Digital Kenyon: Research, Scholarship, and Creative Exchange
Kenyon Summer Science Scholars Program Summer Student Research Scholarship
Summer 2015 Role of Abaxial Trichome Density in Regulating Optical Properties and Photosynthesis in Glycine max Jacob Scharfetter
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Recommended Citation Scharfetter, Jacob, "Role of Abaxial Trichome Density in Regulating Optical Properties and Photosynthesis in Glycine max" (2015). Kenyon Summer Science Scholars Program. Paper 274. https://digital.kenyon.edu/summerscienceprogram/274
This Poster is brought to you for free and open access by the Summer Student Research Scholarship at Digital Kenyon: Research, Scholarship, and Creative Exchange. It has been accepted for inclusion in Kenyon Summer Science Scholars Program by an authorized administrator of Digital Kenyon: Research, Scholarship, and Creative Exchange. For more information, please contact [email protected]. Role of Abaxial Trichome Density in Regulating Optical Properties and Photosynthesis in Glycine max
Jacob B. Scharfetter’17, Alexa Korsberg’17, & Christopher Bickford: Kenyon College
Abstract Results
20 Trichomes, leaf hair structures, serve plants in a variety ways such as 20 10 Abaxial Trichomes herbivory defense, transmittance of radiation or regulation of Removed 18 Abaxial Trichomes Removed temperature. Functions and roles of trichomes are known but the Mejiro 18 9 (Dense Unmanipulated extent of that function based upon trichome morphology and density Pubescence) 16
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Both Trichome is not, especially in abaxial (underside) trichomes. 8 Unmanipulated Surfaces Removed Clark 14 14 Three isolines of Glycine max possessing non-glandular, non-gas (Moderate Isoline exchanging abaxial trichomes were utilized. Two manipulations were 7 Pubescence) 12 Both Trichome Surfaces 12 conducted; in the first manipulation both the abaxial and adaxial Removed 6 trichomes were removed and in the second just the abaxial trichomes 10 10 were removed. Abaxial leaf hair density was manipulated using a 5
novel approach via mechanically removing trichomes. Optical 8 8 Transmittance Clark for Transmittance properties, gas-exchange, and chlorophyll extraction data were then 4
6 6 Trichome Density (mm2) Trichome
collected on control and manipulated leaves. Leaf Leaf Transmittance for Mejiro Isoline Mejiro for Transmittance Leaf
Trichome manipulations reduced density counts 50 to 75% below 3 4 4 control leaf levels (p<0.001). Photosynthetic rates differed between the control and the two manipulated groups. Leaves with abaxial 2 2 2 trichomes removed exhibited a 14.6% reduction in photosynthesis and 0 0
leaves with abaxial and axial trichomes removed showed a 21.4% 1
500 505 510 515 520 525 530 535 540 545 550 555 560 565 570 575 580 585 590 595 600 605 610 615 620 625 630 635 640 645 650
500 506 512 518 524 530 536 542 548 554 560 566 572 578 584 590 596 602 608 614 620 626 632 638 644 650 reduction in photosynthesis when compared to control leaves. Leaf Wavelength (nm) Wavelength (nm) 0 transmittance in manipulated leaves was observed to be lower than Abaxial Trichomes Both Trichome Surfaces Unmanipulated Figure 2: Proportion of light transmitted in the Figure 3: Proportion of light transmitted in the control leaves in the 550-650 nm portion of the electromagnetic Removed Removed moderately pubescent Clark isoline. Data was compared pubescent Mejiro isoline. Error bars=SEM (Paired Manipulation spectrum (p<0.05). We had hypothesized that transmittance would be to the unmanipulated. Error bars=SEM (Paired t-test for t-test for both trichome surfaces removed, higher in shaved leaves compared to unshaved leaves. Figure 1: Trichome Density after removal, for the abaxial trichome removal , p=0.0366) p=0.0433) pubescent isolines.The glabrous isoline (not depicted) exhibited little to no presence of tirchomes. Error Overall, these differences indicate that abaxial trichome density plays bars=SEM (p≈0.001,p≈0.001) a role in leaf carbon uptake and photon transmittance. 18 Results & Discussion 16 Figure 4: Mean Photosynthesis • Differences in transmittance between the unmanipulated and * * rate by trichome manipulation. manipulated groups were present in both pubescent isolines for the 14 Introduction Asterisk indicates signifance 550-650 nm wavelength. from the unmanipulated group.
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- s
2 12 All three isolines are - • Trichomes density is a highly diverse characteristic. Even within incorporated. Error bars=SEM • Clark Isoline: When compared to the unmanipulated group (Figure
some species plants trichome densities can highly pubescent to mol m (ANOVA, F=9.43, μ 2), abaxial trichomes removed (p=0.0366) and both trichome 10 Df =2, Df = 219, glabrous (no trichomes). manipulation error surfaces removed (p=0.0629) respectively. p≈0.001) 8 • Abaxial refers to the lower surface and adaxial refers to the upper • Mejiro Isoline: When Compared to the unmanipulated group
surface of the leaf. 6 (Figure 3), abaxial trichomes removed (p=0.1033). Both trichome Photosynthetic Rate ( Rate Photosynthetic surfaces removed (p=0.0433) • Isolines of the same plant species that vary based upon trichome 4 density provide an excellent tool to quantify the role abaxial • One hypothesis as an explanation for these differences in trichomes in leaf properties. 2 transmittance is that the shaving process induced a chemical response of dense photo-capturing compounds to make up for • G. max (soybeans) were chosen due to the vast array of trichome 0 boundary layer loss. Manipulation density in morphology in isolines developed. • Photosynthesis was lower in manipulated treatments vs Abaxial Shaved Both Surfaces Shaved Unshaven • The purpose of this study was to better understand the importance unmanipulated (p=0.001). Manipulated groups exhibited similar of abaxial trichomes and ultimately provide insight into whether photosynthetic rates. that trichome abaxial densities should (or not) be a characteristic for species grown agriculturally. • Trichome density varied between isolines in unmanipulated treatments (ANOVA, p=0.001), however in manipulated treatments it did not vary (p=0.657). Methods Trichome Removal • Optical transmittance of abaxial trichomes appears to be a density • Three isolines of G. max were grown under all under similar growth chamber conditions; T145 (glabrous pubescence) Clark dependent property (moderate pubescence) and Mejiro (dense pubescence) isolines were utilized. 1 2 • Our findings may suggest that abaxial trichomes play a larger role than adaxial trichomes for the plant’s respective photosynthetic • Leaf optical properties (reflectance, transmittance, and rate. absorptance) were assessed on both sides of the leaf using a spectrometer clip coupled with an integrating sphere (Jaz-TR- • Understanding the trichome density interaction with plant optics Spectroclip, Ocean Optics) and photosynthetic rate, provides a basis for trichome density genetic manipulation, to ultimately increase crop yields under a • Photosynthetic measurements were taken measuring the flux of wider variety of conditions.
CO2 (LI-6400XT, Li-Cor Biosciences)
Figure 5: 1) Adaxial trichomes removed
• Leaf images for trichome density counts, were taken via light 2) Adaxial control leaflet, 3) Abaxial trichomes removed, & 4) Abaxial control microscopy and using imaging software. 3 4 leaflet. Acknowledgements
• Trichome removal was conducted mechanically, using a paired I would like to thank Alexa Korsberg for being an outstanding approach via coarse cutting with a standard razor blade, followed partner in this project. Also I would like to Christopher Bickford by close shaving with optical knives (1.2-1.8 mm). for his substantial guidance throughout the entire project. Lastly I would like to thank Kenyon College and the Kenyon Biology • Damage to the leaf was assessed via pictures and looking for *All leaflets are from the Mejiro (highly department for the use of their facilities, funding, and resources. cuticular shaving damage under a light microscope. pubescent isoline.)