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The instability of in vitro cultures may cause genetic and epigenetic changes in crops called somaclonal variations. Sometimes, these changes produce beneficial effects; for example, they can be used in breeding programs to generate new cultivars with desirable characteristics. In this article, we present a systematic review designed to answer the following question: How does somaclonal variation contribute to plant genetic improvement? Five electronic databases were searched for articles based on pre-established inclusion and exclusion criteria and with a standardized search string. The somaclonal variation technique has been most frequently applied to ornamental plants, with 49 species cited in 48 articles, and to the main agricultural crops, including sugarcane, rice, banana, potato and wheat, in different countries worldwide. In 69 studies, a technique was applied to evaluate the genetic diversity generated between clones, and, in 63 studies, agronomic performance characteristics were evaluated. Other studies are related to resistance to pathogens, ornamental characteristics and resistance to abiotic stresses. The application of the plant growth regulators (PGRs) benzylaminopurine (BAP) and dichlorophenoxyacetic acid (2,4-D) was the most common method for generating somaclones, and randomly amplified polymorphic DNA (RAPD) molecular markers were the most commonly used markers for identification and characterization. Somaclonal variation has been used in genetic improvement programs for the most economically important crops in the world, generating genetic diversity and supporting the launch of new genotypes resistant to diseases, pests and abiotic stresses. However, much remains to be explored, such as the genetic and epigenetic mechanisms from which somaclonal variation is derived.

Agricultural crops are exposed to various abiotic stresses, such as salinity, water deficits, temperature extremes, floods, radiation, and metal toxicity. To overcome these challenges, breeding programs seek to improve methods and techniques. Gene editing by Clustered Regularly Interspaced Short Palindromic Repeats—CRISPR/Cas—is a versatile tool for editing in all layers of the central dogma with focus on the development of cultivars of plants resistant or tolerant to multiple biotic or abiotic stresses. This systematic review (SR) brings new contributions to the study of the use of CRISPR/Cas in gene editing for tolerance to abiotic stress in plants. Articles deposited in different electronic databases, using a search string and predefined inclusion and exclusion criteria, were evaluated. This SR demonstrates that the CRISPR/Cas system has been applied to several plant species to promote tolerance to the main abiotic stresses. Among the most studied crops are rice and Arabidopsis thaliana, an important staple food for the population, and a model plant in genetics/biotechnology, respectively, and more recently tomato, whose number of studies has increased since 2021. Most studies were conducted in Asia, specifically in China. The Cas9 enzyme is used in most articles, and only Cas12a is used as an additional gene editing tool in plants. Ribonucleoproteins (RNPs) have emerged as a DNA-free strategy for genome editing without exogenous DNA. This SR also identifies several genes edited by CRISPR/Cas, and it also shows that plant responses to stress factors are mediated by many complex-signaling pathways. In addition, the quality of the articles included in this SR was validated by a risk of bias analysis. The information gathered in this SR helps to understand the current state of CRISPR/Cas in the editing of genes and noncoding sequences, which plays a key role in the regulation of various biological processes and the tolerance to multiple abiotic stresses, with potential for use in plant genetic improvement programs.

The objective of this study was to evaluate the influence of pH on in vitro germination and pollen grain viability of banana diploids (AA) generated by the breeding program of Embrapa Mandioca e Fruticultura Tropical. The pollen grains were inoculated in culture medium containing 15% sucrose, 0.01% H;BO;, 0.01% KNO;, 0.03% Ca(NO;)>.4H20, 0.02% MgS04.7H,0, solidified with 0.8% agar and pH adjusted to 5.8 or 7.0. Pollen viability was evaluated by staining with 1% acetic carmine. The germination percentages of the genotypes 9187-0] (90.0%) and M-53 (89.7%) in pH 7.0 medium were highest, while the pollen tube length of genotype 9187-01 was approximately half the size (1.79mm) of genotype M-53 (3.84mm). The pollen viability of the genotypes evaluated was higher than 85%, even for the diploids with a low in vitro germination percentage.

The induction of somatic embryogenesis in banana is extremely difficult because of endogenous problems of the species and genotype dependency. Establishing a suitable protocol for somatic embryogenesis is necessary for applying biotechnological approaches to assist the genetic improvement, by facilitating the access to individual cells or groups of cells for use in genetic transformation, and the induction of polyploidy and mutagenesis. Embryogenic cultures were induced from immature male flowers of two important cultivars of banana, ‘Grand Naine’ (AAA) and ‘Tropical’ (AAAB), using immature male flowers. Cell suspensions were established, and regenerated plants were evaluated for their genetic stability using 11 simple sequence repeat markers. For induction of embryogenesis, different doses of autoclaved glutamine in the induction medium were used, and somatic embryos were converted into plants in medium supplemented with benzylaminopurine and naphthalene-1-acetic acid. ‘Grand Naine’ formed somatic embryos in glutamine-free media, while ‘Tropical’ somatic embryos grew in the presence of autoclaved glutamine. During regeneration, ‘Grand Naine’ showed better results for formation of embryos in culture medium without growth regulators, but these embryos were not converted into plants when kept in the same medium, while ‘Tropical’ produced a large number of plants regenerated when kept in the same medium. The simple sequence repeat markers used did not detect any genetic variation. These results suggest that the establishment of embryogenic cell suspension cultures of banana may be effective for production of genetically stable plants on a large scale as well as being a biotechnological tool to support banana genetic improvement.