Dehydration-induced endodormancy in crown buds of leafy spurge highlights involvement of MAF3- and RVE1-like homologs, and hormone signaling cross-talk

Abstract

Vegetative shoot growth from underground adventitious buds of leafy spurge is critical for survival of this invasive perennial weed after episodes of severe abiotic stress. To determine the impact that dehydration-stress has on molecular mechanisms associated with vegetative reproduction of leafy spurge, greenhouse plants were exposed to mild- (3-day), intermediate- (7-day), severe- (14-day) and extended- (21-day) dehydration treatments. Aerial tissues of treated plants were then decapitated and soil was rehydrated to determine the growth potential of underground adventitious buds. Compared to well-watered plants, mild-dehydration accelerated new vegetative shoot growth, whereas intermediate- through extended-dehydration treatments both delayed and reduced shoot growth. Results of vegetative regrowth further confirmed that 14 days of dehydration induced a full-state of endodormancy in crown buds, which was correlated with a significant (P < 0.05) change in abundance of 2,124 transcripts. Sub-network enrichment analyses of transcriptome data obtained from the various levels of dehydration treatment also identified central hubs of over-represented genes involved in processes such as hormone signaling (i.e., ABA, auxin, ethylene, GA, and JA), response to abiotic stress (DREB1A/2A, RD22) and light (PIF3), phosphorylation (MPK4/6), circadian regulation (CRY2, PHYA), and flowering (AGL20, AP2, FLC). Further, results from this and previous studies highlight homologs most similar to Arabidopsis HY5, MAF3, RVE1 and RD22 as potential molecular markers for endodormancy in crown buds of leafy spurge. Early response to mild dehydration also highlighted involvement of upstream ethylene and JA-signaling, whereas severe dehydration impacted ABA-signaling. The identification of conserved ABRE- and MYC-consensus, cis-acting elements in the promoter of leafy spurge genomic clones similar to Arabidopsis RVE1 (AT5G17300) implicates a potential role for ABA-signaling in its dehydration-induced expression. Response of these molecular mechanisms to dehydration-stress provides insights on the ability of invasive perennial weeds to adapt and survive under harsh environments, which will be beneficial for addressing future management practices.

Meta-Analysis Identifies Potential Molecular Markers for Endodormancy in Crown Buds of Leafy Spurge; a Herbaceous Perennial

“…However, the perennial nature of leafy spurge is attributed to vegetative production from an abundance of UABs that undergo well-defined phases of seasonally induced para-, endo-and ecodormancy , which help optimize distribution of new shoots from the soil bud bank over time . Because dormancy in UABs involves arrested development of the shoot apical meristems (Horvath et al 2003;Horvath and Anderson 2009), similar to that reported in buds of perennial tree species (Cooke et al 2012;Rinne et al 2010;Rohde and Bhalerao 2007), it is a key factor allowing herbaceous perennial weeds to escape many control measures and periods of severe abiotic stress (Anderson et al 2001Doğramacı et al 2014).…”

“…However, leafy spurge plants exposed to a RD in temperature alone (RDt; 27 → 10 °C ) under a constant photoperiod of 16 h or a RD in photoperiod alone (RDp; 16-h → 8-h light) at a constant temperature of 26 o C (Foley et al 2009) did not induce endodormancy in UABs. Additionally, exposing leafy spurge plants to 14 days of continuous dehydration induced a transition from para-to endodormancy in UABs (Doğramacı et al 2014), whereas short-term (3 days) dehydration induced growth competence in UABs, which were previously forced into endodormancy by the RDtp treatment (Doğramacı et al 2011).…”

“…Six to eight plants from each replicate were used to determine the dormancy status of buds by measuring the vegetative growth and flowering potential of crown buds after removal of existing aerial tissues by decapitation at soil level (see Fig. 12.1); the remaining plants were used to collect crown buds for studying transcriptome profiles (Doğramacı et al 2010(Doğramacı et al , 2011(Doğramacı et al , 2014. All samples were collected between 1100 and 1300 Central Standard Times to avoid diurnal variation.…”

“…Microarray hybridizations were performed as described in detail by Doğramacı et al (2010). Various bioinformatics tools were utilized for analyses of transcriptome data reported in Doğramacı et al (2010Doğramacı et al ( , 2011Doğramacı et al ( , 2013Doğramacı et al ( , 2014. Specifically, GeneMaths XT 5.1 (Applied Maths Inc., Austin, TX, USA) was used for normalization and statistical analyses, and Pathway Studio (Ariadne Genomics Inc., Rockville, MD, USA) was used for Gene Set Enrichment Analysis and Sub Network Enrichment Analysis.…”

“…Specifically, GeneMaths XT 5.1 (Applied Maths Inc., Austin, TX, USA) was used for normalization and statistical analyses, and Pathway Studio (Ariadne Genomics Inc., Rockville, MD, USA) was used for Gene Set Enrichment Analysis and Sub Network Enrichment Analysis. Expression data are deposited at Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/) as GEO dataset queries GSE19217 (Doğramacı et al 2010), GSE28047 (Doğramacı et al 2011), GSE37477 , and GSE55133 (Doğramacı et al 2014). …”