Differential gene expression between the vigorous and dwarf litchi cultivars based on RNA-Seq transcriptome analysis

Targeted Metabolic and Transcriptomic Analysis of Pinus yunnanensis var. pygmaea with Loss of Apical Dominance

Pinus yunnanensis var. pygmaea demonstrates obvious loss of apical dominance, inconspicuous main trunk, which can be used as an ideal material for dwarfing rootstocks. In order to find out the reasons for the lack of apical dominance of P. pygmaea, endogenous phytohormone content determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and comparative transcriptomes were performed on the shoot apical meristem and root apical meristem of three pine species (P. massoniana, P. pygmaea, and P. elliottii). The results showed that the lack of CK and the massive accumulation of ABA and GA-related hormones may be the reasons for the loss of shoot apical dominance and the formation of multi-branching, the abnormal synthesis of diterpenoid biosynthesis may lead to the influence of GA-related synthesis, and the high expression of GA 2-oxidase (GA2ox) gene may be the cause of dwarfing. Weighted correlation network analysis (WGCNA) screened some modules that were highly expressed in the shoot apical meristem of P. pygmaea. These findings provided valuable information for identifying the network regulation of shoot apical dominance loss in P. pygmaea and enhanced the understanding of the molecular mechanism of shoot apical dominance growth differences among Pinus species.

Walnut Genotypes for High Density Orchards

The aim of this review is to check the possibilities and circumstances regarding how to create a high-density Persian walnut orchard. Increasing yields, decreasing tree size, limiting juveniles, and lowering total costs are the most important objectives of breeders and horticulturists. Reducing the size of walnut trees can increase yield. Breeding programs in several countries have led to the production of walnut dwarf rootstocks. For example, Daixiang and Daihui in China, Alvand in Iran, and Fernette in France are all novel-bred dwarfing Persian walnut rootstocks. These precocious walnuts are considered to be a rare resource in the study of precociousness as well as juvenile and flowering mechanisms. Moreover, they play a potential role in breeding and modifying cultivars by genetic engineering, through walnut ameliorating programs. The CRISPR (clustered regularly interspaced short palindromic repeat) technique is used to improve walnuts, which will be used in the near future.

Advances in genomics and genome editing for breeding next generation of fruit and nut crops

Fruit tree crops are an essential part of the food production systems and are key to achieve food and nutrition security. Genetic improvement of fruit trees by conventional breeding has been slow due to the long juvenile phase. Advancements in genomics and molecular biology have paved the way for devising novel genetic improvement tools like genome editing, which can accelerate the breeding of these perennial crops to a great extent. In this article, advancements in genomics of fruit trees covering genome sequencing, transcriptome sequencing, genome editing technologies (GET), CRISPR-Cas system based genome editing, potential applications of CRISPR-Cas9 in fruit tree crops improvement, the factors influencing the CRISPR-Cas editing efficiency and the challenges for CRISPR-Cas9 applications in fruit tree crops improvement are reviewed. Besides, base editing, a recently emerging more precise editing system, and the future perspectives of genome editing in the improvement of fruit and nut crops are covered.