Details

Autor(en) / Beteiligte

• Suh, Joon Hyuk
• Guha, Anirban
• Wang, Zhixin
• Li, Sheng‐Yang
• Killiny, Nabil
• Vincent, Christopher
• Wang, Yu

Titel

Metabolomic analysis elucidates how shade conditions ameliorate the deleterious effects of greening (Huanglongbing) disease in citrus

Ist Teil von

• The Plant journal : for cell and molecular biology, 2021-12, Vol.108 (6), p.1798-1814

Ort / Verlag

England: Blackwell Publishing Ltd

Erscheinungsjahr

2021

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• Summary Under tropical and subtropical environments, citrus leaves are exposed to excess sunlight, inducing photoinhibition. Huanglongbing (HLB, citrus greening), a devastating phloem‐limited disease putatively caused by Candidatus Liberibacter asiaticus, exacerbates this challenge with additional photosynthetic loss and excessive starch accumulation. A combined metabolomics and physiological approach was used to elucidate whether shade alleviates the deleterious effects of HLB in field‐grown citrus trees, and to understand the underlying metabolic mechanisms related to shade‐induced morpho‐physiological changes in citrus. Using metabolite profiling and multinomial logistic regression, we identified pivotal metabolites altered in response to shade. A core metabolic network associated with shade conditions was identified through pathway enrichment analysis and metabolite mapping. We measured physio‐biochemical responses and growth and yield characteristics. With these, the relationships between metabolic network and the variables measured above were investigated. We found that moderate‐shade alleviates sink limitation by preventing excessive starch accumulation and increasing foliar sucrose levels. Increased growth and fruit yield in shaded compared with non‐shaded trees were associated with increased photosystem II efficiency and leaf carbon fixation pathway metabolites. Our study also shows that, in HLB‐affected trees under shade, the signaling of plant hormones (auxins and cytokinins) and nitrogen supply were downregulated with reducing new shoot production likely due to diminished needs of cell damage repair and tissue regeneration under shade. Overall, our findings provide the first glimpse of the complex dynamics between cellular metabolites and leaf physiological functions in citrus HLB pathosystem under shade, and reveal the mechanistic basis of how shade ameliorates HLB disease. Significance Statement Metabolic mechanisms underlying the effects of shade on Huanglongbing (HLB), a phloem‐affecting disease causing severe citrus yield loss, were elucidated using metabolomics coupled with physiological evaluation. Our study suggests possible metabolic processes induced by shade to alleviate HLB disease, and provides novel insights and a framework to understand complex physiochemical relationships between growth environment and pathosystem (host plant and pathogen) response.