STUDIES ON HYBRID RICE SEED PRODUCTION OF EGYPTIAN CYTOPLASMIC GENETIC MALE STERILE LINE SAKHA 1A / B MULTIPLICATION

Abstract Background Photo-thermo-sensitive genic male sterile (PTGMS) rice (Oryza sativa L.) is usually considered two-line male sterile rice because of its dual-purpose in two-line hybrid rice system: under short days and low temperatures, it is fertile and used for self-propagation, but under long days and high temperatures, it is sterile and used for hybrid seed production. Therefore, photoperiod and temperature conditions are extremely important for the fertility transition of two-line male sterile rice. In recent years, there have been frequent occurrences of abnormally low-temperature (ALT) resulting in failure of two-line hybrid rice seed production. The daily average temperature (DAT) during ALT events is sometimes higher than the critical sterility-inducing temperature (CSIT) of two-line male sterile rice, of which the night temperature is lower than the CSIT. DAT has been traditionally used as the single indicator of pollen fertility transition, but it is unknown why the fertility of two-line male sterile rice in seed production restored fertility under ALT conditions. Results For Hang93S (H93S), a newly released PTGMS line, we hypothesized fertility transition is determined mainly by the cumulative effective low temperature (ELT) and only a certain duration of low temperature is required every day during the fertility-sensitive period. This study simulated ALTs where the DAT was higher than the CSIT while some segments of night temperature were lower than the CSIT. The results showed H93S exhibited a fertility transition to varying degrees. Moreover, fertility was restored under simulated ALT conditions and pollen fertility increased with increasing cumulative ELT, indicating that the fertility transition was affected primarily by the cumulative ELT. Results also indicated that pollen fertility increased as the number of treatment days increased. Conclusions The fertility transition is caused mainly by the cumulative ELT. In two-line male sterile rice breeding, the effects of day length, ALT at night, and continuous response days should be considered together. The present study provides new insight into fertility transition so breeders can more effectively utilize the two-line male sterile rice, H93S, in breeding programs.

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Floral traits and flowering behaviors of Malaysian rice cytoplasmic male sterile and maintainer lines and its relationship with out-crossing performance

Australian Journal of Crop Science ◽

10.21475/ajcs.21.15.02.p1732 ◽

2021 ◽

pp. 180-186

Author(s):

Shahida Hashim ◽

Phebe Ding ◽

Mohd Firdaus Ismail ◽

Asfaliza Ramli

Keyword(s):

Seed Production ◽

Hybrid Rice ◽

Agricultural Research ◽

Floral Traits ◽

Rice Seed ◽

Male Sterile ◽

Floral Trait ◽

Cytoplasmic Male Sterile ◽

Cross Pollination ◽

Parental Lines

Rice is a strictly self-pollinating crop. However, in hybrid rice seed production, an effective male sterility system is used to produce hybrid seed in bulk. In hybrid rice system, the pollen grains of cytoplasmic male sterile (CMS) are sterile and the female organ of the CMS depends on the fertile pollen released by the maintainer or restorer lines via out-crossing or cross-pollination in order to produce seed. Floral trait and flowering behavior of CMS and its corresponding maintainer or restorer lines are essential factors in hybrid rice seed production because they influenced the out-crossing or cross-pollination between parental lines. Two local CMSs and their corresponding maintainer lines were developed through breeding program in Malaysian Agricultural Research and Development Institute (MARDI) namely 0025A/0025B and 0047A/0047B. This study was carried out on floral traits and flowering behavior of these two hybrid line. Present studies have shown that there were variations between the CMS and its maintainer lines whether on floral trait or flowering behavior for both hybrid rice combinations. The results showed that stigma characters for both 0025A and 0047 were superior than their respective maintainers. Therefore, it is expected that the out-crossing rate would be high. Seeding date intervals need to be done on 0025A/0025B during nursery stage because the on-set of flowering between parental lines was significantly different. Panicle of both CMS was also classified as just exserted and partially-exserted and application of exogenous hormones such as gibberellic acid was useful to improve panicle elongation and consequently increase the seed set and yield. Correlation study indicates that the stigma area of both 0025A and 0047A has significant positive correlation with out-crossing rate.

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Effect of different chemicals on traits favouring outcrossing and optimization of GA3 for seed production of cytoplasmic male sterile line in hybrid rice

Seed Science and Technology ◽

10.15258/sst.2004.32.2.17 ◽

2004 ◽

Vol 32 (2) ◽

pp. 473-483 ◽

Cited By ~ 7

Author(s):

P. Jagadeeswari ◽

S.P. Sharma ◽

M. Dadlani

Keyword(s):

Seed Production ◽

Hybrid Rice ◽

Male Sterile ◽

Male Sterile Line ◽

Cytoplasmic Male Sterile

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Detection of QTLs for Outcrossing-Related Traits in CSSL Population Derived from Primitive Japonica Accession Ludao in the Genetic Background of O. sativa spp. Japonica Restorer C-bao Using RSTEP-LRT Method

Agronomy ◽

10.3390/agronomy10010028 ◽

2019 ◽

Vol 10 (1) ◽

pp. 28

Author(s):

Lal Bux ◽

Dalu Li ◽

Muhammad Faheem ◽

Nour Ali ◽

Muzafar Hussain Sirohi ◽

...

Keyword(s):

Seed Production ◽

Hybrid Rice ◽

Oryza Sativa L ◽

Flag Leaf ◽

Leaf Angle ◽

Ratio Test ◽

Phenotypic Variance ◽

Rice Seed ◽

Hybrid Seed Production ◽

Cms Line

The outcrossing traits in rice (Oryza sativa L.) affect the yield of hybrid seed production. Using a cytoplasmic male sterile (CMS) line with good outcrossing traits, such as short flag leaf length (FLL), narrow flag leaf width (FLW), wide flag leaf angle (FLA), and elongated panicle neck length (PNL), for hybrid rice seed production, it is possible to avoid the procedure of cutting flag leaves and make the supplementary pollination feasible by machine. In this study, a japonica restorer C-bao as the receptor parent and a primitive japonica accession Ludao as the donor parent were used to construct a chromosome segment substitution line (CSSL) population. The CSSL population was used to detect quantitative trait loci (QTLs) for the four outcrossing traits using a likelihood ratio test based on the stepwise regression (RSTEP-LRT) method. The CSSL population constructed consisted of 163 lines covering 90.7% of the donor genome. Among the seven QTLs detected in the CSSL population, four QTLs were detected in both years. qFLL-4 explained 6.70% of the two-year-averaged phenotypic variance, and the alleles from Ludao decreased FLL 5.1 cm. qFLA-1.1 and qFLA-1.2 explained 7.85% and 21.29% of the 2-year-averaged phenotypic variance respectively, and the alleles from Ludao increased FLA 17.38° and 31.50°. qPNL-8 explained 8.87% of the 2-year-averaged phenotypic variance, and the alleles from Ludao increased PNL 4.44 cm. These favorable alleles identified could be used to improve the outcrossing traits of parents for hybrid rice seed production in rice.

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