MeRAV5 promotes drought stress resistance in cassava by modulating hydrogen peroxide and lignin accumulation

Abstract

SUMMARY Cassava, an important food and energy crop, is relatively more resistant to drought stress than other crops. However, the molecular mechanism underlying this resistance remains elusive. Herein, we report that silencing a drought stress‐responsive transcription factor MeRAV5 significantly reduced drought stress resistance, with higher levels of hydrogen peroxide (H2O2) and less lignin during drought stress. Yeast two‐hybrid, pull down and bimolecular fluorescence complementation (BiFC) showed that MeRAV5 physically interacted with peroxidase (MePOD) and lignin‐related cinnamyl alcohol dehydrogenase 15 (MeCAD15) in vitro and in vivo. MeRAV5 promoted the activities of both MePOD and MeCAD15 to affect H2O2 and endogenous lignin accumulation respectively, which are important in drought stress resistance in cassava. When either MeCAD15 or MeRAV5 was silenced, or both were co‐silenced, cassava showed lower lignin content and drought‐sensitive phenotype, whereas exogenous lignin alkali treatment increased drought stress resistance and alleviated the drought‐sensitive phenotype of these silenced cassava plants. This study documents that the modulation of H2O2 and lignin by MeRAV5 is essential for drought stress resistance in cassava.

OsGRP3 Enhances Drought Resistance by Altering Phenylpropanoid Biosynthesis Pathway in Rice (Oryza sativa L.)

“…The phenylpropanoid biosynthesis pathway has been reported to participate in various life processes during plant growth [31]. Additionally, two major metabolites of the pathway, lignin and flavonoid, have been reported to positively regulate drought resistance [34][35][36][37][38]. As the KEGG analysis showed that DEGs were significantly enriched in phenylpropanoid biosynthesis and flavonoid biosynthesis under both conditions, we investigated which steps of the pathway these DEGs were distributed in.…”

“…Phenylpropanoid metabolism contributes to plant development and plant-environment interactions [31][32][33]. Two major products of the phenylpropanoid biosynthesis pathway, lignin [34][35][36][37] and flavonoids [38], have been reported to positively regulate drought resistance. As a main component of the cell wall, lignin plays an important role in mechanical support and water transport in plants [39,40].…”

“…Lignin deposition enhances mechanical strength and water impermeability to maintain plant cell turgor, even under water-limiting conditions [41]. Researches have revealed that upregulating the expression of genes involved in lignin biosynthesis, such as phenylalanine ammonia lyase (PAL) in Nicotiana tabacum [42], CAD2 and CAD3 in Cucumis melo [43], or promoting the activities of enzymes involved in lignin biosynthesis, such as MePOD and MeCAD15 in Manihot esculenta [34], leads to the accumulation of lignin, which helps plants to fight against drought stress. Moreover, overexpressing other genes that were not in the phenylpropanoid pathway, such as IbLEA14 in Ipomoea batatas [44], PuC3H35 in Populus ussuriensis [35], OsTF1L and OsERF71 in rice [45,46], also resulted in the deposition of lignin and enhanced drought tolerance.…”

Dimerization of PtrMYB074 and PtrWRKY19 mediates transcriptional activation of PtrbHLH186 for secondary xylem development in Populus trichocarpa

“…Transgenic plants modified for lower overall lignin content or lower lignin quantity in vessel elements are more drought‐sensitive than their wild‐type counterparts (Cao et al ., 2020; Yan et al ., 2021). It is possible that, being hydrophobic, more lignin is needed to help mitigate xylem cavitation and thus facilitate upward water transport (Yan et al ., 2021). The key traits in OE‐PtrbHLH186 transgenics that are consistent with PtrbHLH186 overexpression are all conducive to drought adaptation.…”

Plant Secondary Metabolite Transporters: Diversity, Functionality, and Their Modulation

“…Therefore, regulating the transport and accumulation of SMs linked with drought stress tolerance also seems to be achievable by transporter engineering approaches. Although much information is not available but some of the recent studies in cassava ( Yan Y. et al, 2021 ) and grapevine ( Tu et al, 2020 ) have proposed that enhanced lignin accumulation is also positively linked with drought resistance, which opens up the possibility of modulating the lignin transporters to increase its deposition in the cell wall. Altogether, drought tolerance using transporter modulation should have a positive impact on reducing crop losses in the agricultural sector.…”