Cowpea NAC1/NAC2 transcription factors improve growth and tolerance to drought and heat in transgenic cowpea through combined activation of photosynthetic and antioxidant mechanisms. Issue 1 (25th October 2022)

• Record Type: Journal Article
• Authors: Srivastava, Richa; Kobayashi, Yuriko; Koyama, Hiroyuki; Sahoo, Lingaraj
• Is Part Of: Journal of integrative plant biology. Volume 65:Issue 1(2023)
• Page Start: 25
• Page End: 44
• Publication Date: 2022-10-25
• Subjects: cowpea -- enhanced photosynthetic activity -- improved growth -- improved yield, legume genetic engineering -- multiple stress tolerance -- NAC transcription factor -- VuNAC; Plants -- Periodicals; Plants -- China -- Periodicals; Electronic journals; 580.5
• DOI: 10.1111/jipb.13365
• Languages: English
• ISSNs: 1672-9072

Abstract

ABSTRACT: NAC (NAM/ATAF1/2/CUC2) transcription factors are central switches of growth and stress responses in plants. However, unpredictable interspecies conservation of function and regulatory targets makes the well‐studied NAC orthologs inapt for pulse engineering. The knowledge of suitable NAC candidates in hardy pulses like cowpea ( Vigna unguiculata (L.) Walp.) is still in infancy, hence warrants immediate biotechnological intervention. Here, we showed that overexpression of two native NAC genes ( VuNAC1 and VuNAC2 ) promoted germinative, vegetative, and reproductive growth and conferred multiple abiotic stress tolerance in a commercial cowpea variety. The transgenic lines displayed increased leaf area, thicker stem, nodule‐rich denser root system, early flowering, higher pod production (∼3.2‐fold and ∼2.1‐fold), and greater seed weight (10.3% and 6.0%). In contrast, transient suppression of VuNAC1/2 caused severe growth retardation and flower inhibition. The overexpressor lines showed remarkable tolerance to major yield‐declining terminal stresses, such as drought, salinity, heat, and cold, and recovered growth and seed production by boosting photosynthetic activity, water use efficiency, membrane integrity, Na + /K + homeostasis, and antioxidant activity. The comparative transcriptome study indicated consolidated activation of genes involved in chloroplast development, photosynthetic complexes, cell division and expansion, cell wall biogenesis, nutrient uptake and metabolism, stress response, abscisic acid, and auxin signaling. Unlike their orthologs, VuNAC1/2 direct synergistic transcriptional tuning of stress and developmental signaling to avoid unwanted trade‐offs. Their overexpression governs the favorable interplay of photosynthesis and reactive oxygen species regulation to improve stress recovery, nutritional sufficiency, biomass, and production. This unconventional balance of strong stress tolerance and agronomic quality is useful for translational crop research and molecular breeding of pulses. Abstract : Stress acclimation often retards growth and decreases yield. Overexpressing novel NAC transcription factors that govern synergistic tuning of photosynthesis and stress responses produced effective tolerance to multiple abiotic stresses with simultaneous improvement of growth and yield in cowpea, offering unique a biotechnological approach to engineer food crops without unwanted trade‐offs.