Plant mineral defense against insect herbivores. Flor E. Acevedo, Michelle Peiffer, Gary Felton

Transcription

1 Plant mineral defense against insect herbivores Flor E. Acevedo, Michelle Peiffer, Gary Felton

2 Introduction Plants uptake minerals from the soil. Animals get essential minerals from plants.

3 Introduction Plant mineral defense Calcium oxalate crystals in Medicago truncatula Korth et al., Silicon bodies in Oryza sativa Acevedo, 2016

4 Introduction Herbivore induced plant defenses Maag et al., 2015

5 Hypotheses 1) Insect herbivory modifies leaf mineral composition. 2) Silicon supplementation increases herbivore induced defenses in high and low Si-accumulator plants.

6 Model system High silicon-accumulator Maize Moderate silicon-accumulator Soybean Spodoptera frugiperda Tomato Non-silicon accumulator

7 Objectives 1) To determine changes in plant mineral composition after herbivore attack. 2) To test the effect of silicon (Si) supplementation on plant defense responses against insect herbivores.

8 Methods Maize Soybean Tomato K 2 SiO 3 Foliar mineral accumulation Two weeks later Activity of antinutritional proteins Concentration of total phenolics K 2 SiO 3 Density of trichomes S. frugiperda larvae growth

9 Results

10 Insect herbivory and silicon supplementation modify leaf mineral composition. Maize Soybean Tomato Fe Zn Mn Fe Na Zn Na B Al B Na Cu Al

11 Si (mg100 g D.W) Silicon-supplemented plants accumulated greater amount of this element in their leaves compared with non Si-supplemented controls. Maize Soybean Tomato Si (mg100 g D.W) undamaged controls a 5 mm Si 5 mm KCl b Undamaged controls b a 5 mm Si 5 mm KCl c c Si (mg100 g D.W) Undamaged controls a 5 mm Si 5 mm KCl b Trt1 (Si/KCl) F = 30.61, p < Trt2 (cat/und) F = 4,51, p = Trt1 (Si/KCl) F = 0,21, p = Trt2 (cat/und) F = 5,33, p = Trt1 (Si/KCl) F = 0,81, p = 0.49 Trt2 (cat/und) F = 30,55, p < 0.001

12 Silicon supplementation increased production of peroxidase in tomato, and protease inhibitors in soybean. Trypsin PI activity Peroxidase activity mpi relative expression Maize (mpi) undamaged controls 5mM Si 5mM KCl Trt1 (Si/KCl) F = 1,24, p = Trt2 (cat/und) F = 291,8, p < 0,001 Soybean (Trypsin PI) undamaged controls a 5mM Si 5mM KCl Trt1 (Si/KCl) F = 4,24, p = Trt2 (cat/und) F = 0,07, p = b Peroxidase activity Tomato (POX) undamaged controls a undamaged controls b 5mM Si 5mM KCl 5mM Si 5mM KCl Trt1 (Si/KCl) F = 5,92, p < Trt2 (cat/und) F = 139,3, p < 0.001

13 Silicon supplementation and herbivory affected the concentration of total phenolics in soybean and maize. Maize Soybean Tomato Total phenolics x gm fresh tissue undamaged controls 5mM Si 5mM KCl Trt1 (Si/KCl) F = 1,09, p = 0.36 Trt2 (cat/und) F = 33,88, p < 0,001 Total phenolics x gm fresh tissue undamaged controls a 5mM Si 5mM KCl b Trt1 (Si/KCl) F = 11,19, p < 0,001 Trt2 (cat/und) F = 21,41, p < 0,001 Total phenolics x gm fresh tissue undamaged controls 5mM Si 5mM KCl Trt1 (Si/KCl) F = 0,38, p = 0,765 Trt2 (cat/und) F = 3,47, p = 0,066

14 No. of trichomes Silicon supplementation and herbivory increased production of trichomes in tomato. No. of of trichomes trichomes undamaged controls controls a Maize b c c Si Si + Si KCl undamaged controls a c Tomato b Si KCl c

15 Maize plants supplemented with silicon accumulated greater amount of this element in their trichomes. Si (mg100 g D.W) a b 5 mm Si 5 mm KCl t = -9,85, p = 0,000, df =5, n = 4

16 Larvae fed on Si-supplemented plants previously exposed to herbivory gained less weight than controls. Maize Soybean Tomato Caterpillar weight gain (mg) undamaged controls a b 5 mm Si 5 mm KCl Trt1 (Si/KCl) F = 30.61, p < Trt2 (cat/und) F = 4,51, p = Caterpillar weight gain (mg) Undamaged controls 5 mm Si 5 mm KCl Trt1 (Si/KCl) F = 0,21, p = Trt2 (cat/und) F = 5,33, p = Caterpillar weight gain (mg) Undamaged controls 5 mm Si 5 mm KCl Trt1 (Si/KCl) F = 0,81, p = 0.49 Trt2 (cat/und) F = 30,55, p < 0.001

17 Hypotheses 1) Insect herbivory modifies leaf mineral composition. Plant Fe Al Na Mn Ca Mg Cu B Zn Si Maize Soybean Tomato 2) Silicon supplementation increases herbivore induced defenses in high and low Si-accumulator plants. Plant mpi POX Trypsin PI Phenolics No. Trichomes Cat. Weight gain Maize Soybean? Tomato

18 Hypotheses 1) Insect herbivory modifies leaf mineral composition. Plant Fe Al Na Mn Ca Mg Cu B Zn Si Maize Soybean Tomato 2) Silicon supplementation increases herbivore induced defenses in high and low Si-accumulator plants. Plant mpi POX Trypsin PI Phenolics No. Trichomes Cat. Weight gain Maize Soybean? Tomato

19 Conclusions Silicon supplementation Art work: Nick Sloff

20 Acknowledgements Felton and Luthe labs