Abstract
BackgroundB-box (BBX) genes play important roles in plant growth regulation and responses to abiotic stresses. The plant growth and yield production of allotetraploid rapeseed is usually hindered by diverse nutrient stresses. However, no systematic analysis of Brassicaceae BBXs and the roles of BBXs in the regulation of nutrient stress responses have not been identified and characterized previously.ResultsIn this study, a total of 536 BBXs were identified from nine brassicaceae species, including 32 AtBBXs, 66 BnaBBXs, 41 BoBBXs, 43 BrBBXs, 26 CrBBXs, 81 CsBBXs, 52 BnBBXs, 93 BjBBXs, and 102 BcBBXs. Syntenic analysis showed that great differences in the gene number of Brassicaceae BBXs might be caused by genome duplication. The BBXs were respectively divided into five subclasses according to their phylogenetic relationships and conserved domains, indicating their diversified functions. Promoter cis-element analysis showed that BBXs probably participated in diverse stress responses. Protein-protein interactions between BnaBBXs indicated their functions in flower induction. The expression profiles of BnaBBXs were investigated in rapeseed plants under boron deficiency, boron toxicity, nitrate limitation, phosphate shortage, potassium starvation, ammonium excess, cadmium toxicity, and salt stress conditions using RNA-seq data. The results showed that different BnaBBXs showed differential transcriptional responses to nutrient stresses, and some of them were simultaneously responsive to diverse nutrient stresses.ConclusionsTaken together, the findings investigated in this study provided rich resources for studying Brassicaceae BBX gene family and enriched potential clues in the genetic improvement of crop stress resistance.
Highlights
B-box (BBX) genes play important roles in plant growth regulation and responses to abiotic stresses
BnaBBX1–26 were present respectively on chromosomes A01–10 and C01–09, but BnaBBX52–66 were located on random chromosomes due to the deficiency of B. napus genome assembly (Figure S1–1); Each B. oleracea chromosome, except for chromosome10, contained about four BoBBXs, whereas only one gene (BoBBX30) was present on chromosome 08 (Figure S1–2); All B. rapa chromosomes included BrBBX genes, and seven BrBBXs were identified on
The results of the present study indicated that, like AtBBXs and OsBBXs, BnaBBXs might be involved in response to Cd and salt stresses; they might possibly participate in A metabolism
Summary
B-box (BBX) genes play important roles in plant growth regulation and responses to abiotic stresses. BBXs have been reported to participate in photomorphogenesis, flower induction, shade avoidance, phytohormone signals, and stress responses [3, 4]. AtBBX21 and ABA insensitive 5 (ABI5) form a protein complex to participate in light-mediated ABA signals [20]. AtBBX18 is reported to increase the GA activity, and promote hypocotyl growth [21]. BBX proteins are involved in the responses of plants to both biotic and abiotic stress stimuli in plants. A recent study suggested that BBXs are likely to participate in drought, cold, salt, and heavy metal stresses in rice, and several BBXs are involved in responses to hormonal signals [25]. A rice BBX gene, OsCOL9, enhances the resistance of rice to blast by mediating salicylic acid (SA) and ethylene (ETH) signals [26]
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