SUAKOKO, Liberia - The International Atomic Energy Agency (IAEA) introduces new techniques in mutation by speed breeding, to researchers and plant breeders at the Central Agricultural Research Institute (CARI), to enhance cereal crop improvement in Liberia.

The IAEA training on crop mutation technically exposed researchers and plant breeders at a time when the global community is witnessing far-reaching successes combined with intermediary outcomes from field research activities associated with other available international advanced training opportunities. 

The IAEA facilitator defines mutation by speed breeding techniques (Mbys) as an innovative approach combining mutation breeding and speed breeding. The process involves inducing genetic mutations using physical or chemical agents to create genetic diversity. This method has been used to develop new crop varieties with desirable traits, such as disease resistance, improved yield, and stress tolerance. 

Speed breeding accelerates the plant breeding process by optimizing environmental conditions (light, temperature, etc.) to shorten the generation time of crops. This allows for multiple generations per year, significantly speeding up the development of new varieties.

By integrating mutation breeding with speed breeding, researchers can rapidly generate and select beneficial mutations in cereal crops. This combined approach enhances the efficiency of developing new varieties with improved traits, addressing the global food security challenge.

Molecular Breeding

Presenting on the topic: “Basic aspects of molecular breeding in crop mutation breeding,” Dr. Paul Kofi Ayirebi Dartey, facilitator, says the reason researchers breed is to know how rice differs in many agronomic attributes. This includes yield, maturity period, height, panicle number, and type-compact/open. Panicle branching, seeds per panicle, seed height, weight, culm strength or tendency to lodge, must be considered. 

According to the facilitator, scientists breed to identify culm strength and susceptibility to lodging, to know that rice varieties differ in culm strength, and in many milling attributes in grain length, width, shape, milling yield, and head rice.

Professor Dartey also states that rice panicle and seed characteristics differ and can be consumer specific: considering panicle shape, panicle branching, and seed per panicle. “Varieties also differ in the physical appearance of paddy and milled rice, including many sensory attributes such as cooking time, volume expansion, taste, texture, aroma, and the price consumers are willing to offer.”

The training which brought together participants from the Liberia Agricultural Commodities Regulatory Agency (LACRA), Ministry of Agriculture (MoA), and CARI, covered topics including “genotypic selection of mutant plant population and mutant lines; integration of genomic selection to accelerate mutation breeding for rapid delivery of mutant varieties; data collection, analysis, and interpretation; developing genetically stable lines and varieties tolerant to biotic and abiotic stresses using genomics to contribute to food security, among others.

Plant breeders are researchers that develop mutant populations, followed by their characterization, offer a significant opportunity to isolate genotypes and genes with desired traits of interest. They deal with segregating populations that are not genetically uniform when they are selecting; higher value is preferred in quantity and quality.

Additionally, the lead researcher informs participants that rice varieties differ in many adaptive attributes such as adaptation to ecologies such as upland, rain-fed lowland, and irrigated; adaptation to diverse physical abiotic conditions, including floods; adaptation to diverse biotic conditions or blast, and adaptation to diverse soil conditions including salinity, and iron toxicity.

To generate experimental designs, the facilitator introduces two new tools, CropStat and GenStat, to plant breeders and researchers in the collection, analysis, and interpretation of field data. 

Also presenting on the basic aspects of molecular techniques in crop mutation breeding, Niaba Teme, PhD, the second facilitator from IAEA discusses mutation breeding in crop and mutation detection, among others. 

According to Dr. Teme, also a lead researcher, mutations result from alterations in DNA in the cell replication division process; mutation breeding, also known as variation breeding, is a method that is sped up by physical, chemical, and biological means to induce spontaneous genetic variation for new crop varieties.

“Plant breeding necessitates genetic variety, multiple mutant alleles in many cases, in the functional investigation of the targeted gene, and improves only when a breeder has access to enough variation for a particular trait,” Dr. Teme states. 

Mutant, in biology, and especially in genetics, is an organism or a new genetic character arising or resulting from an instance of mutation.  It is a change in a DNA base pair sequence due to various environmental factors, or mistakes during DNA replication. A mutation is a permanent and heritable change in genetic material, which can result in altered protein function and phenotypic changes.

Spontaneous Mutation

The second facilitator defines spontaneous mutation as one that develops naturally rather than as a result of human involvement. “It happens at random, causes difficult to pinpoint.”

Induced Mutation

Following that, he says induced mutation occurs when a gene comes into contact with mutagens or other environmental factors. Induced mutations are caused by physical irradiation (gamma rays, X-rays, ion beams, etc.) or chemical mutagens. Researchers frequently use high dosages of chemical mutagens or subject experimental organisms to ionizing radiation to increase the frequencies of mutation. 

The senior researcher from the IAEA outlines that the common consideration in the induction of mutation detection includes a perfect understanding of the genetic makeup of traits to be improved, one dene versus polygenic genes (less chance versus one gene).

The determination of the material, according to him, is to be used for the propagation before treatment, i.e. gametes, seeds for sexually propagated crops, and stem cuttings, buds, nodal segments, or twigs for asexually propagated ones.

The advantages of molecular techniques in crop mutation breeding consider that direct mutation are possible or limited breeding effort is required. It is a cheap and rapid method of developing new varieties. It is also the simple, quickest way when a new character is to be induced.

The disadvantage, he adds, most mutants are of no use to breeding even if a large number of mutants can be produced. Also, mutants can have strong negative phenotypic effects on other traits.