Genetic linkage map of peach [Prunus persica (L.) Batsch] using morphological and molecular markers

A genetic linkage map of peach [Prunus persica (L.) Batch] was constructed in order to identify molecular markers linked to economically important agronomic traits that would be particularly useful for long-lived perennial species. An intraspecific F₂ population was generated from self-pollinating a single F₁ plant from a cross between a flat non-acid peach, ‘Ferjalou Jalousia^®’ and an acid round nectarine ‘Fantasia’. Mendelian segregations were observed for 270 markers including four agronomic characters (peach/nectarine, flat/round fruit, acid/non-acid fruit, and pollen sterility) and 1 isoenzyme, 50 RFLP, 92 RAPD, 8 inter-microsatellite amplification (IMA), and 115 amplified fragment length polymorphism (AFLP) markers. Two hundred and forty-nine markers were mapped to 11 linkage groups covering 712 centiMorgans (cM). The average density between pairs of markers is 4.5?cM. For the four agronomic characters studied, molecular markers were identified. This map will be used for the detection of QTL controlling fruit quality in peach and, particularly, the acid and sugar content.     

Water uptake regulation in peach trees with split-root systems

The water uptake of 3- to 4-year-old peach trees ‘May-crest/Prunus Damas’ grown in an aerated nutrient solution was studied using a split-root system. Each container and the whole tree were weighed independently to measure water absorption by both parts of the root system and tree transpiration. Water potential of leaves was measured with a pressure chamber. Water potential of roots was estimated using root suckers sealed in plastic bags before the measurement. The nutrient solution was removed from one container so that half the root system was left in humid air for 48 h. Water potential of roots left in solution decreased, which (partly) maintained water absorption and thus transpiration. No modification of root hydraulic resistance was required to simulate the experimental results. Nevertheless, enhancement of absorption by the roots supplied with solution cannot compensate for the water loss by transpiration. Depletion of water from the plant essentially came from the non-absorbing roots. This was demonstrated by substituting vegetable oil for nutrient solution around one half of the split-root system, and by following the changes in root volume on the basis of Archimedes principle. Conflicting results in the literature about apparent changes in hydraulic resistance are discussed.     

桃ACC合酶基因的分离及其差异表达

利用5′/3′RACE PCR技术,从桃(Prunus persica (L.) Batsch)果实中克隆了植物乙烯生物合成的关键酶--ACC合酶的全长cDNA pacs,对pacs基因进行全序列测定表明,该基因全长1 848个碱基,编码区为1 449个碱基,5′端有177个碱基的非编码区序列,3′端有219个碱基的非编码区序列(不包括终止密码子TAA).pacs基因编码区共编码483个氨基酸,蛋白质大小为54 kD,等电点为6.43.pacs与番茄(S19677)、梅(AB031026)、番木瓜(U68216)、苹果(AB034993)等其他植物ACC合酶cDNA氨基酸序列同源性分别为65%、70%、75%、90%,并存在与这些ACC合酶氨基酸的活性位点保守序列SLSKDMGFPGFR.RT-PCR结合杂交分析表明,pacs和我们以前克隆的桃ACC合酶cDNA pacs12(AF467782)在叶片和花中基因表达模式基本一致,伤处理和IAA均能诱导叶片pacs 和pacs12基因的表达,但pacs在伤处理叶片的表达水平比pacs12高;pacs 和pacs12基因在果实表达有所不同,pacs在绿熟和成熟果实中均有表达,而pacs12在绿熟果实中基本检测不到,在成熟果实中才有表达,两者在果实中的表达水平比伤处理和IAA处理叶片和花中要低.     

Two matrix metalloproteinases inhibitors from Ferula persica var. persica.

Matrix metalloproteinases (MMPs) play a role in several physiologic and pathologic events. There is some evidence indicating the involvement of MMPs in tumor invasion and inflammatory diseases. Here we studied the chloroform extract of Ferula persica var. persica. The influence of these extracts vs. a reference drug, diclofenac sodium, on MMP production by the fibrosarcoma cell line was investigated using an in vitro cytotoxicity assay, sodium dodecyl sulfate-polyacrylamide, and gelatin zymography. The total extract of the roots was found to exhibit a selective inhibitory effect on tumor cell invasion. The bioactivity-guided fractionation of this extract led to the isolation of two compounds. These compounds showed highest MMP inhibitory effect at minimal toxic dose levels. Using conventional spectroscopy methods, the active fractions were identified as t-butyl 3-[(1-methylthiopropyl)dithio]-2-propenyl malonate (persicasulphide B) and umbelliprenin, previously isolated from F. persica var. latisecta. Since inhibition of MMP activity has been employed in modality therapy in diseases such as cancer, this compound might be promising in the preparation of anti-MMP therapeutic derivatives.     

Peach rootstock differences in ring nematode tolerance related to effects on tree dry weight, carbohydrate and prunasin contents

Ring nematode ( Criconemella xenoplax : Cx) predisposes peach trees to the disease peach tree short life. Peach genotypes vary widely in survival rates when they are infested with Cx, but all are suitable hosts to Cx. Differences among peach genotypes in carbohydrate depletion and release of cyanide from prunasin degradation have been correlated with sensitivity to Cx. but cause and effect relations are not known. We compared dry weight, nonstructural carbohydrates (CHO) and prunasin in a highly sensitive (Nemaguard) and a highly tolerant (BY520-9) peach rootstock inoculated with 0 or 10 Cx (ml soil)⁻¹ in a pot study. Plant responses to the four treatment combinations were evaluated after 11 months of incubation with and without Cx. Cx parasitism reduced dry weight and concentrations of starch and soluble carbohydrates of all organs in Nemaguard, but not in those of BY520–9. Prunasin content was not affected by Cx in either rootstock. Increased partitioning of dry weight and carbohydrate fractions from shoots to roots and shifts in proportional composition of individual sugars occurred in Nemaguard but not in BY520–9. These results are consistent with the hypothesis that Nemaguard is more sensitive to Cx than is BY520–9 because it allows more of its CHO reserves to be partitioned from shoot to root in response to Cx parasitism. When parasitism is severe, reduced levels of CHO in the aboveground portion of the tree could result in tree injury or death at levels of environmental and biological stresses that do not injure healthy trees.     

Phloem loading in peach: Symplastic or apoplastic?

Sorbitol and sucrose are the two main soluble carbohydrates in mature peach leaves. Both are translocated in the phloem, in peach as in other rosaceous trees. The respective role of these two soluble carbohydrates in the leaf carbon budget, and their phloem loading pathway, remain poorly documented. Though many studies have been carried out on the compartmentation and export of sucrose in sucrose-transporting species, far less is known about sorbitol in species transporting both sucrose and sorbitol. Sorbitol and sucrose concentrations were measured in several tissues and in sap, in 2-month-old peach (Prunus persica L. Batsch) seedlings, i.e. leaf blade, leaf main vein, petiole, xylem sap collected using a pressure bomb, and phloem sap collected by aphid stylets. The sorbitol to sucrose molar ratio depended on the tissue or sap, the highest value (about 7) found in the leaf main vein. Sorbitol concentration in the phloem sap was about 560 mM, whereas that of sucrose was about 140 mM. The lowest sorbitol and sucrose concentrations were observed in xylem sap collected from the shoot. The volume of the leaf apoplast, estimated by infiltration with ³H-inulin, represented about 17% of the leaf blade water content. This volume was used to calculate a global intracellular concentration for each carbohydrate in the leaf blade. Following these simplifying assumptions, the calculated concentration gradient between the leaf's intracellular compartment and phloem sap is nil for sorbitol and could thus allow for the symplastic loading of the phloem of this alditol. However, infiltration of ¹⁴C-labelled source leaves with 2 mMp-chloromercuribenzenesulfonic acid (PC-MBS), a potent inhibitor of the sucrose carrier responsible for phloem loading in sucrose-transporting plants, had a significant effect on the exudation of both labelled sucrose and sorbitol from the phloem. Therefore, in peach, which is a putative symplastic loader according to minor vein anatomy and sorbitol concentration gradients, apoplastic loading may predominate.     

白碧桃挥发性成分的快速分析(英文)

首次采用顶空固相微萃取结合气质联用技术提取并分析了白碧桃花蕾和花的挥发性成分。分别从白碧桃花蕾和花中鉴定了19和21个化合物。结果发现,油酸-2羟-基乙酯在花蕾中的含量高达43.62%,且仅存在于花蕾中;油酸在花蕾中的含量仅为2.65%,而在花中则高达58.69%,这表明在白碧桃花蕾开放的过程中,油酸-2羟-基乙酯被其体内的水解酶逐渐水解成油酸。     

Effects of nutrient amendments on modular growth,flowering effort and reproduction of snowbed plants

Background: There have been few studies on the effects on alpine flora and vegetation of an increase in nutrient availability. Two main potential sources of increased nutrient availability in alpine ecosystems are enhanced mineralisation caused by climate warming and atmospheric nitrogen deposition. Little is known on how life history traits of different species are related at individual and community levels to enhanced nutrient availability.

Aims: We investigated the effects of nitrogen and phosphorus addition on the modular growth, flowering and germination of four species: two snowbed specialists and two alpine generalists.

Methods: We established in a late snowbed at the Gavia Pass, Italian Alps, a factorial experiment with four fertiliser treatments (N, P, Low N+P, and High N+P) and an unfertilised control. Nutrients were applied in 2003–2006 and we recorded the number of modules per individuals, total number of flowers, number of flowers per flowering module, and calculated the percentage of flowering modules in 2005 and 2006, and counted the number of seedlings in 2006.

Results: The modular growth and flowering effort of the species appeared to be co-limited by N and P. The alpine generalists showed greater responses to fertilization in vegetative growth and flowering compared with snowbed specialists. The number of seedlings recorded indicated species-specific responses to nutrient addition.

Conclusions: Our results suggest that enhanced nutrient availability stimulates modular growth and flowering effort in responsive alpine generalist species. This, in turn, could lead to an increase in their abundance, leading to changes in community structure in snowbeds with enhanced nutrient availability.     

藏药纤毛婆婆纳的愈伤组织诱导和快速繁殖研究

以纤毛婆婆纳（Veronica ciliateFisch.）无菌苗的顶芽作为外植体,在不同激素和浓度组合的MS培养基上进行愈伤组织诱导和快速繁殖的研究。结果表明,愈伤组织诱导的最佳培养基为：MS＋6-BA 0.5 mg/L＋NAA1.0 mg/L,诱导率达到95%;顶芽在MS＋6-BA 0.5 mg/L＋NAA 0.1 mg/L增殖培养基中增殖效果最佳,增殖系数高达5.4;丛生芽在1/2 MS＋IBA 0.05 mg/L生根培养基生根效果最好,不仅根的质量好,而且生根率也达到95%;此再生苗的移栽成活率也最高,在适宜条件下可达40%。     

Deciphering the metabolic pathways influencing heat and cold responses during post‐harvest physiology of peach fruit

Peaches are highly perishable and deteriorate quickly at ambient temperature. Cold storage is commonly used to prevent fruit decay; however, it affects fruit quality causing physiological disorders collectively termed ‘chilling injury’ (CI). To prevent or ameliorate CI, heat treatment is often applied prior to cold storage. In the present work, metabolic profiling was performed to determine the metabolic dynamics associated with the induction of acquired CI tolerance in response to heat shock. ‘Dixiland’ peach fruits exposed to 39 °C, cold stored, or after a combined treatment of heat and cold, were compared with fruits ripening at 20 °C. Dramatic changes in the levels of compatible solutes such as galactinol and raffinose were observed, while amino acid precursors of the phenylpropanoid pathway were also modified due to the stress treatments, as was the polyamine putrescine. The observed responses towards temperature stress in peaches are composed of both common and specific response mechanisms to heat and cold, but also of more general adaptive responses that confer strategic advantages in adverse conditions such as biotic stresses. The identification of such key metabolites, which prime the fruit to cope with different stress situations, will likely greatly accelerate the design and the improvement of plant breeding programs.