Explore the vast range of titles available.

Phytoene desaturase (PDS) is a plant enzyme involved in carotenoid biosynthesis. The PDS gene has been used as a selective marker for genome editing in several plant species, including banana (Musa spp.). Its knockout promotes dwarfism and albinism, characteristics that are easily recognizable and highly favorable. In Musa spp., the A genome increases fruit production and quality, whereas the B genome is associated with tolerance to biotic and abiotic stresses. The objective of this study was to identify a molecular marker in the PDS gene to easily discriminate the A and B genomes of banana. A 2166 bp fragment for the “PDSMa” marker was identified as polymorphic for the A genome (identification accuracy of 99.33%), whereas ~332 and ~225 bp fragments were detected for the “PDSMb” marker with 100% accuracy using MedCalc software. In this study, we used genotypes with A and B genomes that are used in the genetic improvement of bananas and an accession with the BT genome. It was not possible to differentiate the accession with the BT genome from the others, suggesting that the markers do not have the capacity to separate the T genome from the A and B genomes. To the best of our knowledge, this is the first study to use the PDS gene to determine doses of the A genome and identify the B genome in Musa spp., which will aid in evaluating the genomic constitution of banana hybrids and accessions at the seedling stage and accelerating their classification in crop genetic improvement programs.

Fusarium oxysporum f. sp. cubense (Foc) causes Panama disease or Fusarium wilt of bananas. The association between soil-inhabiting fungi and nematodes can increase the severity of symptoms and suppress the resistance of plants to diseases. In this study, the interaction between Foc race 1 and Radopholus similis, a burrowing nematode that parasitizes banana plants, was analyzed using one moderately susceptible cultivar and seven resistant cultivars of banana. Two Foc isolates that differed in virulence were tested. The analyses of symptoms and stained fungal structures in the roots demonstrated that R. similis interacting with Foc in different inoculation sequences caused changes in symptom severity and the resistance pattern to Foc isolate 0801 (race 1) in cultivars ‘Terra Maranhão’, ‘BRS Pacovan Ken’, ‘BRS Vitória’, and ‘BRS Platina’. The data generated in this study have relevant implications for banana breeding programs in the classification of cultivars for durable resistance to Fusarium wilt and for understanding pathogen interactions during occurrence of the disease.

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.

Bananas are a staple food that considerably contributes to both food security and income generation, especially in countries of Africa, Asia, and Central and South America. The banana plant (Musa spp.) is affected by various pathogens, of main concern being the plant-parasitic nematodes associated with the rhizosphere, the most important of which are Radopholus similis (burrowing nematode), Helicotylenchus sp. (spiral nematode), Pratylenchus sp. (root lesion nematode), and Meloidogyne sp. (gall nematode). Infected plants reduce their ability to absorb water and nutrients, which can lead to delayed flowering, fewer bunches, and lower fruit mass. Obtaining nematode-resistant banana cultivars through genetic improvement is an effective and sustainable option compared with chemical control with nematicides. Here, we provide the first systematic review of existing banana sources of resistance to nematodes to aid the management and control of nematodes in banana and plantain crops. Articles selected from different databases were evaluated, and searches were conducted using pre-established inclusion and exclusion criteria. We found 69 studies dealing with genetic improvement for nematode resistance in banana cultivation. Our findings revealed that sources of resistance are currently under investigation to combat the diseases caused by different nematode species in banana plants.

Bananas, a staple food globally and a key agricultural commodity, face a severe threat from the fungus Fusarium oxysporum f. sp. cubense (Foc), significantly impacting production. Genetic improvement to develop resistant cultivars stands out as a crucial strategy to mitigate this disease. This study focused on assessing and recommending enhanced diploid banana varieties for resistance against Foc subtropical race 4 (ST4) and Foc race 1 (R1). Twenty-four improved diploids developed by Embrapa, Brazil, underwent evaluation. Utilizing a scale for internal symptoms at 90 days after inoculation, genotypes were categorized from highly resistant to highly susceptible based on the internal symptom index. The diploid M53 exhibited high resistance to Foc R1 and resistance to Foc ST4, while only the diploid CNPMF 0534 demonstrated complete resistance to both R1 and ST4, with resistance to the latter likely associated with penetration, primarily due to the presence of callose. These findings provide valuable insights for banana and plantain breeding programs, offering selected diploids for crossbreeding with commercial cultivars to develop new, resistant genotypes against Foc.

The fungus Fusarium oxysporum f. sp. cubense (FOC), tropical race 4 (TR4), causes Fusarium wilt of banana, a pandemic that has threatened the cultivation and export trade of this fruit. This article presents the first systematic review of studies conducted in the last 10 years on the resistance of Musa spp. to Fusarium wilt. We evaluated articles deposited in different academic databases, using a standardized search string and predefined inclusion and exclusion criteria. We note that the information on the sequencing of the Musa sp. genome is certainly a source for obtaining resistant cultivars, mainly by evaluating the banana transcriptome data after infection with FOC. We also showed that there are sources of resistance to FOC race 1 (R1) and FOC TR4 in banana germplasms and that these data are the basis for obtaining resistant cultivars, although the published data are still scarce. In contrast, the transgenics approach has been adopted frequently. We propose harmonizing methods and protocols to facilitate the comparison of information obtained in different research centers and efforts based on global cooperation to cope with the disease. Thus, we offer here a contribution that may facilitate and direct research towards the production of banana resistant to FOC.

Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases affecting banana cultivation worldwide. Although Foc tropical race 4 (TR4) has not yet been identified in Brazilian production areas, the damage caused by races 1 and subtropical 4 is the main cause of production losses, especially affecting cultivars of the Prata subgroup. Thus, the induction of somaclonal variation is a promising strategy in biotechnology to generate genetic variability and develop resistant varieties. This study aimed to induce somaclonal variation in the Prata Catarina cultivar (AAB genome) using successive subcultures in Murashige and Skoog (MS) medium enriched with the plant regulator Thiadizuron (TDZ) at two concentrations: 1 and 2 mg/L. After evaluating the symptoms, we selected 13 resistant somaclones that were not infected by the fungus. Histochemical and histological analyses of the somaclones indicated possible defense mechanisms that prevented colonization and/or infection by Foc, such as intense production of phenolic compounds and the presence of cellulose and callose in the roots. Some somaclones showed no pathogen structures in the xylem-conducting vessels, indicating possible pre-penetration resistance. Furthermore, molecular studies indicated that the genetic alterations in the somaclones may have induced resistance to Foc without compromising the agronomic characteristics of the commercial genotype.

This erratum is published due to:

Fusarium wilt is a soil borne fungal disease that has devastated banana production in plantations around the world. Most Cavendish-type bananas are susceptible to strains of Fusarium oxysporum f. sp. cubense (Foc) belonging to the Subtropical Race 4 (STR4) and Tropical Race 4 (TR4). The wild banana diploid Musa acuminata ssp. malaccensis (AA, 2n = 22) carries resistance to Foc TR4. A previous study using segregating populations derived from M. acuminata ssp. malaccensis identified a quantitative trait locus (QTL) (12.9 cM) on the distal part of the long arm of chromosome 3, conferring resistance to both Foc TR4 and STR4. An SNP marker, based on the gene Macma4_03_g32560 of the reference genome ‘DH-Pahang’ v4, detected the segregation of resistance to Foc STR4 and TR4 at this locus. Using this marker, we assessed putative TR4 resistance sources in 123 accessions from the breeding program in Brazil, which houses one of the largest germplasm collections of Musa spp. in the world. The resistance marker allele was detected in a number of accessions, including improved diploids and commercial cultivars. Sequencing further confirmed the identity of the SNP at this locus. Results from the marker screening will assist in developing strategies for pre-breeding Foc TR4-resistant bananas. This study represents the first-ever report of marker-assisted screening in a comprehensive collection of banana accessions in South America. Accessions carrying the resistance marker allele will be validated in the field to confirm Foc TR4 resistance.