Advances in Rootstock Breeding of Nut Trees: Objectives and Strategies (original) (raw)
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Advanced in Rootstock Breeding of Nut Trees: Objectives and Strategies
Plants, 2021
The production and consumption of nuts are increasing in the world due to strong economic returns and the nutritional value of their products. With the increasing role and importance given to nuts (i.e., walnuts, hazelnut, pistachio, pecan, almond) in a balanced and healthy diet and in the prevention of various diseases, breeding of the nuts species has also been stepped up. Most recent fruit breeding programs have focused on scion genetic improvement. However, the use of locally adapted grafted rootstocks also enhanced the productivity and quality of tree fruit crops. Grafting is an ancient horticultural practice use in nut crops to manipulate scion phenotype and productivity and overcome biotic and abiotic stresses. There are complex rootstock breeding objectives and physiological and molecular aspects of rootstock–scion interactions in nut crops. In this review, we provide an overview of these, considering the mechanisms involved in nutrient and water uptake, regulation of phytoh...
Scion–Rootstock Relationship: Molecular Mechanism and Quality Fruit Production
Agriculture
Most tree fruits are commercially grown on different root systems, hence called composite plants. The section provides the root system as the rootstock, and the atop ground portion is called the scion. The combination is selected based on different traits of scion varieties, rootstock, and prevailing edaphic situations. The dated back plant propagation technique of joining two plants (grafting/budding) that directly communicates new physiological traits to the desirable scion variety from the rootstock remains unclear. In spite of this, this propagation technique continues widely applied in the multiplication of several fruit plant species. In a grafted plant, rootstocks impacted the scion variety’s growth, yield and quality attributes, physiology, nutrient accumulation as well as biotic and abiotic stress tolerance in many ways. Modern research in plant science for next-generation sequencing providing new vital information about the molecular interactions in composite plants multip...
Rootstock Development in Temperate Nut Crops
Acta Horticulturae, 2003
The driving force behind the development of rootstocks for nut crops has been the solution of specific problems, often related to the presence of pests or the need for adaptation to particular sites. The use of interspecific hybrids as rootstocks has lead to increased appreciation for the contribution genetic diversity can make to orchard profitability in the face of site specific challenges. The past decade has seen dramatic increases in access to germplasm resources, while technological developments in molecular genetics have contributed to genetic characterization in some species. The focus on clonal propagation through tissue culture has been somewhat abated by the slow pace of nursery incorporation of available techniques, by challenges with anchorage of some clonal rootstocks, and by the recognition of the vulnerability inherent to a monoculture susceptible to an unsuspected root pest. Increased application of spatial analysis systems (GIS) may contribute to prescription use of site-specific rootstocks.
Fruit Research, 2021
Grafting has been commonly practiced for many centuries in the cultivation of horticultural crops. The use of dwarfing rootstocks has enabled a high-density plantation to produce maximum yield. Rootstock regulates scion phenotype, including precocity, fruit size, yield, quality characteristics, and tolerance to various environmental stresses. This review summarizes the existing information on the influence of rootstocks on scion growth and dwarfing mechanisms induced by multiple factors, including hormone signaling, photosynthesis, mineral transport, water relations, anatomical characteristics, and genetic markers. It has been shown that the complex interactions between scion and rootstock can regulate plant development and its structure. This information will provide interesting insights for future research related to rootstock-mediated dwarfing mechanisms and accelerate the breeding progress of dwarfing rootstocks.
Breeding approaches for improvement of temperate fruit crops and nuts - a review
Brazilian Journal of Development, 2024
Fruit breeding is an ancient technology with dynamic current technology and an exciting future (Janick and Moore, 1975, 1996). In its broadest sense, fruit breeding refers to the purposeful genetic improvement of fruit crops through various techniques including selection, hybridization, mutation induction, and molecular techniques. Its origins trace to the domestication process in prehistory and antiquity, where useful species were chosen and cultivated, and improved by continuous selection (Janick, 2005, 2011). Much of the world fruit industry is still based on grower selection from chance seedlings as well as mutations (sports) and as a result many fruit species are characterized by a narrow germplasm base. Spontaneous hybridization between wild plants and cultivated clones was critical to the early domestication of fruits. The lengthy juvenile period and the large field space required to grow temperate fruits have imposed major limitations on conventional breeding and various molecular biological techniques have been employed to make fruit breeding easier. (Igarashi et al.2016). Marker-assisted selection (MAS) uses DNA markers to provide an early DNA-based evaluation of genetic performance potential of seedlings, with the aim of improving cost and/or genetic efficiency of seedling selection (Ru, et al., 2015). Transgenic technology has facilitated the development of fruit trees with resistance to fungal or bacterial diseases, improved fruit quality, or root stocks with better rooting or dwarfing ability. In recent years, new technologies for genetic improvement, such as transgrafting, and genome-editing, have emerged. (Mudge, et al. 2009; Jia and Wang 2014). Using these techniques, no foreign genes are present in the final product, and some of them show considerable promise for application to apple breeding. Furthermore, genome editing, by which only the target gene can be accurately modified, is emerging as a novel breeding technology. These new technologies will undoubtedly facilitate fruit breeding, and yield novel and attractive fruit cultivars.
HortScience, 1996
Rootstocks in various species have been shown to significantly influence vigor of scion growth, yield, fruit size, maturity, quality, and other phenomena. This research studied the effects of combinations of three scions and three rootstocks of Iranian pistachio on characteristics of fruit. A split-plot design was laid out at Rafsanjan/Iran in 1993 and results for a period of 2 years from 1994 to 1995 are presented. Diameter of trunk 5 cm above and below the graft area, weight of nuts with hull, weight of nuts without hull, weight of in-shell nuts, weight of blank, percent of shell splitting and total yield weight were measured. Almost all the treatment differences in the experiment were associated with rootstock effects and not scions. Statistical analysis indicated that different scions had no effect on any of the measured characteristics except the diameter of trunk 5 cm below the graft area. Rootstocks, however, had large and significant effects on all the characters except perc...
Advances in biotechnology and propagation of nut trees in Iran
BIO Web of Conferences
As one of the main origin centers of nut trees, Iran is the fourth leading nut crops producer in the world (6% of total nut production). Due to the high genetic diversity, development of new varieties and rootstocks with desirable characteristics have been highly considered by fruit breeders in Iran. In this regard, molecular breeders concentrate on filling the gaps in the conventional breeding with the aim of accelerating breeding programs. Recent advancements in molecular breeding such as next-generation sequencing (NGS) techniques, high-throughput genotyping platforms and genomics-based approaches including genome wide association studies (GWAS), and genomic selection (GS) have opened up new avenues to enhance the efficiency of nut trees breeding. Over the past decades, Iranian nut crops breeders have successfully used advanced molecular and genomic tools such as molecular markers, genetic transformations and high-throughput genotyping to explore the genetic basis of the desired ...
Walnut: past and future of genetic improvement
Tree Genetics & Genomes, 2017
Persian or English walnut (Juglans regia L.), the walnut species cultivated for nut production, is one of the oldest food sources known. Persian walnuts, native to the mountain valleys of Central Asia, are grown worldwide in temperate areas. World production exceeds three million tons since 2012, mostly provided by China, the USA, and Iran. Despite very ancient culture of walnut species (Juglans spp.), breeding actually started in the twentieth century. Using a range of methodologies, from morphological markers to the most recent advances in genome analysis, many genetic studies of walnut have been conducted during the past 30 years, including examination of diversity, determination of relationships within or among germplasm collections and populations, phylogenetic and origin elucidation, genetic map construction, and biotic or abiotic stress investigations. The genetic improvement of walnut has undergone great evolution. The producing countries of the Middle East have widely studied morphological characteristics of walnut. The USA and France, for example, are behind important cultivar releases such as BChandler^and BFranquette.^Finally, genomics represents a major breakthrough in walnut improvement, in particular by recent sequencing of both chloroplast and nuclear genomes. This review summarizes worldwide molecular and Bomics^studies and gives an overview of the main walnut breeding programs.
Transgenic Research, 2010
Although cultivation of genetic modified (GM) annual crops has been steadily increasing in the recent 10 years, the commercial cultivation of GM fruit tree is still very limited and reports of field trials on GM fruit trees are rare. This is probably because development and evaluation of GM fruit trees require a long period of time due to long life cycles of trees. In this study, we report results from a field trial on three rolB transgenic dwarfing apple rootstocks of M26 and M9 together with non-transgenic controls grafted with five non-transgenic scion cultivars. We intended to investigate the effects of transgenic rootstock on nontransgenic scion cultivars under natural conditions as well as to evaluate the potential value of using the rolB gene to modify difficult-to-root rootstocks of fruit trees. The results showed that all rolB transgenic rootstocks significantly reduced vegetative growth including tree height regardless of scion cultivar, compared with the non-transgenic rootstocks. Flowering and fruiting were also decreased for cultivars grown on the transgenic rootstocks in most cases, but the fruit quality was not clearly affected by the transgenic rootstocks. Cutting experiment and RT-PCR analysis showed that the rolB gene was stably expressed under field conditions. PCR and RT-PCR analyses displayed that the rolB gene or its mRNA were not detectable in the scion cultivars, indicating no translocation of the transgene or its mRNA from rootstock to scion. Our results suggest that rolB modified rootstocks should be used in combination with vigorous scion cultivars in order to obtain sufficient vegetative growth and good yield. Alternatively, the rolB gene could be used to dwarf vigorous rootstocks of fruit trees or produce bonzai plants as it can significantly reduce the vegetative growth of plants.