Identification of cyclopropyl fatty acids in walnut (Juglans regia L.) oil

Aim: Identification of cyclopropyl fatty acids in walnut oil. Method: GC/MS method was developed for the determination of eight cyclopropyl fatty acids in walnut (Juglans regia) oil. Results: Monocyclopropane acids: methyl 9-cyclopropyl-nonanoate, 6,7-methylene-, 8,9-methylene-, 9,10-methylene-, 11,12-methylene octadecanoates, and dicyclic acid - methyl 9,10,12,13-dimethylene octadecanoate, tricyclic acid - methyl 9,10,12,13,15,16-trimethylene octadecanoate, and unsaturated - methyl 2-octylcyclopropene-1-octanoate were detected in walnut oil by GC-MS and their mass spectra studied. Four cyclic fatty acids were identified for the fist time in seed oils. Conclusions: Eight cyclopropyl fatty acids were detected in the Mediterranean nuts for the first time.     

Landscape genetics of Persian walnut (Juglans regia L.) across its Asian range

Persian walnut (Juglans regia L) is an economically important species cultivated worldwide for its wood and nuts. Despite the increasing interest in the development of conservation strategies for walnut germplasm, an accurate and full-scale overview of wild genetic resources of J. regia has not been conducted because natural populations are located in regions of Asia historically difficult to access. In this study, we estimated the genetic diversity and spatial genetic structure of 39 autochthonous Persian walnut populations sampled across its Asian range using 14 neutral microsatellite markers. A landscape genetic overlay approach was applied to detect the areas of current reservoirs of walnut genetic diversity in the Asian range and to evaluate the role of landscape in shaping walnut genetic diversity since the Last Glacial Maximum. Although Persian walnut has been highly manipulated by humans over the last 2,000 years, we determined that patches of high genetic diversity still exist in the Caucasus and mountains of Central Asia where J. regia might have survived after Pleistocene glaciations. We detected a clear separation of Persian walnut into four main genetic clusters centered in (1) western Kyrgyzstan, (2) western and south–central Asia, (3) east–central Uzbekistan, and (4) Xinjiang and Shandong provinces (China). Overlay of maps showed a coincidence between groups of walnut populations and potential barriers to gene flow such as the Hindu Kush, Pamir, Tien Shan, and Himalaya mountains and the Karakum, Kyzyl Kum, and Taklamakan deserts. This study claimed the relevance of the preservation of walnut genetic resources in the Asian range.     

Effects of leaf-to-fruit ratio on chlorophyll fluorescence parameters of walnut (Juglans regia L.) leaves

Photosynthetica - In this study, we investigated maximal quantum yield of PSII photochemistry(Fv/Fm),effective quantum yield of PSII photochemistry (ΦPSII), and nonphotochemical quenching...     

The role of growth regulators in the differentiation of walnut buds (Juglans regia L.)

The character of endogenous regulators in walnut buds was followed by means of bioassays in the course of vegetation. It was ascertained that a rise in the level of gibberellin-like substances precedes the sprouting of buds. The origination of new buds in the axil of young leaves is accompanied by a fall in the level of auxins, by a low gibberellin content and by the presence of inhibitors. In this situation the primordia of staminate catkins are diferentiated in the basal buds. The vegetative buds which are formed in the axils of further leaves, stop developing because of the accumulating inhibitors. Towards the close of vegetation the primordia of pistillate flowers originate in terminal buds and their differentiation is accompanied by a substantial rise in the level of auxin-like substances, while some of the inhibitors keep asserting themselves. On the basis of these findings we have tested the possibility of affecting the differentiation of staminate primordia and of vegetative buds by the exogenous application of selected regulators. Spraying young leaves with IAA and MH solutions will increase the number of vegetative buds in the twigs. A later spray of other twigs by TIBA and GA₃ solutions will increase the number of staminate buds.     

Genotypic differences in branching pattern and fruiting habit in common walnut (Juglans regia L.)

Architectural analysis of 840 Slovenian walnut (Juglans regia L.) genotypes was performed to determine the most typical and frequent morphological types and to evaluate their vegetative and generative potential. Four branching and fruiting patterns (I-IV) were detected. A 3-year-old fruiting branch, consisting of a 3-year-old shoot plus corresponding 2-year-old and 1-year-old shoots, was used as a structural unit for quantitative analysis. In the intermediate fruit-bearing types with mesotonic and acrotonic branching pattern (types II and III), the total lengths of 3-, 2- and 1-year-old shoots were 385 and 380 cm, respectively, compared with 275 and 253 cm in the terminal and lateral-fruiting types (types I and IV). In type I, 1-year-old shoots had significantly fewer nodes than in other types. In addition, they had a thinner basal diameter than types III and IV, and their angles were the most erect (39 degrees ). Only 0.4 out of 3.6 1-year-old shoots were flowering with one mixed bud with 1.9 female flowers. In type IV, 2-year-old shoots had significantly more nodes and a larger basal diameter than other types. One-year-old shoots in type IV are thicker than those in other types. Ratios between the number of flowering and the total number of 1-year-old shoots were 0.7 in type IV, 0.6 in type III, 0.5 in type II and 0.1 in type I. On 1-year-old shoots in type IV, 1.7 mixed buds with a mean of three female inflorescences per bud were counted. Consequently, the generative potential is highest in type IV and lowest in type I. In types II and III, growth and the ability to bear fruits are more balanced.     

The role of endogenous growth regulators in the differentiation processes of walnut (Juglans regia L.)

The character of endogenous growth substances was investigated in developing buds, young fruits and mature walnut leaves. The relatively high content of auxins and gibberellin-like substances was found by means of bioassays in the youngest primordia of vegetative buds. The level of auxins drops in the further course of primordia transformation into the staminate catkins. The development of leaf-buds is characterized by the accumulation of inhibitory activity as revealed by theAvena bioassay, whereas the data obtained from the lettuce bioassay indicate a pronounced stimulation. The onset of terminal bud development is also accompanied by inhibitions and it is only with pistillate flower differentiation that the temporary rise in auxin level is observed. An inhibitory activity was found in these extracts using lettuce bioassay. There is a relatively high auxin level in young fruits, mature leaves and resting buds during the mid-summer period whereas the accumulation of clearcut inhibitions is signalled by the results of lettuce bioassay. The regulatory role of growth substances in differentiation may be better understood during the second year as many leaf-abnormities appear only with the outgrowing of the bud. Abnormal catkins differ in the number of florets and stamens and some even bear pistillate flowers. Fruit development is liable to deviations in the early stages of differentiation. Abnormal fruits enable us to elucidate many structural peculiarities.     

Antioxidative polyphenols from walnuts (Juglans regia L.)

Three hydrolyzable tannins, glansrins A-C, together with adenosine, adenine, and 13 known tannins were isolated from the n-BuOH extract of walnuts (the seeds of Juglans regia L.). Glansrins A-C were characterized as ellagitannins with a tergalloyl group, or related polyphenolic acyl group, based on spectral and chemical evidence. The 14 walnut polyphenols had superoxide dismutase (SOD)-like activity with EC(50) 21.4-190 microM and a remarkable radical scavenging effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (EC(50) 0.34-4.72 microM).     

分子标记及其在核桃遗传多样性研究中的应用

核桃是我国重要的坚果和木本油料树种之一,具有重要的学术研究和经济价值。现代分子标记技术的迅速发展为核桃的种质鉴定、遗传育种、遗传多样性分析、亲缘鉴定等提供了崭新途径。本文主要介绍RFLP、RAPD、AFLP及SSR等几种分子标记技术的主要原理、特点以及在核桃遗传多样性方面的研究进展,分析了分子标记在核桃遗传多样性研究中的主要问题,并对其发展提出了展望。     

Origin of somatic embryos from repetitively embryogenic cultures of walnut (Juglans regia L.): Implications forAgrobacterium-mediated transformation

Early stages of somatic embryo development from embryogenic cultures ofJuglans regia (Persian or English walnut) are described. Histological examination reveals that secondary somatic embryos arise from cotyledons and hypocotyls of primary embryos cultured in the dark. The embryos originate by transverse to oblique divisions of surface cells. Single-cell origin of the secondary embryos confirms the potential of the repetitive embryogenesis system forAgrobacterium-mediated transformation and regeneration of non-chimeric, transgenic walnut plants.     

Endogenous hormone levels in bearing and non-bearing shoots of walnut (Juglans regia L.) and their mutual relationships

The levels of endogenous gibberellic acid equivalents, indole acetic acid, trans-zeatin and trans-zeatin riboside in bearing and non-bearing shoots of walnut (Juglans regia L.) were detected by high-performance liquid chromatography during vegetation period. The levels of endogenous hormones were analysed in four different shoot types of current season, bearing terminal shoot, non-bearing terminal shoot, bearing lateral shoot and non-bearing lateral shoot. Their average levels differed statistically at five sampling times from 25 May to 23 September. Relationships among changes in endogenous gibberellin, auxin and cytokinin contents were computed using correlation and regression analyses. Remarkable positive correlation coefficients were found among changes in gibberellin, auxin and cytokinin contents. Statistical findings indicated that changes in endogenous hormones exhibited a collective behaviour in walnut shoots during vegetation period.     

DNA markers identify hybrids between butternut (Juglans cinerea L.) and Japanese walnut (Juglans ailantifolia Carr.)

Butternut (Juglans cinerea L.) is a temperate deciduous hardwood native to the eastern USA and southern Canada valued for its nuts and wood. Butternut’s survival is threatened by butternut canker, a disease caused by the exotic fungus Sirococcus clavigignenti-juglandacearum Nair, Kostichka & Kuntz. Field observations indicate that trees commonly called buartnut (a hybrid of butternut and its close congener Japanese walnut (Juglans ailantifolia × J. cinerea)) may be more resistant to butternut canker than is either parental species. Hybrids are difficult to distinguish morphologically from butternuts, and scientists have expressed concern over the possibility of range-wide genetic invasion by Japanese walnut via hybridization with butternut. We used pair-wise combinations of 40 random primers to screen bulked DNA pools of butternut, Japanese walnut, and buartnuts to identify genomic regions unique to Japanese walnut. We ultimately identified one ITS region marker, one chloroplast marker, one mitochondrial marker, and six nuclear markers. The utility of the markers for identifying hybrids was tested and verified using more than 190 genotypes. The markers will be used to identify buartnut hybrids based on the presence of introgressed genomic fragments inherited from Japanese walnut. We confirmed that hybrids have a complex genetic history and present features of the parental species in all possible combinations. These results will assist in the identification and testing of (non-hybrid) butternut for breeding and reintroduction of the species to its former habitats.     

Somatic embryogenesis and plant regeneration from cotyledons of walnut,Juglans regia L.

Immature cotyledons of open-pollinated seeds from five walnut (Juglans regia L.) cultivars were excised from fruits at 6–11 weeks after full pistillate bloom and grown on a sequence of media to induce somatic embryogenesis. Globular, heart, cotyledonary and complete somatic embryos were obtained. Embryogenic cultures were maintained for more than a year by repetitive embryogenesis in which the roots, cotyledons and hypocotyls of somatic embryos formed additional adventive somatic embryos. Mature somatic embryos required a cold treatment of 8–10 weeks at 2–4°C to overcome apical dormancy. Selected plantlets derived from these somatic embryos were grown to young plants in soil. In addition, somatic embryogenesis was induced in J. hindsii (Jeps.), Jeps., and in Pterocarya sp., another member of the Juglandaceae.     

Pure and mixed plantations of Persian walnut (Juglans regia L.) for high quality timber production in Chile,South America

波斯胡桃(Juglans regia L.)是用于装饰工业的一种森林物种,需要适当的管理才能生产出经济效益好的高质量原木。由于种间关联和管理水平可以提高林分生产力,因此本研究的创新之处在于评估波斯胡桃在不同混合种植中以及在适度的管理强度的纯人工林中的表现。在两种截然不同的管理方案下种植纯林和混交林后,连续7年每年对波斯胡桃的生长、直度和存活率进行测定。在第7年时,记录所有人工林中病害情况。在每种管理强度下,除纯林外,检验三种混交林：仅与主要森林物种混交、主要森林物种和黑桤木(Alnus glutinosa L.,伴生种)混交,以及主要物种和灌木俄罗斯橄榄(Elaeagnus angustifolia L.,保育种)混交。利用重复生长数据对人工林类型与管理方案之间的交互作用进行检验。研究发现人工林类型与管理方案的交互作用显著,表明在管理水平高和低的条件下,人工林效应存在不同的机制。与纯林相比,在低管理水平下,有保育灌木混交的波斯胡桃的树高增加了78%、直径生长增加了53%。同样,在管理强度不高的情况下,与灌木混交有更多的健康益处(胡桃枯萎病的发生率低于单一栽培)和更好的直度。在高管理强度下(灌溉、施肥、抚育和频繁修剪),与俄罗斯橄榄混交时这些有益效应消失。因此,波斯胡桃种植园的具体选址设计取决于可预见的管理强度。     

Root growth dynamics linked to above-ground growth in walnut (Juglans regia)

Background and Aims Examination of plant growth below ground is relatively scant compared with that above ground, and is needed to understand whole-plant responses to the environment. This study examines whether the seasonal timing of fine root growth and the spatial distribution of this growth through the soil profile varies in response to canopy manipulation and soil temperature.Methods Plasticity in the seasonal timing and vertical distribution of root production in response to canopy and soil water manipulation was analysed in field-grown walnut (Juglans regia ‘Chandler’) using minirhizotron techniques.Key Results Root production in walnuts followed a unimodal curve, with one marked flush of root growth starting in mid-May, with a peak in mid-June. Root production declined later in the season, corresponding to increased soil temperature, as well as to the period of major carbohydrate allocation to reproduction. Canopy and soil moisture manipulation did not influence the timing of root production, but did influence the vertical distribution of roots through the soil profile. Water deficit appeared to promote root production in deeper soil layers for mining soil water. Canopy removal appeared to promote shallow root production.Conclusions The findings of this study add to growing evidence that root growth in many ecosystems follows a unimodal curve with one marked flush of root growth in coordination with the initial leaf flush of the season. Root vertical distribution appeared to have greater plasticity than timing of root production in this system, with temperature and/or carbohydrate competition constraining the timing of root growth. Effects on root distribution can have serious impacts on trees, with shallow rooting having negative impacts in years with limited soil water or positive impacts in years with wet springs, and deep rooting having positive impacts on soil water mining from deeper soil layers but negative impacts in years with wet springs.     

Branching of annual shoots in common walnut (Juglans regia L.) as affected by bud production and indol-3-acetic acid (IAA) content

Relationship of bud production (axillary and terminally) of annual shoot (1Y) and/or the content of bud-derived indol-3-acetic acid (IAA) to branching of the 1Y was studied in common walnut (Juglans regia L.), cvs. Franquette and Lara. Cultivar-related branch architecture was determined. Lara tended to branch more densely than Franquette (53 vs. 42%). Significantly more fruiting off-spring shoots (FO) than vegetative ones (VO) grew-out per 1Y in both cultivars, whereas the ratio FO/VO of Lara exceeded that of Franquette by four times. An acrotonic branching pattern was more strongly expressed in Lara compared to Franquette. Bud-derived IAA was influenced by the cultivar (Franquette had 3.6 times more cumulative IAA along the 1Y than Lara), and by the relative position (terminal, subterminal, medial and basal) of the buds along 1Y. An opposite relationship between branching density and cumulative IAA content was established in both cultivars. At the 1Y relative position level, the opposite ratio between branching density and IAA content was clearly shown only on the basal position of the bud along 1Y in the Lara cultivar. Such an inconsistent linkage between bud production and the IAA spatial distribution along the 1Y illustrated that hormonal factors probably weakly affect the branching of Franquette and Lara. The length of the parent 1Y, the position of the buds along the 1Y-length, and the fate of the buds seemed to have a stronger influence on the bud out-growth and further development of the off-springs. In further analyses, seasonal fluctuations of the IAA, and the following activity of the buds should be investigated in order to improve the understanding of a complex branching phenomenon in walnut.     

CDKA orthologue isolation and its expression during cambial activity in hybrid walnut (Juglans nigra×Juglans regia)

Trees - Improved wood production is a major aim for walnut forests and especially for hybrid walnut (Juglans nigra×Juglans regia). This paper presents the first report describing the structure...