Effects of Light on Tissue Cultures

Cell & Tissue CultureBSc (Hons) Biotechnology

University of Mauritius

Presented By:- Ritesh Bhagea- Rouksaar Buctowar

- Huda Nazeer- Christabelle Cecile- Keshavi Ghoorbin

Date: 20th March 2014

Overview

● Aims and Objectives● Introduction● Materials and Methods● Result● Discussion● Problem with varying light intensity - How varying light

intensity affects tissue cultures● Alternatives / Improvements● Conclusion● References

● Luxmeter: Device to measure light intensity (SI unit: lux, Symbol: lx) per unit area.

Introduction

● Importance of light in tissue culture:

○ Type of light source will affect light intensity.

○ Light intensity affects photosynthesis ability: leaf anatomy, chlorophyll formation & chloroplast differentiation (Aitken-Christie J., et al, 1994).

○ Callus formation & growth: low light works better for carrot callus.

MaterialsLuxmeter

Fluorescent Tubes Incubator

Laminar Flow Hood (covered it with dark cloth)

Tray Aluminium Foil

Newspaper

Measuring light intensity using a luxmeter:

● Experiment carried out in the Biotechnology lab and outside on FoA ground.

● Light meter placed in the middle of the work area.

● Light sensor gripped steadily and flat - pointing towards light source.

● Three readings taken for the same place.

● Lux values converted into Watt - mean and standard deviation calculated.

Note: The range on the luxmeter was changed depending on the environment - outside and inside - to get more exact values of lux.

Methods

Results

Conditions Light Intensity Means (Watt)

A Using one fluorescent tube 0.014 ± 2.84 x 10^-3

B Using two fluorescent tubes 0.043 ± 4.12 x 10^-3

C Using three fluorescent tubes 0.056 ± 7.36 x 10^-3

D Using four fluorescent tubes 0.069 ± 5.24 x 10^-3

E In the incubator 0.000

F In dark laminar airflow 0.000

G In a tray covered with aluminium foil 0.000028 ± 0.019 x 10^-3

H In a tray covered with newspaper 0.00012 ± 0.025 x 10^-3

I Outside in sunlight 0.86389 ± 0.042

Table 1 : Intensity of light from different sources.

How light intensity affects tissue cultures:● More light = increased adaptation of leaves in terms of leaf

anatomy, chlorophyll formation & chloroplast differentiation.● In vitro = low light = lack of grana stacking, thinner leaves,

poorly defined mesophyll with large intercellular spaces, 1 layer of palisade cells only.

● Hence, cultures cannot use light to its maximum, photosynthesis saturates at low light levels.

● Increasing light intensity during culture would increase photosynthesis, given all other conditions required are present (Aitken-Christie J., et al, 1994).

● However, low light intensity, for instance the dark, is beneficial for callus formation in carrot.

Discussion

● Explants are placed in jars that are short and have an opaque/ metallic cap.

● This prevents light from reaching the explant which is carrying out photosynthesis.

● Stressful for the explant when the jars are crammed.

Problems

Figure 1: Jars crammed unto shelf - bad light distribution.

● The lighting system● Use of fluorescent tubes-cool

daylight/white● 5 tubes per shelves

○ Some were flashing (defective ones)

● Different brands: Lamptan, Astra, Tungsram, Osram○ Leads to different quality of

light

Problems

Figure 2: Out of 5, only 3 lamps are working.

● Osram lamps- 36W○ Colour - Daylight○ Luminous flux at 25 °C = 3350 lm○ Color rendering index Ra = ≥ 80○ Color temperature = 2700 K○ Lifespan = 20000 hours

● Lamptan lamps

Problems

Use of LED lights● Precise beam control.● Accelerate plant growth.● Do not generate heat hence do not heat the plants below.● 3 times for efficient than fluorescent lamps ( LED: 20W, Fluorescent:

~58W).● LED are used for about 12 hrs compared to fluorescent light 16hr

per day.● Lifetime: approximately 8 years.

Overall, LED is best for raising the best plants for the least amount of money. Commercial growers can cut their electric bills for plant lighting roughly in half by using colored LED lighting instead of fluorescent lighting because they essentially pay only for the light the plants need.

Improvements

● Plants use red and blue light the most.

● Using LED of Red and Blue colour,

○ Plants get light of required wavelength

○ Money is saved

● Correct ratios must be established for red:blue

Improvements

● Transparent caps- Allowing transparency for maximum light to enter the jars so that the explant can carry out photosynthesis

● Spacing the culture jars- To allow light to pass sideways

● Use of same lighting brands- To avoid variation in quality of light

Improvements

● Source of light affects light intensity.

● Increasing no. of fluorescent tubes increases light intensity.

● Light intensity outside is greatest.

● Aluminium foil is more effective at preventing light from passing through - more opaque.

Conclusion

References

● http://www.hemp-technologies.com/page87/page87.html● http://www.ehow.com/about_5452900_led-vs-fluorescent-lighting.html● http://cipotato.org/genebank/conservation-methods/images/in-vitro-jpg\● http://www.ledinside.com/news/2011/7/illumitex_20110712 ● http://www.osram.com/osram_com/index.jsp● http://www.carnivorousplants.org/howto/SoilsWater/Lighting.LED.php● http://www.rapidtables.com/calc/light/lux-to-watt-calculator.htm● http://upload.wikimedia.

org/wikipedia/commons/0/09/Plant_Tissue_Culture_Lab_-_Atlanta_Botanical_Garden.JPG

Thank you for your attention!