CRISPR/Cas9-mediated editing of the TM6 MADS-box gene in the octoploid strawberry (Fragaria x ananassa)

El contenido del poster presentado está desarrollado en: doi:10.1093/jxb/ery400 y Publicado por Oxford University pressThe B-class of MADS-box transcription factors has been studied in many plant species, but remain functionally uncharacterized in the Rosaceae family. APETALA3 (AP3), a member of this class, controls the identity of petals and stamens in Arabidopsis thaliana. In this work, we identified two members of the AP3 lineage in the cultivated strawberry (Fragaria × ananassa): FaAP3 and FaTM6. Interestingly, FaTM6, and not FaAP3, shows an expression pattern equivalent to that of AP3 in Arabidopsis. Genome editing using Cluster Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system is becoming a robust tool for targeted and stable mutagenesis of DNA. However, whether it can be efficiently used in an octoploid species such as F. × ananassa is not known. In our study, we report the application of the CRISPR/Cas9 in F. × ananassa to characterize the function of FaTM6 in flower development. An exhaustive analysis by high-throughput sequencing of the FaTM6 locus spanning the target sites showed a high efficiency genome editing already in the T0 generation. The phenotypic characterization of the mutant lines indicates that FaTM6 plays a key role in petal and especially in anther development in strawberry. Our results validate the CRISPR/Cas9 strategy for gene functional analysis in an octoploid species such as F. × ananassa, and offer new opportunities for engineering strawberry to improve traits of interest in breeding programs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Targeted gene modification in Fragaria vesca mediated by CRISPR/Cas9 system

Genome editing is becoming an important biotechnological tool for gene function analysis and crop improvement, being the CRISPR-Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat-CRISPR associated protein 9) system the most widely used. The natural CRISPR/Cas9 system has been reduced to two components: a single-guide RNA (sgRNA) for target recognition via RNA-DNA base pairing, which is commonly expressed using a promoter for small-RNAs (U6 promoter), and the Cas9 endonuclease for DNA cleavage (1). To validate the CRISPR/Cas9 system in strawberry plants, we designed two sgRNAs directed against the floral homeotic gene APETALA3 (sgRNA-AP3#1 and sgRNA-AP3#2). This gene was selected because ap3 mutations induce clear developmental phenotypes in which petals and stamens are missing or partially converted to sepals and carpels respectively (2). In this work, we used two different U6 promoters to drive the sgRNA-AP3s expression: AtU6-26 from Arabidopsis (4), and a U6 promoter from Fragaria vesca (FvU6) (this work). We also tested two different coding sequences of Cas9: a human- (hSpCas9) (3) and a plant-codon optimized (pSpCas9) (this work). Transient expression experiments using both CRISPR/Cas9 systems (AtU6-26:sgRNA-AP3#1_35S:hSpCas9_AtU6-26:sgRNA-AP3#2 and FvU6:sgRNA-AP3#1_35S:pSpCas9_FvU6:sgRNA-AP3#2) were performed infiltrating Agrobacterium tumefaciens into F. vesca fruits. PCR amplification and sequencing analyses across the target sites showed a deletion of 188-189 bp corresponding to the region comprised between the two cutting sites of Cas9, confirming that the CRISPR/Cas9 system is functional in F. vesca. Remarkably, the two systems showed different mutagenic efficiency that could be related to differences in expression of the U6 promoters as well as differences in the Cas9 transcripts stability and translation. Stable transformants for both F. vesca (2n) and Fragaria X anannassa (8n) are currently being established to test whether is possible to obtain heritable homozygous mutants derived from CRISPR/Cas9 strategies in strawberry. Thus, our work offers a promising tool for genome editing and gene functional analysis in strawberry. This tool might represent a more efficient alternative to the sometimes inefficient RNAi silencing methods commonly used in this species.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Genome Editing of the Octoploid Fragaria x ananassa Using the CRISPR/Cas9 System

Due to its octoploid nature, gene functional analyses in the cultivated strawberry (Fragaria × ananassa) are commonly carried out via gene silencing using self-complementary “hairpin” double-stranded RNA (RNAi) constructs. However, this system is not always as efficient as expected. First, an efficient silencing of the target gene is not always achieved, and second, its effect might not be stable after several clonal propagations of the transgenic lines. Recently, genome editing is becoming an important biotechnological tool for gene functional analysis and crop improvement, in particular since the development of the CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat-CRISPR associated protein 9) system. To investigate the functionality of the CRISPR/Cas9 in strawberry, we designed two sgRNAs directed against two regions of the floral homeotic gene APETALA3 (AP3) in order to induce a deletion of around 200 nt. A vector containing both sgRNAs and Cas9 was used to transform leaf disks of F. × ananassa cv. Camarosa. Several independent stable transgenic lines displayed defects in stamen and fruit development, partially phenocopying that of the Arabidopsis ap3 mutants. Molecular analysis of the targeted AP3 locus indicated differences in gene editing among different transgenic lines and suggests mutations in all the possible AP3 alleles. Phenotypic analyses indicate that impaired fruit development might be caused by the lack of proper development of the anthers due to the CRISPR/Cas9 induced mutation in AP3. In summary, we show that the CRISPR/Cas9 system is a functional tool to perform genome editing in the octoploid F. × ananassa. We propose this system as an alternative to the traditional RNAi strategy to stably mutagenize a particular gene of interest for functional analyses in this species.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Targeted mutagenesis of FaTM6 in the Octoploid Strawberry (Fragaria x ananassa) using the CRISPR/Cas9 System

The B-class of MADS-box transcription factors has been studied in many plant species, but remain functionally uncharacterized in the Rosaceae family. APETALA3 (AP3), a member of this class, controls the identity of petals and stamens in Arabidopsis thaliana. In this work, we identified two members of the AP3 lineage in the cultivated strawberry (Fragaria × ananassa): FaAP3 and FaTM6. Interestingly, FaTM6, and not FaAP3, shows an expression pattern equivalent to that of AP3 in Arabidopsis. Genome editing using Cluster Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system is becoming a robust tool for targeted and stable mutagenesis of DNA. However, whether it can be efficiently used in an octoploid species such as F. × ananassa is not known. In our study, we report the application of the CRISPR/Cas9 in F. × ananassa to characterize the function of FaTM6 in flower development. An exhaustive analysis by high-throughput sequencing of the FaTM6 locus spanning the target sites showed a high efficiency genome editing already in the T0 generation. The phenotypic characterization of the mutant lines indicates that FaTM6 plays a key role in petal and especially in anther development in strawberry. Our results validate the CRISPR/Cas9 strategy for gene functional analysis in an octoploid species such as F. × ananassa, and offer new opportunities for engineering strawberry to improve traits of interest in breeding programs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Study of Transcriptional Regulatory Network Controlling Strawberry Fruit Ripening and Quality

Ponencia invitadaRipening is a critical step for the development of flavor quality in fruits. This character has significantly declined in many fleshy fruits over recent decades. This is particularly significant in strawberry (Fragaria × ananassa), where current cultivars are derived from a narrow germplasm collection. Improving fruit quality requires two important breakthroughs: 1) a precise understanding of the fruit ripening process that will allow the targeting of relevant genes, and 2) the identification of novel alleles responsible for fruit quality traits. In our project, we aim at the identification and characterization of key transcription factors involved in fruit ripening regulation and their target genes, in order to infer the Gene Regulatory Network controlling this process. Also, we are using a collection of around two hundred wild strawberry (Fragaria vesca) accessions to identify loci involved in important traits such as aroma, size or resistance to pathogens. Finally, we are implementing the use of the genome-editing tool CRISPR/Cas9 in the cultivated strawberry, which we expect it might open opportunities for engineering this species to improve traits of economic importance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Functional analysis of TM6 MADS-Box gene in the octoploid strawberry by CRISPR/Cas9 directed mutagenesis

The B-class of MADS-box transcription factors has been studied in many plant species, but remain functionally uncharacterized in Rosaceae. APETALA3 (AP3), a member of this class, controls petal and stamen identities in Arabidopsis. In this study, we identified two members of the AP3 lineage in the cultivated strawberry (Fragaria x ananassa): FaAP3 and FaTM6. Interestingly, FaTM6, and not FaAP3, shows an expression pattern equivalent to that of AP3 in Arabidopsis. Genome editing using CRISPR/Cas9 system is becoming a robust tool for targeted and stable DNA mutagenesis. However, whether it can be efficiently used in an octoploid species such as F. x ananassa is not yet established. Here we report the application of CRISPR/Cas9 to characterize the function of FaTM6 in strawberry flower development. An analysis by high-throughput sequencing of the FaTM6 locus spanning the target sites showed a highly efficient genome editing already in the T0 generation. The phenotypic characterization of the mutant lines indicates that FaTM6 plays a key role in anther development in strawberry. Our results validate the CRISPR/Cas9 strategy for gene functional analysis in F. x ananassa as an octoploid species, and they offer new opportunities for engineering strawberry to improve traits of interest in breeding programs.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Digitalisierung und künstliche Intelligenz – wie behalten wir das ethisch im Griff?

Ethik und künstliche Intelligenz, wie passt das zusammen? Im Artikel erfahren Sie, welche Überlegungen aus der Wissenschaft der Ethik notwendig sind, um Digitalisierung, Automatisierung und Roboterisierung so zu gestalten und zu entwickeln, dass eine menschen- und naturgerechte Digitalisierung möglich ist

Functional Analysis of TM6 MADS-box gene in the Octoploid Strawberry by CRISPR/Cas9 directed mutagenesis

The B-class of MADS-box transcription factors has been studied in many plant species, but remain functionally uncharacterized in the Rosaceae family. APETALA3 (AP3), a member of this class, controls the identity of petals and stamens in Arabidopsis thaliana. In this work, we identified two members of the AP3 lineage in the cultivated strawberry (Fragaria x ananassa): FaAP3 and FaTM6. Interestingly, FaTM6, and not FaAP3, shows an expression pattern equivalent to that of AP3 in Arabidopsis. Genome editing using Cluster Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system is becoming a robust tool for targeted and stable mutagenesis of DNA. However, whether it can be efficiently used in an octoploid species such as F. ananassa is not known. Here we report for the first time the application of CRISPR/Cas9 in F. x ananassa to characterize the function of FaTM6 in flower development. An exhaustive analysis by high-throughput sequencing of the FaTM6 locus spanning the target sites showed a high efficiency genome editing already in the T0 generation. The phenotypic characterization of the mutant lines indicates that FaTM6 plays a key role in petal and especially in anther development in strawberry. Our results validate the CRISPR/Cas9 strategy for gene functional analysis in an octoploid species such as F. x ananassa, and offer new opportunities for engineering strawberry to improve traits of interest in breeding programs

Identification and characterization of RIPENINGLESS, a key transcription factor in the regulation of fruit development and ripening in the cultivated strawberry Fragaria × ananassa

Despite the advances that have allowed to elucidate transcription factors (TFs) involved in the development and ripening of non-climacteric strawberry fruits, key regulators of these processes remain to be identified. Among the plant TFs, the BEL class of Homeobox genes has been shown to control meristem formation and/or maintenance, organ morphogenesis, organ position, and several aspects of the reproductive phase in Arabidopsis thaliana (Bhatt et al., 2004; Byrne et al., 2003; Roeder et al., 2003; Smith and Hake, 2003). In this work, we have identified RIPENINGLESS (FaRPL), a BEL-like Homeodomain TF of the cultivated strawberry (Fragaria × ananassa), that shows an increase in its expression during ripening, peaking at the turning stage. To functionally characterize the role of FaRPL, we have established stable silencing (RNAi) and over-expression lines under the 35S promoter. FaRPL-RNAi lines showed a high rate of abortions. However, some lines achieved to develop full fruits, being firmer and with a lower water content than those of the control. Furthermore, the ripening progress was significantly delayed in these RNAi lines, in which a high percentage of fruits displayed a complete blockage at a stage similar to the turning stage in wt. Interestingly, fruits overexpressing FaRPL showed aberrant shapes, being enlarged in the base of the receptacles. All these results support an important role of this TF in fruit development and ripening. Finally, gene expression and hormone analyses point to an essential role of FaRPL in the regulation of ABA biosynthesis, being this phytohormone the main promoter of strawberry fruit ripening.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech