Abstract
Capsicum annuum L. is one of the most cultivated Solanaceae species, and in the open field, water limitation leading to drought stress affects its fruit quality, fruit setting, fruit size and ultimately yield. We identified stage-specific and a common core set of differentially expressed genes, following RNA-seq transcriptome analyses of a breeding line subjected to acute drought stress followed by recovery (rewatering), at three stages of plant development. Among them, two NAC transcription factor (TF) genes, i.e., CaNAC072 and CaNAC104, were always upregulated after drought stress and downregulated after recovery. The two TF proteins were observed to be localized in the nucleus following their transient expression in Nicotiana benthamiana leaves. The expression of the two NACs was also induced by NaCl, polyethylene glycol (PEG) and abscisic acid (ABA) treatments, suggesting that CaNAC072 is an early, while CaNAC104 is a late abiotic stress-responsive gene. Virus-induced gene silencing (VIGS) of CaNAC104 did not affect the pepper plantlet’s tolerance to drought stress, while VIGS of CaNAC072 increased drought tolerance. Heterologous expression of CaNAC072 in Arabidopsis thaliana as well as in plants mutated for its homolog ANAC072 did not increase drought stress tolerance. This highlights a different role of the two NAC homologs in the two species. Here, we discuss the complex role of NACs as transcriptional switches in the response to drought stress in bell pepper.
Highlights
Drought stress is one of the key limiting factors affecting plant growth, development and survival, with a substantial impact on crop yield (Sinclair, 2011; Boyer et al, 2013)
We studied the effects of drought stress and recovery on a C. annuum inbred line at different plant developmental stages
Following RNA-sequencing, we identified two transcription factors, CaNAC072 and CaNAC104, that were always upregulated by acute drought stress and down-regulated after recovery when water was again supplied, at three stages of bell pepper development
Summary
Drought stress is one of the key limiting factors affecting plant growth, development and survival, with a substantial impact on crop yield (Sinclair, 2011; Boyer et al, 2013). Drought Stress, NAC various molecular mechanisms to adjust their growth to limited water availability, and the elucidation of such mechanisms is essential for implementing breeding strategies aimed at developing crop varieties more resilient and capable to deal with water shortage while maintaining yield (Osakabe et al, 2014; Iovieno et al, 2016). Comparative transcriptomic analyses have proven to be a valuable approach for identifying key genes controlling the response to low water availability (Seki et al, 2002) in plants such as Arabidopsis (Zhang et al, 2019), rice (Chung et al, 2018), maize (Kakumanu et al, 2012), potato (Sprenger et al, 2018), and tomato (Lee et al, 2018). In C. annuum, studies on transcriptional changes occurring in response to water shortage are to date rather limited (Zinselmeier et al, 2002; Ji et al, 2010; Sharoni et al, 2012; Lee and Choi, 2013)
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