The Systematics, Reproductive Biology, Biochemistry, and Breeding of Sea Buckthorn-A Review

Taming the wild: domesticating untapped northern fruit tree and shrub resources in the era of high-throughput technologies

New crop`s need to emerge to provide sustainable solutions to climate change and increasing abiotic and biotic constraints on agriculture. A large breadth of northern fruit trees and shrubs exhibit a high potential for domestication; however, obstacles to implementing traditional breeding methods have hampered or dissuaded efforts for improvement. This review article proposes a unique roadmap for de novo domestication of northern fruit crops, with a focus on biotechnological (e.g. genome editing, rapid cycle breeding, and in planta transformation) approaches that can boast rapid evolutionary gains. In addition, numerous biotechnological (e.g. virus-induced flowering and grafting-mediated flowering) and breeding strategies (e.g. adaptation of speed breeding to fruit trees) that can hasten the transition from juvenility to sexual maturity are described. A description of an accelerated genetic breeding strategy with insights for 16 underutilized species (e.g. shagbark hickory, running serviceberry, horse chestnut, and black walnut) is provided to support their enhancement. Deemed unrealistic only a decade ago, progress in the realm of bioengineering heralds a future for northern orphan crops through the implementation of fast-tracked crop improvement programs. As such, the roadmap presented in this article paves the way to integrating these novel biotechnological discoveries and propel the development of these forgotten crops in a sustainable and timely manner.

Development of sex-specific molecular markers for early sex identification in Hippophae gyantsensis based on whole-genome resequencing

Hippophae gyantsensis is a dioecious plant endemic to the Qinghai-Tibet Plateau and is significant for ecological restoration and sand stabilization. Its fruit is rich in bioactive compounds that offer economic potential. However, the inability to distinguish sexes before flowering and prolonged maturation hinder breeding and cultivation. We performed whole-genome resequencing on male and female plants, identified large insertion/deletion (InDel) variants, and developed two sex-specific primers (Higy_04 and Higy_06). These primers enable rapid, accurate PCR-based sex identification. All sex-specific sites were located on chromosome 2, suggesting its potential role as the sex chromosome. Additionally, we found a 1:1 sex ratio among offspring from the same mother plant, consistent with Mendelian inheritance, indicating that sex segregation is mainly genetically controlled. This work lays the foundation for developing molecular markers applicable across the entire genus Hippophae and contributes to understanding sex chromosome formation and adaptive evolution within the genus.

Development and validation of sex-linked molecular markers for rapid and accurate identification of male and female Hippophae tibetana plants

Hippophae tibetana, one of the highest-altitude woody plants endemic to the Qinghai-Tibet Plateau, primarily thrives on riverbanks formed by glacial meltwater. As a dioecious species, it demonstrates significant ecological and economic value in extreme alpine environments. However, the lack of sex identification techniques outside of the flowering period severely limits research on sex ratio, differentiation, and breeding. There is an urgent need to develop effective sex-linked molecular markers that are independent of developmental stages, but current research in this area remains limited. This study developed a set of accurate sex-linked molecular markers for the rapid identification of male and female individuals of H. tibetana. Through whole-genome resequencing of 32 sexually differentiated H. tibetana samples, this study offers strong evidence supporting chromosome 2 as the sex chromosome and successfully identified key loci related to sex determination on this chromosome. Utilizing these loci, we, for the first time, developed three reliable pairs of sex-specific molecular markers, which exhibited high accuracy during validation across various geographic populations, offering an effective tool for the sex identification of H. tibetana. Additionally, this study lays the groundwork for further research into the mechanisms of sex determination and the evolution of sex chromosomes in H. tibetana.