A nuclear-localized cysteine desulfhydrase plays a role in fruit ripening in tomato

Kang-Di Hu,Zhong-Qin Huang,Yan-Hong Li,Xiao-Yan Chen,Feng Yang,Xiao-Yue Zhang,Hua Zhang,Lan-Ying Hu,Jun Tang,Yu-Lei Rong,Zi-Mu Xu,Gai-Fang Yao,Chen Ding

doi:10.1038/s41438-020-00439-1

Kang-Di Hu, Zhong-Qin Huang + Show 11 more

Open Access

https://doi.org/10.1038/s41438-020-00439-1

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Abstract

Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays multiple roles in plant development. However, whether endogenous H2S plays a role in fruit ripening in tomato is still unknown. In this study, we show that the H2S-producing enzyme l-cysteine desulfhydrase SlLCD1 localizes to the nucleus. By constructing mutated forms of SlLCD1, we show that the amino acid residue K24 of SlLCD1 is the key amino acid that determines nuclear localization. Silencing of SlLCD1 by TRV-SlLCD1 accelerated fruit ripening and reduced H2S production compared with the control. A SlLCD1 gene-edited mutant obtained through CRISPR/Cas9 modification displayed a slightly dwarfed phenotype and accelerated fruit ripening. This mutant also showed increased cysteine content and produced less H2S, suggesting a role of SlLCD1 in H2S generation. Chlorophyll degradation and carotenoid accumulation were enhanced in the SlLCD1 mutant. Other ripening-related genes that play roles in chlorophyll degradation, carotenoid biosynthesis, cell wall degradation, ethylene biosynthesis, and the ethylene signaling pathway were enhanced at the transcriptional level in the lcd1 mutant. Total RNA was sequenced from unripe tomato fruit treated with exogenous H2S, and transcriptome analysis showed that ripening-related gene expression was suppressed. Based on the results for a SlLCD1 gene-edited mutant and exogenous H2S application, we propose that the nuclear-localized cysteine desulfhydrase SlLCD1 is required for endogenous H2S generation and participates in the regulation of tomato fruit ripening.

Highlights

Hydrogen sulfide (H2S) is a gaseous signaling molecule that is widely present in living organisms
Confocal and fluorescence microscopy confirmed that SlLCD1 showed strong nuclear localization, as fluorescence from SlLCD1-GFP merged with the nuclear stain Hoechst 33342 in transfected tobacco leaf cells (Fig. 2)
To verify whether the nuclear localization signal (NLS) segment was essential for the nuclear localization of SlLCD1, a truncation mutant, SlLCD1 (Δ1–26)-GFP, which lacked the first 26 amino acid residues at the

Summary

Introduction

Hydrogen sulfide (H2S) is a gaseous signaling molecule that is widely present in living organisms. Accumulating evidence has confirmed multiple functions of H2S in plant root development, stomatal movement, postharvest senescence, petiole abscission, and response to abiotic stresses[1,2,3,4,5,6]. Similar to the role of nitric oxide in the regulation of fruit ripening and senescence, multiple studies have found that H2S can alleviate postharvest ripening and senescence of fruits, such as strawberry, kiwifruit, and banana, by regulating the antioxidant system and ethylene pathway[2,7,8]. H2S could act as a regulator of fruit ripening by antagonizing the effect of ethylene in tomatoes[9]. Transcriptome analysis indicated that H2S could delay the ripening and senescence of kiwifruit by modulating genes involved in cell wall degradation and in the ethylene signaling pathway[10]. H2S could perform a signaling role through persulfidation, which is the posttranslational modification of cysteine residues (R-SHs) in target proteins by covalent addition of thiol groups to form persulfides (R-SSHs)[11,12]

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