We can improve crop photosynthesis and so yield? Steve Long, Departments of Crop Sciences and Plant Biology, University of Illinois, UK Lancaster Environment Centre, Lancaster University, UK
ROADMAP Why photosynthesis? The Gates Foundation RIPE Project Accelerating regeneration of the CO2 acceptor Sun Shade Sun transitions
ROADMAP Why photosynthesis? The Gates Foundation RIPE Project Accelerating regeneration of the CO 2 acceptor Sun Shade Sun transitions
RICE YIELD IMPROVEMENT HAS SLOWED IN MAJOR PRODUCING COUNTRIES
UNDERSTANDING POTENTIAL YIELD STAGNATION Harvested yield t ha -1 Interception efficiency Sunlight energy GJ ha -1 Conversion efficiency Partitioning efficiency (Harvest index) Energy content of seed GJ t -1 S i x x c x p 4.6 = 6200 x 0.89 x 0.032 x 0.60 / 23 W h = / c Morgan, Bollero, Nelson & Long (2005) Global Change Biology 11, 1856 1865 Dermody, Long, McConnaughay, DeLucia (2008) Global Change Biology 14, 556 564
WHY PHOTOSYNTHESIS? % Theoretical Maximum100 Pre-Green Revolution Pre-Green Revolution Pre-Green Revolution Post- Green Reolution Post- Green Reolution 0 ε i Interception ε c Conversion ε p Partitioning Efficiency Factor Zhu, Long & Ort (2010) Ann. Rev. Pl. Biology 2010, 61: 235-261
NEED FOR MORE PHOTOSYNTHESIS
OPEN-AIR ENRICHMENT OF CO 2 FACE Leaf photosynthesis increased 25% across growing season. Rogers, Allen, Bernacchi, Ainsworth & Long (2004) Plant, Cell and Environment 27, 449 458 Long, Ainsworth, Leakey, Noesberger & Ort (2006) Science 312 : 1918-1921
INCREASE IN YIELD WITH ELEVATED CO 2 IN FIELD Long et al. (2006) Science 312, 1918-1921; (2007) Science 315, 460. Soybeans Rice Wheat 16% 12% 15%
WHY IS ENGINEERING OF CROP PHOTOSYNTHESIS SCIENTIFICALLY AND TECHNOLOGICALLY TIMELY? Photosynthesis known in more detail than any other plant process, and is highly conserved. High performance computing Crop transformation becoming increasingly routine.
160 QUANTITATIVELY VARIABLE STEPS A FEW TRILLION PERMUTATIONS WHERE DO WE START!?!
DYNAMIC MODEL OF LEAF PHOTOSYNTHESIS Represented as a system of differential equations to guide improvement of existing system Zhu, DeSturler & Long (2007) Plant Physiology 145: 513-526 Zhu, Ort & Long (2013) Plant, Cell & Env. 36: 1711-1727
DYNAMIC MODELING OF PHOTOSYNTHESIS AT CELL AND CROP CANOPY LEVEL Donna Cox; National Center for Supercomputer Applications
ROADMAP Why photosynthesis? The Gates Foundation RIPE Project Accelerating regeneration of the CO 2 acceptor Sun Shade Sun transitions
EVOLUTIONARY ALGORITHM TO PREDICT OPTIMUM INVESTMENT Increased carbohydrate production Zhu, DeSturler & Long (2007) Plant Physiology 145, 513 526
SBPASE TESTING THE REALITY WT4 WT12 WT14 11.5 60.12 30.15
SBPASE: TESTING THE HYPOTHESIS Significant positive interaction of elevated SbPase with increase in CO 2 and in temperature. Kohler et al. (2017) Journal of Experimental Botany 68: 715.
ROADMAP Why photosynthesis? The Gates Foundation RIPE Project Accelerating regeneration of the CO 2 acceptor Sun Shade Sun transitions
Too much sun! Too little sun! Heat Heat Heat Photosynthesis Photosynthesis Photosynthesis
35 30 25 20 15 10 5 0 0 10 20 30 40 50 time (minutes) Rate of leaf CO2 uptake (umol m -2 s -1 )
SLOW RECOVERY OF EFFICIENCY Zhu & Long (2004) J. Exp. Bot. 55, 1167-1175.
SELECTING FASTER RELAXATION IN ENGINEERED PLANTS Chlorophyll fluorescence of young seedlings 1000 PFD (µmol m 2 s 1 ) 500 0-5 0 5 10 15 20 Time (min) PFD (µmol m 2 s 1 ) 2000 1000 0-5 0 5 10 15 20 25 30 Time (min)
35 30 25 20 15 10 5 0 0 10 20 30 40 50 time (minutes) Leaf CO2 uptake ( mol m-2 s -1 )
RELAXING PHOTOPROTECTION
2016 FIELD TRIALS Johannes Kromdijk, Katarzyna Głowacka, Lauriebeth Leonelli, Stéphane T. Gabilly, Masakazu Iwai, Krishna K. Niyogi, Stephen P. Long (2016) Science 354, 857-861
TRANSFORM STAPLE CROPS RICE CASSAVA COWPEAS MAIZE SOYBEANS RIPE is now implementing successful strategies to improve the yield of staple food crops.
Productivity improvement with trait and trait stacking 120 100 % INCREASE 80 60 40 20 0 TRAIT CORRESPONDING TO OBJECTIVES 2 THRU 8
A BIG THANKS TO THOSE WHO MAKE THIS WORK POSSIBLE Small chance of success. What are we waiting for? J.R.R. Tolkien
Right Modern Wheat Left Wild Ancestor Right Modern Soybean Left Wild Ancestor Can photosynthesis really be improved? Could evolution have left a free lunch on the table? Selection for survival and fecundity Average CO 2 of past 25 My = 220 ppm Sun plants with most leaves now in shade
RAIN-FED MIDWEST MAIZE AND CLIMATE CHANGE Limit of Limit of yield increase 2022 Need to achieve more yield on the land we are already using - sustainably. Ort & Long (2016) Science 344, 484-5.
& GENOTYPING