Response of Organ Structure and Physiology to Autotetraploidization in Early Development of Energy Willow Salix viminalis

Abstract

The biomass productivity of the energy willow Salix viminalis as a short-rotation woody crop depends on organ structure and functions that are under the control of genome size. Colchicine treatment of axillary buds resulted in a set of autotetraploid S. viminalis var. Energo genotypes (polyploid Energo [PP-E]; 2n = 4x = 76) with variation in the green pixel-based shoot surface area. In cases where increased shoot biomass was observed, it was primarily derived from larger leaf size and wider stem diameter. Autotetraploidy slowed primary growth and increased shoot diameter (a parameter of secondary growth). The duplicated genome size enlarged bark and wood layers in twigs sampled in the field. The PP-E plants developed wider leaves with thicker midrib and enlarged palisade parenchyma cells. Autotetraploid leaves contained significantly increased amounts of active gibberellins, cytokinins, salicylic acid, and jasmonate compared with diploid individuals. Greater net photosynthetic CO 2 uptake was detected in leaves of PP-E plants with increased chlorophyll and carotenoid contents. Improved photosynthetic functions in tetraploids were also shown by more efficient electron transport rates of photosystems I and II. Autotetraploidization increased the biomass of the root system of PP-E plants relative to diploids. Sections of tetraploid roots showed thickening with enlarged cortex cells. Elevated amounts of indole acetic acid, active cytokinins, active gibberellin, and salicylic acid were detected in the root tips of these plants. The presented variation in traits of tetraploid willow genotypes provides a basis to use autopolyploidization as a chromosome engineering technique to alter the organ development of energy plants in order to improve biomass productivity.

Enhanced ROS scavenging and sugar accumulation contribute to drought tolerance of naturally occurring autotetraploids in Poncirus trifoliata

“…As these conditions may vary from the actual situations in the nature, tolerance of the tetraploids to milder water stress conditions might be investigated in the future experiments. The tetraploids exhibit dramatically morphological changes when compared with the diploids, which is consistent with earlier studies (Dudits et al, 2016;Tan et al, 2015). One of the major changes in the tetraploids is the smaller number of stomatal density relative to the diploids, implying that polyploidization may negatively regulate the stomatal development under normal conditions.…”

“…The tetraploids exhibit dramatically morphological changes when compared with the diploids, which is consistent with earlier studies (Dudits et al ., ; Tan et al ., ). One of the major changes in the tetraploids is the smaller number of stomatal density relative to the diploids, implying that polyploidization may negatively regulate the stomatal development under normal conditions.…”

“…Chromosome count using fresh root tips was conducted according to Dudits et al . (). Cells were stained with orcein dye and observed with an upright light microscope (Nikon 80i).…”

“…However, increasing attention has been invested to autopolyploids due to their profound effects on plant morphology and physiology relative to their diploid progenitors. Such alterations may include larger organ structure (Dudits et al ., ), slower growth (Allario et al ., ), improved fruit yield (Hussain et al ., ) and different anatomical features (Allario et al ., ). In addition, accumulating evidence demonstrate that autotetraploids exhibit dramatically enhanced tolerance to a variety of abiotic stresses, including cold (Oustric et al ., ), drought (Allario et al ., ), salt (Liu and Sun, ; Ruiz et al ., ; Tu et al ., ), heat (Zhang et al ., ), chromium toxicity (Balal et al ., ) and boron excess (Ruiz et al ., ).…”

Combined Analysis of mRNAs and miRNAs to Identify Genes Related to Biological Characteristics of Autotetraploid Paulownia

“…Polyploidy species usually exhibit greater vigor, have more biomass [1] and are more adaptable and tolerant to different environmental conditions than diploids [2,3]. Many woody plants, such as mulberry, jujube, and willow carry multiple copies of the same genome, are classified as autopolyploid [4][5][6], and are attracting considerable attention for forest tree breeding.…”