ARS | Publication request: Optimizing chlorophyll content in soybean

Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 31, 2011
Publication Date: August 6, 2011
Citation: Slattery, R.A., Ort, D.R. 2011. Optimizing chlorophyll content in soybean [abstract]. American Society of Plant Biologists. Paper No. P22015.

Technical Abstract: Traditionally, leaf chlorophyll content has not been among the target traits for improving crop yield. However, current chlorophyll concentrations may be in excess of the amount that would maximize the season integral of photosynthesis in a crop monoculture, such as soybean, that achieves a high leaf area index. We hypothesized that energy conversion efficiency Ec of crop canopies could be substantially improved by decreasing leaf chlorophyll content and thereby improve the distribution of light resources within the canopy, which in turn would lead to increased rates of canopy photosynthesis. An ancillary effect of absorbing less of the light at the top of canopy would be decreased photoinhibition and heat stress in upper leaves. These effects are predicted to lead to a greater Ec and increase the potential for higher yields as calculated by the Monteith equation. Two chlorophyll-b deficient soybean mutants (LG69-4755 and L72-1937) were grown in the field to assess canopy characteristics such as light distribution, leaf area index, photosynthetic rates, and leaf temperature. Ec will be determined next season when seed supplies are sufficient for destructive harvests. The disadvantages to chlorophyll-b deficient soybean mutants include a developmental lag and delay in canopy closure compared to the wild-type. Future work will consider altering chlorophyll content by regulation at specific points within the biosynthetic pathway to maintain a normal a/b ratio and avoid the negative effects in current mutants.