Overexpression of Grain Amaranth (Amaranthus hypochondriacus) AhERF or AhDOF Transcription Factors in Arabidopsis thaliana Increases Water Deficit- and Salt-Stress Tolerance, Respectively, via Contrasting Stress-Amelioration Mechanisms

Abstract

Two grain amaranth transcription factor (TF) genes were overexpressed in Arabidopsis plants. The first, coding for a group VII ethylene response factor TF (i.e., AhERF-VII) conferred tolerance to water-deficit stress (WS) in transgenic Arabidopsis without affecting vegetative or reproductive growth. A significantly lower water-loss rate in detached leaves coupled to a reduced stomatal opening in leaves of plants subjected to WS was associated with this trait. WS tolerance was also associated with an increased antioxidant enzyme activity and the accumulation of putative stress-related secondary metabolites. However, microarray and GO data did not indicate an obvious correlation between WS tolerance, stomatal closure, and abscisic acid (ABA)-related signaling. This scenario suggested that stomatal closure during WS in these plants involved ABA-independent mechanisms, possibly involving reactive oxygen species (ROS). WS tolerance may have also involved other protective processes, such as those employed for methyl glyoxal detoxification. The second, coding for a class A and cluster I DNA binding with one finger TF (i.e., AhDof-AI) provided salt-stress (SS) tolerance with no evident fitness penalties. The lack of an obvious development-related phenotype contrasted with microarray and GO data showing an enrichment of categories and genes related to developmental processes, particularly flowering. SS tolerance also correlated with increased superoxide dismutase activity but not with augmented stomatal closure. Additionally, microarray and GO data indicated that, contrary to AhERF-VII, SS tolerance conferred by AhDof-AI in Arabidopsis involved ABA-dependent and ABA-independent stress amelioration mechanisms.

Diversity in Grain Amaranths and Relatives Distinguished by Genotyping by Sequencing (GBS)

“…The utility of GWAS association mapping in the grain amaranths may be greatest in understanding their high drought tolerance, associated with the accumulation of compatible solutes ( Huerta-Ocampo et al, 2011 ), and the expression of stress-related genes and transcription factors ( Huerta-Ocampo et al, 2014 ; Massange-Sánchez et al, 2016 ). In GWAS, unique SNPs can be used to distinguish genotypes with novel functional alleles for drought and heat tolerance.…”

Effects of Exogenous Spermidine on Root Metabolism of Cucumber Seedlings under Salt Stress by GC-MS

“…Citrulline was the most abundant in Cucurbitaceae plants and occurred as a primary carrier of organic nitrogen in the form of free amino acid [65,66]. Compared to mannitol, citrulline was identified as the most effective among compatible solutes in response to abiotic stress [67,68]. In this study, further exogenous Spd citrulline accumulation indicated that Spd-induced salt-tolerance was correlated with citrulline effectively protecting DNA and scavenging hydroxyl radicals.…”

Non-destructive Plant Morphometric and Color Analyses Using an Optoelectronic 3D Color Microscope

“…The images obtained with the microscope can be exported as .jpeg or .tiff files with 16 bit resolution (with RGB data from each pixel). This allows post-imaging analyses using different software (as done in Massange-Sánchez et al, 2016 ). Therefore, alternative workflows are possible, for example, if a very large number of plants should be analyzed, or different analyses not available in the microscope software are required.…”