Abstract
BackgroundAs an important cash crop, the yield of peanut is influenced by soil acidification and pathogen infection. Receptor-like protein kinases play important roles in plant growth, development and stress responses. However, little is known about the number, location, structure, molecular phylogeny, and expression of RLKs in peanut, and no comprehensive analysis of RLKs in the Al stress response in peanuts have been reported.ResultsA total of 1311 AhRLKs were identified from the peanut genome. The AhLRR-RLKs and AhLecRLKs were further divided into 24 and 35 subfamilies, respectively. The AhRLKs were randomly distributed across all 20 chromosomes in the peanut. Among these AhRLKs, 9.53% and 61.78% originated from tandem duplications and segmental duplications, respectively. The ka/ks ratios of 96.97% (96/99) of tandem duplication gene pairs and 98.78% (646/654) of segmental duplication gene pairs were less than 1. Among the tested tandem duplication clusters, there were 28 gene conversion events. Moreover, all total of 90 Al-responsive AhRLKs were identified by mining transcriptome data, and they were divided into 7 groups. Most of the Al-responsive AhRLKs that clustered together had similar motifs and evolutionarily conserved structures. The gene expression patterns of these genes in different tissues were further analysed, and tissue-specifically expressed genes, including 14 root-specific Al-responsive AhRLKs were found. In addition, all 90 Al-responsive AhRLKs which were distributed unevenly in the subfamilies of AhRLKs, showed different expression patterns between the two peanut varieties (Al-sensitive and Al-tolerant) under Al stress.ConclusionsIn this study, we analysed the RLK gene family in the peanut genome. Segmental duplication events were the main driving force for AhRLK evolution, and most AhRLKs subject to purifying selection. A total of 90 genes were identified as Al-responsive AhRLKs, and the classification, conserved motifs, structures, tissue expression patterns and predicted functions of Al-responsive AhRLKs were further analysed and discussed, revealing their putative roles. This study provides a better understanding of the structures and functions of AhRLKs and Al-responsive AhRLKs.
Highlights
As an important cash crop, the yield of peanut is influenced by soil acidification and pathogen infec‐ tion
Based on the structure of the extracellular domain, Receptor-like protein kinase (RLK) have been classified into several families such as S-domain RLK (S-RLK), Leucine-Rich Repeat RLK (LRR-RLK), Epi‐ dermal growth factor like RLK (EGF-RLK), Lectin-like RLK (LecRLK), TNFR-RLKs and PR5K-RLKs [21].While many RLKs involved in the environmental stress response have been found, few RLKs have been reported to be involved in Al stress response
We calculated the divergence time, and the results showed that many tandem duplication events appeared to have occurred during relatively recent key periods 0–10 MYA, and many segmental duplication events appeared to have occurred during 0–30 MYA (Fig. 5b; Additional file 6), illustrating that these AhRLKs were generated by recent gene duplication events in Arachis hypogaea L
Summary
As an important cash crop, the yield of peanut is influenced by soil acidification and pathogen infec‐ tion. Receptor-like protein kinases play important roles in plant growth, development and stress responses. Al signal information and its transmembrane transduction are unknown Both pathways use plasma membrane and/or cell wall-localized receptors to sense environmental stimuli and efficiently transduce signals between cells, which perceive and transduce signals to modulate gene expression and/or enzyme activity as well as motility [13]. Receptor-like protein kinase (RLK) play important roles in the process of cell signal transduction, and are involved in a variety of plant physiological processes including: self-incompatibility [14], environmental signal processing [15], organ shape and meristem activity [16], hormone signal transduction [17], PCD [18], and tolerance to oxidative stress [19]. The results showed that RLKs play an important role in Al-induced PCD, but the mechanism of RLKs in the regulation of Alinduced PCD is unknown
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