidity decreased with ripening regardless of the cultivars. The total phenol content significantly reduced with ripening from May 30 to July 30 (p<0.05). Substantially, the total phenol content of ‘Hongro’ in May 30 was four times higher than that of ‘Summerking’ in the same period and ten times higher than that of ‘Hongro’ in August 30. The total flavonoid content reduced with ripening regardless of cultivars (p<0.05) and that of ‘Hongro’ in May 30 was significantly highest (p<0.05). The ascorbic acid content was the highest in ‘Hongro’ in May 30 (p<0.05). The contents of tannin and ursolic acid significantly reduced with ripening from May 30 to July 30 (p<0.05), while no significant difference was observed between Hogro and Fuji after July 30. Therefore, 'Hongro' harvested in May 30 was considered to be best in the utilization of the effective components of immature apple.

고온은 사과(Malus domestica Borkh) 과실의 품질에 영향을 끼치는 가장 중요한 환경 요인 중 하나이다. 착색기의 ‘홍로’ 사과 과실을 3단계로 구분하여 Real-time PCR을 통해 온도조건에 따른 안토시아닌 합성과 당 축적 관련 유전자의 발현 차이를 조사하였다. 당 합성관련 유전자인 β-amylase(BMY)와 polygalacturonase(PG)의 발현은 변색 시작단계보다 마지막 단계에서 월등히 높았다. 과피의 착색과 관련있는 phenylalanine ammonia-lyase(PAL), chalcone synthase(CHS), flavanone 3-hydroxylase(F3H)와 malate dehydrogenase(MDH)유전자는 변색 초기작단계에서는 고온 처리 24시간후에 발현이 증가하는 경향을 보였으며 변색 중간단계에서는 점차 증가하는 경향을 보였다. 변색단계별로 보았을 때 25oC처리구가 다른 온도처리구보다 발현 정도가 더 높았으며, 변색 시작단계보다 마 지막 단계에서의 발현이 강하게 유도되었다. 본 연구의 결과로 착색 초기단계의 과실이 고온스트레스가 가장 영향을 끼치므로 착색초기단계의 과실을 이용하여 전사체를 분석하면 분자생물학적 수준에서 사과의 성숙대사에서 유용한 정보를 얻을 수 있을 것으로 사료된다.

The ripening behavior of three apple cultivars, ‘Tsugaru’, ‘Hongro’ and ‘Fuji’ was distinctive and the involvement of POLYGALACTURONASE(PG) in the fruit softening process was confirmed to be ethylene dependent. Fruit softening is genetically coordinated by the action of several cell wall enzymes, including PG which depolymerizes cell wall pectin. Also, loss of firmness is associated with increasing of the ripening hormone, ethylene. In this work, climacteric ripening of three apple cultivars, Tsugaru, Hongro and Fuji, producing different ethylene levels and ripening responses, was examined. Correspondingly in Fuji, a linear and basal ethylene level was observed over the entire period of measurements, and Tsugaru and Hongro displayed a typical climacteric rise in ethylene production. Transcript accumulation of genes involved in ethylene biosynthesis (MdACS3 and MdACO1) and MdPG1 was studied in Tsugaru, Hongro and Fuji cultivars. Expression of MdACO1 transcripts was shown in all three ripened apple fruits. However, the MdACS3 and MdPG1 were transcribed differently in these cultivars. Comparing the MdPG1 of ‘Tsugaru’, ‘Hongro’ and ‘Fuji’, structural difference was discovered by genomic Southern analysis. Overall results pointed out that MdACS3 and MdPG1 play an important role in regulation of fruit ripening in apple cultivar.