Climate-Resilient Rice Varietal Development and Targeted Deployment in Asia and Africa

Fluctuating climatic patterns in recent years resulted in unprecedented floods, drought, and salinity, insects and disease outbreaks especially making rice bowls of Asia and Africa highly vulnerable. Climate resilient rice varieties will be required that possess multiple abiotic and biotic stresses tolerances without compromising on grain yield and quality. We developed 195 elite cultivars for testing, released 12 varieties and nominated 42 promising multiple abiotic and biotic stress tolerant materials across Asia and Africa within a short span of 6-years adopting an innovative genomics assisted breeding strategy. Introgression breeding and designed QTL pyramiding (DQP) was employed for developing varieties with multiple abiotic and biotic stress tolerance without compromising on grain yield and quality. BC₁F₂populations derived from Huanghuazhan(HHZ), WTR1, TME80518 (recipient parents) and 16 donors at IRRI were screened simultaneously for three rounds for different abiotic (Drought, salinity, submergence and low fertilizer input conditions) and biotic stresses (blast, BLB, Tungro) and normal irrigated condition that resulted in identification of 1333 (HHZ-ILs) + 2232 (WTR1-ILs) + 1408 (TME80518-ILs) trait specific introgression lines (ILs) superior over tolerant checks. QTLs governing complex traits (drought, salinity, cold) were identified by genome sequencing 495 ILs in HHZ background and tGBS for 575 ILs in WTR1 background. GSR IR1-8-S6-S3-Y2 and GSR IR1-12-D10-S1-D1 highlights the strength of this innovative breeding strategy. In WTR1 based ILs we raised the genetic yield potential and demonstrated a yield advantage of 20% over the best yielding inbred check NSICRc238 across seasons over 5 locations in MET0 trials. We developed 3-yield barrier breaking and multiple stress tolerant materials (GSR IR2-8-Y14-SU3-R2, GSR IR2-5-L10-Y1-Y2, and GSR IR2-1-R5-N1-Y3) for the first time and ready to be deployed. These materials gave an average of 5.9% and 18.3% higher yield over the best hybrid check Meztizo 6 and NSIC Rc38 respectively. Climate resilient materials in HHZ and IR64 were deployed over 1mha in Asia and East & South Africa. In India, 13 cultivars were nominated into Coordinated trials and initial on-farm experimental testing with key rice farmers showed encouraging results. Cultivars were also selected with lower GT in order save on fossil fuel, as it saves 3-4 minutes of cooking time. These resilient cultivars with customized grain quality matching the market requirements are also nutritionally good e.g. IR83140-B-11-B with 11% protein. Success may be attributed to an innovative introgression breeding effort combined with appropriate cross-tolerance screening and selection techniques that tapped the hidden genetic diversity from a large number of donors into an adaptable varietal backgrounds like HHZ, WTR1 and TME80518. Designed QTL pyramiding of ILs across different donors by utilizing the whole genome sequence data may further enhance the grain yield and resilience of these cultivars.