Article Highlight | 9-Apr-2024

Unlocking sweetness and ripeness: the pioneering study of SWI/SNF complexes in citrus fruit quality

Maximum Academic Press

In eukaryotic cells, nucleosomes—composed of histone octamers—address the topological challenge of DNA packaging by condensing the DNA within the nucleus., crucial for genetic information storage and inheritance. This compact structure, however, restricts DNA accessibility, necessitating ATP-dependent chromatin remodeling for essential processes like transcription. Among these, SWI/SNF complexes are notable for regulating DNA-histone interactions. While significant strides have been made in understanding these complexes in various plants, research in citrus fruits remains unexplored. Given its economic and nutritional importance, citrus offers unique opportunities to explore the effects of SWI/SNF complexes on flavor quality, particularly in terms of sweetness and ripeness.

Fruit Research published online a paper entitled “SWI3 subunits of SWI/SNF complexes in Sweet Orange (Citrus sinensis): genome-wide identification and expression analysis of CsSWI3 family genes on 02 January 2024.

The study commenced with the identification of the SWI3 gene family within the Citrus sinensis genome, utilizing homologous sequence alignment against the Arabidopsis AtSWI3 genes. This methodological approach revealed four CsSWI3 genes, all containing specific domains known from Arabidopsis, thus highlighting their potential structural and functional similarities..Subsequent analyses encompassed phylogenetic studies and chromosomal localization, revealing evolutionary relationships with SWI3 family members across various species and determining the genes' distribution across three C. sinensis chromosomes. The gene structure, conserved motif, and domain investigations offered deeper insights into the evolutionary kinship and potential functional analogies among the CsSWI3s, with particular attention to the unique presence of a Zinc finger-ZZ type domain in one subfamily, suggesting specialized functions.

Further, subcellular localization assays indicated that all CsSWI3 proteins are nuclear, aligning with their presumed roles in chromatin remodeling. Promoter cis-regulatory element analysis exposed a broad spectrum of elements responsive to stress, phytohormones, and developmental signals, emphasizing the genes' involvement in stress resistance and growth processes. Expression analysis across different fruit developmental stages and various tissues of 'Bingtang' sweet orange highlighted tissue-specific expression patterns and a positive correlation between CsSWI3 gene expression and sugar content in fruits, notably absent in relation to organic acid content. This suggests a specific regulatory role of CsSWI3s in sugar metabolism, with CsSWI3B showing a particularly strong correlation, implying its significant involvement in sugar accumulation processes.

Conclusively, this comprehensive characterization of the CsSWI3 gene family in C. sinensis provides foundational insights into their chromosomal organization, evolutionary relationships, structural features, and expression profiles. The findings underline the importance of CsSWI3s in plant stress responses, growth, and development, and notably in regulating sugar accumulation in citrus fruits, thereby setting the stage for further functional analyses and elucidation of their roles in chromatin remodeling within citrus and potentially other fruit crops.





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Yinchun Li1, Mengjie Xu1, Dingwang Lu1, Dengliang Wang3, Shengchao Liu2, *,  & Shaojia Li1, *


1.College of Agriculture & Biotechnology, Zhejiang University, Zijingang Campus, Hangzhou 310058, PR China

2.Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518124, PR China

3.Quzhou Academy of Agricultural Science, Quzhou 323000, PR China

About Shaojia Li

Associate Professor, College of Agriculture & Biotechnology, Zhejiang University.

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