Marker-assisted identification of restorer gene(s) in iso-cytoplasmic restorer lines of WA cytoplasm in rice and assessment of their fertility restoration potential across environments

Abstract

Iso-cytoplasmic restorers possess the same male sterile cytoplasm as the cytoplasmic male sterile (CMS) lines, thereby minimizing the potential cyto-nuclear conflict in the hybrids. Restoration of fertility of the wild abortive CMS is governed by two major genes namely, and. Therefore, assessing the allelic status of these restorer genes in the iso-cytoplasmic restorers using molecular markers will not only help in estimating the efficiency of these genes either alone or in combination, in fertility restoration in the hybrids in different environments, but will also be useful in determining the efficacy of these markers. In the present study, the efficiency of molecular markers in identifying genotypes carrying restorer allele of the gene(s) and restoring male fertility of WA cytoplasm in rice was assessed in a set of 100 iso-cytoplasmic rice restorers using gene linked as well as candidate gene based markers. In order to validate the efficacy of markers in identifying the restorers, a sub-set of selected 25 iso-cytoplasmic rice restorers were crossed with four different cytoplasmic male sterile lines namely, IR 79156A, IR 58025A, Pusa 6A and RTN 12A, and the pollen and spikelet fertility of the Fs were evaluated at three different locations. Marker analysis showed that was the predominant fertility restorer gene in the iso-cytoplasmic restorers and had a synergistic effect on fertility restoration. The efficiency of gene based markers, DRCG-RF4-14 and DRRM-RF3-10 for (87%) and (84%) genes was higher than respective gene-linked SSR markers RM6100 (80%) and RM3873 (82%). It is concluded that the gene based markers can be effectively used in identifying fertility restorer lines obviating the need for making crosses and evaluating the Fs. Though gene based markers are more efficient, there is a need to identify functional polymorphisms which can provide 100% efficiency. Three iso-cytoplasmic restorers namely, PRR 300, PRR 363 and PRR 396 possessing both and genes and good fertility restoration have been identified which could be used further in hybrid rice breeding.

Identification of Suitable Restorers for WA-CMS Lines of Rice (Oryza sativa L.) through Conventional and Molecular Breeding Methods

“…2R (94.3) and IR58025A x CNR 45 (94.28). Similar results involving IR58025A as the female parent were reported earlier byKumar et al (2017). Among the test crosses with IR69897A, thirty fertile reactions were observed with fifteen crosses exhibiting spikelet fertility of 90% and above.The top five best performing crosses in terms of spikelet fertility % included IR69897A x KMR 3 (95.46), IR69897A x CNR 55-3 (94.63), IR69897A x CNR 55-15 (94.48), IR69897A x CNR 93 (94.28) and IR69897A x BR 1356 Sel 2R (94.03).…”

Development of New Restorer Lines Carrying Some Restoring Fertility Genes with Flowering, Yield and Grains Quality Characteristics in Rice (Oryza sativa L.)

“…Iso-cytoplasmic lines are those carrying the same cytoplasm in which interactions between the cytoplasm and the fertility restoring ( Rf ) genes are maintained at a similar level. Iso-cytoplasmic restorer lines derived from wild abortive WA-CMS based rice hybrids with more than 85% spikelet and pollen fertility [ 23 ] have a unique feature, in that they all carry WA cytoplasm [ 24 ]. An effective male sterility system is used to produce hybrid seeds in large quantities in hybrid rice seed production.…”

Molecular mapping of QTLs for yield related traits in recombinant inbred line (RIL) population derived from the popular rice hybrid KRH-2 and their validation through SNP genotyping

“…Moreover, our results also demonstrate a large variation in the pollen fertility among the selected high-yielding RILs. This indicates that during the course of development of RIL population, the probable genetic interaction of fertility restorer genes with modifiers 107 – 110 may have resulted in different genomic backgrounds of RILs (with respect to fertility restoration). Such interactions would have resulted in the development of RILs which may not inherit the complete complement of fertility restorer genes and thus may remain as partial restorers (RIL-2, RIL-3, RIL-5, RIL-7, RIL-10, and RIL-11) as observed in our study.…”