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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #345938
Title: Rootstock effects on metabolite composition in leaves and roots of young navel orange (Citrus sinensis L. Osbeck) and pummelo (C. grandis L. Osbeck) trees

Author
item ALBRECHT, UTE - Southwest Florida Research And Education Center
item TRIPATHI, INDU - Southwest Florida Research And Education Center
item KIM, HOYOUN - Southwest Florida Research And Education Center
item Bowman, Kim

Submitted to: Trees
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2018
Publication Date: 10/3/2018
Citation: Albrecht, U., Tripathi, I., Kim, H., Bowman, K.D. 2018. Rootstock effects on metabolite composition in leaves and roots of young navel orange (Citrus sinensis L. Osbeck) and pummelo (C. grandis L. Osbeck) trees. Trees. 33(1):243-265. https://doi.org/10.1007/s00468-018-1773-1.
DOI: https://doi.org/10.1007/s00468-018-1773-1

Interpretive Summary: The rootstock is a critical component of modern commercial citrus production, but all existing rootstocks have flaws that limit the fruit production, tree longevity, and disease tolerance of citrus trees in the field. Development of new and better rootstocks is limited by the need for very long duration and expensive field testing to identify the presence or absence of the necessary traits. The metabolic components of a rootstock cultivar can potentially be used at an early age to determine the ability of that rootstock to support high fruit production and long tree life, as well as its ability to tolerate disease and environmental stress. This study used mass spectrometry to characterize rootstock cultivars based on their metabolite profile at an early seedling stage. Those metabolite profiles were then associated with rootstock-specific traits, and can be used to guide early selection within the breeding program, improving the efficiency of the long-term citrus rootstock breeding effort.

Technical Abstract: Rootstock is an important component of commercial citrus production. Choice of rootstock affects not only the quality of fruit and size of trees, but also the ability to tolerate unfavorable environmental conditions and disease. The choice of rootstocks for commercial citrus production is influenced strongly by tolerance to the diseases citrus tristeza virus (CTV) and huanglongbing (HLB). This study aims to characterize rootstock cultivars based on their metabolite profile at an early seedling stage and to develop biochemical markers that are associated with rootstock-specific traits. The ability to characterize rootstocks biochemically at a young age, and associate those biochemical markers with horticultural traits, would reduce the need for long-term field trials and greatly accelerate the development of new varieties. For this study, the rootstock cultivars Cleopatra, Sour orange, Ridge pineapple, and Swingle, which are commercial rootstock cultivars in Florida, were used. Greenhouse-grown seedlings were analyzed for their metabolite composition in leaves and roots via gas chromatography-time of flight-mass spectrometry (GC-TOF-MS). Principal component analysis, hierarchical cluster analysis, and partial least-squares-discriminant analysis showed clear differences between the tissue types and cultivars. Heat map and enrichment analysis revealed unique profiles for each cultivar, and metabolites that may be associated with rootstock traits. Notable was the finding of high amounts of squalene, a compound associated with chilling tolerance, in Swingle. High amounts of mannitol were detected in Cleopatra and Sour orange rootstocks, known for their tolerance to conditions of high salinity. The information gained from this study provides important insight for understanding the metabolic basis of scion and rootstock characteristics.