Mutation Plant Breeding Using Ultraviolet Light

John Wells

Since 1970, I have worked professionally with a range of ionising radiations and also cytotoxic poisons, including nitrogen mustard. I started out irradiating bacteria and then moved onto human tumours and normal tissues including skin, blood and individual hair follicles. I specialised in beta emitters with different depths of penetration into tissue.  In the late 1990s, up until 2002, I developed an interest, as a hobby, in mutation plant breeding using X-rays. Here are some of the hardy Osteospermums that I produced at that time:

After 20 years, I have returned to plant breeding. Instead of irradiating with X-rays, I am now using low-cost 3w and 20w, 254nm UV-C lamps (pictured below) that also emit ozone-producing far UV at wavelengths less than 200nm. This puts the project into the realm of affordable citizen science, as were my kite aerial photography (60 pages) and aerial thermography projects.

Not all lamps produce ozone as some use doped glass to block the shorter wavelengths. These doped glass lamps are more appropriate for indoor use and I will be using them too including 311nm UV-B and 365nm UV-A lamps.

Unlike previously with X-rays, where seeds were irradiated uniformly before germination, I am considering non-uniform UV irradiation (both in terms of exposure and depth of penetration) at all stages of growth from the dormant seed through to pollen.

The photo below is only to illustrate some irradiation configurations, as the UV lamps should always be fully shielded.

All irradiations are normally done in a secure location outdoors because of the high levels of toxic ozone. A fume hood/cabinet should be used indoors, especially if irradiating with multiple 20w lamps.

Safety is a crucial consideration and appropriate wide UV spectrum goggles should be worn. Even with goggles, best practice should always be to avoid looking at the lamps and to keep skin unexposed. These are not the black UV-A lamps that are used in nightclubs or those used in tanning beds etc. They are hazardous and should not be used around pets or children or adults who are unaware of the risks. Knowledge of the very short range of these wavelengths in tissue should not be allowed to lead to complacency.

Also, I have an interest in digital microscopy using light outside the visible spectrum, where the transmission of light through a specimen can be differentially increased or decreased using near-infrared (NIR) or near-ultraviolet (NUV) light. For safety, modified conventional microscopes should not have a functional eyepiece.

For some background reading see:

Introduction

Mutation Breeding in Ornamentals

Principle and application of plant mutagenesis in crop improvement: a review

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

Wavelength‐dependent DNA Photodamage in a 3‐D Human Skin Model over the far‐UVC and Germicidal‐UVC Wavelength Ranges from 215 to 255 nm

 

Leucanthemum Vulgare

Currently determining appropriate exposure levels for the seed both before and after hydration.

 

 

Kernza®

Currently determining appropriate exposure levels for the seed both before and after hydration. Is the seed size an issue with 254nm UV!? Will I have to use a longer wavelength?

The seeds were provided by Dr Lee DeHaan of the Land Institute in Kansas.