Abstract
BackgroundThere have been few studies on the partial defoliation response of grass. It has been unclear how partial defoliation may affect roots at the levels of nutrient accumulation and transcriptional regulation. Hereby we report a comprehensive investigation on molecular impacts of partial defoliation by using a model grass species, Brachypodium distachyon.ResultsOur Inductively Coupled Plasma Mass Spectrometry analyses of B. distachyon revealed shoot- and root-specific accumulation patterns of a group of macronutrients including potassium (K), Phosphorus (P), Calcium (Ca), Magnesium (Mg), and micronutrients including Sodium (Na), iron (Fe), and Manganese (Mn). Meanwhile, our genome-wide profiling of gene expression patterns depicts transcriptional impacts on B. distachyon roots by cutting the aerial portion. The RNAseq analyses identified a total of 1,268 differentially expressed genes in B. distachyon with partial defoliation treatment. Our comprehensive analyses by means of multiple approaches, including Gene Ontology, InterPro and Pfam protein classification, KEGG pathways, and Plant TFDB, jointly highlight the involvement of hormone-mediated wounding response, primary and secondary metabolites, and ion homeostasis, in B. distachyon after the partial defoliation treatment. In addition, evidence is provided that roots respond to partial defoliation by modifying nutrient uptake and rhizosphere acidification rate, indicating that an alteration of the root/soil interaction occurs in response to this practice.ConclusionsThis study reveals how partial defoliation alters ion accumulation levels in shoots and roots, as well as partial defoliation-induced transcriptional reprogramming on a whole-genome scale, thereby providing insight into the molecular mechanisms underlying the recovery process of grass after partial defoliation.
Highlights
Defoliation by means of cutting causes mechanical damage (MD) to plants, which need to respond quickly and to adapt to such a challenge
Hereby we report a comprehensive investigation on molecular impacts of partial defoliation by using a model grass species, Brachypodium distachyon
Cutting aerial portions alters nutrient uptake patterns in B. distachyon To examine the impact of partial defoliation on nutrient uptake in B. distachyon, we performed inductively coupled plasma mass spectrometry (ICP-MS) to measure the levels of a group of macronutrients which including K, P, Ca Mg, and micronutrients including Na, Fe, Mn elements in both roots and shoots
Summary
Defoliation by means of cutting causes mechanical damage (MD) to plants, which need to respond quickly and to adapt to such a challenge. As a common practice for grass or forage crops, defoliation causes severe MD to plants, yet how defoliation impacts roots at the molecular level on a whole-genome scale remains to be elucidated. There have been few studies on the partial defoliation response of grass It has been unclear how partial defoliation may affect roots at the levels of nutrient accumulation and transcriptional regulation. Our comprehensive analyses by means of multiple approaches, including Gene Ontology, InterPro and Pfam protein classification, KEGG pathways, and Plant TFDB, jointly highlight the involvement of hormone-mediated wounding response, primary and secondary metabolites, and ion homeostasis, in B. distachyon after the partial defoliation treatment. Conclusions: This study reveals how partial defoliation alters ion accumulation levels in shoots and roots, as well as partial defoliation-induced transcriptional
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