Physiological and Transcriptome Analyses Reveal Short-Term Responses and Formation of Memory Under Drought Stress in Rice

Abstract

In some plants, exposure to stress can induce a memory response, which appears to play an important role in adaptation to recurrent stress environments. However, whether rice exhibits drought stress memory and the molecular mechanisms that might underlie this process have remained unclear. Here, we ensured that rice drought memory was established after cycles of mild drought and re-watering treatment, and studied gene expression by whole-transcriptome strand-specific RNA sequencing (ssRNA-seq). We detected 6,885 transcripts and 238 lncRNAs involved in the drought memory response, grouped into 16 distinct patterns. Notably, the identified genes of dosage memory generally did not respond to the initial drought treatment. Our results demonstrate that stress memory can be developed in rice under appropriate water deficient stress, and lncRNA, DNA methylation and endogenous phytohormones (especially abscisic acid) participate in rice short-term drought memory, possibly acting as memory factors to activate drought-related memory transcripts in pathways such as photosynthesis and proline biosynthesis, to respond to the subsequent stresses.

Transcriptome Response to Drought, Rehydration and Re-Dehydration in Potato

“…When exposed to drought again, although the expressions of most of them were slightly lower than the initial drought-induced expression, they were still upregulated by re-drought ( Figure 8). They might be involved in the early response of plants to drought and affected by the drought hardening, which was similar to the ABA signal in Arabidopsis and rice participating in drought memory response after repeated drought treatments [13,22]. It is suggested that ABA signal plays an important role in the response of drought resistance and also in the improvement of subsequent drought resistance in plant.…”

“…The regulation of plant drought tolerance includes not only the key signaling metabolites and hormones, but also their activity-regulating proteins, such as kinases/phosphatases and TFs [13]. ABA is an important signal molecule in response to drought stress.…”

“…Ethylene synthesis could be induced by drought, and ethylene regulates the response to drought by activating the transcription factor of ethylene response factors (ERFs) [23,24]. In potato, the kinase and transcription factor related to ethylene signal were induced by drought, similar to ABA signal, but jasmonate (JA) signal was more obvious in rice [13], suggesting…”

“…These results suggest the complexity of the molecular mechanism of potato drought-resistance. Moreover, drought stress will have positive impacts on the subsequent stress, and drought hardening can improve the drought resistance of plants [12,13]. The adaptation of plants to repeated and long-term drought showed up stress memory [4].…”

“…Some genes will have memory effect on stress in this process and will show higher expression level when drought occurs again. For example, response to dehydration 29B (RD29B) and response to ABA 18 (RAB18) in Arabidopsis [14], 120 genes in coffee including resistant protein RGA2, gibberellin dioxygenase 1 and gibberellin oxidase 1 [15], and also lncRNA, DNA methylation and endogenous phytohormones (especially abscisic acid) participate in rice short-term drought memory [13]. Potato can also adapt to drought through repeated and long-term drought [16,17].…”