Dehydrin MsDHN1 improves aluminum tolerance of alfalfa (Medicago sativaL.) by affecting oxalate exudation from root tips

Abstract

SUMMARY A SK3‐type dehydrin MsDHN1 was cloned from alfalfa (Medicago sativa L.). Its function and gene regulatory pathways were studied via overexpression and suppression of MsDHN1 in alfalfa seedlings or hairy roots. The results showed that MsDHN1 is a typical intrinsically disordered protein that exists in the form of monomers and homodimers in alfalfa. The plant growth rates increased as a result of MsDHN1 overexpression (MsDHN1‐OE) and decreased upon MsDHN1 suppression (MsDHN1‐RNAi) in seedlings or hairy roots of alfalfa compared with the wild‐type or the vector line under Al stress. MsDHN1 interacting with aquaporin (AQP) MsPIP2;1 and MsTIP1;1 positively affected oxalate secretion from root tips and Al accumulation in root tips. MsABF2 was proven to be an upstream transcription factor of MsDHN1 and activated MsDHN1 expression by binding to the ABRE element of the MsDHN1 promoter. The transcriptional regulation of MsABF2 on MsDHN1 was dependent on the abscisic acid signaling pathway. These results indicate that MsDHN1 can increase alfalfa tolerance to Al stress via increasing oxalate secretion from root tips, which may involve in the interaction of MsDHN1 with two AQP.

Adaptive Mechanisms Make Lupin a Choice Crop for Acidic Soils Affected by Aluminum Toxicity

“…Malate, citrate and oxalate are involved in Al resistance in plants ( Ma, 2000 ; Ma et al, 2001 ). Malate and citrate are secreted from root tips and regulated by specific transporters ( Sharma et al, 2016 ; Wang et al, 2017 ); however, oxalate secretion transport pathways are mostly unknown ( Lv et al, 2021 ). CR exudates consist mainly of OA anions ( Dessureault-Rompré et al, 2007 ), protons, phenolic compounds and phosphatases ( Gerke et al, 1994 ; Gilbert et al, 1999 ; Lamont, 2003 ) that generate changes in the rhizosphere and mobilize nutrients and toxic metals from insoluble phosphates ( Dakora and Phillips, 2002 ).…”

“…Besides malic and citric, oxalic, fumaric, malonic and α-ketoglutaric acids have been identified in the rhizosphere of white lupin ( Mimmo et al, 2008 ), and might contribute to lupin Al tolerance. In certain plants, oxalate rather than citrate or malate is involved in Al tolerance ( Yang et al, 2011 ; Lv et al, 2021 ), but the regulation of oxalate secretion requires further study. Recently, a potential mechanism for Al tolerance in alfalfa has been described that involves oxalate secretion and ABA-mediated signaling ( Lv et al, 2021 ).…”

“…In certain plants, oxalate rather than citrate or malate is involved in Al tolerance ( Yang et al, 2011 ; Lv et al, 2021 ), but the regulation of oxalate secretion requires further study. Recently, a potential mechanism for Al tolerance in alfalfa has been described that involves oxalate secretion and ABA-mediated signaling ( Lv et al, 2021 ). Flavonoids exuded by lupin roots play a key role in the establishment of symbiosis by inducing the expression of rhizobial nod genes ( Cooper, 2007 ), but flavonoids secreted by CR do not differ from those secreted by regular roots ( Weisskopf et al, 2006 ; Cesco et al, 2010 ).…”

AnDHN, a Dehydrin Protein From Ammopiptanthus nanus, Mitigates the Negative Effects of Drought Stress in Plants

“…OsDHN1 has been shown to play a core role in drought and salt stress (Kumar et al, 2014;Verma et al, 2017). ShDHN has been reported to promote resistance against drought and cold stress (Liu et al, 2015), and MsDHN1 can increase tolerance to Al stress in Medicago sativa (Lv et al, 2021). In addition to abiotic stresses, there is evidence that LEA family proteins are involved in antibacterial activity.…”

Data_Sheet_1.docx

“…In our study, the SOD, POD, APX and CAT activities of the SiLEA4 expressing plants were significantly higher than in the WT strain under both chilling and freezing conditions, with them being more substantial under freezing conditions. On the one hand, LEA proteins can act as transcription factors to increase the transcription level of ROS scavengers (Yu et al, 2016), while on the other hand, they can act as molecular chaperones and enzyme protectors 10.3389/fpls.2022.957133 to maintain the 3D conformation of ROS scavengers at low temperatures (Lv et al, 2021). Therefore, we suggest that the rapid and substantial up-regulation of SOD under cold conditions is important for tomato low temperature resistance.…”