Effect of the physical nature of the culture medium on the metabolism of benzyladenine and endogenous cytokinins in Actinida deliciosa tissues cultured in vitro

Endogenous cytokinin and benzyladenine (BA) metabolites were studied in kiwifruit explants grown on solidified and liquid Murashige and Skoog media supplemented with BA. The same proliferation rate was observed in both media. However, in the liquid medium the release from apical dominance was faster and the growth rate was higher than on solid medium. At the same time the number of vitrified shoots increased considerably in the liquid cultures. Exogenous BA was transformed into 9-β-D-glucopyranosyl-BA ([9G]BA), 7-β-D-glucopyranosyl-BA ([7G]BA). 7-β-D-ribofura-nosyl-BA ([9R]BA) and the 5¹-monophosphate of [9R]BA ([9R-5¹P]BA). The proportion of active forms (BA, [9R-5¹P]BA and [9R]BA) in respect to total BA metabolites, was generally higher in shoots from liquid than from solid media. An exception was found at day 20 when this balance was inverted. Endogenous cytokinins in kiwifruit shoots were measured by enzyme-linked immuno sorbent assay (ELISA). The content of natural cytokinins was influenced by the levels of active forms of BA.     

猕猴桃优良株系果实生长发育规律研究

猕猴桃果实生长发育过程可分为三个时期。(1)迅速增长期:中华猕猴桃大约从4月中旬至6月上旬;美味猕猴桃大约从4月底或5月初至6月中下旬。(2)缓慢增长期:中华猕猴桃约自6月上旬至7月下旬;美味猕猴桃自6月下旬至7月下旬。(3)停滞增长期:中华猕猴桃从7月下旬至8月底或9月初;美味猕猴桃自8月上旬至9月上中旬。 中华猕猴桃优株果实可溶性固形物含量增长过程可分为四个阶段:(1)微升增长阶段,持续时间5周左右;(2)活跃增长阶段,持续2周左右;(3)迅速增长阶段,持续2周左右;(4)渐缓增长阶段。美味猕猴桃优株及绿果猕猴桃果实固形物含量增大变化的阶段性不明显。     

Pollen-pistil interaction in kiwifruit (Actinidia deliciosa; Actinidiaceae)

The pollen-pistil interaction has been examined in kiwifruit (Actinidia deliciosa). In this species a large number of seeds are produced in each fruit and a great many pollen grains germinate and grow to reach the ovules. This growth is assisted by an abundant secretion that is present all along the pistilar tract. At anthesis, the stigma is covered by a secretion where the pollen grains germinate and grow. The stylar transmitting tissue is initially rich in starch reserves, but the starch gradually disappears and, concomitantly, an abundant secretion that stains for carbohydrates appears in all of the intercellular spaces. Pollen tube growth relies on this secretion since it is depleted after pollen tube passage, while in unpollinated flowers it remains unaltered throughout the flower life-span. In the ovary a similar situation occurs. The placental surface, where the pollen tubes grow before reaching the ovules, is covered by a number of obturators. At anthesis, these obturators are rich in starch reserves and have an abundant secretion on their outer surface. As time passes, starch disappears while the secretion increases. It is in this secretion that the pollen tubes grow on their way toward the ovules. These observations are discussed in terms of the support given by the pistil to pollen tube growth to achieve the highly successful reproductive performance of this species.     

Cytokinins and fruit development in the kiwifruit (Actinidia deliciosa). II. Effects of reduced pollination and CPPU application

The significance of changes in cytokinin content during early fruit growth was examined in the kiwifruit ( Actinidia deliciosa var. deliciosa cv. Hayward). Fruit growth was modified by the reduction of seed number or by the application of the synthetic phenylurea cytokinin N -(2-chloro-4-pyridyl)- N -phenylurea (CPPU). The influence of these treatments on cell division was monitored by flow cytometry and changes in the endogenous cytokinins were measured at days 10 and 20 after anthesis, using high-performance liquid chromatography and radioimmunoassay. Total cytokinin levels appeared not to be limiting growth since the highest total cytokinin concentration was detected in unpollinated fruit, which abscised by day 25 after anthesis. However, compared with control fruit which had the highest concentration of zeatin (Z) 10 days post anthesis, Z levels were low in unpollinated fruit. It is hypothesised that an increase in Z is the critical change in cytokinin metabolism required for the initiation of cell division and fruit growth. The synthetic cytokinin CPPU promoted fruit development, but there was a decrease in the endogenous cytokinin concentration. Zeatin was not detected in CPPU-treated fruit. Cell division was reduced in unpollinated fruitlets but there was no significant difference ( P > 0.05) between the other treatments. Differences in final fruit size appeared to be due to cell expansion.     

Exploration and exploitation of soil by apple,kiwifruit, peach,Asian pear and grape roots

Measurements of root-length density (RLD) in a range of 31 apple, kiwifruit, peach, Asian pear and grape orchards were used to derive indices to describe the exploration and exploitation of rooting volumes. Orchards were of various ages and located on a range of soil types, geographic regions, management systems etc. Data were obtained from core samples of volume 1.66×10^-4 m³ randomly taken within a standard volume, determined by average planting grids, of 2 m radius centred on tree stems, and 1 m depth. Root systems were described using an exploitation index, E(), and an exploration index, E(0). E() is defined as the proportion of the soil volume which contains roots at RLD greater than or equal to some specified value, . E(0) is defined as the proportion of the soil volume which contains roots at any RLD greater than zero. These indices are dependent on sample size, as are all volumetric or soil-coring data.Estimates of E(0) for each orchard were obtained as the proportions of cores containing any RLD>O and assessed for dependence on species. Peach trees had a significantly higher value of E(0), equal to almost 1.0, compared to the other four species where E(0) was approximately 0.8 (p0.01) or less. There was also some variation with age. E(0) was lower for very young plants which had not fully occupied the sampled soil volume. Exploration indices for woody roots increased with rootstock age but otherwise did not explain large differences in E() between species for given values.For example at =0.05×10⁴ m.m^-3, E() was approximately 0.45 for peach and kiwifruit, and 0.05 for apple, Asian pear and grape, whereas at =0.5×10⁴ m.m^-3 the corresponding values were 0.1 and almost zero. Negative exponential curves relating E(), scaled by dividing by E(0), to were fitted for each of the 31 orchards. Exponents for these curves, k, were significantly smaller for kiwifruit and peaches than apples, grapes and Asian pears (p0.05), and smaller for apples than grapes and Asian pears (p0.05). A larger k implies a rapid fall-off in E() as increases. Although all five species contained zero and low RLD samples, only kiwifruit and peaches contained higher RLD values and consequently have higher mean RLD. This trend was consistent across all soils, regions, sampling dates, and plant ages.The analyses demonstrate that core sampling can give useful insights into macro-scale root-system distribution, such as the proportion of a soil volume explored and how it is exploited. If positions of core samples are noted during sampling using angular direction, depth and radial distance as spatial coordinates the method can be used to describe root-system structures.     

美味猕猴桃和软枣猕猴桃种间杂交花粉管行为和早期胚胎发生的观察

美味猕猴桃（Ａｃｔｉｎｉｄｉａ ｄｅｌｉｃｉｏｓａ Ｎｏ．２６）和软枣猕猴桃（Ａ． ａｒｇｕｔａ）杂交,观察了花粉管在花柱内的行为和早期胚胎发生,结果如下： 花粉粒在柱头的乳突细胞表面萌发,在开放型的Ｖ 形花柱道内生长,生长速度比对照的缓慢, 到达胚珠珠孔处的时间延迟５０ 到６０ ｈ。当花粉管生长到花柱基部时出现波纹状弯曲;顶端膨大或尖细;部分花粉管的直径发生变化;少数花粉管生长极不规则。花粉管中胼胝质沿管壁不规则沉积, 有的不形成胼胝质塞,或整个管壁被胼胝质所覆盖。约有２６．７４％ 的胚珠受精, 并发育成种子,其中正常种子占６８．５０％ ;败育种子占３１．５０％ ,其中约有１１．４１％ 为空瘪种子;未受精胚珠占６１．４５％ 。正常种子及其胚均较对照的小。胚发育为茄型,胚乳为细胞型,合子保持休眠十几天后开始分裂形成胚,传粉后５０ｄ 见到子叶胚     

湖南猕猴桃属植物地理分布及其区系特点研究

湖南猕猴桃属植物有２１种１３变种,主要分布于湘南和湘西两地区,经分析研究,湖南猕猴桃属植物区系有如下特点：１、种类比较丰富,是构成湖南森林植物区系林间植物的主要成分之一;２、地理成分比较复杂,种的分析显示出以中国特有分布为主的特点;３、种间、种内分化强烈;４、特有种较多;５、与邻近地区猕猴桃属植物区系的关系密切,最后,作者对湖南猕猴桃属植物的起源问题进行了分析和推测。     

Sex determination in Actinidia. 1. Sex-linked markers and progeny sex ratio in diploid A. chinensis

 First results from two strategies aimed at elucidating the genetics of sex in the dioecious genus Actinidia Lindl. (Actinidiaceae) support the hypothesis that sex-determining genes are localized in a pair of chromosomes which, although cytologically indistinguishable, function like an XX/XY system with male heterogamety. A. chinensis Planch., a close relative of the kiwifruit [A. deliciosa (A. Chev.) CF Liang et AR Ferguson], has diploid and tetraploid races. Bulk segregant analysis to find sex-linked markers revealed two markers whose inheritance patterns in three diploid families showed X and Y linkage and indicated that the male is the heterogametic sex. Some recombination between the markers and the sex-determining loci was also demonstrated. Sex ratios in 12 progenies from controlled crosses varied around 1:1, as expected for an XX/XY system. Received: 20 December 1995 / Revision accepted: 24 April 1997     

危害猕猴桃的新害虫——端齿材小蠹

【目的】本文描述了首次在贵州猕猴桃上发生的一种害虫——端齿材小蠹Anisandrus apicalis(Blandford)。【方法】通过对当地修文县谷堡乡平滩村猕猴桃病树上小蠹的观察和形态研究,进行分类和鉴定。【结果】此次发现的端齿材小蠹是贵州省境内第一次报道,也是首次发现在猕猴桃病枝上发生。本文提供了该小蠹的分类和鉴别,附有相关近缘种的形态特征图和检索表,并介绍了其寄主和分布,以及在贵阳修文猕猴桃的危害和发生等情况。【结论】此次发生在猕猴桃上的端齿材小蠹是贵州省境内的首例,本文结果可以为当地植物检疫和猕猴桃种植管理提供参考。虽然此次端齿材小蠹在猕猴桃上发生,但是未发现其会直接为害猕猴桃健康植株,需要在将来进行深入的实验调查。