Abstract
The molecular mechanisms of symbiosis in cultivated peanut with a ‘crack entry’ infection process are largely understudied. In this study, we investigated the root transcriptional profiles of two pairs of non-nodulating (nod−) and nodulating (nod+) sister inbred peanut lines, E4/E5 and E7/E6, and their nod+ parents, F487A and PI262090 during rhizobial infection and nodule initiation by using RNA-seq technology. A total of 143, 101, 123, 215, 182, and 289 differentially expressed genes (DEGs) were identified in nod− E4, E7 and nod+ E5, E6, F487A, and PI262090 after inoculation with Bradyrhizobium sp. Different deficiencies at upstream of symbiotic signaling pathway were revealed in the two nod− genotypes. DEGs specific in nod+ genotypes included orthologs to some known symbiotic signaling pathway genes, such as NFR5, NSP2, NIN, ERN1, and many other novel and/or functionally unknown genes. Gene ontology (GO) enrichment analysis of nod+ specific DEGs revealed 54 significantly enriched GO terms, including oxidation-reduction process, metabolic process, and catalytic activity. Genes related with plant defense systems, hormone biosynthesis and response were particularly enriched. To our knowledge, this is the first report revealing symbiosis-related genes in a genome-wide manner in peanut representative of the ‘crack entry’ species.
Highlights
Activates two parallel developmental processes of nodulation, bacterial infection and nodule organogenesis[7]
Transcriptome profiling of M. truncatula root hairs discovered that rhizobial infection was associated with the expression of genes involved in cell cycle, hormone signaling, and flavonoid biosynthesis, and that the initiation of ITs requires auxin signaling regulation[21]
A total of 67,536 and 92,620 novel transcript sequences aligned to the reference genomes near perfectly were identified from A and B genomes, respectively, which were most likely the transcripts un-annotated in the reference genomes
Summary
Activates two parallel developmental processes of nodulation, bacterial infection and nodule organogenesis[7]. Transcriptome profiling of M. truncatula root hairs discovered that rhizobial infection was associated with the expression of genes involved in cell cycle, hormone signaling, and flavonoid biosynthesis, and that the initiation of ITs requires auxin signaling regulation[21]. These studies provided molecular insights into symbiosis in legumes that use the ‘root hair entry’ mode. The nod−peanut lines were noticed in a F3 population derived from the cross between nodulating (nod+) 487A-4–1–2 (a Virginia botanical type from the University of Florida peanut breeding program) and nod+PI262090 (a Virginia botanical type). This is the first report revealing symbiosis-related genes in a genome-wide scale in cultivated peanut
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