HERBICIDE RESISTANCE

Transcription

1 HERBICIDE RESISTANCE This image is copyright protected. The copyright owner reserves all rights. Ian Burke Associate Professor

2 What does HOS mean? Herbicide Only Solution.

3 Overview Types of Herbicide Resistance ACCase (Group 1/A) ALS (Group 2/B) Operational Assessment Activity Cost of Resistance Management How Resistance Testing Can Help

4

5

6 Current Status of Herbicide Resistance in the PNW A/1 B/2 C1/5 C3/6 G/9 H/10 K1/3 N/8 O/4

7

8 Types of Herbicide Resistance Enhanced Metabolism Commonly found in crops Depends on the chemical structure of the herbicide Can confer resistance to multiple modes of action Much less common than an altered target site Altered Site of Action Most common type of herbicide resistance Can produce complicated cross resistance patterns within the same mode of action Does not cause resistance to other modes of action

9 Target Site Resistance

10 Target Site Herbicide Resistance Point Mutation: Change in one nucleotide in the DNA sequence of the gene resulting in a single amino acid change at protein target site SUSCEPTIBLE WEED RESISTANT WEED Proline ACCase Herbicide ACCase Herbicide blocks fatty acid formation amino acid change Histidin e ACCase Herbicide ACCase Herbicide Serine Alanine Serine Alanine Biosynthetic pathway Glutamin e Valine Biosynthetic pathway Glutamin e Valine

11 Mechanism of Herbicide Resistance Point Mutations ACCase Inhibitors Point Mutation Location Ile 1781 Trp 1999 Trp 2027 Ile 2041 Asp 2078 Phe/Cys 2088 Gly 2096 Substitution Leu or Val Cys or Leu Cys Asn or Val Gly Arg Ala or Ser 11 known amino acid substitutions First case of ACCase resistant Italian ryegrass: 1982, Australia Herbicide classes can share target binding sites FOP s and DIM s ACCase Inhibitor Classes within Mode of Action Class FOP s DIM s DEN s Example Herbicide Discover NG (clodinafop) Select Max (clethodim) Axial XL (pinoxaden)

12 Cd, clodinafop; Dc, diclofop; Fx, fenoxaprop; Fz, fluazifop; Hx, haloxyfop. Ct, clethodim; Cx, cycloxydim; Sx; sethoxydim; Tk, tralkoxydim. Group A/1 ACCase Target Site Resistance Resistance a Amino acid residue b APPs c CHDs d Wild-type Resistant Weed species Cd Dc Fx Fz Hx Ct Cx Sx Tk References Ile 1781 Leu A. myosuroides S R R R S S R R R Délye et al. 2002b, unpublished data; Moss et al Leu A. fatua ND R ND ND ND ND ND R ND Christoffers et al Leu S. viridis ND R R ND ND ND ND R R Délye et al. 2002c; Heap and Morrison 1996 Leu Lolium sp. S R R ND ND ND R ND ND Délye et al. 2002b; Tal and Rubin 2004 Trp 2027 Cys A. myosuroides R ND R ND R S S ND ND Délye et al. in press Ile 2041 Asn A. myosuroides R ND R ND R S S ND ND Délye et al Asn Lolium sp. R R ND ND R ND S ND ND Délye et al Val Lolium sp S ND ND ND R ND S ND ND Délye et al Asp 2078 Gly A. myosuroides R ND R ND R R R ND ND Délye et al. in press Gly 2096 Ala A. myosuroides R ND R ND R S S ND ND Délye et al. in press

13 Group B/2 Target Site ALS Resistance Chemical Family Residue SUs IMIs PTBs TPs SCTs Ala 122 S HR S S Nd Pro 197 HR S HR HR HR Ala 295 LR LR LR LR Nd Asp 375 HR HR HR HR HR Trp 574 HR HR HR HR HR Ser 653 S HR HR S LR S = Susceptible LR = Low Resistance Level (<10 fold) HR = High Resistance Level (>10 fold) SU = Sulfonylurea IMI = Imidazolinone PTB = Pyrimidinylthiobenzoate TP = Triazolopyrimidine SCT = Sulfonylaminocarbonyltriazolinone

14 Herbicide Metabolism P450s are largely responsible for herbicide metabolism Herbicide P450 Herbicide Site Inactive Products Herbicide P450 Herbicide Site Inactive products

15 Mechanism of Herbicide Resistance Point Mutations Photosystem II Inhibitors D1 protein encoded by the psba gene Val 219 to Ile Ser 264 to Gly or Ala Asn 266 to Thr (Ser 264 to Gly) Figure 1: Common lambsquarters resistant to metribuzin

16 Glyphosate N-[phosphonomethyl]-glycine is an amino acid inhibitor Broad spectrum, post emergence and non-selective Rapidly broken down by soil organisms A zwitterion a neutral molecule with a positive and negative charge Sold as a salt, or rarely as an acid Isopropylene or potassium

17 Shikimate Pathwayconverts carbohydrate precursors from glycolysis into aromatic amino acids Glyphosate blocks enzyme EPSP synthase which prevents formation of Chorismate

18 Enzyme action

19 Types of Glyphosate Resistance Leaf Uptake 1. Epicuticular wax barrier Membrane Transport 2. Reduced cell uptake 3. Vacuole Sequestration 4. Chloroplast exclusion Target Enzyme - EPSPS 5. Active site mutation 6. Gene duplication Sacrificial (herbivory mimic) 7. Hypersensitive (source leaf) 8. Amputation of sinks Chemical Modification 9. Metabolism

20 Leaf Uptake Epicuticular Wax Barrier Ferreira et al. 2008

21 Membrane Transport Reduced cell uptake? Vacuole Sequestration of Glyphosate? Chloroplast exclusion? Horseweed, Feng et al. 2004

22 Genetic Resistance Target Enzyme EPSPS 5. Active site mutation EPSPS P106X substitutio n 6. Gene amplification

23 Enzyme Overexpression or Gene Amplification Glyphosate Resistance in Weeds Target site resistance in the EPSPS gene: horseweed 2 to 3 fold greater level Gene Amplification: Palmer amaranth, kochia Greater amounts of EPSPS due to gene amplification, 5 to 160-fold more copies of EPSPS 20 to 50 fold greater level

24 Pigweed vs. Monsanto Pigweed Winning!

25 Sacrificial (herbivory mimic) 7. Hypersensitive (source leaf) 8. Amputation of sinks

26 Metabolism-based Resistance Chemical Modification 9. Metabolism Not reported in weeds! Mechanism of resistance to glyphosate in several crop species.

27 The Problem with Prepackaged Products Need to know active ingredients, not products, to manage herbicide resistance. A single active ingredient may be working on a given weed species (particularly true for mayweed).

28

29 Factors indicating possible herbicide resistance: The level of weed control of other susceptible species The presence of alive plants adjacent to dead plants Past experience Herbicide history Occurrence of resistance in the vicinity

30 Identifying Resistant Weeds Field patterns were Herbicide Resistance is not suspected: Multiple weed species are present Uniform injury response of weed species from herbicide Pattern of weeds not controlled is correlated with herbicide application

31

32 Preventing Herbicide Resistance Any management action that reduces the selection pressure for resistance will reduce the rate of resistance evolution Rotation Manipulation of planting time Crop competitiveness Cultivation techniques Short herbicide persistence Herbicides with different mode of action Using two herbicides with different modes of action with activity on the same weed

33 Risk of Resistance on a Per Species Basis Management Option: Low Moderate High Herbicide mix or rotation in cropping system Weed control in cropping system > 2 modes of action Cultural, mechanical, and chemical 2 modes of action 1 modes of action Cultural and chemical Chemical alone Use of same mode of Once More than once Many times action per season Cropping system Full rotation Limited rotation No rotation Resistance status to Unknown Limited Common mode of action Weed infestation Low Moderate High Control in last 3 years Good Declining Poor Moss 1998

34 Cost of Herbicide Resistance Knowledge of the kind of resistance enables employment of older herbicides with some assurance of success. Failure to manage resistance ultimately costs money. Prioritize weeds by risk of herbicide resistance development.

35 WSU Resistance Testing Sample Submission Plant seed or Leaf Material? Testing Leaf Material = Genetic Test Seed = Grow Out and Spray Time Frame ~7 days for ACCase, ALS, and PSII No target site resistance = seed request ~6 weeks, more if space is limited Reports will include data and interpretation!

36 Submission Form

37

38 Information on Resistance Information on the distribution of herbicide resistance in this presentation from Other sites with information on herbicide resistance can be found at: Herbicide Resistance Action Committee: Weed Science Society of America has some great recorded modules: