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Starch is one of the most important storage carbohydrates in plants. Kiwifruit typically accumulate large amounts of starch during development. The fruit retain starch until commercial maturity, and its postharvest degradation is essential for consumer acceptance. The activity of genes related to starch degradation has, however, rarely been investigated. Based on the kiwifruit genome sequence and previously reported starch degradation-related genes, 17 novel genes were isolated and the relationship between their expression and starch degradation was examined using two sets of materials: ethylene-treated (100 µL/L, 20 °C; ETH) vs. control (20 °C; CK) and controlled atmosphere stored (CA, 5% CO2 + 2% O2, 0 °C) vs. normal atmosphere in cold storage (NA, 0 °C). Physiological analysis indicated that ETH accelerated starch degradation and increased soluble solids content (SSC) and soluble sugars (glucose, fructose and sucrose), while CA inhibited starch reduction compared with NA. Using these materials, expression patterns of 24 genes that may contribute to starch degradation (seven previously reported and 17 newly isolated) were analyzed. Among the 24 genes, AdAMY1, AdAGL3 and AdBAM3.1/3L/9 were significantly induced by ETH and positively correlated with starch degradation. Furthermore, these five genes were also inhibited by CA, conforming the likely involvement of these genes in starch degradation. Thus, the present study has identified the genes with potential for involvement in starch degradation in postharvest kiwifruit, which will be useful for understanding the regulation of kiwifruit starch content and metabolism.

The viability and life span of pollen were evaluated by TTC (2,3,5-triphenyl tetrazlium chloride) and the peroxidase solution, the stigma receptivity were estimated by benzidine-H2O2 method and the fruiting characteristics were investigated. The results showed that (1) Anoectochilus roxburghii and A. formosanus appeared the same up-and-down trend of the pollen viability, increased and then decreased. The storage temperature and storage time had significant impact on the pollen viability. With the extension of storage time, the pollen activity decreased. 4 degrees C refrigerator storage may be extended the pollen vitality. (2) The stigma had receptivity in 1st day and reached the highest level in the 4th day after blooming. A. roxburghii lost receptivity in the 8th day while A. formosanus lost receptivity in the 10th day after blooming. (3) The different pollination had significant impact on seed setting rate. The seed setting rate of artificial cross-pollination was higher than that of the artificial self-pollination. Collecting pollen in the 3rd day and carrying out artificial cross-pollination in the 4th day after blooming can significantly improve seed setting rate. The results provided technical assurance for A. roxburghii and A. formosanus breeding of new varieties and seed breeding.

Harvested fruits of three Chinese bayberry (Myrica rubra Sieb.Zucc.) varieties, i.e. "Biqi", "Dongkui" and "Zaodamei" which were divided into three maturities (designated as "Immature", "Mature" and "Ripe") according to fruit colour, were investigated for the changes in climacteric pattern and quality at 20 degrees C. Respiration rate and ethylene production rate were underwent 3 h during 48 h storage. Our result showed that both Immature and Mature fruits underwent rises in respiration and ethylene production rate of a climacteric rise, but no such peak was observed in Ripe fruit (Fig.1 and 2). Total soluble solids (TSS) contents increased with maturity and decreased over the 48 h at 20 degrees C (Fig.3); titratable acidity (TA) decreased with the maturity and throughout 48 h storage period (Fig.4). In "Biqi" Chinese bayberry fruit, PAL activities increased in Immature and Mature fruit, but, it decreased in Ripe fruit during the storage period; the change in Cy-3-Glu with fruit ripening was consistent with PAL activities (Table 1); there was significant positive correlation between CIRG (Color Index for Red Grape) values and Cy-3-Glu content (r=0.96**). This study provides important information on the postharvest behaviour of Chinese bayberry fruit, and our result shows that it is climacteric fruit.

According to the conserved amino acid sequence from ethylene receptors in other plants, a pair of degenerate primers was designed and a 657-bp cDNA fragment encoding an ethylene receptor fruit was obtained by RT-PCR from ripening kiwifruit (Actinidia deliciosa cv. Bruno) (Fig. 1). The cDNA fragment encoding 219 amino acids was named Ad-ETR1, and its sequences shared high similarity at both nucleotide and polypeptide level with the sequences from the plants of Arabidopsis, tomato, persimmon, avocado, citrus and peach (Fig. 2, Table 1). Northern blot analysis indicated that the levels of Ad-ETR1 mRNA increased during kiwifruit ripening and reached peak at 144 h after treatment, then dropped immediately. The expression of Ad-ETR1 could be induced by ethylene treatment, while acetylsalicylic acid (ASA) treatment inhibited its expression (Fig. 4). In consistency with the changes of Ad-ETR1 mRNA, ethylene or ASA treatment had marked effects on the kiwifruit ethylene production and fruit softening (Fig. 3). The significance of these results was discussed.