Breeding of Persian walnut: Aiming to introduce late-leafing and early-harvesting varieties by targeted hybridization

Fallah, Mehdi; Vahdati, Kourosh; Hasani, D; Sarikhani, Saadat

doi:10.1016/j.scienta.2022.110885

Cited by 18 publications

(11 citation statements)

References 28 publications

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“…Regardless if we consider air as part of the total walnut volume or not, we observe that walnuts with large shell volume ratio tend to have thicker, stronger, and denser shells, a low ratio of kernel volume and weight, and make kernel removal more difficult. This agrees with reports that thin shells allow easier kernel extraction (Amiri et al, 2010; Arzani et al, 2008; Fallah et al, 2022). Moreover, inner air may play a key role in walnut development.…”

Section: Discussionsupporting

confidence: 93%

The shape and volume of air, kernels and cracks, in a nutshell

Amézquita,

Quigley,

Brown

et al. 2023

Preprint

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Walnuts are the second most produced and consumed tree nut, with over 2.6 million metric tons produced in the 2022-23 harvest cycle alone. The United States is the second largest producer, accounting for 25% of the total global supply. Nonetheless, producers face an ever-growing demand in a more uncertain climate landscape, which requires effective and efficient walnut selection and breeding of new cultivars with increased kernel content and easy-to-open shells. Past and current efforts select for these traits using hand-held calipers and eye-based evaluations. Yet there is plenty of morphology that meets the eye but goes unmeasured, such as the volume of inner air or the convexity of the kernel. Here, we study the shape of walnut fruits based on X-ray CT (Computed Tomography) 3D reconstructions. We compute 49 different morphological phenotypes for 1264 individuals comprising 149 accessions. These phenotypes are complemented by traits of breeding interest such as ease of kernel removal and kernel weight. Through allometric relationships —relative growth of one tissue to another—, we identify possible biophysical constraints at play during development. We explore multiple correlations between all morphological and commercial traits, and identify which morphological traits can explain the most variability of commercial traits. We show that using only volume and thickness-based traits, especially inner air content, we can successfully encode several of the commercial traits.Core IdeasX-ray Computed Tomography (CT) imaging is used to compute a broad array of morpho-logical phenotypes in walnuts.These morphological traits suggest biophysical constraints at play during walnut development.Relative inner air, shell, and packing tissue volumes are significantly correlated to the rest of shape phenotypes.These volumes produce the best prediction models for traits of commercial interest such as shell strength.Inexpensive phenotyping platforms that focus solely on volume measurement would enable better walnut breeding.

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Section: Discussionsupporting

confidence: 93%

The shape and volume of air, kernels and cracks, in a nutshell

Amézquita,

Quigley,

Brown

et al. 2023

Preprint

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“…Numerous studies have demonstrated wide genetic variability among ‘Sorrento’ genotypes using simple sequence repeat markers [ 38 , 42 ] but few works focus on compositional and morphological characterization [ 44 ], and to our knowledge, no data regarding the characteristics of waste products such as the shells are yet available. However, over the last 20 years, modern walnut orchards have been established using cultivars of great commercial interest obtained from Californian breeding programs by implementing innovative approaches to their management [ 45 ], while the cultivation of the Sorrento variety has been limited to traditional areas and systems. Among the cultivars of commercial interest, ‘Tulare’ is a walnut cultivar selected at the University of California (UC Davis) from a controlled crossing (Tehama × Serr) with good production and excellent yield used to create modern orchards in Italy.…”

Section: Introductionmentioning

confidence: 99%

‘Sorrento’ and ‘Tulare’ Walnut Cultivars: Morphological Traits and Phytochemical Enhancement of Their Shell Waste

Ferrara,

Cice,

Piccolella

et al. 2024

Molecules

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Walnut processing generates considerable quantities of by-products that could be reprocessed into value-added products that have food and non-food applications. In this context, the aim of this study is to characterize the ‘Sorrento’ and ‘Tulare’ walnut cultivars using the UPOV guidelines and analyze the chemical composition and antioxidant activity of their shells. Insight into the chemical composition of the different granulometric fractions of walnut shell, obtained by sieving, was obtained following ultrasound-assisted extraction by Ultra-High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry (UHPLC-HRMS). The total phenolic, flavonoid, and tannin content and antiradical capacity, obtained by DPPH and ABTS assays, and the Fe(III) reducing power of the extracts were also evaluated. The UHPLC-HRMS analysis indicated the presence of thirty-two compounds ascribable to four major classes of specialized metabolites. Furthermore, the extraction efficiency of gallic acid, ellagic acid derivatives, as well as glansreginin A, increased with the decrease in shell matrix particle size in contrast to chlorogenic acids and flavonoid glycosides. This is the first study to highlight new knowledge on the chemical composition of walnut shells. The results obtained demonstrate the feasibility of recovering valuable bioactive components from agro-waste that may be further valorized.

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“…The majority of Iran's north and northwest walnut orchards were thus damaged by late-spring frost in 2018 (Kazemi et al, 2018). Therefore, breeding for late-lea ng is an e cient strategy to mitigate the severe damage caused by latespring frost (Vahdati et al, 2019b;Fallah et al, 2022b).…”

Section: Introductionmentioning

confidence: 99%

Validation and implementation of marker-assisted selection (MAS) for the leafing date trait in Persian walnut populations from Iran

Fallah

Paizila

Arab

et al. 2023

Preprint

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The development of late-leafing genotypes is the greatest strategy to deal with the late-spring frosts (LSFs). Due to the long breeding cycle, marker-assisted selection (MAS) is a fast strategy for screening walnut populations in breeding programs. The first aim of this study was to validate Turkish molecular markers associated with leafing date on Iranian walnut population. In addition, our final goal was to implement MAS on the Iranian population and identify the late-leafing genotypes. For this purpose, validation of two polymorphic SSR primers, including JRHR209732 and CUJ-RBO12, was determined by 14 early- and late-leafing cultivars/genotypes. Then, MAS was implemented for a population of 91 Iranian walnuts obtained from a breeding program. The results showed that the markers introduced on the walnut population of Turkey were able to distinguish the walnut population originated from Iran. This shows that the walnut populations of these two countries are genetically close to each other. In addition, the results showed that alleles with band sizes of 277 and 115 were related to late-leafing, and band sizes of 289 and 92 to early-leafing. The phenological data of three consecutive years of leafing date and validation and implementation of MAS were consistent according to SSR analysis. SSR analysis identified 14 alleles for all accessions, with allele numbers ranging from 5 (CUJRBO12) to 9 (JRHR209732) and an av-erage value of 7 alleles per locus. All analyses showed a high level of leafing time variation in our studied population, and cluster analysis (CA) revealed the similarities and dissimilarities among the accessions by identifying four major clusters. Finally, based on screening by late-leaf alleles, geno-types Ch35T12, ChLa1, ChFr2, ChFr3, Ped35T1, Ped35T4, PedLa1, PedLa3, PedOp1, and ChPed2 were introduced as late-leafing genotypes.

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Breeding of Persian walnut: Aiming to introduce late-leafing and early-harvesting varieties by targeted hybridization

Cited by 18 publications

References 28 publications

The shape and volume of air, kernels and cracks, in a nutshell

The shape and volume of air, kernels and cracks, in a nutshell

‘Sorrento’ and ‘Tulare’ Walnut Cultivars: Morphological Traits and Phytochemical Enhancement of Their Shell Waste

Validation and implementation of marker-assisted selection (MAS) for the leafing date trait in Persian walnut populations from Iran

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