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The MADS-box transcription factors have garnered substantial attention due to their crucial involvement in various biological processes, particularly in flower organogenesis. A comprehensive investigation into the MADS-box genes remains lacking in loquat (Eriobotrya japonica Lindl.). In the current study, to preliminarily explore the potential candidate genes related to flower and fruit development, a genome-wide analysis was carried out to identify and characterize the MADS-box gene family in loquat. Among the 125 identified EjMADS-box members, 49 genes belonged to type Ⅰ, which were subsequently assigned to three subfamilies: Mα (25 genes), Mβ (10 genes), and Mγ (14 genes). Additionally, 76 genes fell under type II, which were categorized into two groups: MIKCC (70 genes) and MIKC* (6 genes). Through the collinearity analysis and comparison of the gene numbers between loquat and other Rosaceae genomes, it was revealed that the type Ⅱ MADS-box members were expanded in Maloideae after a whole genome duplication. The gene expression analysis utilizing various tissues during flower development revealed that the expression patterns of the ABCDE model homologs were conserved in loquat. In addition, several candidate genes potentially involved in flower bud differentiation (EjMADS107/109) and fruit expansion (EjMADS24/46/49/55/61/67/77/86) were identified. This analysis could serve as a fundamental basis for investigating the molecular functions of the MADS-box genes in the development of flowers as well as fruits in loquat. [ABSTRACT FROM AUTHOR]

Microbial symbiosis in legumes is achieved through nitrogen-fixing root nodules, and these are important for sustainable agriculture. The molecular mechanisms underlying development of root nodules in polyploid legume crops are largely understudied. Through map-based cloning and QTL-seq approaches, we identified a pair of homoeologous GRAS transcription factor genes, Nodulation Signaling Pathway 2 (AhNSP2-B07 or N b ) and AhNSP2-A08 (N a ), controlling nodulation in cultivated peanut (Arachis hypogaea L.), an allotetraploid legume crop, which exhibited non-Mendelian and Mendelian inheritance, respectively. The segregation of nodulation in the progeny of N a n a n b n b genotypes followed a 3:1 Mendelian ratio, in contrast to the 5:3~1:1 non-Mendelian ratio for n a n a N b n b genotypes. Additionally, a much higher frequency of the n b allele (13%) than the n a allele (4%) exists in the peanut germplasm collection, suggesting that N b is less essential than N a in nodule organogenesis. Our findings reveal the genetic basis of naturally occurred non-nodulating peanut plants, which can be potentially used for nitrogen fixation improvement in peanut. Furthermore, the results have implications for and provide insights into the evolution of homoeologous genes in allopolyploid species. [ABSTRACT FROM AUTHOR]

Background: Peanut is an important legume crop growing worldwide. With the published allotetraploid genomes, further functional studies of the genes in peanut are very critical for crop improvement. CRISPR/Cas9 system is emerging as a robust tool for gene functional study and crop improvement, which haven't been extensively utilized in peanut yet. Peanut plant forms root nodules to fix nitrogen through a symbiotic relationship with rhizobia. In model legumes, the response of plants to rhizobia is initiated by Nod factor receptors (NFRs). However, information about the function of NFRs in peanut is still limited. In this study, we applied the CRISPR/Cas9 tool in peanut hairy root transformation system to explore the function of NFR genes. Results: We firstly identified four AhNFR1 genes and two AhNFR5 genes in cultivated peanut (Tifrunner). The gene expression analysis showed that the two AhNFR1 and two AhNFR5 genes had high expression levels in nodulating (Nod+) line E5 compared with non-nodulating (Nod-) line E4 during the process of nodule formation, suggesting their roles in peanut nodulation. To further explore their functions in peanut nodulation, we applied CRISPR technology to create knock-out mutants of AhNFR1 and AhNFR5 genes using hairy root transformation system. The sequencing of these genes in transgenic hairy roots showed that the selected AhNFR1 and AhNFR5 genes were successfully edited by the CRISPR system, demonstrating its efficacy for targeted mutation in allotetraploid peanut. The mutants with editing in the two AhNFR5 genes showed Nod- phenotype, whereas mutants with editing in the two selected AhNFR1 genes could still form nodules after rhizobia inoculation. Conclusions: This study showed that CRISPR-Cas9 could be used in peanut hairy root transformation system for peanut functional genomic studies, specifically on the gene function in roots. By using CRISPR-Cas9 targeting peanut AhNFR genes in hairy root transformation system, we validated the function of AhNFR5 genes in nodule formation in peanut. [ABSTRACT FROM AUTHOR]