Libertyʼ) were monitored in the fi eld over a diurnal course at about 3 months after full bloom. Compared with leaves, sun-exposed peel of apple fruit had much lower photosystem II operating effi ciency at any given photon fl ux density (PFD) and a larger xanthophyll cycle pool size on a chlorophyll basis. Zeaxanthin (Z) level increased with rising PFD in the morning, reached the highest level during midday, and then decreased with falling PFD for the rest of the day. At noon, Z accounted for >90% of the xanthophyll cycle pool in the fruit peel compared with only 53% in leaves. Effi ciency of excitation transfer to PSII reaction centers (Fv'/Fm') was negatively related to the level of Z in fruit peel and leaves throughout the day. In fruit peel, the antioxidant enzymes in the ascorbate-glutathione cycle, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) showed a diurnal pattern similar to that of incident PFD. In contrast, the activities of APX and GR in leaves did not change signifi cantly during the day although activities of both MDAR and DHAR were higher in the afternoon than in the morning. In both fruit peel and leaves, superoxide dismutase activity did not change signifi cantly during the day; catalase activity showed a diurnal pattern opposite to that of PFD with much lower activity in fruit peel than in leaves. The total ascorbate pool was much smaller in fruit peel than in leaves on an area basis, but the ratio of reduced ascorbate to oxidized ascorbate reached a maximum in the early afternoon in both fruit peel and leaves. The total glutathione pool, reduced glutathione and the ratio of reduced glutathione to oxidized glutathione in both fruit peel and leaves also peaked in the early afternoon. We conclude that the antioxidant system as well as the xanthophyll cycle responds to changing PFD over the course of a day to protect fruit peel from photooxidative damage.

介绍了一种从木本植物组织中获得高质量RNA 的快速、简单和高效的核酸提取方法。该方法是基于核酸的二氧化硅捕获，避免了使用苯酚、氯仿等有机溶剂。利用该方法从樱桃组织中提取的总RNA 用RT 2PCR技术检测PDV，PNRSV 均获得成功。从感病植株的一年生枝的叶片、韧皮部及芽组织中扩增出了预期的目的片段，即172和449bp，而健康组织中无此扩增带。该法提取的总RNA用于RT 2PCR技术检测，其敏感性至少与商业出售的Qiagen RNeasy提取试剂盒相当，但简单经济。

通过对原产于不同地区的51个杏品种的性器官发育和结实性的系统调查和测定，结果表明，1. 花粉大小和形状少数虽有一定差异，而绝大多数品种相似，品种问花粉萌发率尽管差异很大，但所有品种均为花粉可育型；2. 大多数品种不完全花百分率很高，自然授粉结实率很低，其主要原因是雌蕊败育；3. 品种间不完全花百分率与花粉萌发率呈正相关；4. 欧洲生态群品种与中国生态群品种比较花粉大小和形状基本相似，而花粉萌发率和不完全花百分率低，自然授粉结实率高；5. 欧洲生态群品种能白花结实，而中国生态群品种均为自花不实品种。

Approximately 80 days after full bloom, well-exposed fruit on the south part of the canopy of mature Liberty/M9 apple (Malus domestica Borkh.) trees were randomly assigned to one of the following two treatments. Some fruits were turned about 180◦ to expose the original shaded side to full sun, whereas the rest served as untreated controls. On days 0, 1, 2, 4, 7 and 10 after treatment, fruit peel samples were taken from the original shaded side of the treated fruit and both the sun-exposed side and the shaded side of the control fruit at midday, to determine photosynthetic pigments, enzymatic and non-enzymatic antioxidants. Maximum photosystem II (PSII) efficiency, measured as Fv/Fm (maximum fluorescence) of chlorophyll fluorescence at pre-dawn, was higher in the shaded side than the sun-exposed side of the control fruit. Fv/Fm of the original shaded side decreased sharply after 1 day exposure to full sun, and then gradually recovered to a similar value of the sun-exposed side of the control fruit by day 10. The shaded side of the control fruit had much lower xanthophyll cycle pool size, conversion and antioxidant enzymes and also soluble antioxidants of the ascorbate–glutathione cycle than the sun-exposed side. Xanthophyll cycle pool size of the original shaded side increased in response to full sun exposure, reaching a similar value of the sun-exposed side by day 10. Almost all the xanthophyll cycle pool was converted to zeaxanthin and antheraxanthin starting from the first day of exposure to full sun. In contrast, chlorophyll content decreased whereas lutein or neoxanthin content remained unchanged. In response to full sun exposure, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase and total pool size and reduction state of both ascorbate and glutathione, all increased to the corresponding values found in the sun-exposed side of the control fruit over a 10-day period. It is concluded that both xanthophyll cycle and the ascorbate-glutathione cycle in the original shaded side are up-regulated in response to full sun exposure to minimize photo-oxidative damage and contributes to its acclimation to full sun.

在45℃下对猕猴桃一年生盆栽苗进行2，4，6，8，10h的高温胁迫，测定高温胁迫下叶绿素含量、相对膜透性、丙二醛（MDA）含量、抗氧化酶活性和抗氧化剂含量及热激蛋白等生理生化指标。结果表明，高温胁迫下叶绿素含量下降，相对膜透性增大，MDA 含量增加； 超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）、抗坏血酸还原酶（APX）活性均在胁迫初期呈上升趋势，随处理时间延长，活性下降；随胁迫时间延长，还原型谷胱甘肽（GSH） 含量先升后降，抗坏血酸（ASA）含量总体呈下降趋势，谷胱甘肽还原酶（GR）和脯氨酸含量一直呈上升趋势；热激蛋白（HSP）在高温下被诱导。