The transcription factor VviNAC60 regulates senescence- and ripening-related processes in grapevine

Abstract

Grapevine (Vitis vinifera L.) is one of the most widely cultivated fruit crops because the winemaking industry has huge economic relevance worldwide. Uncovering the molecular mechanisms controlling the developmental progression of plant organs will prove essential for maintaining high-quality grapes, expressly in the context of climate change, which impairs the ripening process. Through a deep inspection of transcriptomic data, we identified VviNAC60, a member of the NAC transcription factor family, as a putative regulator of grapevine organ maturation. We explored VviNAC60 binding landscapes through DNA affinity purification followed by sequencing and compared bound genes with transcriptomics datasets from grapevine plants stably and transiently overexpressing VviNAC60 to define a set of high-confidence targets. Among these, we identified key molecular markers associated with organ senescence and fruit ripening. Physiological, metabolic, and promoter activation analyses showed that VviNAC60 induces chlorophyll degradation and anthocyanin accumulation through the up-regulation of STAY-GREEN PROTEIN 1 (VviSGR1) and VviMYBA1, respectively, with the latter being up-regulated through a VviNAC60-VviNAC03 regulatory complex. Despite sharing a closer phylogenetic relationship with senescence-related homologues to the NAC transcription factor AtNAP, VviNAC60 complemented the non-ripening(nor) mutant phenotype in tomato (Solanum lycopersicum), suggesting a dual role as an orchestrator of both ripening- and senescence-related processes. Our data support VviNAC60 as a regulator of processes initiated in the grapevine vegetative- to mature-phase organ transition and therefore as a potential target for enhancing the environmental resilience of grapevine by fine-tuning the duration of the vegetative phase.

Transcriptome and metabolome combine to analyze the mechanism of leaf coloration formation in Aeonium arboretum ‘Pink Sybil’

“…Furthermore, the activation of PpMYB10.1 by the BLOOD (BL) gene, encoding an NAC TF, is essential for anthocyanin synthesis in Prunus persica (Zhou et al 2015). VviNAC60 and VviMYBA1 interacted in grapes to cause a notable anthocyanin accumulation in immature leaves (D'Incà et al 2023). High expression of ANAC078 in Arabidopsis caused anthocyanins to accumulate in response to HL stress (Morishita et al 2014).…”

NAC61 regulates late-and post-ripening associated processes in grapes involving a NAC60-dependent regulatory network

“…The DAP-seq was performed according to previously described procedure (Galli et al, 2018) and a total of 7.0 (control replicate 1), 5.6 (control replicate 2), 24 (NAC61 replicate 1) and 22 (NAC61 replicate 2) millions reads were obtained. DAP-seq bioinformatic analysis was performed as previously described (D'Inca et al, 2023;Orduna et al, 2022;Orduña-Rubio et al, 2023). Briefly, DAP-seq libraries were aligned to the PN40024 12X.v2 reference genome using bowtie2 (Langmead and Salzberg, 2012), with post-processing to remove reads with a MAPQ score lower than 30.…”

“…By inspecting the 600 top scoring peaks, we identify the major binding motif [CA(C/A)G(C/T)(A/C)A] (Fig. 4B), correlated with A. thaliana ANAC46, controlling cell death during leaf senescence (Huysmans et al, 2018), ANAC55 involved in ABA and jasmonic acid responses (Jiang et al, 2009), and ANAC047, the NAC60 closest homologue (D'Inca et al, 2023; Supplementary Fig. S5) according with RSAT Plants phylogenetic footprints.…”

“…In grapevine, NAC33 and NAC60 have been functionally investigated as putative master regulators of the vegetative-tomature transition in several plant organs (D'Inca et al, 2021;D'Inca et al, 2023). NAC33 plays a major role in leaf and fruit, terminating photosynthetic activity and organ growth, while for NAC60, able to complement the nor mutant phenotype in tomato, a dual role as an orchestrator of both ripening-and senescence-related processes has been proposed.…”

“…Moreover, it has been shown that NAC60 homodimer is the prevalent form in berries during ripening, although its ability to form heterodimers with NAC03 and NAC33 has also been demonstrated, suggesting the existence of a NAC60-NAC regulatory network (D'Inca et al, 2023). Interestingly, NAC60, together with the still uncharacterized NAC61, were also identified as markers of post-harvest dehydration (Zenoni et al, 2016).…”