Establishment and optimization of mRNA in situ hybridization system in turnip (Brassica rapa var. rapa)

Application of Biotechniques for In Vitro Virus and Viroid Elimination in Pome Fruit Crops

Sustainable production of pome fruit crops is dependent upon having virus-free planting materials. The production and distribution of plants derived from virus- and viroid-negative sources is necessary not only to control pome fruit viral diseases but also for sustainable breeding activities, as well as the safe movement of plant materials across borders. With variable success rates, different in vitro-based techniques, including shoot tip culture, micrografting, thermotherapy, chemotherapy, and shoot tip cryotherapy, have been employed to eliminate viruses from pome fruits. Higher pathogen eradication efficiencies have been achieved by combining two or more of these techniques. An accurate diagnosis that confirms complete viral elimination is crucial for developing effective management strategies. In recent years, considerable efforts have resulted in new reliable and efficient virus detection methods. This comprehensive review documents the development and recent advances in biotechnological methods that produce healthy pome fruit plants. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Improvement of RNA In Situ Hybridisation for Grapevine Fruits and Ovules

The European grapevine (Vitis vinifera L.) is one of the world's most widely cultivated and economically important fruit crops. Seedless fruits are particularly desired for table grapes, with seedlessness resulting from stenospermocarpy being an important goal for cultivar improvement. The establishment of an RNA in situ hybridisation (ISH) system for grape berries and ovules is, therefore, important for understanding the molecular mechanisms of ovule abortion in stenospermocarpic seedless cultivars. We improved RNA in situ hybridisation procedures for developing berries and ovules by targeting two transcription factor genes, VvHB63 and VvTAU, using two seeded varieties, 'Red Globe' and 'Pinot Noir', and two seedless cultivars, 'Flame Seedless' and 'Thompson Seedless'. Optimisation focused on the time of proteinase K treatment, probe length, probe concentration, hybridisation temperature and post-hybridisation washing conditions. The objectives were to maximise hybridisation signals and minimise background interference, while still preserving tissue integrity. For the target genes and samples tested, the best results were obtained with a pre-hybridisation proteinase K treatment of 30 min, probe length of 150 bp and concentration of 100 ng/mL, hybridisation temperature of 50 °C, three washes with 0.2× saline sodium citrate (SSC) solution and blocking with 1% blocking reagent for 45 min during the subsequent hybridisation. The improved ISH system was used to study the spatiotemporal expression patterns of genes related to ovule development at a microscopic level.

Establishment of Agrobacterium-mediated genetic transformation and application of CRISPR/Cas9 genome-editing system to Brassica rapa var. rapa

BACKGROUND

Genome editing is essential for crop molecular breeding. However, gene editing in turnip (Brassica rapa var. rapa) have not been reported owing to the very low transformation efficiency.

RESULTS

In this study, we established a transformation procedure involving chemical-inducible activation of the BrrWUSa gene, which resulted in high transformation frequencies of turnip. Estradiol-inducible BrrWUSa transgenic plants were fertile and showed no obvious developmental defects. Furthermore, we used CRISPR/Cas9 gene-editing technology to edit BrrTCP4b and generated 20 BrrTCP4b-edited seedlings with an increase in leaf trichome number.

CONCLUSION

The results demonstrate that BrrWUSa improves the regeneration efficiency in turnip. The transformation procedure represents a promising strategy to improve genetic transformation and for functional characterization of genes in turnip.

RNA in situ hybridization and expression of related genes regulating the accumulation of triterpenoids in Cyclocarya paliurus

Cyclocarya paliurus (Batal.) Iljinskaja, a woody medicinal species in the Juglandaceae, grows extensively in subtropical areas of China. Triterpenoids in the leaves have health-promoting effects, including hypoglycemic and hypolipidemic activities. To understand triterpenoid biosynthesis, transport and accumulation in C. paliurus during the growing season, gene cloning, gene expression and RNA in situ hybridization of related genes were used, and accumulation was examined in various organs. The complete coding sequences (CDSs) of three genes, CpHMGR, CpDXR and CpSQS, were obtained from GenBank and RACE. RNA in situ hybridization signals of the three genes mainly occurred in the epidermis, palisade tissue, phloem and xylem of leaf, shoot and root, with the signals generally consistent with the accumulation of metabolites in tissues, except in the xylem. Both gene expression and triterpenoid accumulations showed seasonal variations in all organs. However, total triterpenoid content in the leaves was significantly higher than that in the shoots, with the maximum in shoots in August and in leaves in October. According to Pearson correlation analysis, triterpenoid accumulation in the leaves was significantly positively related with the relative expression of CpSQS. However, the relation between gene expression and accumulation was dependent on the role of the gene in the pathway as well as on the plant organ. The results suggested that most of the intermediates catalyzed by CpHMGR and CpDXR in young shoots and roots were used in growth and flowering in the spring, whereas subsequent triterpenoid biosynthesis in the downstream catalyzed by CpSQS mainly occurred in the leaves by using transferred and in situ intermediates as substrates. Thus, this study provides a reference to improve triterpenoid accumulation in future C. paliurus plantations.