Conversion of a rice CMS maintainer into a photo- or thermo-sensitive genetic male sterile line

Abstract

A maintainer line of 3-line hybrid rice commonly presents a certain genetic distance to a 2-line restorer line, but in many cases, 2-line restorer lines present defects upon recovery of the object cytoplasmic male sterile (CMS) line of the maintainer line, which impedes the utilization of their heterosis. Here, we report a strategy and an example of converting a maintainer into a photoperiod/temperature-sensitive genic male sterile (P/TGMS) line with an almost identical genetic background, thus maximizing the heterosis. Firstly, through treatment of maintainer line T98B with 60CO-γ irradiation, we identified the TGMS line T98S, which is sterile at higher temperatures and fertile at lower temperatures. Secondly, the T98S line was proven to be identical to T98B with regard to genetic background via an examination of 48 parental polymorphous SSR markers and exhibited excellent blossom traits similar to those of T98B, with an extensive forenoon flowering rate of 75.92% and a high exertion rate of 64.59%. Thirdly, in a combination test, three out of six hybrids from T98S crossed with 2-line restorer lines showed a yield increase of 6.70–15.69% for 2 consecutive years. These results demonstrated that the strategy can generate a new P/TGMS line with strong general combining ability (converted from a maintainer line), thus helping to increase the genetic diversity of male sterile heterotic groups.Electronic supplementary materialThe online version of this article (10.1007/s11032-018-0805-2) contains supplementary material, which is available to authorized users.

The Cds.71 on TMS5 May Act as a Mutation Hotspot to Originate a TGMS Trait in Indica Rice Cultivars

“…Our work herein demonstrated that T98S is genetically a real sibling of T98B ( Figures 3 and 4 , Table 2 ) and another tms5 mutant with a C-to-A transvertion at cds.71 ( Figures 1 and 2 ). Coincidentally, we also reported another TGMS mutant “BM2-23” (also irradiation-induced from T98B) that was found to be allele to T98S ( Tan et al, 2018 ).…”

“…So, in this sense, it was important for us to verify the true identity of the TGMS mutant T98S. Previous works found T98S featured a rapid stability and showed quite similar morphological traits as T98B ( Tan et al, 2018 ). Our work herein demonstrated that T98S is genetically a real sibling of T98B ( Figures 3 and 4 , Table 2 ) and another tms5 mutant with a C-to-A transvertion at cds.71 ( Figures 1 and 2 ).…”

“…The line T98B is an indica maintainer of wild-type CMS line T98A ( Deng et al, 2001 ). The line T98S is a TGMS mutant identified from T98B through 60 Co-γ irradiation ( Tan et al, 2018 ). The two indica TGMS lines, AnnongS-1 (ANS) and Zhu1S (ZhS), were reportedly bred from different sources but are commonly controlled by tms5 ( Zhou et al, 2014 ).…”

“…To support this, additional tms5 mutants from diverse genetic backgrounds were screened. We identified a TGMS mutant named T98S that is a 60 C O -γ irradiation-induced mutant at M 2 from T98B (an elite indica maintainer for three-line hybrid rice in China) ( Tan et al, 2018 ). Observations on morphological specificity revealed that T98S was very similar to T98B in plant shape, yield factors, and flowering habits.…”

“…Observations on morphological specificity revealed that T98S was very similar to T98B in plant shape, yield factors, and flowering habits. Furthermore, T98S was found to be controlled by a recessive nuclear gene, and it presented sterile at 28.0°C and fertile at 22.0°C regardless of the day-length being adjusted to 12.0 h or 13.5 h in the chamber ( Tan et al, 2018 ). Although T98S is quite similar to the TGMS lines AnS and ZhuS in fertility, whether it is controlled by tms5 remains unknown.…”