枳属的核型研究

枳属(Poncirus Raf.)是Swingle于1913年从柑桔属(Citrus L.)中独立出的一个单种属,原产于我国,类型繁多,是柑桔类的一种主要砧木,具有树势矮化,抗寒,抗裙腐病、流胶病及线虫病,丰产、稳产、提早结实等优点。与其它柑桔类杂交,其后代均具很强的抗性。此外,该属未成熟果实中含有的枳苷(ponciridin)为著名中药材。     

真正柑桔果树群植物的分支学研究

本文用相容性分析方法(Compatability snalysis)分析了真正柑桔果树群(芸香科Rutaceae-柑桔亚科Aurantioideae-柑桔族(Citreae)-柑桔亚族(Citrinae)植物内各属间的分支学关系。给出了建立在7个相容性性状组成的最大族所决定的分支图。性状极性的确定使用了外群法。结果表明,柑桔属(Citrus L.)和多蕊桔属(Clymenia Swing)构成一个单系类群,他们的姐妹群是金柑属(Fortunella Swing.)。被认为起源于中国的3个属,柑桔属(Citrus)、金柑属(Fortunella)和积属(Poncirus Raf.)并未构成一个单系类群。本文还利用分支关系分析和讨论了真正柑桔果树群的种系发生关系。     

利用DNA片段测序方法探究枳属和富民枳的分类地位

富民枳(Poncirus polyandra)属于芸香科(Rutaceae)枳属(Poncirus Raf.)。自发表以来,分类地位一直备受争议,其中在Flora of China中认为富民枳为柑橘杂交种(Poncirus polyandra),把枳属归并于柑橘属(Citrus)。该研究选取枳属的富民枳、枳(Poncirus trifoliata)及柑橘属下8个种共10个种47个个体作为研究材料,以九里香(Murraya exotica)为外类群,利用3个叶绿体片段(trn L-trn F、trn S-trn G、rbc L)、ITS片段和1个单拷贝核基因(Chr 5)数据构建系统发育树,探究枳属和富民枳的分类地位。结果表明:基于3个叶绿体片段数据构建的最大似然树(ML)和贝叶斯树(BI)的拓扑结构基本一致,10个物种聚为两大分支,即柑橘属的8个物种聚为一大分支,富民枳和枳聚为另一大分支。其中,富民枳所有个体聚为一小单系分支,枳的所有个体聚为一小单系分支,支持枳属和富民枳独立存在。2个核DNA片段数据结果显示,枳属的两个种与柑橘属的8个物种聚在一个大分支里,无法确立枳属的单系地位,但富民枳的9个个体聚在一起,暗示富民枳在遗传上是一个独立的类群。综上研究认为,无论是叶绿体DNA数据还是核DNA数据均支持富民枳是一个独立的物种,但核DNA数据不支持枳属成立。     

富民枳的分类地位及其在进化中的作用研究——叶片同工酶证据

富民枳(Poncirus polyandra S.Q.Ding et al.)是分布于云南省富民县的一个新枳属类型。在形态上,它不同于普通枳(P.trifoliata Raf.)。富民枳为常绿类型,子房10室,花瓣5—9,花丝35—43,一年开花2—3次。通过对富民枳、普通枳、金柑属及柑桔属的叶片谷氨酸草酰乙酸转氨酶(GOT)、6-磷酸葡萄糖变位酶(PGM)、6-磷酸葡萄糖异构酶(PGI)、过氧化物酶(PX)、苹果酸酶(ME)、超氧化物歧化酶(SOD)以及四唑氧化酶(TO)同工酶的比较后发现,富民枳独具Sod-1-M基因,具有稀有的To-2-R基因,在To-1及Got-3位点上,存在无效基因,这些结果表明,富民枳能够以种的地位存在于枳属中。在进化过程中,富民枳可能是联结枳属与柑桔属的“桥梁”。     

部分柑桔属及其近缘属Giemsa C-带带型研究

本文应用Giemsa显带技术研究了枳属(Poncirus)、金柑属(Fortunella)和柑桔属(Citrus)16个分类群的染色体。枳属以末端带和着丝点带为主,金柑属与柑桔属主要以末端带为主;统计分析了各分类群每对染色体及全组染色体的异染色质含量,并列出其带型公式;探讨了金柑属的分类学地位;赞同把柚(C.grandis)作为柑桔属的基本种之一;根据异染色质含量的变化对柑桔属的带型演化进行了讨论。     

中国枳属一新种

枳Poncirus trifoliata(L.)Rafin.原产我国秦岭淮河南北,古代有“橘踰淮为枳”之说,但据近代记载主要分布于长江流域,北可至山东青岛,南至广西、广东,而以华中一带栽培最盛。云南未见有报道。七十年代中期开展云南富民县柑桔资源调查中,根据当地群众提供的情况,发现枳属的一个新种,报道如下。     

用组织培养法繁殖柑桔

继代培养了两年半的锦橙(Citrus sinensis Osbeck)×枳(Poncirus trifoliata Raf.)无性胚的愈伤组织通过下列三个阶段恢复了分化植株的能力:(1)在N_6培养基+BA(0.25ppm)+NAA(0.1ppm)+ME(1,000 ppm)上形成芽原基;(2)在1/2 MT培养基+BA(5ppm)+IAA(0.5ppm)+CH(500ppm)上芽原基分化为茎芽,进而形成茎;(3)将带叶的小茎扦插于MT培养基+NAA(1ppm)上,诱导生根,形成完整的小植株。根尖染色体检查,初步证明这些小植株是2n=18的二倍体。     

柑橘MYB15基因的克隆与表达分析

采用电子克隆和RT-PCR方法从柚(Citrus maxima(Burm.)Merr.)、枳(Poncirus trifoliata(L.)Raf.)和柠檬(Citrus limon(L.)Burm.f.)实生苗中克隆了3个MYB蛋白基因,分别命名为CmMYB15、PtMYB15和ClMYB15;并用实时定量qRT-PCR技术检测了该基因在脱落酸(ABA)、干旱、低温和高盐胁迫处理下的时空表达。结果显示,CmMYB15、PtMYB15和ClMYB15的cDNA序列全长分别为994、992、988 bp,分别编码267、266、265个氨基酸,且编码的氨基酸序列N端均含有2个串联的不完全重复的MYB DNA-binding结构域,由此推测该3个基因均属于R2R3亚类;MYB15基因均能被ABA、干旱、低温和高盐胁迫诱导表达,且在柚、枳和柠檬中存在表达差异。本研究表明柚CmMYB15、枳PtMYB15和柠檬ClMYB15是MYB基因家族成员,可能在柑橘响应非生物胁迫过程中起到一定的作用。     

柑桔与金柑的器官发生研究

国内外关于芸香科植物的器官发生研究较多集中于柑桔属,其次是金柑属与枳属,这与它们具有重要经济价值有关。业已证明柑桔属(Citrus)中的16个种的未受精的珠心能分化不定胚;金柑属(Fortunella)的金弹、枳属(Porcirus)的枳的株心也能分     

柑桔胚的人工培养

为了提高柑桔杂交育种效率和探讨胚培养在柑桔生产上应用的可能性,我们研究了锦橙(Citrus sinensis Osbeck)×枳(Poncirus trifoliata Raf.)的杂交种子胚培养技术。证明:怀特(White)培养基 IAA(1ppm) CH(600ppm)和 MT 培养基 GA(1ppm)能使第五个小胚(E 胚)萌发成苗;在 MT 培养基 2,4-D(0.7ppm) BA(0.23ppm)上,有些胚先形成愈伤组织,然后从原有的胚中生根出苗。将此愈伤组织切下,移入含 BA(5ppm)和 IAA(1ppm)的MT 培养基中,则能出芽成茎,但不能形成根。再移入只含 NAA(1ppm)的 MT 培养基中,则能分化出根,形成完整的小植株。为研究合子胚分布和克服珠心胚干扰杂交育种工作提供了合适的技术。     

The role of frugivorous birds in fruit removal and seed germination of the invasive alien Cotoneaster franchetii in central Argentina

Many invasive plant species have fleshy fruits that are eaten by native frugivorous birds which disperse their seeds and may facilitate their germination, playing an important role in plant invasion success. The fleshy‐fruited shrub Cotoneaster franchetii (Rosaceae) is an important invasive alien in the mountainous regions of central Argentina. To determine the role of avian frugivorous in fruit removal of this species, we conducted a frugivore exclusion experiment including bagged and unbagged branches in 75 plants of C. franchetii. At the end of the dispersal period, we compared the percentage of missing fruits (removed by birds + naturally dropped) in unbagged branches with the percentage of naturally dropped fruits in bagged branches. To assess whether any mechanism acting on seeds during their passage through bird guts (de‐inhibition by pulp removal and/or seed scarification) affects seed germination of this species, we compared percentage and speed of germination among seeds obtained from faeces of the native frugivorous Turdus chiguanco, from manually de‐pulped fruits, and from intact fruits. The percentage of missing fruits per shrub in unbagged branches was significantly higher than the percentage of naturally dropped fruits in bagged branches, suggesting that frugivorous birds play an important role in fruit removal of C. franchetii in the study area. Seeds from bird faeces and from manually de‐pulped fruits germinated in higher percentage and faster than seeds from intact fruits. Germination percentage and speed of seeds from manually de‐pulped fruits were significantly higher than those of gut‐passed seeds. These results indicate that T. chiguanco increases and accelerates seed germination of C. franchetii through pulp removal, but not through seed scarification. Overall, our findings indicate that native frugivorous birds facilitate the dispersal and germination success of C. franchetii, likely playing an important role in its invasion throughout the mountainous region of central Argentina.     

Does attraction to frugivores or defense against pathogens shape fruit pulp composition?

Fruit traits evolve in response to an evolutionary triad between plants, seed dispersers, and antagonists that consume fruits but do not disperse seeds. The defense trade-off hypothesis predicts that the composition of nutrients and of secondary compounds in fruit pulp is shaped by a trade-off between defense against antagonists and attraction to seed dispersers. The removal rate model of this hypothesis predicts a negative relationship between nutrients and secondary compounds, whereas the toxin-titration model predicts a positive relationship. To test these alternative models, we evaluated whether the contents of nutrients and secondary compounds can be used to predict fruit removal by mutualists and pathogens in 14 bird-dispersed plants on a subtropical island in São Paulo state, southeastern Brazil. We selected eight to ten individuals of each species and prevented fruit removal by covering four branches with a net and left fruits on four other branches available to both, vertebrate fruit consumers and pathogens. The persistence of ripe fruits was drastically different among species for bagged and open fruits, and all fruit species persisted longer when protected against seed dispersers. We found that those fruits that are quickly removed by vertebrates are nutrient-rich, but although the attack rate of pathogens is also high, these fruits have low contents of quantitative defenses such as tannins and phenols. Thus, we suggest that the fruit removal rate by seed dispersers is the primary factor selecting the levels of fruit defense. Likewise, nutrient-poor fruits have low removal of seed dispersers and low probability of attack by pathogens. These species retain ripe fruits in an intact condition for a prolonged period because they are highly defended by secondary compounds, which reduce overall attractiveness. However, this strategy might be advantageous for plants that depend on rare or unreliable dispersers.     

The persistence of ripe fleshy fruits in the presence and absence of frugivores

A trade-off between antimicrobial defences and palatability to dispersers may place limits on fruit persistence in nature. The retention times of ripe fruits on 34 wild plant species under natural conditions (unbagged persistence) and when fruits had been bagged with nylon mesh to exclude frugivores (bagged persistence) were compared in Hong Kong, China (22°N). Bagged persistence is a measure of the effectiveness of fruit defence while unbagged persistence is an inverse measure of attractiveness to vertebrate frugivores. Bagged fruits persisted significantly longer than unbagged fruits in 30 species, with half the species tested persisting for more than 2 months. There was a significant positive relationship between the median persistence times of bagged and unbagged fruits, suggesting that species with a high resistance to microbial infection are also less attractive to frugivores. Both bagged and unbagged fruits persisted significantly longer at lower temperatures. There was a significant positive relationship between bagged persistence time and fibre content of the fruit pulp, but no significant relationships between unbagged persistence and the six fruit traits tested (diameter, pulp as a percentage of fruit fresh weight, and lipid, total soluble carbohydrate, nitrogen and fibre as percentages of pulp dry weight). Mechanical damage significantly decreased the bagged persistence time for half of the species. Although some fruits decayed or dried up while attached to the plant, fruits of 53% of the species remained visually attractive until they fell off.     

Characteristics of fleshy fruits in southeast Alaska: phylogenetic comparison with fruits from Illinois

Over 30 species of fleshy-fruited plants are found in southeast Alaska. In this paper we examine traits such as plant growth form, phenology, fruit color, seed load, pulp dry weight, and pulp nutrient content and compare them with those of fruits from central Illinois. Two comparative methods (continuous time Markov model and phylo-Anova) were used to compare both qualitative and quantitative traits between the two regions. Although fleshy-fruited plants from SE Alaska appear to be predominantly shrubs or herbs in contrast to central Illinois, where trees and vines tend to be more common, no significant differences among growth forms were found when accounting for plant phylogeny. In SE Alaska, most fruits mature in August and September, whereas most fruits mature later in the autumn in Illinois. Red fruits are more common in Alaska than in Illinois, where blue-black fruits predominate. Alaskan fruits have a significantly greater seed load than fruits in Illinois, while pulp dry weight does not differ between the two regions. Although the proportion of sugars and lipids in the pulp was not statistically different between the two regions, total reward of the pulp (estimated as the absolute amount of sugars plus twice the amount of lipids, as lipids provide about twice the energy of sugars) was greater in Alaskan than in Illinois fruits. Neither phylogenetic constraints nor selection by frugivores appear to account fully for the regional distribution of fruit characteristics.     

Patterns of frugivory in the columnar cactus Pilosocereus leucocephalus

In the frugivory networks of many arid and semi‐arid Mesoamerican ecosystems, columnar cacti act as keystone species that produce fruits with a high content of water and nutrients attractive to numerous vertebrates. The aim of this investigation was to assess the fruit removal patterns of two guilds of frugivores on the fruits of the woolly torch Pilosocereus leucocephalus. We assessed fruit pulp removal in two ways: by estimating the consumption of seeds given the amount of pulp removed per visit and by estimating the percentage of pulp removal over time. We put exclosures on unripe, intact fruits to keep frugivores from removing material. Once ripe, we removed the exclosures and tracked animal visitation of 69 fruits using camera traps. We obtained a total of 2,162 hr of footage (14:47 hours of them with effective pulp removal). The highest number of visitors is that of diurnal species (n = 12, all birds) versus only four nocturnal (three bats, one rodent). The most effective species in pulp removal are birds. Bats play a modest role in frugivory of this cactus. The significance of this work is twofold: (a) birds and bats consume the fruit pulp of this cactus and likely disperse its seeds, and (b) although bats rank high in pulp removal effectiveness, birds as a guild far outweigh their importance in this system, as they are not only more frequent but also remove more pulp and seeds. Both groups are known to be important in cacti seed dispersal, and our findings are essential in understanding the population dynamics of the woolly torch and in elucidating its seed dispersal ecology.     

Xylem-to-Phloem Transfer of Organic Nitrogen in Young Soybean Plants

Xylem-to-phloem transfer in young vegetative soybean (Glycine max [L.] Merr.) plants (V4 stage) was identified as the difference in the distribution of [¹⁴C]inulin, a xylem marker, and [¹⁴C]aminoisobutyric acid (AIB), a synthetic amino acid, fed via the transpiration stream. Since [¹⁴C]AIB was retained in the stem to some extent, whereas [¹⁴C]inulin was not, the distribution of these marker compounds in each leaf was expressed as a percentage of the total [¹⁴C] radioactivity recovered in the foliage. The developing third trifoliolate was a consistent and reliable indicator of xylem-to-phloem transfer. The phloem stream provided to the developing trifoliolate up to fourfold the relative proportion of solute received from the xylem stream; this was markedly reduced by increased light intensity and consequently water flow through the xylem. Evidence from heat girdling experiments is discussed with respect to the vascular anatomy of the soybean plant, and interpreted to suggest that direct xylem-to-phloem transfer in the stem, in the region of the second node, accounted for about one-half of the AIB supplied to the developing trifoliolate, with the remainder being provided from the second trifoliolate. Since AIB is not metabolized it seems likely that rapid transfer within the second trifoliolate occurred as direct veinal transfer rather than indirect cycling through the mesophyll. This study confirmed that xylem-to-phloem transfer plays a major role in the partitioning of nitrogen for early leaf development.     

Effect of Pulp Cell Number and Assimilate Availability on Dry Matter Accumulation Rate in a Banana Fruit [ Musa sp. AAA group 'Grande Naine' (Cavendish subgroup)]

Fruit position on the bunch (inflorescence) is an importantpart of variability in banana fruit weight at harvest, as fruitsat the bottom of the bunch (distal fruits) are approx. 40% smallerthan those at the top (proximal fruits). In this study, therespective roles of cell number and cell filling rate in thedevelopment of pulp dry weight are estimated. To this end, thesource/sink ratio in the plant was altered at different stagesof fruit development. Leaf shading (reducing resource availability),bunch bagging (increasing sink activity by increasing fruittemperature), and bunch trimming (decreasing sink size by fruitpruning), applied once cell division had finished, showed thatthe pulp filling rate depends on resource availability. Bunchbagging and bunch trimming were also carried out before theend of cell division to estimate the role of pulp cell numberin the development of pulp dry weight. A sampling method wascalibrated to evaluate pulp cell number from the digestion ofa fixed portion of the pulp in a solution of chromic and nitricacids. A relationship was found between pulp cell number andfruit length at the end of cell division. It was observed thatpulp cell number is a determining factor in pulp dry weightvariability within a bunch. On the other hand, the cell fillingrate was identical for all fruits in the bunch and was influencedby the source/sink ratio. A Michaelis-Menten relationship wasinvoked to relate the cell filling rate in a bunch to the source/sinkratio during bunch filling. Copyright 2001 Annals of BotanyCompany Banana fruit, Musa sp., fruit growth, cell number, cell filling rate, source/sink ratio, temperature     

Directed vertebrate-mediated seed dispersal of a fleshy-fruited amaryllid in a heterogenous habitat

Most plants with fleshy fruits have seeds that are ingested by animals, but a less well-understood mode of seed dispersal involves fleshy fruits containing seeds that are discarded by frugivorous animals because they are too large or toxic to be ingested. We studied the seed dispersal biology of Haemanthus deformis, an amaryllid lily species found in a mosaic of bush clumps in a grassland matrix in South Africa. We asked whether seed dispersal is directed in and among bush clumps and whether germination and survival are greater for seeds dispersed to bush clumps than for those dispersed into grassland. Using camera trapping, we found that fruits are consumed mainly by birds and rodents. The pulp was removed from the seeds which were then discarded without ingestion. While many seeds were dispersed close to the parent plant, most (c. 78.5%) were dispersed further than 1 m away from the parent plant. Longer distance dispersal resulted mainly from birds flying off with fruits in their bill or from rodents engaging in scatter-hoarding behavior. Seedling survival was most successful within bush clumps as compared to grasslands and shade was identified as a primary requirement for seedling survival. Seeds from which the fruit pulp had been removed germinated faster than those in intact fruits. Haemanthus deformis deploys a system of directed seed dispersal, whereby both birds and rodents contribute to the dispersal of seeds within patchy bush clumps that are favorable for seedling survival.     

The impact of consumption of fruit by vertebrate and invertebrate frugivores on the germination success of an Australian rainforest seed

Abstract The consumption of fruits by vertebrates and invertebrates can be both advantageous or detrimental to the survival of the seeds they contain. This study investigated the effect of fruit size and consumption of fruit pulp by rodents and beetles on the germination of the seeds of Acmena graveolens, a tropical rainforest canopy tree found in northern Australia. As fruit size increased, germination success and the amount of pulp remaining on the fruits was greater. When beetles were absent, germination success was highest when most of the pulp was removed by rodents, suggesting that they removed an inhibitor of germination. When beetles were present, germination success did not differ significantly across pulp categories, so beetles apparently enhanced germination in seeds with little pulp initially removed, possibly by further removal of fruit pulp. In this study, both rodents and beetles enhanced germination success of A. graveolens seeds by consumption of fruit pulp. Acting as facilitators of germination is a relatively unusual role for both these frugivores that are generally considered to act as seed predators or (in the case of rodents) dispersers.