Abstract
Plants remember what they have experienced and are thereby able to confront repeated stresses more promptly and strongly. A subset of the drought responsive genes, called stress memory genes, displayed greatly elevated levels under recurrent drought conditions. To screen for a set of drought stress memory genes in soybean (Glycine max L.), we designed a 180K DNA chip comprising 60-bp probes synthesized in situ to examine 55,589 loci. Through microarray analysis using the DNA chip, we identified 2,162 and 2,385 genes with more than fourfold increases or decreases in transcript levels, respectively, under initial (first) drought stress conditions, when compared with the non-treated control. The transcript levels of the drought-responsive genes returned to basal levels during recovery (watered) states, and 392 and 613 genes displayed more than fourfold elevated or reduced levels, respectively, under subsequent (second) drought conditions, when compared to those observed under the first drought stress conditions. Gene Ontology and MapMan analyses classified the drought-induced memory genes exhibiting elevated levels of transcripts into several functional categories, including those involved in tolerance responses to abiotic stresses, which encode transcription factors, protein phosphatase 2Cs, and late embryogenesis abundant proteins. The drought-repressed memory genes exhibiting reduced levels of transcripts were classified into categories including photosynthesis and primary metabolism. Co-expression network analysis revealed that the soybean drought-induced and -repressed memory genes were equivalent to 172 and 311 Arabidopsis genes, respectively. The soybean drought stress memory genes include genes involved in the dehydration memory responses of Arabidopsis.
Highlights
Prolonged or habitual drought may be one of the most serious detrimental stresses for crops during their lifetime
We identified drought stress memory genes in soybean by microarray analysis using a newly designed 180K DNA chip
Williams 82) genome has been sequenced (Schmutz et al, 2010), and the database is available through Phytozome7 (Goodstein et al, 2012)
Summary
Prolonged or habitual drought may be one of the most serious detrimental stresses for crops during their lifetime. A subset of genes called ‘memory genes’ are expressed at highly elevated or reduced levels during subsequent dehydration events (Ding et al, 2012; Kinoshita and Seki, 2014; Godwin and Farrona, 2020), thereby enabling plants to respond more promptly and strongly to the repeated drought stress. This response has been referred to as memory, imprinting, priming, training, and acclimation to stress (Bruce et al, 2007; Conrath, 2011; Walter et al, 2011). Ding et al (2012) showed that Arabidopsis plants trained with previous dehydration events wilted much slower than non-trained plants
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