A transcriptome analysis reveals a role for the indole GLS-linked auxin biosynthesis in secondary dormancy in rapeseed (Brassica napus L.)

Abstract

Background Brassica napus L. has little or no primary dormancy, but exhibits great variation in secondary dormancy. Secondary dormancy potential in oilseed rape can lead to the emergence of volunteer plants that cause genetic contamination, reduced quality and biosafety issues. However, the mechanisms underlying secondary dormancy are poorly understood. In this study, cultivars Huaiyou-WSD-H2 (H) and Huaiyou-SSD-V1 (V), which exhibit low (approximately 5%) and high (approximately 95%) secondary dormancy rate, respectively, were identified. Four samples, before (Hb and Vb) and after (Ha and Va) secondary dormancy induction by polyethylene glycol (PEG), were collected to identify the candidate genes involved in secondary dormancy via comparative transcriptome profile analysis. Results A total of 998 differentially expressed genes (DEGs), which are mainly involved in secondary metabolism, transcriptional regulation, protein modification and signaling pathways, were then detected. Among these DEGs, the expression levels of those involved in the sulfur-rich indole glucosinolate (GLS)-linked auxin biosynthesis pathway were markedly upregulated in the dormant seeds (Va), which were validated by qRT-PCR and subsequently confirmed via detection of altered concentrations of indole-3-acetic acid (IAA), IAA conjugates and precursors. Furthermore, exogenous IAA applications to cultivar H enhanced secondary dormancy. Conclusion This study first (to our knowledge) elucidated that indole GLS-linked auxin biosynthesis is enhanced during secondary dormancy induced by PEG, which provides valuable information concerning secondary dormancy and expands the current understanding of the role of auxin in rapeseed. Electronic supplementary material The online version of this article (10.1186/s12870-019-1866-z) contains supplementary material, which is available to authorized users.

Cold‐induced secondary dormancy and its regulatory mechanisms in Beta vulgaris

“…Mature seeds of most crop species, including Brassica napus (oilseed rape) and Beta vulgaris (sugar beet), are reported to be nondormant (Hermann et al, 2007 ; Soltani et al, 2019 ). Despite the low or lacking primary dormancy of fresh mature B. napus seeds, the secondary dormancy potential of many oilseed rape cultivars is high, and secondary dormant seeds can remain viable in the soil for many years, which eventually can lead to the emergence of weedy volunteer B. napus (L. Liu, Liu, et al, 2019 ; Nee et al, 2015 ; Soltani et al, 2019 ). Although B. napus and A. thaliana seeds differ in primary dormancy, the induction of secondary dormancy in the two Brassicaceae relatives was associated with similar molecular mechanisms and regulation of dormancy and hormone‐related genes.…”

Temperature Regulation of Primary and Secondary Seed Dormancy in Rosa canina L.: Findings from Proteomic Analysis

“…The dormancy cycling phenomenon has been widely studied, but the molecular mechanism responsible remains largely unknown. Recent transcriptomic studies indicate that seeds vary and remain active at a molecular level in both primary and secondary dormancy [ 13 , 16 , 24 , 25 , 26 ]. Despite the many studies of primary dormancy proteomics, not one has considered secondary dormancy.…”

Comparative transcriptome analyses reveal different mechanism of high- and low-tillering genotypes controlling tiller growth in orchardgrass (Dactylis glomerata L.)

“…The cluster Profiler R package was used to conduct Gene Ontology (GO) enrichment analysis of the identified differentially expressed genes (DEGs). In addition, GO terms with corrected P < 0.05 were considered significantly enriched among DEGs [34]. Finally, we used the cluster Profiler R package to test the statistical enrichment of DEGs among Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, using the minimum E-value as the filter parameter.…”