Transcription factor LcNAC002 coregulates chlorophyll degradation and anthocyanin biosynthesis in litchi

Abstract

Chlorophyll degradation and anthocyanin biosynthesis, which often occur almost synchronously during fruit ripening, are crucial for vibrant coloration of fruits. However, the interlink point between their regulatory pathways remains largely unknown. Here, two litchi (Litchi chinensis Sonn.) cultivars with distinctively different coloration patterns during ripening, i.e. slow-reddening/stay-green ‘Feizixiao’ (FZX) vs rapid-reddening/degreening ‘Nuomci’ (NMC), were selected as the materials to study the key factors determining coloration. L. chinensis STAY-GREEN (LcSGR) was confirmed as the critical gene in pericarp chlorophyll loss and chloroplast breakdown during fruit ripening, as LcSGR directly interacted with pheophorbide a oxygenase (PAO), a key enzyme in chlorophyll degradation via the PAO pathway. L. chinensis NAM (No apical meristem), ATAF1/2(Arabidopsis transcription activation factor 1/2) and CUC2 (cup-shaped cotyledon 2) (LcNAC002) was identified as a positive regulator in the coloration of litchi pericarp. The expression of LcNAC002 was significantly higher in NMC than in FZX. Virus induced gene silencing (VIGS) of LcNAC002 significantly decreased the expression of LcSGR as well as L. chinensis MYELOBLASTOSIS1 (LcMYB1), and inhibited chlorophyll loss and anthocyanin accumulation. A dual-luciferase reporter (DLR) assay revealed that LcNAC002 significantly activates the expression of both LcSGR and LcMYB1. Furthermore, yeast one-hybrid (Y1H) and electrophoretic mobility shift assay (EMSA) results showed that LcNAC002 directly binds to the promoters of LcSGR and LcMYB1. These findings suggest that LcNAC002 is an important ripening-related transcription factor that interlinks chlorophyll degradation and anthocyanin biosynthesis by co-activating the expression of both LcSGR and LcMYB1.

Genome-wide identification of GA2ox genes family and analysis of PbrGA2ox1-mediated enhanced chlorophyll accumulation by promoting chloroplast development in pear

“…Notably, we also observed the downregulation of two key anthocyanin-induced genes in the OE lines compared to the WT lines (Fig. S6a and b in Additional File 1 ), indicating suppressed anthocyanin synthesis in the OE plants, which represented an opposing trend to Chl accumulation [ 50 , 51 ]. In addition, KEGG pathway enrichment also showed that some DEGs were closely associated with MAPK signaling and plant-pathogen interaction (Fig.…”

Natural variation in STAYGREEN contributes to low‐temperature tolerance in cucumber

“…Tomato SlSGR1 is able to regulate fruit color formation during ripening, by directly interacting with a carotenoid biosynthetic enzyme SlPSY1 (Luo et al, 2013). The Litchi LcSGR gene functions in fruit chloroplast breakdown during ripening by interacting with LcNAC002, which is an important transcriptional activation factor that integrates Chl degradation and anthocyanin biosynthesis (Zou et al, 2023). In banana, MaSGR1 is bound by a MYB transcription factor, MaMYB60, which is ubiquitinated by a RING‐type E3 ligase MaBAH1, to form a temperature‐responsive MaBAH1‐MaMYB60‐CCG module that regulates ripening in banana (Wei et al, 2023).…”

An integrated multi-omics approach reveals polymethoxylated flavonoid biosynthesis in Citrus reticulata cv. Chachiensis

“…All the vectors were introduced into A. tumefaciens strain GV3101.The Agrobacterium cells harboring the TRV1 and TRV2 recombinants were grown in LB broth to OD600 = 1.0 27 , and then Agrobacterium cultures were centrifuged at 6000 × g for 10 min and resuspended in infiltration buffer (10 mM MgCl 2 , 10 mM MES, 200 μM acetosyringone, 0.01% Tween20; pH 5.6). Resuspended A. tumefaciens TRV1 and TRV2- CcOMT1 were mixed at a 1:1 ratio and infiltrated into the citrus fruit on the trees, three single-tree-based biological replicates were set up 98 . Citrus fruits were collected at two weeks after infiltration.…”