Association Mapping of Fertility Restorer Gene for CMS PET1 in Sunflower

Abstract

The phenomenon of cytoplasmic male sterility (CMS), consisting in the inability to produce functional pollen due to mutations in mitochondrial genome, has been described in more than 150 plant species. With the discovery of nuclear fertility restorer (Rf) genes capable of suppressing the CMS phenotype, it became possible to use the CMS-Rf genetic systems as the basis for practical utilization of heterosis effect in various crops. Seed production of sunflower hybrids all over the world is based on the extensive use of the PET1 CMS combined with the Rf1 gene. At the same time, data on Rf1 localization, sequence, and molecular basis for the CMS PET1 type restoration of fertility remain unknown. Searching for candidate genes of the Rf1 gene has great fundamental and practical value. Therefore, in this study, association mapping of fertility restorer gene for CMS PET1 in sunflower was performed. The genome-wide association study (GWAS) results made it possible to isolate a segment 7.72 Mb in length on chromosome 13, in which 21 candidates for Rf1 fertility restorer gene were identified, including 20 pentatricopeptide repeat (PPR)family genes and one Probable aldehyde dehydrogenase gene. The results will serve as a basis for further study of the genetic nature and molecular mechanisms of pollen fertility restoration in sunflower, as well as for further intensification of sunflower breeding.

Mapping of the New Fertility Restorer Gene Rf-PET2 Close to Rf1 on Linkage Group 13 in Sunflower (Helianthus annuus L.)

“…BLAST of three sequenced AFLP markers mapping close to Rf-PET2 against HanXRQ v1r1 confirmed the localization between ORS1030 and ORS630. This region contains a large cluster of PPR genes [37]. Mutations of one of these PPR genes might have created the Rf-PET2 gene.…”

“…Position of the markers used in mapping of restorer gene Rf-PET2 according to the BLAST against HanXRQ v1r1 [35]. Potential candidate genes in the area are shown according to Goryunov et al [37]. The three PPR genes that showed SNPs significantly associated with fertility restoration by Rf1 are marked in red [36].…”

“…All three genes are based in the 3.9-Mb region between 169,655,088 (ORS1030) and 173,581,392 (OP-H13) [36]. Genome-wide association studies using whole sunflower genome sequences [37][38][39] and data from SNP arrays [40] had also identified the distal region of LG13 for Rf1 but could not tag a specific gene due to the insufficient resolution of the whole genome analyses.…”

The ideas of N.I. Vavilov and current problems of crop genetics

“…Recently, based on GWAS analysis, 21 Rf1 candidate genes were identified in a vast region (7.72 Mb) of chromosome 13. Twenty genes belonged to the PPR family and only one coded for aldehyde dehydrogenase (Goryunov et al, 2019).…”

“…In sorghum hybrid breeding, the A1 CMS type is predominantly used. With the use of hybridological analysis at least two major Rf genes have been identified, Rf1 located on chromosome SDI08 (Klein et al, 2005) and Rf2 located on the SDI02 chromosome region which is syntenic to the Rf1-containing chromosome region of the rice (Oryza sativa L.) genome (Jordan et al, 2010). The dominant and recessive alleles of the Rf1 gene were highly polymorphic (Klein et al, 2005).…”