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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #353544
Title: Does phloem loading strategy and capacity alter plant response to elevated atmospheric [CO2]?

Author
item LEMONNIER, PAULINE - Oak Ridge Institute For Science And Education (ORISE)
item QUEBEDEAUX, JENNIFER - University Of Illinois
item BISHOP, KRISTEN - University Of Illinois
item BUSH, DANIEL - Colorado State University
item LEAKEY, ANDREW D B - University Of Illinois
item Ainsworth, Elizabeth - Lisa

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/22/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A better understanding of the interactions between photosynthesis, photoassimilate translocation and sink activity is necessary to improve crop productivity. Rising atmospheric [CO2] perturbs source-sink balance which needs to be addressed to adapt crops to future growing conditions. This project takes two approaches to investigate the importance of phloem loading in plant photosynthetic responses to elevated [CO2]. First, we postulated that species with different phloem loading strategies are differentially adapted to high mesophyll sucrose concentrations, and may have fundamentally different photosynthetic responses to elevated [CO2]. Over three field seasons, six species with apoplastic loading, passive loading, or polymer-trapping were grown at ambient and elevated [CO2] at the Soybean Free Air Concentration Enrichment (SoyFACE) facility. Our results indicated that in contrast to our hypothesis, there was little difference in photosynthetic response to elevated [CO2] among these species. However, phylogenetically controlled comparative analysis may be required to fully reject the hypothesis. Second, we hypothesized that plants could have insufficient sugar export capacity from the photosynthetic source to sink tissues under conditions of high carbon availability. This is suggested by feedback inhibition of photosynthetic capacity at elevated [CO2]. To overcome this potential limitation, soybean was transformed to overexpress a proton/sucrose symporter in the phloem companion cells. Photosynthesis, transgene expression, sucrose transport activity, and carbohydrate content in leaves were assessed during experiments conducted at SoyFACE in 2016 and 2017 to test how increasing sucrose transport capacity in soybean impacts the seed yield response to elevated [CO2].