Processes affected by CO 2 1) Pathways that consume CO 2 2) pathways that release CO 2 3) transpiration & stomatal number

C4 and CAM photosynthesis Adaptations that reduce PR & water loss Both fix CO 2 with a different enzyme

C4 and CAM photosynthesis Adaptations that reduce PR & water loss Both fix CO 2 with a different enzyme later release CO 2 to be fixed by rubisco use energy to increase [CO 2 ] at rubisco

C4 and CAM photosynthesis Adaptations that reduce PR & water loss Both fix CO 2 with a different enzyme later release CO 2 to be fixed by rubisco use energy to increase [CO 2 ] at rubisco C4 isolates rubisco spatially (e.g. corn)

C4 and CAM photosynthesis Adaptations that reduce PR & water loss Both fix CO 2 with a different enzyme later release CO 2 to be fixed by rubisco use energy to increase [CO 2 ] at rubisco C4 isolates rubisco spatially (e.g. corn) CAM isolates rubisco temporally (e.g. cacti)

C4 and CAM photosynthesis C4 isolates rubisco spatially (e.g. corn) CAM isolates rubisco temporally (e.g. cacti) Advantages: 1) increases [CO 2 ] at rubisco

C4 and CAM photosynthesis Advantages: 1) increases [CO 2 ] at rubisco reduces PR prevents CO 2 from escaping

C4 and CAM photosynthesis Advantages: 1) increases [CO 2 ] at rubisco reduces PR CO 2 compensation point where CO 2 uptake by PS = CO 2 loss by “dark” respiration is ppm in C3

C4 and CAM photosynthesis CO 2 compensation point where CO 2 uptake by PS = CO 2 loss by “dark” respiration is ppm in C3 0-5 ppm in C4 & CAM

C4 and CAM photosynthesis CO 2 compensation point where CO 2 uptake by PS = CO 2 loss by “dark” respiration is ppm in C3 0-5 ppm in C4 & CAM C4 and CAM also get saturated at lower pCO 2

C4 and CAM photosynthesis Advantages: 1) increases [CO 2 ] at rubisco 2) reduces water loss

C4 and CAM photosynthesis reduces water loss: don't need to open stomata as wide C3 plants lose H 2 O/CO 2 fixed C4 plants lose CAM plants lose

C4 photosynthesis = spatial isolation C4 plants have Kranz anatomy Mesophyll cells fix CO 2 with PEP carboxylase Bundle sheath cells make CH 2 0 by Calvin cycle

C4 photosynthesis = spatial isolation C4 plants have Krantz anatomy Mesophyll fix CO 2 with PEP carboxylase Send 4C product to B-S cell

C4 photosynthesis = spatial isolation B-S cells convert 4C to pyruvate releasing CO 2 Calvin cycle fixes it Change pyruvate to PEP in mesophyll

C4 photosynthesis = spatial isolation B-S cells convert 4C to pyruvate releasing CO 2 Calvin cycle fixes it Change pyruvate to PEP in mesophyll Has evolved independently >50 times!

C4 photosynthesis = spatial isolation Has evolved independently >50 times! Found in 18 families: both monocots & dicots Some have C3 and C4 spp!

C4 photosynthesis = spatial isolation Has evolved independently >50 times! Found in 18 families: both monocots & dicots Some have C3 and C4 spp! 3 ways to shuttle C!

C4 photosynthesis = spatial isolation 3 ways to shuttle C! All generate C4 acid in Mesophyll & release CO 2 in BS, but details vary

C4 photosynthesis = spatial isolation Has evolved independently >50 times! 3 ways to shuttle C! Can occur w/in same cell! 3 diff spp do it 3 diff ways!

C4 photosynthesis = spatial isolation Benefits over C3 1) no PR 2) less water loss

C4 photosynthesis = spatial isolation Benefits over C3 1) no PR 2) less water loss Disadvantage C4 use 30 ATP/ glucose; C3 use 18 ATP

C4 photosynthesis = spatial isolation Benefits over C3 1) no PR 2) less water loss Disadvantage C4 use 30 ATP/ glucose C3 use 18 ATP Lower Quantum efficiency

C4 photosynthesis = spatial isolation C4 use 30 ATP/ glucose; C3 use 18 ATP At high T C4 grow better At high CO 2 C3 grow better Both T and CO 2 are going up! Hard to predict which will do better!

Crassulacean acid metabolism (CAM) Also uses C3 & C4 pathways Uses C4 pathway at night: open stomata, let CO 2 in Close stomata & use C3 pathway during day

Crassulacean acid metabolism (CAM) At night open stomata, let CO 2 in Fix with PEP carboxylase build up C4 acids all night stored in vacuole

Crassulacean acid metabolism (CAM) During day close stomata decarboxylate stored C4 acids fix CO 2 using Calvin cycle

Crassulacean acid metabolism (CAM) advantages 1) no PR 2) minimal water loss 3) photosynthesize when have lots of energy

Crassulacean acid metabolism (CAM) advantages 1) no PR 2) minimal water loss 3) photosynthesize when have lots of energy disadvantages 1) can ’ t store much C4 acid 2) uses lots of energy

Crassulacean acid metabolism (CAM) CAM is mainly used in dry environments Some aquatic plants do CAM

Crassulacean acid metabolism (CAM) Some aquatic plants do CAM Take up CO 2 at night when concentration is higher: can be very low during the day! also some in tropical rainforests! >20,000 CAM spp!

Crassulacean acid metabolism (CAM) CAM is mainly used in dry environments Facultative CAM induce CAM during drought, do C3 when humid

Crassulacean acid metabolism (CAM) CAM is mainly used in dry environments Facultative CAM induce CAM during drought, do C3 when humid Inactivate PEPC & open stomata normally

Crassulacean acid metabolism (CAM) CAM is mainly used in dry environments Facultative CAM induce CAM during drought, do C3 when humid Inactivate PEPC & open stomata normally Can tell by  13C

Crassulacean acid metabolism (CAM) Can tell by  13C rubisco discriminates against 13C, so C3 plants have  13C of / 00 if it can choose CAM & C4 have  13C of / 00 because 13C diffuses more slowly

Crassulacean acid metabolism (CAM) Can tell by  13C rubisco discriminates against 13C, so C3 plants have  13C of / 00 if it can choose CAM & C4 have  13C of / 00 because 13C diffuses more slowly Can tell if sugar came from C3 or C4/CAM by  13C

Crassulacean acid metabolism (CAM) Can tell by  13C rubisco discriminates against 13C, so C3 plants have  13C of / 00 if it can choose CAM & C4 have  13C of / 00 because although use up most CO 2 in leaf 13C diffuses more slowly Can tell if sugar came from C3 or C4/CAM by  13C Also tells about stomatal opening &water use efficiency

Processes affected by [Sugar] Energy Biosynthesis Storage Structure Osmotic regulation Signaling molecules

Processes affected by [Sugar]

1) Flowering: adding sucrose promotes early flowering

Processes affected by [Sugar] 1)Flowering: adding sucrose promotes early flowering apex in induction

Processes affected by [Sugar] 1)Flowering: adding sucrose promotes early flowering apex in induction affects FT & LFY expression, also mir399

Processes affected by [Sugar] 1)Flowering 2)Photosynthesis

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Represses rbcS & CAB genes

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Sensed by hexokinase: acts as both an enzyme and a sensor Catalytically-inactive mutants still sense glucose! Form complex in nucleus with subunits of the proteasome and of the vacuolar H + pump!

HXK1/GIN2 Flavonoid synthesis Cell wall synthesis Cytokinin signaling Auxin signaling Light signaling Ca 2+ signaling ROS scavenging / Detoxification Antioxidant protection Sucrose metabolism Starch biosynthesis Respiration Nitrogen metabolism Fatty acid synthesis & mobilization Defense Photosynthesis Photorespiration AtHXK1-Dependent Gene Expression WT vs. gin2

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects partitioning inside cells 1 in 6 G3P becomes (CH 2 O) n either becomes starch in cp (to store in cell)

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects partitioning inside cells 1 in 6 G3P becomes (CH 2 O) n either becomes starch in cp (to store in cell) or is converted to DHAP & exported to cytoplasm to make sucrose

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects partitioning inside cells 1 in 6 G3P becomes (CH 2 O) n either becomes starch in cp (to store in cell) or is converted to DHAP & exported to cytoplasm to make sucrose Pi/triosePO 4 antiporter only trades triosePO 4 for Pi: mechanism to regulate PS

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects starch accumulation

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects starch accumulation

Processes affected by [Sugar] Photosynthesis Sugar turns down light & dark rxns Affects starch accumulation & degradation