Nitric oxide in fruit ripening: Trends and opportunities

Monitoring ethylene is crucial in regulating post-harvest life of fruits. The concept of nitric oxide (NO) involvement in antagonizing ethylene is new. NO mediated physiologies casted through regulation of plant hormones are widely reported during developmental and stress chemistry having no direct link with ripening. Research in NO biology and understanding its interplay with other signal molecules in ripening fruits suggest ways of achieving greater synergies with NO applications. Experiments focused at convincingly demonstrating the involvement of NO in altering ripening-related ethylene profile of fruits, would help develop new processes for shelf life extension. This issue being the central theme of this review, the putative mechanisms of NO intricacies with other primary and secondary signals are hypothesized. The advantage of eliciting NO endogenously may open up various biotechnological opportunities for its precise delivery into the target tissues.     

淫羊藿属7种植物的雌蕊及果实形态描述的订正

采用了野外观察和光学显微技术对淫羊藿属（Epimedium L.）7种植物的雌蕊及果实的形态结构进行了研究。结果表明：7种植物的心皮数目为1个,胎座类型为边缘胎座,果实类型为蓇葖果。比较了《中国植物志》等文献的记载,订正了文献对7个种＂侧膜胎座＂或＂蒴果＂的记述,并对淫羊藿属的相应特征提出观点。     

Response of ‘Clausellina’ Satsuma mandarin to 3,5,6-trichloro-2-pirydiloxyacetic acid and fruitlet abscission

The application of the synthetic auxin 3,5,6-trichloro-2-piridyloxyacetic acid (3,5,6-TPA) isopropyl ester at the onset of cell enlargement stage, significantly thinned fruitlets in ‘Clausellina’ Satsuma mandarin. The magnitude of the response was related to the concentration applied, increasing the percentage of abscised fruit with higher concentrations, which was up to 70% at 25 mg l⁻¹. The magnitude of the response also depended on the organ subject to treatment, abscission being greater when applied to the leaves rather than to fruit. Results suggest that a photosynthetic disorder was responsible for a reduction in fruit growth rate, triggering abscission mechanisms producing ethylene and abscission.     

Identification of novel small RNAs in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>)

To date, the majority of plant small RNAs (sRNA) have been identified in rice, poplar and Arabidopsis. To identify novel tomato sRNAs potentially involved in tomato specific processes such as fruit development and/or ripening, we cloned 4,018 sRNAs from tomato fruit tissue at the mature green stage. From this pool of sRNAs, we detected tomato homologues of nine known miRNAs, including miR482; a poplar miRNA not conserved in Arabidopsis or rice. We identified three novel putative miRNAs with flanking sequence that could be folded into a stem-loop precursor structure and which accumulated as 19-24nt RNA. One of these putative miRNAs (Put-miRNA3) exhibited significantly higher expression in fruit compared with leaf tissues, indicating a specific role in fruit development processes. We also identified nine sRNAs that accumulated as 19–24nt RNA species in tomato but genome sequence was not available for these loci. None of the nine sRNAs or three putative miRNAs possessed a homologue in Arabidopsis that had a precursor with a predicted stem-loop structure or that accumulated as a sRNA species, suggesting that the 12 sRNAs we have identified in tomato may have a species specific role in this model fruit species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

绢蒿属8种植物果实微形态特征及其分类学意义

为寻找绢蒿属系统学的新证据,应用解剖镜和扫描电镜对我国8种绢蒿属植物的果实微形态特征进行了比较观察。结果表明,绢蒿属8种植物果实形状相似性较高,呈倒卵形或长倒卵形,直或稍弯曲;果脐圆形,常偏向一侧;顶端中央均可见花柱残留物,边缘具衣领状环;果实表面纹饰为搓板状和不规则皱褶纹饰。这些果实微形态特征中,果实的表面纹饰具有一定的差异,特别是次级结构,可作为绢蒿属植物区分种的参考性状之一。     

Evaluation of Eupatorium cannabinum Linn. oil in enhancement of shelf life of mango fruits from fungal rotting

Essential oils extracted from 17 higher plants belonging to different families were screened against Botryodiplodia theobromae and Colletotrichum gloeosporioides causing stem end rot disease and anthracnose disease in mango respectively. The essential oil of Eupatorium cannabinum was found to be fungitoxic in nature against both the mango-rotting fungi. Eupatorium oil was standardized through physico-chemical and fungitoxic properties. Gas Liquid Chromatography (GLC) analysis of the oil led to the identification of 16 components, which represented 77.97% of the oil. Germacrene D (16.11%) was found to be the major component. The oil showed a broad fungitoxic spectrum and was recorded to be more efficient than some synthetic fungicides. The oil also showed an inhibitory effect on pectinase and cellulase enzymes. The oil enhanced the shelf life of mango fruits by protecting from fungal rotting when tested as a fumigant. The LD₅₀ of Eupatorium oil was found to be 22.01 ml/kg body weight on mammalian mice.     

Isolation and characterization of the gene encoding a chitin synthase with a myosin motor-like domain from the edible basidiomycetous mushroom, <Emphasis Type="Italic">Lentinula edodes</Emphasis>, and its expression in the course of fruit-body formation

We isolated and characterized the genomic and complementary DNAs encoding a chitin synthase from an edible basidiomycetous mushroom, Lentinula edodes. The gene (which we designated Lechs1) contains a large open reading frame encoding a polypeptide of 1937 amino acid residues. The open reading frame is interrupted by 14 small introns (49–116 bp). The gene product (LeChs1) consists of a myosin motor-like domain in its N-terminal half and a chitin synthase domain in its C-terminal half, analogous to the class V and VI chitin synthases of other filamentous fungi. Phylogenetic analysis demonstrated that LeChs1 is classified into class VI chitin synthases. Southern blot analysis indicated that Lechs1 is a single-copy gene per haploid genome and that L. edodes has no other highly homologous chitin synthase genes. Northern blot analysis revealed that Lechs1 is expressed throughout the whole stages of fruit-body formation of L. edodes, but its expression level gradually declines in a fruit body-maturation-dependent manner with highest expression in vegetative mycelia and fruit body at the early stage of maturation (immature fruit body). This is the first report on the isolation and characterization of the gene encoding a chitin synthase with a myosin motor-like domain from basidiomycetes.     

Expression of phytoene synthase gene (Psy) is enhanced during fruit ripening of Cara Cara navel orange (Citrus sinensis Osbeck)

Citrus is an important fruit crop as regards accumulation of carotenoids. In plant carotenoid biosynthesis, phytoene synthase gene (Psy) plays a key role in catalyzing the head-to-head condensation of geranylgeranyl diphosphate molecules to produce colorless phytoene. In the present paper, we reported the phytoene contents determination and characterization of Psy during fruit ripening of “Washington” navel orange and its red-fleshed mutant “Cara Cara”. Results showed that phytoene was exclusively accumulated in peel and pulp of “Cara Cara”. Although phytoene was observed accumulating with fruit ripening of “Cara Cara”, the contents in pulp were 10 times higher than those in peel. The isolated two Psy cDNAs were both 1520 bp in full length, containing 436 deduced amino acid residues, with a different amino acid at 412th. Genomic hybridization results showed that one or two copies might be present in “Cara Cara” and “Washington” genomes. During “Cara Cara” and “Washington” fruit coloration, expression of Psy was observed to be up-regulated, as revealed by tissue specific profiles in the flavedo, albedo, segment membrane and juice sacs. However, Psy expression in albedo of “Cara Cara” was higher than that in “Washington”, as evidenced by phytoene accumulation in the peel.     

Fruit removal efficiency and success: influence of crop size in a neotropical treelet

The reproductive success of animal-dispersed plants is closely linked to the number of seeds that they are able to disperse. The fruit crop size hypothesis states that a plant with large fruit crop size will attract more dispersers than a plant with a smaller fruit crop, which may result in more seeds being dispersed from the foremost. In this study, we experimentally examined the effect of crop size and other factors on primary seed dispersal in a neotropical shrub/tree, Casearia corymbosa (Flacourtiaceae). We used two predictive variables of reproductive success, which produce an accurate picture of seed dispersal ratio: fruit removal efficiency (proportion of a fruit crop removed by frugivores) and fruit removal success (relative contribution of each individual tree to the number of fruits removed in the population). We established two levels of fruit crop size at the C. corymbosa individuals, using plants with large (150 fruits) and small crops (50 fruits). We found that individual plants with larger crops had significantly higher values of fruit removal efficiency (92.6%) and success (5%) than plants with smaller crops (69.3% and 1.3%, respectively). Fruit removal efficiency was related to vegetation type, plant height and fruit width, but the variance explained by these variables was low ( < 8%). Fruit removal success was significantly related to crop size ( > 90% of the variance explained). These results suggest that fruit removal efficiency and success are strongly related to fruit crop size of C. corymbosa plants.