桑树肌动蛋白actin基因全长序列的克隆与分析

肌动蛋白在植物的各种生理活动中起着重要作用,是研究基因表达与调控模式的内标参考。通过染色体步移方法获得了桑树肌动蛋白actin基因1612bp的序列,该基因CDS长1312bp(GenBank登录号:HM623866),编码377个氨基酸残基,与水稻、葡萄等的同源基因的序列一致性在90%以上。基因内含子的数目及其在基因组上的位置也与水稻、葡萄等的相似。对来自不同物种的24个肌动蛋白基因进行聚类分析的结果显示,基因被分为ClassⅠ和ClassⅡ两个明显的亚群。     

Shoot-tip abscission and adventitious abscission of internodes in mulberry (Morus alba)

In mulberry ( Morus alba L. cv. Shin-ichinose), shoot-tip abscission following the cessation of apical growth could be induced in different internodes, depending on the vigour of the shoot and its apex and other internal and external factors. In the lateral, short shoots of 1-year-old stems of low-pruned trees, the apical growth cessation and shoot-tip abscission (May–June) resulted primarily from the dominance of the upper, long shoots and intense competition among laterals along the stem. Decapitation of the laterals, before abortion of their apices took place (early May), readily caused adventitious abscission of the distal internode. Similar decapitation-induced, adventitious abscission of the distal internode of the upper, long shoots of 1-year-old stems of pruned trees also occurred (May–September), demonstrating that the abscission itself is not directly associated with photoperiod. In May and June, decapitation induced abscission primarily in parallel with or after sprouting of lateral buds and shoot elongation, while in July, August and September, the abscission was induced by decapitation and independently of sprouting. Shoot (stem) orientation positively affected the abscission, which is related to gravimorphic effects on buds and shoots on the lower and lateral sides of the horizontally trained stem. These results suggest that the vigour of shoots and apices is an important determinant of growth and apex abscission in mulberry.     

The sexual dimorphism displayed by the roots of mulberry (Morus alba) saplings depends on the sex of the neighboring plants

桑树幼苗根系表现出的性别二态性取决于相邻植株的性别 雌雄异株植物通常呈现性别二态性,但其雌株和雄株的根系性状和养分吸收如何响应相邻植株 的性别变化尚不清楚。本研究以中国广泛栽培的雌雄异株植物桑树(Morus alba)为试验对象,在水培环境 下,采取雌-雌、雄-雄和雌-雄3种组合种植模式进行试验。植株生长3个月后,分别测定雌雄植株根系的解剖结构、形态、营养浓度和生物量。研究结果表明,在水培环境中,与同性相邻相比,当桑树雄株与异性相邻时,其根系木质部变小,根和径生物量减少,根系中N、P、K浓度增加。相比,当桑树雌株与异性相邻时,其根系木质部变大,细根长度、表面积和体积以及根系δ¹³C和N、P、K浓度增加。雌雄植株根系δ¹³C和N、P、K浓度的变化与根系性状的改变有关。这些结果表明,相邻植株的性别影响了雌雄桑树根系解剖结构和形态。同时,雌雄植株对相邻植株性别改变的响应呈现性别二态性,这种二态性响应影响了雌雄植株水分利用效率和营养吸收。这些发现对于理解森林和自然系统中其它雌雄异株物种的种群动态变化具有重要意义。     

Apical control of lateral bud development and shoot growth in mulberry (Morus alba)

Measurements of changes in the degree of dominance by upper laterals over lower ones in coppice shoots (1-year-old stems) of 12-year old low- pruned stumps of mulberry ( Morus alba L. cv. Shin-ichinose) were made by removal of upper stem sections (pruning) or of lateral buds (debudding.) before spring bud burst, as part of a study of the factors involved in dominance relationships between the developing buds and elongating shoots. Besides inhibition of lower laterals by the upper, leading shoots, there was evidence for mutual inhibition (competition) of neighboring laterals along the stem. Thus in stems in which every other bud, or 4 out of every 5 buds were removed, there was a delay in growth cessation of lower laterals and their greater elongation than in controls. Such competition was seen to exist even between the uppermost and sub-terminal laterals, since the former elongated more in the absence of the latter.
In contrast to high and middle pruned stems, the delay in sprouting of the buds in low-pruned stems resulted in limited elongation of the shoots from such buds. This inhibition was removed when all the stems on a stump were pruned to the same length, suggesting that it was associated with intact stems with actively growing laterals. Patterns of regrowth of the short shoots (lower laterals) after summer pruning (middle-pruned) depended on the extent of removal of other stems with vigorously growing, upper laterals. These results demonstrate that both acropetal and basipetal influences are important in bud and shoot dominance relationships.     

Endosperm culture: a novel method for triploid plant production

Triploid nature of endosperm is the characteristic feature of angiosperms and is formed as a result of triple fusion. Present review discusses the morphogenic response and production of triploid plantlets by endosperm culture. Both mature and immature endosperm used for culture initiation responded differently in cultures. A key factor for the induction of cell divisions in mature endosperm cultures is the initial association of embryo but immature endosperms proliferate independent of embryo. In almost all the parasitic angiosperms, endosperm shows a tendency of direct differentiation of organs without prior callusing, whereas in autotrophic taxa the endosperm usually forms callus tissue followed by differentiation of shoot buds, roots or embryos. The endosperm tissue often shows a high degree of chromosomal variations and polyploidy. Mitotic irregularities, chromosome bridges and laggards are the other important characteristics of endosperm tissues. Triploids are usually seed sterile and is undesirable for plants where seeds are commercially useful. However, in cases where seedlessness is employed to improve the quality of fruits as in banana, apple, citrus, grapes, papaya etc. the induction of triploid plants would be of immense use. Triploid plants have more vigorous vegetative growth than their diploid counterparts. Hence, in plants where the vegetative parts are economically useful, triploids are of good use. This review focuses on the progress achieved so far in endosperm culture to obtain triploid plants.     

Dormancy and spring development of lateral buds in mulberry (Morus alba)

Patterns of spring development of lateral buds of mulberry (Morus alba L. cv. Shin-ichinose) coppice shoots on 11-year-old low-pruned stumps varied in response to girdling, pruning and arching. The erect controls showed a weak acrotonic (apex-favoring) growth habit, in which the majority of the buds, including the basal ones, sprouted and elongated in mid- and late April, and hence there was a prolonged imposition of dominance on the upper laterals in mid- and late May. In contrast, early spring girdling or pruning enhanced the activity of the upper buds of the proximal (lower) halves of the girdled stems or of the pruned stems, resulting in considerable dominance of the laterals from such buds in late April. Arching markedly inhibited buds on the under side of the arched stems, leading to poor shoots. By late April, the buds on the adaxial (upper) side readily grew into new vertical shoots, which dominated over the lateral ones. When studied by a multiple-node-cutting test, increased length of segments of post-dormant mulberry stems was accompanied by decreased bud activity of the segments and by decreased breaking ability of the lower buds within the segments, suggesting the importance of roots in the weak acrotonic habit of the erect stem in spring. By contrast, the acropetal influences of the attached stems can in part affect dominance relationships, perhaps mediated through competition for factors translocated from the roots. Continuous basal applications of abscisic acid inhibited bud break and shoot growth of the postdormant stem segments, but these inhibitory effects could be reversed by applied gibberellic acid A₃ (GA₃). Two phases of lateral bud dormancy in erect mulberry coppice shoots were identified. The first was characterized by a smaller breaking capacity in the upper buds than in the lower ones and hence by a basitonic (base-favoring) gradient in bud growth potential. The second phase corresponded to a restoration of these capabilities in the upper buds and to a change towards a linear gradient in bud growth potential, with disappearance of the dormant condition, in February and March. This gradient change during dormancy release may represent the physiological basis for the weak acrotonic habit of erect mulberry stems in spring.     

In vitro induction of tetraploidy in mulberry (Morus alba L.)

A high frequency of tetraploidy was induced in mulberry (Morus alba L.) through apical bud treatment under in vitro conditions. Apical buds from in vitro-grown plants were treated with three different concentrations (0.05, 0.1 and 0.2%) of colchicine in MS medium for 24 h. Tetraploidy at a frequency of 39.4±4.8% was obtained using 0.1% colchicine, whereas the frequency of tetraploidy was significantly reduced to 16.7±2.3% when 0.2% colchicine was used. Morphological, histological and cytological evidence indicated a phenotypic and genomic similarity of in vitro- with ex vitro-induced tetraploids. Rooting of tetraploids was on basal medium containing 2.6 μm NAA. The recovery of tetraploids was 80.8% more efficient using the in vitro method instead of the ex vitro method. The use of the same colchicine medium for up to 4 weeks with additional explants was found to be equally effective for the induction of tetraploidy. Received: 6 January 1997 / Revision received: 6 October 1997 / Accepted: 12 December 1997     

Comparative proteomic analysis provides new insights into mulberry dwarf responses in mulberry (Morus alba L.)

Mulberry dwarf (MD) is a serious infectious disease of mulberry caused by phytoplasma. Infection with MD phytoplasma results in stress phenotypes of yellowing, phyllody, stunting, proliferation, and witches' broom. Physiological and biochemical analysis has shown that infection with MD phytoplasma causes an increase in soluble carbohydrate and starch content, and a decrease in the net photosynthesis rate, carboxylation efficiency, and pigment content of leaves. Furthermore, damage to the chloroplast ultrastructure was detected in infected leaves. To better understand the pathogen‐stress response of mulberry (Morus alba L.) to MD phytoplasma, we conducted a comparative proteomic analysis using 2‐DE of infected and healthy leaves. Among 500 protein spots that were reproducibly detected, 20 were down‐regulated and 17 were up‐regulated. MS identified 16 differentially expressed proteins. The photosynthetic proteins rubisco large subunit, rubisco activase, and sedoheptulose‐1,7‐bisphosphatase showed enhanced degradation in infected leaves. Based these results, a model for the occurrence mechanism of MD is proposed. In conclusion, this study provides new insights into the mulberry response to MD phytoplasma infection.     

Production of triploid plants of papaya by endosperm culture

Triploid papaya (Carica papaya) plants were obtained by immature endosperm culture. Visible callusing of the endosperm occurred 21 days after initiation of cultures. A continuously growing callus was observed and a maximum of 68.7% of callus induction frequency was obtained when immature endosperm with embryo was cultured on Murashige and Skoog (MS) medium containing 6.0 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 2.5 μM α-naphthaleneacetic acid (NAA) and 4.0 μM 6-furfurylamino purine (Kn). Shoot buds were produced when the callus was subcultured on a medium supplemented with 6-benzyladenine (BA) or thidiazuron (TDZ) along with NAA. Shoots were detached from the callus and transferred to the elongation medium supplemented with indole-3-acetic acid (IAA) and BA. The combination of 3.0 μM IAA and 1.5 μM BA was the best in terms of the number of cultures (93.8%) showing axillary shoot proliferation. The addition of 2.0 μM indole-3-butyric acid (IBA) to the 1/2 MS medium was most effective at inducing root formation with 90% of the shoots developing four to five roots. Healthy rooted plantlets were transferred to pots containing sterilized bed soil and perlite (3:1) mixture in the greenhouse and 78% of the micropropagated plants survived transplantation. The leaves from endosperm-derived plants showed larger stomata and more chloroplasts in guard cells than that from the parent plants. Over 75% of the endosperm-derived plants were triploid with chromosome number 2n = 3x = 27.     

Ultrastructural and immunochemical features of the cell wall sac formed in mulberry (Morus alba) idioblasts

A peculiar inward growth, named a “cell wall sac”, formed in mulberry (Morus alba) idioblasts, is a subcellular site for production of calcium carbonate crystals. On the basis of ultrastructural observations, a fully expanded cell wall sac could be divided into two parts—an amorphous complex consisting of multi-layered compartments with multiple fibers originating from the innermost cell wall layer, and a peripheral plain matrix with fiber aggregates. Immunofluorescent localization showed that low and highly esterified pectin epitopes were detected at the early stages of development of the cell wall sac, followed by complete disappearance from the both parts of fully enlarged mature sac. In contrast, the xyloglucan epitope remained in the compartment complex; this was supported by the observation that the xyloglucan epitope labeled with immuno-gold particles is found on fibers in the complex part.     

桑树叶肉原生质体培养再生植株

近年来,木本植物原生质作诱导再生植株的研究越来越受到国内外学者关注。但在林木树种中,迄今成功的种类仍然不多,在文     

Cryopreservation of white poplar (Populus alba L.) by vitrification of in vitro-grown shoot tips

 Shoot tips from in vitro-grown, cold-hardened stock plants of white poplar (Populus alba L.) were successfully cryopreserved at –196  °C by one-step vitrification. After preculturing at 5  °C for 2 days on hormone-free MS medium containing different sucrose concentrations, and loading for 20 min with 2 m glycerol and 0.4 m sucrose, shoot tips were treated with the PVS2 vitrification solution and plunged directly into liquid nitrogen. Best survival rate (90%) was obtained when shoot tips were precultured on 0.09 m sucrose, hormone-free MS medium, vitrified by exposure to PVS2 solution for 60 min at 0  °C and, following cryopreservation, rewarmed at 40  °C and washed in 1.2 m sucrose solution for 20 min. Regrowth was improved by plating shoot tips on a gelled MS medium containing 1.5 μm N⁶-benzyladenine plus 0.5 μm gibberellic acid, while shoot rooting was achieved on MS medium containing 3 μm indole-3-butyric acid. Following this procedure, almost 60% rooted shoots were obtained from cryopreserved shoot tips. Received: 1 February 1999 / Revision received: 3 May 1999 · Accepted: 21 May 1999     

High-speed pollen release in the white mulberry tree, Morus alba L

Anemophilous plants described as catapulting pollen explosively into the air have rarely attracted detailed examination. We investigated floral anthesis in a male mulberry tree with high-speed video and a force probe. The stamen was inflexed within the floral bud. Exposure to dry air initially resulted in a gradual movement of the stamen. This caused fine threads to tear at the stomium, ensuring dehiscence of the anther, and subsequently enabled the anther to slip off a restraining pistillode. The sudden release of stored elastic energy in the spring-like filament drove the stamen to straighten in less than 25 μs, and reflex the petals to velocities in excess of half the speed of sound. This is the fastest motion yet observed in biology, and approaches the theoretical physical limits for movements in plants. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. An erratum to this aticle is available at .     

Dosage effects in the endosperm of diplosporous apomictic Tripsacum (Poaceae)

 Imprinting in the endosperm of angiosperms, a phenomena by which expression of alleles differs depending on whether they originate from the male or female parent, has been shown to explain most failure of interploidy or interspecific crosses in plants. Because of imprinting, seeds develop normally only if a specific dosage is represented in the endosperm, with the relative contributions of genomes in the ratio of two maternal doses to one paternal dose (2m:1p). In Tripsacum, a wild relative of maize, all polyploids reproduce through the diplosporous type of apomixis. Diplospory results from meiotic failure in megasporocytes that develop into eight-nucleate unreduced female gametophytes. The male gametophytes remain unaffected. Flow cytometry was used to determine ploidy levels in the endosperm of both apomictic and sexual Tripsacum accessions. In both cases, fertilization appeared to involve only one sperm nucleus. Therefore, endosperm of apomictic Tripsacum develops normally even though the ratio of genomic contributions deviates from the normal 2m:1p ratio. Ratios of 2:1, 4:1, 4:2, 8:1 and 8:2 were observed, depending on both the ploidy level of the parents and the mode of reproduction. Thus, specific dosage effects are seemingly not required for endosperm development in Tripsacum. These findings suggest that evolution of diplosporous apomixis might have been restricted to species with few or no imprinting requirements, and the findings have strong implications regarding the transfer of apomixis to sexually reproducing crops. Received: 17 February 1997 / Revision accepted: 7 July 1997     

辽西北风沙地区不同无性系桑树抗旱性

为选育适合辽西北风沙地区生长的优良桑树品种,以沈阳农业大学选育的"沈桑1号"(SS)、辽宁省阜新市彰武县优株(ZW)、吉林省通化市集安县桑树优株(JS)3种优质桑树无性系以及东北主栽品种"龙桑1号"(LS)为试验材料,通过测定不同无性系桑树在干旱胁迫下的叶片光合色素含量、光响应曲线、不同光强对气体交换参数的影响以及光系...     

Occurrence of Hop Stunt Viroid in Mulberry (Morus alba) in Lebanon and Italy

The presence of Hop stunt viroid (HSVd) was detected using RT‐PCR and Northern blot hybridization in five of 60 samples from symptomless mulberry trees (Morus alba) collected in Italian and Lebanese orchards in July 2010. Infection levels were c. 10% in Lebanese and 8% in Italian samples. Nucleotide alignments showed that sequences of the mulberry HSVd isolates shared 95–96% identity with those of the same viroid occurring elsewhere. In a phylogenetic tree, mulberry HSVd isolates clustered together with those of HSVd‐citrus, regardless of their geographical origin. This is the first report of infection in mulberry trees by HSVd.     

Autonomous endosperm induction by in vitro culture of unfertilized ovules of Viola odorata L.

Autonomous endosperm was found in unfertilized ovules of V. odorata L. cultured on MS medium supplemented with 2,4-D as a sole growth regulator or on media with 2,4-D and BAP or kinetin. Frequency of endosperm induction was approximately 9% in ovules analyzed. The induction rate depended mainly on genotype of the donor plant, and to lesser degrees, on floral stage, flower series and medium type. Multinuclear endosperms consisting of 10–37 nuclei were found in ovules after as few as 4 days of culture. In some ovules at this stage, the egg cell and two polar nuclei were present. The process of endosperm degeneration began after 3 weeks of culture. In some ovules, degenerating autonomous endosperm was observed up to the 7th week. Parthenogenetic development of egg cells or apogamy did not accompany autonomous endosperm, supporting the hypothesis of independent pathways for embryo and endosperm development. Received: 1 December 1998 / Revision accepted: 6 April 1999