Walnut

Silver nanoparticles (AgNPs) are of great interest due to their unique and controllable characteristics. Different synthesis methods have been proposed to produce these nanoparticles, which often require elevated temperatures/pressures or toxic solvents. Thus, green synthesis could be a replacement option as a simple, economically viable and environmentally friendly alternative approach for the synthesis of silver nanoparticles.
Here, the potential of the walnut green husk was investigated in the production of silver nanoparticles. An aqueous solution extracted from walnut green husk was used as a reducing agent as well as a stabilizing agent. Then, the synthesized nanoparticles were characterized with respect of their anticancer, antioxidant, and antimicrobial properties.
Results showed that the synthesized nanoparticles possessed an average size of 31.4 nm with a Zeta potential of -33.8 mV, indicating high stability. A significant improvement in the cytotoxicity and antioxidant characteristics of the green synthesized Ag nanoparticles against a cancerous cell line was observed in comparison with the walnut green husk extract and a commercial silver nanoparticle (CSN). This could be due to a synergistic effect of the synthesized silver nanoparticles and their biological coating. AgNPs and the extract exhibited 70% and 40% cytotoxicity against MCF-7 cancerous cells, respectively, while CSN caused 56% cell death (at the concentration of 60 μg/mL). It was observed that AgNPs were much less cytotoxic when tested against a noncancerous cell line (L-929) in comparison with the control material (CSN). The free radical scavenging analysis demonstrated profound anti-oxidant activity for the synthesized nanoparticles in comparison with the extract and CSN. It was also detected that the synthesized AgNPs possess antibacterial activity against nosocomial and standard strains of both Gram-positive and Gram-negative bacteria (minimum inhibitory concentration =5–30 μg/mL).
These findings imply that the synthesized nanoparticles using green nanotechnology could be an ideal strategy to combat cancer and infectious diseases.

One of the important problem in walnut production is establishing orchards with unfruitfulness trees and using cultivars that doesn't suitable for this area. In recent years walnut cultivation is began to be done with high lateral bearing capacity cultivars. For this aim, in unfruitfulness orchards topworking studies has begun with these cultivars. Grafting methods and periods, ecology, the cutting time of the rootstock's top before grafting and the applications made after grafting affect the graft success on walnut. In this study, the effects the cutting times of the rootstock's top before grafting on graft success and shoot growth were examined. Also the effect of the rootstocks thickness to graft success and shoot growth were examined. For this aim rootstocks were divided into three groups and their top were cut in two periods (60 and 20 days before graft). Graft success was determined one month after grafting as sprouting ratio. On the other hand, length and diameter of graft scion shoots, number of internodes per shoot, the distances of internodes, sugar, starch and carbohydrate (mg L-1) contents of shoots were investigated after vegetation period. The cutting time of the rootstock's top affected the graft success, the distance of internodes, sugar, starch and carbohydrate (mg L-1) contents of sprouts statistically. In the study, highest graft sprouting ratio was 92.7% on thick rootstocks which cut off in early period (60 days before grafting).Rootstock's diameter didn't affect the scion's starch, sugar and carbohydrate level statistically. According to the study, we can advise that bark grafting on walnut should be made on thick rootstocks and rootstock's top should be cut before leaf appearance. Cevizde çeşit değiştirme aşılarında anaçlarda tepe kesimi zamanı ve kalınlıklarının aşı başarısı üzerine etkisi ÖZET Ülkemizde ceviz yetiştiriciliğindeki en önemli sorunlardan biri şimdiye kadar ceviz bahçelerinin ekolojiye uygun olmayan ve genellikle verimi düşük çeşitler ile kurulmasıdır. Son yıllarda yan dal verimi yüksek çeşitlerin ülkemizde yetiştirilmeye başlanması ile birlikte mevcut bahçelerinde bu çeşitlerle değiştirilmesi amacıyla aşılama çalışmaları yapılmaya başlanmıştır. Cevizde aşı başarısı aşı yöntemi ve zamanına, ekolojiye, anaçlarda tepe kesim zamanına ve aşıdan sonra yapılan uygulamalara göre değişiklik göstermektedir. Bu çalışmada, cevizde çeşit değiştirme aşısında anaçta aşıdan önce yapılan tepe kesimi zamanının aşı sürme ve sürgün gelişimi üzerine etkisinin belirlenmesi hedeflenmiştir. Bunun yanı sıra çevirme aşısı yapılan anaçlarda, anaç kalınlığının aşı başarısı ve sürgün gelişimi üzerine etkisi de belirlenmeye çalışılmıştır. Bu amaçla 3 farklı kalınlıktaki anaçlarda aşılamadan önce iki dönemde (60 ve 20 gün önce) tepe kesimleri yapılmıştır. Çeşit değiştirme aşısı olarak kabuk altı aşı yöntemi kullanılmış ve aşılar 20 Haziran'da yapılmıştır. Uygulamaların cevizde aşı başarısı ve aşı sürgünü gelişimi üzerine etkisini belirlemek amacıyla aşıdan bir ay sonra aşı sürme oranı (%), vejetasyon sonunda ise aşı sürgünü boyu (cm) ve çapı (mm), sürgündeki boğum sayısı (adet), boğumlar arası mesafe (cm), sürgünlerde şeker, nişasta ve karbonhidrat (mg L-1) içerikleri belirlenmiştir. Tepe kesimi zamanının aşı sürme oranı (%), boğumlar arası mesafe ile sürgünlerdeki şeker, nişasta ve karbonhidrat içerikleri üzerine istatistiksel olarak önemli etki yaptığı saptanmıştır. Araştırmada en yüksek aşı sürme oranı %92.7 ile erken dönemde kesilen kalın anaçlardan elde edilmiştir. Anaç çapının sürgünlerdeki nişasta, şeker ve karbonhidrat içeriği üzerine etkisi istatistiksel olarak önemsiz bulunmuştur. Araştırma sonucunda, cevizde çeşit değiştirme (kabuk altı) aşılarının özellikle kalın anaçlara uygulanması ve tepe kesimi işleminin erken dönemde yapılması önerilmiştir.

Transgenic walnuts (Juglans regia L.) were produced in the presence of the Agrobacterium strain LBA4404 and the plasmid pBI121. This plasmid contains a BADH gene driven by a CaMV 35S promoter. It further includes an NPTII gene as a selectable marker which, in turn, is driven by a NOS promoter. Somatic embryos of the walnut cultivar ‘Chandler’ were inoculated using an Agrobacterium suspension. Secondary embryos that developed on a selection medium were driven towards germination so as to develop micro-shoot cultures. The regeneration rate was 5.5%. PCRand southern blot analysis were used for confirming that the BADH transgene is successfully integrated into the plant genome. Transgenic and wild-type plants raised from somatic embryos were exposed to four osmotic stress levels (i.e. 0%, 2%, 4%, and 8% PEG) and four salinity levels (i.e. 0, 50, 100, and 200 mM NaCl). After 21 days, the transgenic plants grew almost vigorously in saline and drought-stress conditions, whereas the wild-type ones showed retarded levels of growth and did not survive after the cradle stage. These results show that the BADH gene can be expressed effectively in transgenic plantlets of walnut and can be used for breeding walnuts against drought and salinity.

Persian plateau (including Iran) is considered as one of the primary centers of origin of walnut. Sampling walnut trees originating from this arena and exploiting the capabilities of next-generation sequencing (NGS) can provide new insights into the degree of genetic variation across the walnut genome. The present study aimed to explore the population structure and genomic variation of an Iranian collection of persian walnut (Juglans regia L.) and identify loci underlying the variation in nut and kernel related traits using the new Axiom J. regia 700K SNP genotyping array. We genotyped a diversity panel including 95 walnut genotypes from eight Iranian provinces with a variety of climate zones. A majority of the SNPs (323,273, 53.03%) fell into the "Poly High Resolution" class of polymorphisms, which includes the highest quality variants. Genetic structure assessment, using several approaches, divided the Iranian walnut panel into four principal clusters, reflecting their geographic partitioning. We observed high genetic variation across all of the populations (H o = 0.34 and H e = 0.38). The overall level of genetic differentiation among populations was moderate (F st = 0.07). However, the Semnan population showed high divergence from the other Iranian populations (on average F st = 0.12), most likely due to its geographical isolation. Based on parentage analysis, the level of relatedness was very low among the Iranian walnuts examined, reflecting the geographical distance between the Iranian provinces considered in our study. Finally, we performed a genome-wide association study (GWAS), identifying 55 SNPs significantly associated with nut and kernel-related traits. In conclusion, by applying the novel Axiom J. regia 700K SNP array we uncovered new unexplored genetic diversity and identified significant marker-trait associations for nut-related traits in Persian walnut that will be useful for future breeding programs in Iran and other countries. The genus Juglans, one of the most important genera of the Juglandaceae family, contains approximately 21 species , of which Persian walnut (Juglans regia L.) is the most economically important for nut production. Persian walnut is a long-lived, monoecious, open-pollinated and dichogamous tree, widely cultivated across temperate and subtropical regions 1-4. Persian walnut trees are native to the mountainous regions of central Asia 5-7 , and today are distributed and grown commercially over a wide geographical range, including west-central Asia, southern Europe, North and South America, Australia and New Zealand 1,8-10 .

Background: Flower development and sufficient fruit set are important parameters with respect to walnut yield. Knowledge about flowering genes of fruit trees can help to conduct better molecular breeding programs. Therefore, this study was carried out to investigate the expression pattern of some flowering genes (FT, SOC1, CAL, LFY and TFL1) in Persian walnut (cv. Chandler) during the growing season and winter dormancy.

Climate change may cause a significant decline in winter chill over the coming decades and is becoming an important issue forwalnut (Juglansregia L.) breeding programs to address. The current study was conducted to identify superior walnut genotypes with low-chilling requirements in western Iran (Ilam province). In the first step, approximately 200 walnut trees of seed-origin were pre-selected based on a questionnaire. Based on this primary evaluation for phenotypic and horticultural traits, 55 of the 200 genotypes were selected for further study. Morphological and phenological traits of these 55 were evaluated for two consecutive years and 11 genotypes were selected as superior. These superior genotypes were moderate to late-leafing with high yield, lateral fruitfulness, thin shells, and light to extra light kernel color. Nut weight, kernel weight and kernel percentage of the 11 superior genotypes ranged between 12.6–15.9 g, 6.9–8.2 g, and 49.7–62.0%, respectively. These superior genotypes had high levels of protein (13.3–18.2%), oil (55.3–65.9%) and PUFAs content. Assessment of chilling requirement of these superior genotypes showed that eight (IrIlZg1, IrIlZg13, IrIlZg7, IrIlZg12, IrIlAa92, IrIlAa47, IrIlAa48 and
IrIlAa27) had significantly lower chilling requirements than the cultivar ‘Chandler’. Although having low-chill requirements, these genotypes were moderate to late-leafing. This may be due to their high heat requirement, since chilling requirement together with heat accumulation determines the leafing and flowering date. In conclusion, the selected low chilling requirement genotypes having moderate to late leafing could be used in walnut breeding programs to release commercial cultivars which are suitable for areas with spring frost concerns and expected future loss of winter chill due to climate change.