Transcriptome and Physio-Biochemical Profiling Reveals Differentially Expressed Genes in Seedlings from Aerial and Subterranean Seeds Subjected to Drought Stress in <i>Amphicarpaea edgeworthii</i> Benth

Abstract

Drought stress represents a prevalent environmental challenge that significantly impedes plant growth. The Chinese hog-peanut (Amphicarpaea edgeworthii Benth.), an amphicarpic legume, can produce both aerial seeds (ASs) and subterranean seeds (SSs). However, it is largely unknown whether there are differences between the seedlings from ASs and SSs in response to drought stress. In this study, the 30-day old AS and SS seedlings of A. edgeworthii are subjected to drought stress by withholding watering for five or ten days. Then, we identify the morphological and physio-biochemical characteristics of seedlings from both ASs and SSs under drought stress. Following ten days of drought treatment, the contents of proline (PRO) and malondialdehyde (MDA), the root shoot ratio, and the rate of water loss were significantly increased, whereas the chlorophyll content and the relative water content were significantly decreased in both AS and SS seedlings. Moreover, compared to AS seedlings, SS seedlings accumulated more hydrogen peroxide (H2O2) while exhibiting significantly lower peroxidase (POD) and superoxide dismutase (SOD) activities after exposure to ten days of drought stress. These findings indicate that SS seedlings are more susceptible to drought stress. To identify drought-associated genes and reveal the mechanisms underlying drought adaptability in AS and SS seedlings, we performed an RNA-seq-based transcriptomic analysis in AS and SS seedlings exposed to drought stress. We identified 1317 and 2029 differentially expressed genes (DEGs) in AS seedlings five and ten days post-drought treatment, respectively, and 1793 DEGs in SS seedlings ten days post-drought treatment compared to the normal treatment (CK). These DEGs were commonly enriched in response-related GO terms. Furthermore, hundreds of transcription factor (TF) genes were identified among the DEGs in AS and SS seedlings after drought treatment. Notably, the ERF, bHLH, NAC, and C2H2 families were predominant in AS seedlings five days following drought treatment, while the bHLH, ERF, MYB-related, and WRKY families were prevalent in both AS and SS seedlings ten days following drought treatment. These findings suggest that the identified TFs may play crucial roles in the response of AS and SS seedlings of A. edgeworthii to drought stress.

Keywords

• Chinese hog-peanut (<i>Amphicarpaea edgeworthii</i> Benth.)
• drought stress
• RNA-seq
• differentially expressed genes (DEGs)
• transcription factor