A novel Rf gene controlling fertility restoration of Ogura male sterility by RNA processing of orf138 found in Japanese wild radish and its STS markers

Abstract

To reveal the molecular and genetic mechanism of fertility restoration in Ogura male sterility in Japanese wild radish (Raphanus sativus var. hortensis f. raphanistroides), we investigated fertility restoration of a plant that lacks the dominant type of orf687, a previously identified fertility restorer gene. A total of 100 F2 plants were made from the cross between a male-sterile strain with the Ogura cytoplasm, 'MS-Gensuke', and a Japanese wild radish plant. Segregation of pollen fertility in the F2 plants led us to assume that 2 dominant complementary genes controlled the fertility restoration of the plants. However, the fertility of 27 of 59 male-fertile plants was not completely restored, resulting in a group of plants with partial male fertility. Northern blot analysis of the CMS-associated gene orf138 indicated that one restorer allele (termed Rft) was involved in the processing of orf138 RNA. Rapid amplification of cDNA ends (RACE) and subsequent Northern blot analysis confirmed that the orf138 transcript lost a 5' part of the coding region of the orf138 gene in the restored plants. The accumulation of ORF138 protein was significantly reduced by Rft, but trace amounts of the protein were recognized in both partially male-fertile and male-sterile plants with Rft. The relationship of pollen fertility and segregation of co-dominant sequence tagged site (STS) markers in the F2 generation suggested that the penetrance of Rft was so low that Rft needs suitable conditions to function sufficiently for the complete restoration of fertility.

An insertion–deletion at a pentatricopeptide repeat locus linked to fertility transition to cytoplasmic male sterility in radish (Raphanus sativus L.)

“…We guess that RsRf3-4 could possess new functions involving different molecular mechanisms to repress the radish CMS-inducing gene. Consistent with this, an Rf gene from the wild radish T-14 was suggested to be involved in the processing of orf138 RNA (Yasumoto et al 2009), while the dominant RsRfo gene inhibits the expression of orf138 at the translational level (Brown et al 2003;Desloire et al 2003;Koizuka et al 2003).…”

PPR‐B‐31: a new maintainer allele in the male‐fertility restorer gene of radish (Raphanus sativus) Ogura cytoplasm

“…However, these results may have also indicated limited effectiveness of the segregating restorer. Thus, it is possible that the population 339 × 24/15 contains another restorer gene, derived from the 24/15 line that is probably similar to the previously described Rft gene (Yasumoto et al., ). However, it seems prudent to check whether reduction of the orf138 protein could be observed in the fertile plants of F 2 generation and whether the PPR‐B‐31 gene is expressed.…”

Cytoplasmic male sterility in Brassicaceae crops

“…In Japanese wild radishes, where Rf genes for Ogura CMS are common, the frequency of plants with orf687 is small (Yasumoto et al 2008). Another Rf gene ( Rft ), found in most Japanese wild radishes, regulates orf138 mRNA processing (Yasumoto et al 2009). This finding indicates that Rf genes with different molecular mechanisms have evolved in radish to suppress the expression of orf138 , the causal gene of Ogura CMS.…”