Physiology and genetics of self-incompatibility in Echinopsis chamaecereus (Cactaceae)

The self-incompatibility (SI) system of a geophytic cactus (Echinopsis chamaecereus Friedrich & G. Rowley) was examined in a series of experiments. Pollination tests indicated that E. chamaecereus is an obligate outbreeding species with a functional SI system. Incompatible matings were characterized by stylar inhibition of pollen tube growth and lack of fruit set. Two S₁ seedlings were recovered when plants of one clone were exposed to 42°C for 16 h and flowers were selfed immediately after incubation. The two S₁ seedlings and the parental (S₀) clone were crossed in a full diallel. Results were consistent with a one-locus, gametophytic SI system with two different S alleles. Disturbed segregation at isozyme locus Lap-1 was attributed to close linkage with the S locus (recombination frequency = 11±8%). This is the second report of close linkage between Lap-1 and S in the Cactaceae. Recevied: 1 February 2001 / Revision accepted: 13 March 2001     

Disproportionately large ecological role of a recently mass-culled flying fox in native forests of an oceanic island

Human-wildlife conflicts pose a growing threat to many species worldwide and require increasingly innovative and multi-disciplinary resolutions. Because of their apparent simplicity and political appeal, lethal approaches like culling are often favoured, decisions to cull are typically poorly supported by scientific evidence and the limitations and drawbacks of culls minimised. As natural habitats decline and fruit crop production expands, fruit-eating bats in the Old World (family Pteropodidae) are increasingly in conflict with fruit farmers. This conflict is exemplified on Mauritius where the government has implemented two mass culls of a threatened flying fox (Pteropus niger) since 2015 in response to fruit-grower concerns. The culls and illegal hunting reduced the bat population by >50%. In this context, we sought to investigate the ecological role and service provided by the targeted flying fox through seed dissemination to gauge what may be lost as the species becomes rarer or extinct. We randomly sampled the woody native community in six of the best-preserved moist-to-wet native forests of Mauritius using 90 plots of 100 m² each and identified and measured the stem size of all woody plants ≥1 cm in diameter. Species were classified by whether their fruits occur in the diet of the flying fox in an exclusive, confirmed or likely manner and we assumed that fruit consumption is equivalent to potential seed dissemination. The relative importance of these three categories to the total woody plant community was then quantified as the proportion of species richness, stem density and basal area (as a surrogate of biomass) that they represent. We also investigated whether the main traits of species (seed size, fruit size, and maximum stem diameter) vary among bat-dispersal categories and differ from those of species whose fruits are not currently known to be eaten by the flying fox. On average, although about a quarter of the native woody species (24.6%) have fruits confirmed as eaten and seeds dispersed by the flying fox, these species comprise about half (53.1%) of the stems sampled and the majority (63.1%) of the basal area of native woody plant in the island’s native forests. About half of that latter biomass figure comprises species for which the flying fox is the exclusive native vertebrate frugivore and seed disperser. Plants disseminated by the flying fox are typically large trees with large fruit and seeds. These trees are often key components of the canopy, therefore fulfilling structural engineer roles that provide resources and conditions for the survival of many forest species. The flying fox plays a disproportionally large ecological role in maintaining forest structure and biodiversity in the long-term. Consequently, lethal approaches to the conflict with fruit-farmers threaten not only an endangered species, but ecological processes central to the viability of native forests. Our findings highlight the importance of including the ecological costs of culling in decision-making processes intended to resolve human-wildlife conflicts.     

Curculionid beetles in aborted flower buds and immature fruits of <Emphasis Type="Italic">Ceiba</Emphasis><Emphasis Type="Italic">pentandra</Emphasis> (Bombacaceae)

We determined the incidence of curculionid beetles of the genus Lonchophorus on aborted and not aborted flower buds and developing fruits of the tree Ceiba pentandra in southeastern Costa Rica. Beetle larvae were found in reproductive parts of all trees sampled trees. The frequency of beetle larvae was greater in aborted buds and immature fruits. A positive correlation between larvae development and flower bud development indicates that female oviposition occurred in an early flower developmental stage and time until bud abortion is variable. Weevil herbivory could be considered as one of the main factors that cause flower bud and fruit abortion in C. pentandra.

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Resumen Determinamos la incidencia de curculiónidos del género Lonchophorus en botones florales y frutos inmaduros tanto abortados como no abortados en el árbol Ceiba pentandra en el SE de Costa Rica. Las larvas de curculiónidos fueron encontradas en todos los árboles muestreados. La frecuencia de larvas fue mayor en botones y frutos abortados. Una correlación positiva entre el desarrollo larval y el desarrollo del botón indica que la oviposición ocurre en una fase temprana de este y que el tiempo hasta el aborto es variable. La herbivoría por larvas de curculiónidos puede ser uno de los factores más importantes en el aborto de botones y frutos inmaduros en C. pentandra.

     

授粉方式对铁皮石斛种质座果及种子萌发的影响

为进行铁皮石斛(Dendrobium officinale)的良种选育和种苗生产,对46个铁皮石斛种质进行人工授粉试验,研究了不同授粉方式的授粉成功率、座果率和种子的萌发能力。结果表明,4种授粉方式的授粉成功率明显不同,不同种质间的授粉成功率可达100%,且座果率普遍较高。只有31.3%的种质可以成功自花授粉,且座果率相差较大。同株异花授粉和种质内异株授粉的成功率和座果率均介于上述二者之间。授粉后所得种子的萌发率和萌发速度在4种授粉方式间也呈现与授粉成功率和座果率一致的趋势。这表明在铁皮石斛种质中存在自交不亲和现象,因此以不同产地来源的铁皮石斛种质为亲本进行人工授粉,可大大提高授粉的成功率和座果率,以及后代种子的萌发能力。     

热水处理对金柑果实采后腐烂及生理特性的影响

金柑是果皮和果肉同食的柑果类型,对采后处理要求极为严格。该研究以金柑(Fortunella crassifolia)为材料,研究了其经30、40和50℃热水浸泡后果实的腐烂率、失重率、可溶性固形物、硬度、有机酸、细胞渗透率以及抗氧化酶活性变化。结果表明:经30℃热水处理5 min的果实失重率高于对照,而经40℃和50℃处理的果实失重率低于对照或差异不显著。经热水处理的果实总酸含量略低于对照,可溶性固形物含量在18%上下波动且差异不显著。热水处理可提高果实硬度,降低贮藏前期果实细胞渗透率以及贮藏过程中果实过氧化物酶和超氧化物歧化酶活性,激发过氧化氢含量升高,可有效降低贮藏过程中金柑果实腐烂率,但不同采收期的金柑所需的热水处理温度和时间不同。对于1月初采收的果实,处理时间为5 min或10 min可降低果实腐烂率;2月初采收的果实,40℃或50℃热水处理10 min可有效降低果实腐烂率;3月初采收的果实,当处理温度达到50℃,处理时间达到10 min,才可有效降低果实腐烂率,且对果实品质没有明显的不利影响。     

辣椒果色相关研究进展

辣椒是全球广泛种植的高经济价值茄科作物之一。在辣椒的各个经济性状中果色是最直观的重要性状之一。由于辣椒果色丰富多彩,目前已经成为研究果色遗传的一种模式植物。辣椒青熟果色与老熟果色存在差异且遗传、分子调控机制不同,本文将就辣椒这两个时期果色的遗传及分子调控机制研究做一个综述。     

Complete mitochondrial genome of Bactrocera ritsemai (Insecta: Tephritidae) and phylogenetic relationship with its congeners and related tephritid taxa

Bactrocera ritsemai is a dacine fruit fly found in Indonesia. We report here the complete mitogenome of this fruit fly from Lombok, Indonesia determined by Illumina MiSeq sequencing and its phylogenetic relationship with its congeners and related tephritid taxa. The whole mitogenome of B. ritsemai had a total length of 15,927 bp, comprising 37 genes – 13 protein-coding genes (PCGs), 2 ribosomal ribonucleic acid (rRNA) and 22 transfer ribonucleic acid (tRNA) genes – and a control region (D-loop). Of the PCGs, 6 (atp6, cob, cox2, cox3, nad4, nad4l) had ATG start codon, 4 (nad2, nad3, nad5, nad6) had ATT, and one each had ATA (nad1), GTG (atp8) and TCG (cox1). Seven PCGs (atp6, atp8, cox2, cox3, nad2, nad4l, nad6) had TAA stop codon, 3 (cob, nad3, nad4) had TAG, and 3 had incomplete stop codon (cox1 – TA; nad1, nad5 – T). The TΨC-loop of tRNA was absent in trnF while trnS1 lacked the DHU-loop. Phylogenetic analysis based on 15 mt-genes (13 PCGs + 2 rRNA genes) indicated B. ritsemai forming a sister group with B. umbrosa and the subgenus Bactrocera was monophyletic. The genera Bactrocera and Zeugodacus were monophyletic while the subfamilies Dacinae and Tephritinae were paraphyletic. A broader taxa sampling of the Tephritidae is needed to better elucidate the phylogenetics and systematics of the tribes and subfamilies of tephritid fruit flies.     

濒危植物黄梅秤锤树野生与迁地保护种群的果实性状比较

黄梅秤锤树(Sinojackia huangmeiensis J.W.GeX.H.Yao)是我国120个极小种群野生植物之一。本研究运用独立样本t检验和贝叶斯方差分析比较黄梅秤锤树仅存的1个迁地保护种群和1个野生种群的环境条件、果实形态性状和果实元素含量。结果显示,迁地保护种群和野生种群同处于亚热带地区,年均温和年降水量基本一致。迁地保护种群的果实长度、宽度和长宽比均显著大于野生种群;2个种群在果实重量上呈现相同的趋势,但差异不显著。迁地保护种群在果实形态性状方面,种内变异程度不低于野生种群;土壤和果实中绝大多数元素(Ni元素除外)的含量在2个种群间的变化规律不一致。研究结果表明该物种的迁地保护基本成功,但存在迁地保护种群较小的问题。     

Management of Fruit Flies (Diptera: Tephritidae) of the Most Perishable Fruits

We investigated to minimize the dependency on the use of chemicals and thus develop safe and environmental friendly control program for the most perishable fruits i.e., apple,‘ber’, guava and mango. Our findings on the composition of fruit fly species reveal that Bactrocera dorsalis was dominant on apple (33.96% existence), Corpomya incompleta on‘ber’(51.91% existence) and Bactrocera zonata on guava (49.62% existence) and mango (74.66% existence). The correlation between population and infestation percentage was non‐significant in apple orchards, whereas positive and highly significant in between population and infestation, as well as on the cumulative basis in‘ber’, guava and mango orchards during 1998‐1999. Hoeing, baiting and methyl eugenol were statistically equal resulting about 77% decrease in infestation. The maximum control of 91.68% was observed where all four‐control operations including Dipterex® were integrated together. Weather factors, when computed together, had maximum effect on population fluctuation and infestation with rainfall contributing the major role. For guava fruits, the months of August (14.06A individuals/trap/day) and September (13.81A individuals/trap/day) were important, resulting in maximum infestation percentage of 10.76 to 14.74%, respectively.     

Changes in tonoplast protein and density with the development of pear fruit

Protoplasts isolated from pear fruit at the end of the cell‐division stage, 30 days after flowering (DAF), had already formed a large central vacuole and the vacuole occupied most of the protoplast. The changes in protein composition and density of the tonoplast (vacuolar membrane) were investigated during fruit development. After a linear sucrose density gradient centrifugation, the distribution of tonoplasts at 30 and 48 DAF was broad and began to narrow with further fruit development. This suggests that the tonoplast of young fruit is heterogeneous and becomes homogeneous with fruit development. The apparent density of the tonoplast at 30 DAF was approximately 1.12 g ml⁻¹; it decreased with fruit development and was finally 1.09 g ml⁻¹ in mature fruit. The phospholipid amount on the basis of tonoplast protein was 0.80 mg mg⁻¹ at 30 DAF. It increased with fruit development, and finally reached 7.49 mg mg⁻¹. This result indicates that the decrease in the density of the tonoplast was caused by the increase in the ratio of phospholipid to membrane protein. The protein composition of the tonoplast at each stage was quite different. The level of polypeptides of 94, 70, 61, 52, 48 and 41 kDa was low in young fruit and high in the middle or later stages of fruit development. In contrast, the level of a 76‐kDa polypeptide was high in young fruit and decreased with fruit development. Although their functions are still unclear, these tonoplast proteins may play important roles in fruit development.