Physiology of Cold Acclimation and Deacclimation of Cool-Season Grasses

Transcription

1 Physiology of Cold Acclimation and Deacclimation of Cool-Season Grasses Michelle DaCosta Stockbridge School of Agriculture University of Massachusetts

2 Photo by A. Maddocks Winter

3 Photo provided by G. Tanner Winter

4 Kreuser and Reicher, 2014 Winter

5 Winter

6 Photo by C. James Extensive renovation efforts

7 Photo by J. Poro Extensive renovation efforts

8 Causes of Winter Injury Low temperature kill Crown hydration Ice encasement (anoxia) Desiccation Winter diseases Photo by J. Poro

9 Grasses can enhance freezing tolerance by undergoing cold acclimation (hardening) 20 C Killing Temp -30 C FALL WINTER SPRING

10 Conditions that Favor Cold Hardening Low non-freezing temperatures, followed by exposure to freezing temperatures Gradual dehydration of leaf/crown tissues

11 Crown Water Content Livingston

12 Ice crystals can form inside of well-hydrated cells when temps drop below 32 F Ice expands, cells rupture

13 Relationship between crown hydration and freezing tolerance Crown Hydration Freezing Tolerance Beard 1973

14 Crown Hydration Potential Low spots, poor drainage Shade Photo by P. Hasak High N fertility

15

16 7 th Hole Long-End Compacted areas also tend to have more poa Photo by A. Maddocks

17 Conditions that Favor Cold Hardening Low non-freezing temperatures (couple of weeks below 45 F), followed by <32 F Gradual dehydration of leaf/crown tissues Accumulation of antifreeze such as sugars and antifreeze proteins

18 Sugars and antifreeze proteins help to lower freezing point & protect cell from dehydration

19 Shade Height of cut Surge growth Photo by L. Golden

20 Conditions that Favor Cold Hardening Low temperatures Dehydration of tissues Sugar accumulation Depends on plant genetics (species/cultivar)

21 Differences in freezing tolerance of coolseason turfgrasses High Tolerance Agrostis stolonifera, A. canina Poa pratensis, P. trivialis Fine fescues Festuca arundinaceae Low Tolerance Poa annua Lolium perenne *Cultivars of the same species vary in freezing tolerance

22 Annual bluegrass vs creeping bentgrass survival Fairway re-sodded with creeping bentgrass previous fall Photo by A. Maddocks

23 bentgrass nursery Poa green

24 Winter injury at UMass Turf Research Facility: Perennial ryegrass

25

26 Photo by S. Ebdon

27 Photo by S. Ebdon

28 Photo by S. Ebdon 100% survival of annual bluegrass

29 Annual bluegrass biotypes vary in freezing tolerance.and anoxia tolerance, and snow mold tolerance

30 Conditions that Favor Cold Hardening Low temperatures Dehydration of tissues Sugar accumulation Depends on plant genetics (species/cultivar) Maintenance of freezing tolerance depends on conditions around the crown (temperature stability, free water)

31 Maintenance of freezing tolerance depends on temperature stability around the crowns Photo by J. Inguagiato

32 Loss of freezing tolerance can be triggered by warming temperatures, freeze-thaw cycles (deacclimation) 20 F Killing temp -30 F FALL WINTER SPRING

33 Temperature conditions January to March 2014

34 Canopy Temperatures Impermeable w/ insulation No Cover (northern VT) F

35 Annual bluegrass growth in mid-january, following warm temperatures and 0.7 rain

36 Potential negative physiological effects due to exposure to warmer winter temperatures 1. Plants start to take up water 2. Protective compounds break down and are re-directed towards growth

37 Without antifreeze compounds, ice crystals form inside of well-hydrated cells Cells burst!

38 Factors that may influence deacclimation Use of covers Thatch levels

39 Research Questions Do annual bluegrass and creeping bentgrass vary in their cold hardening capacity?

40 Cold acclimation capacity varies among species and ecotypes following prolonged exposure at -2 C (28 F) LT 50 ( C) a b c

41 Research Questions Do annual bluegrass and creeping bentgrass vary in their cold hardening capacity? Do annual bluegrass and creeping bentgrass vary in their deacclimation resistance? If so, why? Goal: Gain a better understanding of how to manipulate deacclimation in grasses

42 Comparing Deacclimation Resistance of Annual Bluegrass (AB) and Creeping Bentgrass (CB) Objective: Quantify the effects of different deacclimation conditions on freezing tolerance and growth of AB and CB (L. Hoffman, Ph.D.)

43 Cold Acclimation and Deacclimation Treatments 20 C 2 weeks 4 C 1 day 4 C 5 days 2 C 2 weeks 8 C 1 day 8 C 5 days -2 C 2 weeks 12 C 1 day 12 C 5 days

44 Changes in freezing tolerance (LT 50 ) in response to warming temperatures j ij h LT 50 ( C) c ef g fg d e i b c b a Hoffman et al., C 4 C 1 d 4 C 5 d 8 C 1 d 8 C 5 d 12 C 1 d 12 C 5 d

45 Deacclimation of annual bluegrass and creeping bentgrass: % loss in freezing tolerance % Loss in freezing tolerance (LT 50 ) a b a b a a 4 C 8 C 12 C

46 Deacclimation sensitivity of Annual bluegrass vs Creeping bentgrass AB CB Cold hardened -2 C 4 C 8 C 12 C Deacclimation

47 Summary CB achieved a greater degree of freezing tolerance following acclimation compared to AB Both the increase in temperature and the duration of the warming period affected deacclimation sensitivity Both species exhibited deacclimation sensitivity, but AB exhibited a 2.5-fold greater loss in freezing tolerance at 4 C compared to CB

48 Carbon and Nitrogen Metabolism Responses Associated with Cold Deacclimation Lindsey Hoffman Ph.D. thesis research Xian Guan M.S. thesis research CB AB- Tolerant AB- Sensitive LT 50 = -22 C -19 C -15 C

49 Cold Acclimation and Deacclimation Treatments 20 C 2 weeks 2 C 2 weeks -2 C 2 weeks 8 C 1 to 5 days

50 Materials & Methods Measurements (cold acclimation and deacclimation) Freezing tolerance (LT 50 ) Canopy photosynthesis, respiration, and chlorophyll fluorescence Carbohydrate and amino acid contents of leaves, crowns Soluble proteins, dehydrin expression

51 Photosynthesis Rates µmol m 2 s -1 * * *

52 Respiration Rates * * µmol m 2 s -1

53 High Molecular Weight (HMW) Fructans Hoffman et al., 2014 Environ. Exp. Botany 350 CB AB-T AB-S 300 mg g -1 DW Deacclimation Duration (d)

54 Summary Both AB and CB exhibited deacclimation (loss of freezing tolerance) when exposed to 8 C Increase in carbon metabolism (photosynthesis, respiration) Decrease in storage carbohydrates (HMW fructans) Changes in protein expression (18 KD dehydrin for CB)

55 Summary AB up-regulated carbon metabolism to a greater extent than CB in response to warming events (changes observed as early as 1 d)

56 Current Projects Early hormone changes of leaves and crowns regulating deacclimation (AB, CB) Identification of genes involved in deacclimation (perennial ryegrass) Seed priming techniques to improve germination at low temperatures

57 Establishment following simulated winterkill (cultivars, cover) Low temperature germination traits in Agrostis species/cultivars (5 to 25 C)

58 Number of days to reach 50% germination (Penncross) Days

59 Establishment following simulated winterkill (cultivars, cover) Emergence at 10 C soil temperature Days to achieve 90% cover: Perennial ryegrass 16 d Colonial bentgrass 18 to 21 d Creeping bentgrass 18 to 25 d Velvet bentgrass 23 to 26 d

60 Establishment following simulated winterkill (cultivars, cover) Next steps: Covers and nitrogen treatments Seed priming

61 Acknowledgements Graduate students: Lindsey Hoffman Xian Guan Collaborators: J.S. Ebdon, A. Bertrand, Y. Castonguay, E. Merewitz, S. Krishnan, E. Watkins

62 Thank you!

63 Recovery after winter injury

64 April 6 Photo by M. Buras, Longwood Cricket Club

65 Photo by M. Buras, Longwood Cricket Club

66 Photo by M. Buras, Longwood Cricket Club May 10

67 May 29 Photo by M. Buras, Longwood Cricket Club

68 Recovery!!! Photo courtesy of Mike Buras, Longwood Cricket Club

69 Braeburn C.C Noer/Milorganite Image Collection

70

71 Materials and Methods Freezing Tolerance (LT 50 ) : Controlled freeze tests were conducted in a programmable chamber from 2 C to -30 C Percent survival at each temperature was rated following a 3 wk recovery period LT 50 was determined by fitting % survival to temperature using a four-parameter sigmoid model

72 LT 50 was calculated based on fitting whole plant survival rate to temperature 100 Freezing tolerance (LT 50 ) Survival (%) 50 LT Temperature

73 Dehydrins CB 18 kda AB-T 40 kda AB-S Deacclimation Duration (d) 40 kda

74 Glutamine Synthetase ( 45 kda) CB Chloroplastic Gln Cytoplasmic Gln AB- T AB-S Deacclimation Duration (d)

75 Total Amino Acids (21) Proline Remaining 14 Amino Acids (25%) Serine Glutamine γ-aminobutyric acid Alanine Asparagine Glutamate

76 Total Amino Acids (21) μmol g -1 DW Species/Ecotype CB 40.0 b AB-T 62.6 a AB-S 40.2 b Deacclimation 0 d 56.6 a 0.5 d 51.7 ab 1 d 43.4 bc 3 d 37.7 c 5 d 48.7 abc

77 Abscisic acid (ABA) ng g -1 FW AB CB C 2 C -2 C 8 C 1d 8 C 5d Temperature Treatments

78 Auxin (IAA) ng g -1 FW C 2 C -2 C 8 C 1d 8 C 5d Temperature Treatments AB CB

79