Plant regeneration through somatic embryogenesis provides a solution for maintaining and genetically improving crop or fruit varieties with desirable agronomic traits. For the fruit tree pomegranate (Punica granatum L.), despite some successful applications, the existing somatic embryogenesis protocols are limited by low availability of explants and susceptibility to browning. To address these problems, in this study, we developed an effective system for induction of high-vigor pomegranate somatic embryos derived from stem explants. The usage of stem explants breaks through the difficulty in obtaining material, thus making our system suitable for widespread commercial production. To enhance the performance of our system, we identified the optimal explants, subculture cycles and combination of basal media and plant growth regulators for each step. The results showed that inoculating stem explants onto a Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzylaminopurine (6-BA) and 1.0 mg/L 1-naphthaleneacetic acid (NAA) achieved the best induction rate and growth status of pomegranate calli (induction rate = ~72%), and MS medium containing 0.5 mg/L 6-BA and 1.0 mg/L NAA was the optimal condition for the induction of embryogenic calli and somatic embryos (induction rate = ~74% and 79%, respectively). The optimal subculture period for embryogenic calli was found to be 30–35 days. Strong roots were then induced in the developed somatic embryo seedlings, which survived and grew well after transplantation to the natural environment, indicating the good vitality of the induced pomegranate somatic embryos. Together, our system provides a solution to mass somatic embryo induction and plant regeneration of pomegranate and lays a foundation for future genetic transformation and bioengineering improvement of pomegranate with favorable agronomic traits.

Dwarfed stature is a desired agronomic trait for pomegranate (Punica granatum L.), with its advantages such as lower cost and increased yield. A comprehensive understanding of regulatory mechanisms underlying the growth repression would provide a genetic foundation to molecular-assisted dwarfing cultivation of pomegranate. Our previous study induced dwarfed pomegranate seedlings via exogenous application of plant growth retardants (PGRs) and highlighted the important roles of differential expression of plant growth-related genes in eliciting the dwarfed phenotype of pomegranate. Alternative polyadenylation (APA) is an important post-transcriptional mechanism and has been demonstrated to act as a key regulator in plant growth and development. However, no attention has been paid to the role of APA in PGR-induced dwarfing in pomegranate. In this study, we characterized and compared APA-mediated regulation events underlying PGR-induced treatments and normal growth condition. Genome-wide alterations in the usage of poly(A) sites were elicited by PGR treatments, and these changes were involved in modulating the growth and development of pomegranate seedlings. Importantly, ample specificities were observed in APA dynamics among the different PGR treatments, which mirrors their distinct nature. Despite the asynchrony between APA events and differential gene expression, APA was found to regulate transcriptome via influencing microRNA (miRNA)-mediated mRNA cleavage or translation inhibition. A global preference for lengthening of 3’ untranslated regions (3’ UTRs) was observed under PGR treatments, which was likely to host more miRNA target sites in 3’ UTRs and thus suppress the expression of the corresponding genes, especially those associated with developmental growth, lateral root branching, and maintenance of shoot apical meristem. Together, these results highlighted the key role of APA-mediated regulations in fine-tuning the PGR-induced dwarfed stature of pomegranate, which provides new insights into the genetic basis underlying the growth and development of pomegranate.

Ulomoides dermestoides (Chevrolat) (Coleoptera, Tenebrionidae) is a storage pest and an insect of medical importance. Since this insect lives in the dark and does not emit sounds, its sensation of the external environment is based primarily on sensilla, so it could serve as an ideal model for the study of these structures. Scanning electron microscopy was used to identify the types of antennal sensilla of male and female U. dermestoides and to characterize the function of different types of sensilla observed. The bead-like antenna of U. dermestoides is composed of a scape (one segment), a pedicel (one segment), and a flagellum (nine segments). Six types of sensilla were observed on the antennae of both females and males: the sensilla trichoidea (subtypes I, II, and III), sensilla chaetica (subtypes I, II, and III), sensilla basiconica, basiconic mastoid sensillum, sensilla styloconica (subtypes I and II), and the Bohm bristle. The Student's t test was used to compare the distribution of these sensilla.

Pomegranate (Punica granatum L.) is a popular fruit tree with high edible and ornamental values. However, the traditional breeding strategies are lacking in efficiency for the improvement of agronomic traits of pomegranate. Gene editing technologies offer a solution for promoting desired growth or metabolic processes in pomegranate trees. In this study, we established a CRISPR-mediated gene editing system for pomegranate, using Agrobacterium tumefaciens as the delivery vehicle and unlignified stems of the ‘Baihuayushizi’ cultivar as explants. The editing efficiency of our system was inferred to be 38.00%, which is substantially higher than those in some other plant species. The impacts of different culture conditions on the system were further assessed. Pre-culture duration was found to have the largest influence on the success of genetic transformation, followed by A. tumefaciens infection time and concentration. The optimal pre-culture time for this system is 3 days, and the A. tumefaciens concentration, infection time, and co-culture duration are OD₆₀₀ = 0.8, 10 min, and 2 days, respectively. With the help of our system, we successfully knocked the PgBZR1 gene out from ‘Baihuayushizi’ pomegranate, which encodes a key transcription factor that regulates the growth and development of pomegranate. Given these advantages, we anticipate that our gene editing system is a useful tool for future studies on pomegranate gene functions and genetic improvement.