Bacterial canker was first observed on the kiwifruit cv. 'Hort16A (Actinidia chinensis)' in Jeju Province, Korea, in spring 2006. Die back or blight on young canes, often with red-rusty exudation on canes or trunks, and dark brown irregular spots surrounded with yellowish halos on leaves are the typical symptoms. These symptoms closely resemble those caused by Pseudomonas syringae pv. actinidiae on the kiwifruit cv. 'Hayward (Actinidia deliciosa)'. A sudden outbreak and rapid spread of the bacterial canker resulted in the death of severely infected vines and eradication of completely devastated orchards of the kiwifruit cv. 'Hort16A'. Contaminated pruning shears and climatic conditions appear to have been responsible for the sudden outbreak and rapid spread of the epidemics on the kiwifruit cv. 'Hort16A' vines. The causal bacterium was isolated from diseased vines of the kiwifruit cv. 'Hort16A' and identified as P. syringae pv. actinidiae, which is the same bacterial pathogen responsible for cankers on the kiwifruit cv. 'Hayward' by morphological, cultural, physiological and biochemical, molecular and pathogenicity analyses.

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The overall disease incidence of postharvest fruit rots of kiwifruit (Actinidia deliciosa) in Korea averaged 32%, but the incidence ranged from 5% to 68% in the orchards surveyed. The percentage of kiwifruit showing internal and external symptoms were 21.9% and 4.9%, respectively, and an additional 5.2% of the kiwifruit showed both internal and external symptoms. Botryosphaeria dothidea and Diaporthe actinidiae cause ripe rot and stem-end rot, respectively, and were identified as the major postharvest pathogens with average isolation rates of 83.3% and 11.9%. Incidence of the postharvest fruit rots was closely correlated with ripening temperatures favourable to the mycelial growth of the major pathogens. Postharvest fruit rots occurred at all ripening temperatures 11°C and maximum disease incidence was observed at 29°C. No mycelial growth of B. dothidea and D. actinidiae occurred on potato dextrose agar plates under 11°C and the optimum temperature ranges for mycelial growth of the pathogens were 26-35°C and 26-29°C, respectively. The optimum kiwifruit ripening conditions for minimising damage from the postharvest fruit rots were a 20-day ripening at 17°C. Intensive application of fungicides just before or after the rainy season is conducted to control postharvest fruit rots in kiwifruit orchards of Korea. Benomyl WP and thiophanate-methyl WP, registered as preventive fungicides against postharvest fruit rots, are usually applied 5-6 times at 10-day intervals beginning in early June in the kiwifruit orchards. Tebuconazole WP, iprodione WP, and flusilazole WP were selected as alternative fungicides to prevent emergence of fungicide-resistant strains and reduce the number of fungicide applications. The optimum spray programme for controlling postharvest fruit rots was four applications at 10-day intervals from mid June for tebuconazole WP, iprodione WP, and flusilazole WP, compared with five applications for benomyl WP and thiophanate-methyl WP.

A xylanase gene, xynX, of Clostridium thermocellum had one thermostabilizing domain (TSD) between the signal peptide sequence and the catalytic domain (CD). The TSD of a truncated xylanase gene, xynX′TSD-CD, was transpositioned from the N terminus to the C terminus of the CD by overlapping PCRs, and a modified product, xynX′CD-TSD, was constructed. XynX′TSD-CD had a higher optimum temperature (70°C versus 65°C) and was more thermostable (residual activity of 68% versus 46% after a 20-min preincubation at 70°C) than the one without the TSD, XynX′CD. However, the domain-transpositioned enzyme, XynX′CD-TSD, showed a lower optimum temperature (30°C) and thermostability (20%) than XynX′CD. Both XynX′TSD-CD and XynX′CD-TSD showed significantly higher binding capacity toward xylan than XynX′CD, and the domain transposition did not cause any change in the binding ability. XynX′TSD-CD and XynX′CD-TSD also showed considerable binding to lichenan but not to carboxymethyl cellulose and laminarin. XynX′TSD-CD and XynX′CD-TSD had higher activities for insoluble xylan than XynX′CD, while XynX′CD was more active against soluble xylan than XynX′TSD-CD and XynX′CD-TSD. These results indicate that the TSD of XynX has dual functions, xylan binding and thermostabilization, and the domain should also be classified as a xylan-binding domain (XBD). The binding capacity of the XBD was not affected by domain transpositioning within the gene