Changes in Starch Synthesis and the Characteristics of Photosynthate Translocation at High Temperature during the Ripening Stage in Barley

등숙기 고온에 따른 전분합성 및 동화산물 전류 특성에 미치는 영향을 분석한 결과는 다음과 같다. 1. 등숙기 평균온도가 약 $3^{\circ}C$ 상승함에 따라 등숙기간은 약 5일정도 단축되었으며, 천립중이 약 4.2 g 정도 감소하였고, 전분함량이 감소함에 따라 상대적으로 단백질 함량이 증가하는 경향을 보였다. 2. 등숙기 고온($+3^{\circ}C$)에 따라 전분합성 최대속도는 약 11%정도 증가하였지만, 전분합성속도가 최대가 되는 시점은 약 3일, 전분합성 완료 시점은 약 4일정도 앞당겨지는 경향을 보였다. 3. 전분합성 각 단계에 관여하는 유전자의 발현양상은 앞에서의 전분합성과 마찬가지로 고온처리에서 초기 발현량이 증가하였지만, 발현 지속정도가 빠르게 감소하는 경향을 확인하였으며, 특히 soluble starch synthase의 감소가 두드러졌다. 4. 동화산물의 이삭분배 속도는 전분합성속도와 마찬가지로 고온처리구에서 증가하였지만, 줄기 및 지엽에서의 분배비율은 고온처리구에서 급격하게 감소한 결과를 보아 동화산물의 전류속도가 고온처리구에서 빨라진 것으로 생각된다. 5. 엽신의 노화속도(Nr)는 온도가 상승할수록 크게 증가하였음을 확인할 수 있었으며, 노화속도가 등숙이 거의 완료된 이후에 크게 증가하는 것으로 보아, 고온에 따른 등숙기간의 단축은 엽신의 노화 기간에 영향을 받지 않는 것으로 생각된다. This experiment was conducted to evaluate the effects of high temperature on the stem, leaf and grain of barley during the ripening period and to provide information for the development of high-temperature cultivation techniques and adaptive varieties. We used an artificial climate control facility, to provide a temperature $3^{\circ}C$ higher than the normal average temperature during the ripening stage. Although the maximum rate of starch synthesis was increased at high temperature by approximately 11%, the starch content was decreased, because the period of starch synthesis ended 4 days earlier. As in the case of starch synthesis, the expression of genes related to starch synthesis was increased at the early ripening stage in the high temperature treatment, however, the duration of expression tended to decrease rapidly. Furthermore, the partitioning rate of assimilation products in the panicle increased to a greater extent in the high temperature treatment than in the control. In contrast, for the stem and leaf, the partitioning rate of assimilation products decreased more rapidly in the high temperature treatment than in the control. On the basis of these results, it can be considered that the translocation rate of assimilation products increased to a greater extent in the high temperature treatment than in the control at the early ripening stage. These results indicate that the decrease in grain weight at high temperature during the ripening stage is attributable to an increase in the speed of starch synthesis at high temperature, but the increase in ripening speed does not compensate for the shortening of the ripening period. Finally to develop varieties and cultivation techniques suited to high temperature, we need to focus on physiological characteristics related to the duration of starch synthesis.