Oil palm (Elaeis guineensis) is the highest oil-yielding commercially grown perennial tree. Oil palm germplasm conservation and in vitro clonal propagation strengthened the world’s efforts to ensure future food security. Cryopreservation provides long-term storage for germplasm. The storage of plant material at cryogenic temperatures (−196 °C) following dehydration causes cryoinjury. The cryotolerance mechanism has rarely been studied in oil palm zygotic embryos (ZE) and embryogenic calli (EC). A simple and effective cryopreservation method was established for ZE. ZE surrounded by endosperm was air-dried for 3 days without any complicated chemical pre-treatments before cryopreservation, while the viability rate and following germination rate could reach up to 96.67% and 90.88%, respectively. As for EC, the preferred method could be pre-culture in liquid MS medium with 0.3 M sucrose for 12 h and PVS2 treatment for 5 min prior to cryopreservation, and the viability rate reached 68.33%. SSR markers were used to verify the genetic stability after cryopreservation. In addition, changes in enzyme activities (CAT, POD, and SOD) showed a consistent trend with H₂O₂ production among ZE samples, indicating that these antioxidants were involved in ROS scavenging. Furthermore, differently expressed genes (DEGs) related to ROS, osmotic, and cold stress responses were selected for correlation network analysis. Most genes involved in ROS production (RBOH, PAO, and PRX) and ROS scavenging (APX, PER, SOD, CAT, GPX, and AOX) showed higher expression levels in EC, suggesting that EC was more sensitive to oxidative stress than ZE. The cryotolerance mechanism was further summarized accordingly. These results contributed to cryopreservation methods and provided a better understanding of cryotolerance in oil palm.

The coconut palm (Cocos nucifera L.) is a perennial, cross-pollinated, oil-bearing tropical forest tree. Recently, the demand for coconut goods has surged to 5 to 10 times its former value; however, coconut production is in jeopardy. Coconut senility is one of the most apparent factors that influence productivity. Adequate replanting is urgently required to maintain the growing demand for coconut products. However, coconut palm mass replanting might not be possible with traditional approaches. To overcome this snag, micropropagation via somatic embryogenesis (SE) has enormous potential for proficient clonal propagation in the coconut palm. During SE, the stimulation of cell proliferation, acquisition of embryogenic cell competence, and induction of somatic embryos undergo a series of developmental events. This phenomenon requires regulation in gene expression patterns and the activation of specific signaling pathways. This review summarizes gene regulatory mechanisms involved in the cell cycle, dedifferentiation, totipotency, embryo initiation, and meristem development during somatic embryo formation. Plant hormonal signal transduction is also highlighted during the formation of SE in coconut.

Areca palm (Areca catechu L.) is an economically significant crop in tropical and subtropical regions. However, an efficient transformation and gene editing system for genetic improvement has still not been established. In this study, protoplasts were isolated from juvenile leaves, followed by PEG-mediated transformation and gene editing targeting the areca palm AcPDS via the CRISPR/Cas9 system. High yield (9.08 × 10⁶ cells/g FW) and viability (91.57%) protoplasts were isolated successfully by digestion for 5 h in an enzyme solution. Transformation efficiency (11.85%) was obtained through PEG-mediated transformation (incubation for 30 min in the mixture containing 40% PEG-4000, 400 mM CaCl₂, 30 µg of plasmid DNA, and 100 µL of protoplasts). Furthermore, subcellular localization was established by the cotransformation of GFP and pNLS-mCherry in the protoplasts. Moreover, the editing efficiency (2.82%) of AcPDS using the CRISPR/Cas9 system was detected by Hi-TOM sequencing. This study established an efficient transformation and gene editing system based on protoplasts in areca palm, which will be beneficial for gene function verification and genetic improvement in areca palm and other tropical palm crops.

Coconut genetic improvement remains challenging due to low regeneration efficiency and limited transformation success. We optimized major components of a gene gun-mediated transient transformation system and evaluated explant types to support future establishment of a stable transformation pipeline. Three reporter genes (eGFP, GUS, and RUBY) were compared in coconut callus, and eGFP was selected as the most suitable due to its strong and non-destructive fluorescence. Background interference in GUS staining was reduced by adjusting the methanol–GUS ratio to 4:10. Single-factor optimization using callus tissue identified 0.4 M mannitol, 300–500 μg gold particles, 1.5 μg plasmid DNA, a 6.5 cm target distance, and 7 MPa pressure as effective parameters for biolistic delivery. Among the callus types, spongy callus showed strong transient eGFP expression but displayed loose and watery morphology consistent with non-embryogenic callus. In contrast, crumbly and smooth callus exhibited compact structures previously associated with embryogenic competence, although transient expression levels were lower. Among differentiated tissues, germinated zygotic embryo plumules and distal young leaflets exhibited moderate transient expression, supporting their suitability as transformation targets. These findings provide practical guidance on reporter selection, parameter refinement, and explant choice for future establishment of an efficient genetic transformation system in coconut.

Longer inflorescence stalks in oil palm enhance harvesting efficiency and reduce labor costs. However, the research on this topic is limited. This study aimed to investigate the differences in stalk lengths between male and female inflorescences in Tenera oil palm and to elucidate the underlying hormonal and transcriptomic mechanisms. The stalk lengths from inflorescences associated with the fourth to eighteenth leaf positions of Tenera oil palm trees were measured, and hormone profiling and RNA sequencing (RNA-seq) were conducted in immature (F4 and M5) and mature (F14 and M13) stalks from an individual tree. The male stalks were significantly longer than the female stalks since the thirteenth inflorescences and the differences increased with maturation. The elevated levels of indole-3-acetic acid (IAA) in both immature and mature male stalks suggested auxin’s critical role in promoting stalk elongation. In M13, we identified the upregulated auxin influx carrier LAX2, Gibberellic Acid-Stimulated Arabidopsis 6 (GASA6), and SMALL AUXIN UP RNA (SAUR) genes, indicating enhanced auxin accumulation, signaling, and response. Moreover, the auxin response factor (ARF11) was upregulated, linking auxin transport to gene activation for cell elongation. Conversely, in F14, higher levels of abscisic acid (ABA) and the expression of ABA receptor PYL3 and gibberellin 2-beta-dioxygenase 8 GA2ox8, which may inhibit stalk elongation, were identified. The results suggested that LAX2-mediated IAA accumulation activates ARF11 and SAURs, promoting stalk elongation, with GASA6 possibly acting as a downstream modulator. This study provides insights into the hormonal and genetic regulators of stalk elongation in oil palm and may guide breeding strategies for oil palm varieties with longer stalks of female inflorescences, thereby enhancing harvesting efficiency.