Precision breeding with genomic tools: A decade long journey of molecular breeding in rice

Abstract

Plant breeding helps in recombining and fixation of desirable alleles which enables the development of improved varieties with better productivity. Though classical plant breeding has contributed enormously in achieving genetic gains in different crops including rice, the challenges imposed by resource constraints as well as greater anticipated demand need better tools to meet the expectations. Molecular breeding which uses modern genomic tools integrated with plant breeding offers enormous potential for improvement of crop varieties. The present review focusses on the achievements of ICAR-IARI in molecular breeding in rice wherein as many as eight rice varieties were incorporated with genes governing resistance/tolerance to different traits and released for commercial cultivation in India. The various factors which enabled the successful integration of molecular breeding including development of infrastructure, human resources and the genetic and genomic resources have been discussed in detail. All the examples of translational research are from the marker assisted backcross breeding strategy, which limits the scope for achieving yield gains. In the foregoing discussion, the challenges and the opportunities for implementation of molecular breeding in rice to realize the full potential of these tools in plant breeding are discussed based on the decade long experience, which may be valuable for other crops as well.

Molecular Breeding for Improving Productivity of Oryza sativa L. cv. Pusa 44 under Reproductive Stage Drought Stress through Introgression of a Major QTL, qDTY12.1

“…Among undesirable traits, grain quality is a complex of multiple factors that can be affected when the donor is inferior in grain quality. In practical molecular breeding, stringent phenotypic selection has been recognized as a key criterion for imparting all the desirable qualities such as grain quality [ 21 , 30 ].…”

“…MABB has been established as a successful approach to the introgression of target genes/QTLs, particularly in rice, with high precision, very good success rates, and a short developmental period [ 34 ]. This can be construed from the fact that, within the decade from 2008 to 2018, eight varieties were developed and released by ICAR-IARI using the MABB approach [ 30 ]. Additionally, several other improved lines targeting multiple features are also under development.…”

Recent trends in crop breeding, the varietal induction in seed chain and its impact on food grain production in India

“…Unlike other varieties, the maintenance breeding of MAS-derived varieties involves testing genetic purity of the seeds through gene-based/gene-linked markers for the homozygosity of the target allele(s) for tolerance or stress resistance. This follow-up step is very important not only at the nucleus and breeder seed production levels but also during the certified seed production, for the maintenance of seed quality (Singh et al 2019).…”

Technological Innovations for Improving Cassava Production in Sub-Saharan Africa

“…This has enabled breeders to focus on fewer genotypes at an early stage of the breeding program, saving the breeder time and labor cost ( Blair et al, 2007 ; Okogbenin et al, 2012 ; do Carmo et al, 2015 ). MAS is appropriate for moderate to highly inherited traits that are controlled by a few major genes and not sufficiently predictive for quantitatively inherited traits controlled by many genes at different loci, each contribution to a small effect of the phenotypic expression ( Singh et al, 2019 ). The time and investment required to develop reliable markers have also been a limiting factor for MAS implementation in cassava breeding programs in SSA.…”

“…Development of novel breeding strategies or models that not only capture additive effects, but also account for dominance and epistatic interactions, could contribute to the introgression of the QTLs into desired varieties. Likewise, the model should account for QTL-environment interactions for an effective MAS scheme ( Singh et al, 2019 ). Recent genomic innovations have prompt for the search of new tools for population improvement.…”