| Summary: | 碩士 === 國立嘉義大學 === 農藝學系研究所 === 104 === Although Sugarcane (Saccharum officinarum L.) is a dryland crop, however, it has a high water requirement and sensitive to drought stress. In cooperation with Taiwan Sugar Corporation, this study Compared drought tolerance among four Taiwanese cultivars, ROC8, ROC10, ROC16 and ROC23, at seedling stage by soil culture and tissue culture. The zymography and gene expression analysis of antioxidant enzymes were further determined under drought stress. The results showed that ROC10 have the strongest sprouting vigor at the early stage after transplanting, but no significant differences in plant height among varieties after two weeks. Under drought stress condition for 3 weeks, shoot growth was decreased, leaves turned wilting and yellowing, and chlorophyll fluorescence (Fv/Fm) was decreased. After one month of drought treatment, all ROC10 plants died, where as 30% of the ROC23 seedlings survived. In addition, it showed deeper roots and robust root system of ROC23 under drought treatment, indicating were that ROC23 is more tolerant to drought stress. Similar results observed in MS liquid medium supplemented with 15% polyethylene glycol (PEG-6000) among four varieties. ROC10 observed drought sensitive where as the ROC8 showed tolerant drought stress. Analysis of antioxidant enzyme activity between these two contrast cultivars showed that the phenotype stayed green and newly plantlets propagated in ROC8 under MSBN medium containing 6% sorbitol for one month, However, all explants showed browning and no newly sprouting bud produced in ROC10. Zymography analysis showed that the drought tolerance cultivar, ROC8, possessed higher enzyme activities of glutathione reductase (GR1/GR3), catalase (CAT) and ascorbate peroxidase (APX). Compared to ROC10 the expression levels of ScPOD1 gene in seedily were significantly higher in ROC8 under sorbitol treatment. At present study, we have success fully established the screening system for drought tolerance at bud sprouting and seedling stage of sugarcane. The possible relationship between drought tolerance and antioxidant enzymes activity were also clarified. The results could be very useful for further drought tolerance breeding in sugarcane.
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