Vahdati Kourosh, Sadeghi-Majd Rasoul, Sestras Adriana F, Licea-Moreno Ricardo Julián, Peixe Augusto, Sestras Radu E
Department of Horticulture, College of Aburaihan, University of Tehran, Tehran 3391653755, Iran.
Department of Forestry, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania.
Plants (Basel). 2022 Nov 10;11(22):3040. doi: 10.3390/plants11223040.
Walnuts ( sp.) are allogamous species. Seed-derived plants are not always superior to the selected parent. Clonal propagation of selected stock plants is an essential requirement for the clonal fidelity of the descendants and to maintain their genetic structure. Selection of the desired plant is realized only after reaching maturity, and characterizing and evaluating the performance of adult trees require a long time. Clonal propagation methods ensure proper transmission of characters to descendants and can be used effectively in breeding programs. The commercialization of a cultivar or rootstock depends on the success of vegetative propagation. Walnuts, like other tree species, are recalcitrant to conventional vegetative propagation methods and even non-conventional in vitro culture (micropropagation). Elucidation of factors determining the success of cloning of desired plants would contribute to understanding current limitations for most genotypes of . We outline the role of grafting and cuttings and stool layering, as well as in vitro culture on walnut multiplication. These techniques are, in practice, entirely different; nevertheless, they are affected by common factors. The incompatibility of stock-scion and the reduced ability of stem cuttings to root are the main bottlenecks for grafting and cutting, respectively. Genotype, age, and physiological status, reinvigoration or rejuvenation-treatment of donor plant, period of harvesting and processing of explants critically affect the results of methods followed. The in vitro culture technology is the most suitable for walnut cloning. This also has constraints that affect commercial propagation of most desired genotypes. We describe comprehensive results and synthesis in this review on the asexual reproduction of walnuts, providing a better comprehension of the limiting factors and the ways to overcome them, with direct implications on commercial propagation and the releasing of outstanding genotypes.
核桃（属）为异花授粉物种。种子繁殖的植株并不总是优于所选亲本。对选定母株进行克隆繁殖是确保后代克隆保真度及维持其遗传结构的必要条件。只有在植株成熟后才能实现对所需植株的选择，而对成年树的特性表征和性能评估需要很长时间。克隆繁殖方法可确保性状正确传递给后代，并能在育种计划中有效应用。一个品种或砧木的商业化取决于营养繁殖的成功与否。与其他树种一样，核桃对传统营养繁殖方法甚至非常规的离体培养（微繁殖）都具有顽拗性。阐明决定所需植株克隆成功的因素将有助于理解目前大多数基因型所面临的限制。我们概述了嫁接、扦插和压条以及离体培养在核桃繁殖中的作用。实际上，这些技术完全不同；然而，它们受到一些共同因素的影响。砧木与接穗的不亲和性以及茎插条生根能力的降低分别是嫁接和扦插的主要瓶颈。基因型、年龄和生理状态、供体植株的复壮或幼化处理、外植体的采集和处理时期都会严重影响后续方法的结果。离体培养技术最适合核桃克隆。但这也存在一些限制因素，影响了大多数所需基因型的商业繁殖。我们在本综述中描述了关于核桃无性繁殖的综合结果并进行了总结，以便更好地理解限制因素以及克服这些因素的方法，这对商业繁殖和优良基因型的推广具有直接意义。
