Drought is the most devastating abiotic stress factor worldwide affecting crop production, severely limiting plant growth and development and reducing crop yields. It is projected to worsen with anticipated climate change. Improving drought tolerance in crops to increase the efficiency of water use and enhance agricultural water productivity under rain-fed conditions is a top priority of agricultural policy for most countries. Drought has been found to be one of the major environmental factors limiting both the quantity and quality of rice, maize, sorhgum and wheat production in Africa and South Asia, which are considered to be the region’s most vulnerable to climate change. Both regions have large populations living in poverty with inadequate access to water and productive land. Although rice, maize, sorghum and wheat are grown in arid and semi-arid tropical areas of Africa and South Asia, these crops are frequently affected by drought stress during the growing season, particularly during the flowering to grain filling period.
Improving Resilience to Drought in Rice and Sorghum through Mutation Breeding
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A field with drought resilience rice. (Photo: Dr. Nguyen Thi Hong/Agricultural Genetics Institute (AGI))
CRP Overall Objective: Improving drought resilience of rice and sorghum germplasm through induced mutation and development/adaptation of screening techniques for sustainable food security
Brief description: Improving drought tolerance in food crops to increase the efficiency of water use and to enhance agricultural productivity under rain-fed conditions is a top priority for agriculture policy in most countries. Breeding for hardy, input use-efficient ‘smart crop varieties’ that are drought tolerant and produce larger yields would be part of the solution to abiotic stresses arising in water-scarce regions in developing and underdeveloped countries.
Among the cereal crops, rice and sorghum have contributed substantial part of food requirement for major population worldwide. Rice is a staple crop for 50% of the population, contributing up to 80% of the calorific need. Frequent drought stress causes significant yield, especially during the most vulnerable vegetative and reproductive stages. Reported losses range from 20 to 80% depending upon whether the vegetative or reproductive growth stage is affected. Grain quality and nutritional parameters are also severely affected by drought stress.
Sorghum is widely cultivated in arid and semi-arid regions covering an area of 44 million ha, with production estimates of 62.5 million tonnes. Major sorghum producing countries include Australia, Ethiopia, India, Mexico, Nigeria, Sudan and the USA, contributing about 77% of world production.
Considering the importance of breeding crops under moisture stress conditions, the Joint FAO/ IAEA Centre launched a Coordinated Research Project (CRP) in 2017 to improve grain yields of rice and sorghum under the negative effects foreseen by different climate change scenarios, especially drought stress conditions.
Fourteen principal scientists/breeders from eleven participating countries contributed to this research project and developed screening protocols for assessing drought-responsive varieties using mutation breeding principles. The approaches used included i) morpho-physiological, ii) gene expression markers and iii) physiological and biochemical traits in response to drought.
The project results revealed that the isolation of drought-tolerant rice and sorghum mutants was feasible upon exposure to pre- and post-flowering moisture stress conditions. This was achieved by employing precise phenotyping and physiological selection for drought-responsive traits in addition to yield components used as a criterion for improving drought tolerance in rice and sorghum.
Specific Research Objectives
Specific objectives:
- To develop robust protocols for rapid advancement of generation and efficient screening of mutant populations for drought tolerance,
- To generate drought-tolerant rice and sorghum mutant germplasm,
- To disseminate methods and guidelines to the broader plant breeding and research communities.
Impact:
Brief description of the general impact of the CRP.
- Efficient phenotyping screening protocols have been developed for drought tolerance under rainout shelter/field conditions at seedling, pre/post flowering stages to screen mutant populations and identify drought-tolerant mutants in rice and sorghum. The protocols are optimized and tested for efficient screening of mutant lines for drought tolerance in rice and sorghum that has been specifically adapted for a mutation breeding program. Physiological, biochemical, genetic and molecular protocols were optimized for confirmation of mutants for drought tolerance. Secondary traits were investigated for drought tolerance, measurement of antioxidant enzyme activity at different levels of the stresses. Genetic and molecular confirmation to validate drought tolerance were explored in rice and sorghum, such as transcription analysis for seedling stage of rice, expression profiling of DREBs, TPS and GLY genes in gamma-induced mutant lines, and genetic mapping of selected drought tolerant rice lines by Mutmap analysis. The CRP results will be released as a book for the scientific community to provide assistance to Member States.
- To generate drought-tolerant rice and sorghum mutant germplasm.
All participating countries generated new mutant populations/lines in rice and sorghum and characterized using optimized greenhouse, screen house and field-based phenotyping screening protocols with the physiological, biochemical and molecular techniques developed/adapted under the project. Developed drought-tolerant advanced mutant lines were submitted/will be submitted for release to farmers in Bangladesh, Brazil, India, Indonesia, Mali, Malaysia and Vietnam.
- The excellent sense of integration between mutation breeding and molecular genetics scientists in this CRP developed bi- and multi-lateral collaborations and facilitated sharing of genetic and knowledge resources on different platforms. Many fruitful collaborations produced new techniques/technologies which are disseminated through peer-reviewed publications, national training courses/workshops and capacity building BSc, MSc and PhD programmes. Several publications were made available that included applied methods/techniques under the CRP. Also, a CRP book was prepared with chapters on methods, techniques and protocols that were developed/adapted under the CRP. This book will be published as an IAEA publication soon.
Impact on MSs:
The Coordinated Research Project on improving resilience to drought in rice and sorghum through mutation breeding has resulted in tangible outputs that contribute to the development of effective drought-screening protocols for drought tolerance.
These techniques will be used by plant breeders who need practical screening to process large mutant populations, including segregating populations, advanced generations and germplasm collections of rice and sorghum. In addition to developed technology, identified advanced mutant lines will be released as climate-smart varieties to support sustainable intensification of crop production and food security.
Relevance:
The CRP has enhanced human capacity and improved drought resilience of rice and sorghum through induced mutation and development/adaptation of screening techniques that are expected to impact sustainable food security, particularly in drought-affected countries. It has improved the delivery of knowledge /experience for strengthening resilience to climate change and specifically to drought stress.
General information about Member State participation
Eight research contracts (BGD, BRA, CPR, INS, MLI, PAK, SUD, VIE), four agreement holders (IND (2), JPN, MAL) and two technical contract holders (CPR, IND) were awarded from developing to developed countries and advanced laboratories and research institutes with recognized expertise in the targeted technologies.
For further information about this CRP, please see Improving Resilience to Drought in Rice and Sorghum through Mutation Breeding
