NAC Transcription Factor Family Regulation of Fruit Ripening and Quality: A Review

Abstract

The NAC transcription factor (TF) family is one of the largest plant-specific TF families and its members are involved in the regulation of many vital biological processes during plant growth and development. Recent studies have found that NAC TFs play important roles during the ripening of fleshy fruits and the development of quality attributes. This review focuses on the advances in our understanding of the function of NAC TFs in different fruits and their involvement in the biosynthesis and signal transduction of plant hormones, fruit textural changes, color transformation, accumulation of flavor compounds, seed development and fruit senescence. We discuss the theoretical basis and potential regulatory models for NAC TFs action and provide a comprehensive view of their multiple roles in modulating different aspects of fruit ripening and quality.

Knock-Out of CmNAC-NOR Affects Melon Climacteric Fruit Ripening

“…This phenotype has not previously been reported in the tomato NOR mutant or in other NAC genes in species such as peach (Pirona et al, 2013), apple (Yeats et al, 2019), andstrawberry (Martín-Pizarro et al, 2021). However, there are some reports suggesting that NAC transcription factors regulate seed development and play a role in seed germination (Kim et al, 2008;Park et al, 2011;Wang et al, 2021;Liu et al, 2022). In a recent study, knock out of the ClNAC68 gene in watermelon delayed seed maturation and germination, but the germination rate was not affected (Wang et al, 2021), suggesting that there are additional NAC genes with diverse functions that regulate seed development.…”

“…APETALA2a (AP2a) is a negative regulator of tomato fruit ripening, with its silencing causing elevated ethylene production and early fruit ripening (Chung et al, 2010;Karlova et al, 2011). Other NAC proteins have also been found to be involved in regulating ripening, among them SlNAC1, SlNAC3, SlNAC4, and SlNAM1, suggesting that a complex regulatory network of fruit ripening exists (reviewed in Liu et al, 2022). For non-climacteric fruit, strawberry is one of the most studied plants (Osorio et al, 2013) and several genes involved in strawberry fruit ripening have recently been identified, including FaPYR1 (Chai et al, 2011), FaExp2 (Civello et al, 1999), FaASR (Chen et al, 2011), FaABI1 (Jia et al, 2013), andFaRIF (Martín-Pizarro et al, 2021).…”

Genome-Wide Identification and Analysis of the NAC Transcription Factor Gene Family in Garden Asparagus (Asparagus officinalis)

“…Transcription factors (TFs) are one kind of regulatory protein that stimulates or inhibits the transcriptional rates of its targeted genes by binding to specific cis-acting elements, thereby controlling plant growth and development, as well as abiotic and biotic stress responses [ 2 , 3 , 4 ]. According to the different DNA-binding domains (DBDs) in target genes’ promoters, plant transcription factors can be classified into 58 families [ 5 ], such as MYB (v-myb avian myeloblastosis viral oncogene homolog), AP2/ERF (APETALA 2/ethylene-responsive element binding factor), HD-Zip (homeodomain leucine zipper), RHR (rel-homology region), Sp1 (specificity protein 1), ARF (auxin response factor), MRKY, NAC, and so on [ 6 ].…”

“…As one of the significant and diverse plant-specific transcription factor families, the name of the NAC gene family originated from three important proteins with similar DNA-binding domains: NAM (no apical meristem) in Petunia , ATAF1/2 (transcription activation factors), and CUC2 (cup-shaped cotyledon 2) in Arabidopsis [ 4 , 6 ]. The NAM domain affects the formation and differentiation of apical meristem of petunia [ 6 ]. ATAF1 and ATAF2 are found to negatively regulate the defense responses against necrotrophic fungal and bacterial pathogens [ 7 ].…”

Transcriptional regulation of fleshy fruit texture

“…Many studies carried out in tomato indicate that the accumulation of transcripts encoding at least eight different ripening‐associated CW genes is regulated by upstream transcriptional regulators, and similar findings have emerged from studies on several other fruits (Figure1; Table 2). These include MADS box TFs such as MADS‐RIN, NACs (NAM, ATAF, and CUC) and a range of ethylene response factors (ERFs), plus other TFs discussed below (Fujisawa et al, 2011; Zhong et al, 2013; Shi et al, 2021; Deng et al, 2022; Liu et al, 2022; Wang and Seymour, 2022) (Table 2). The general criteria used for identifying transcriptional activation and repression of target genes by specific TFs, include electrophoretic mobility shift assay (EMSA), Chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP‐qPCR) or sequencing (ChIP‐seq), yeast one‐hybrid assay (Y1H assay), dual‐luciferase reporter assay, or Gus ( β ‐glucuronidase) assay.…”