Improving Blast Resistance of a Thermo-Sensitive Genic Male Sterile Rice Line GD-8S by Molecular Marker-Assisted Selection

The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast, by using backcross breeding and molecular marker-assisted selection. Five elite improved male sterile lines, RGD8S-1, RGD8S-2, RGD8S-3, RGD8S-4 and RGD8S-5, were selected based on the results of molecular marker analysis, spikelet sterility, recovery rate of genetic background and agronomic traits. Thirty-three representative blast isolates collected from Guangdong Province, China were used to inoculate the improved lines and the original line GD-8S artificially. The resistance frequencies of the improved lines ranged from 76.47% to 100%, much higher than that of the original line GD-8S （9.09%）. On the agronomic characters, there were no significant differences between the improved lines and GD-8S except for flag leaf length and panicle number per plant. The improved lines could be used for breeding hybrid rice with high blast resistance.

Marker-Assisted Breeding of Thermo-Sensitive Genic Male Sterile Line 1892S for Disease Resistance and Submergence Tolerance

Rice line 1892S is an elite thermo-sensitive genic male sterile(TGMS)line for two-line hybrid rice production.However,1892S is susceptible to rice blast,bacterial blight and submergence.Here we reported the introduction of blast resistance(R)gene Pi9,bacterial blight R gene Xa21 and submergence tolerance gene Sub1A into 1892S genetic background through backcrossing and marker-assisted selection.The improved TGMS line 31892S and its hybrids conferred disease resistance to rice blast and bacterial blight,and showed submergence tolerance for over 14 d without significant loss of viability.The sterility-fertility conversion of 31892S was similar to that of 1892S.31892S and its derived hybrid rice had similar agronomic traits and grain quality with 1892S and the control hybrid rice,respectively.The newly developed 31892S provided an improved TGMS line for two-line hybrid rice production with disease resistance to rice blast and bacterial blight,and submergence tolerance with no yield penalty or change in grain quality.

Inheritance of the Male Sterility in a New Photo/Thermo-Sensitive Genie Male Sterile Line B06S of Rice

The major male sterile genes in a new photo/thermo-sensitive genie male sterile (PTGMS) line B06S of rice were analyzed by the manipulation of mixture distribution theory. The results indicated that a pair of major male sterile nuclear genes with large effects were responsible for controlling the male sterility of B06S.

Elongation of the Uppermost Internode for Changxuan 3S,a Thermo-Sensitive Genic Male Sterile Rice Line

Changxuan 3S, a thermo-sensitive genic male sterile （TGMS） rice line with eui gene, is derived from the TGMS rice line Pei＇ai 64S by irradiation with 350 Gy of ^60Co γ-ray. To elucidate the uppermost internode elongation of the TGMS line with eui gene, Changxuan 3S and its parent Pei＇ai 64S were used to study the effects of temperature on panicle exsertion. At 24℃, the uppermost internode of Changxuan 3S elongated the fastest from the 4^th day before flowering to 0 day （flowering）, being 2.1-fold as that of Pei＇ai 64S, whereas it elongated slowly during the 12^th day to the 4^th day before flowering and the 1^st to the 3^rd day after flowering. The uppermost internode of Changxuan 3S exserted from the flag leaf sheath at 22℃, 24℃ and 26℃, and the length of elongated uppermost internode increased with the decreasing temperatures. At 28℃, though the panicles of Changxuan 3S were still enclosed in the leaf sheath, the degree of panicle enclosure was significantly lower compared with Pei＇ai 64S. Cytological studies on Changxuan 3S showed that the uppermost internode elongation was attributed to the increase of cell number and cell elongation, and the latter was more significant. Moreover, the numbers of outermost and innermost parenchyma cells and the cell length of the uppermost internode reduced with the increasing temperatures.

Characterizations and identification of the candidate gene of rice thermo-sensitive genic male sterile gene tms5 by mapping

Previous study indicated that the thermo-sensitive genic malesterile(TGMS) gene in rice was regulated by temperature.TGMS rice plays an important role in hybrid rice production,because the application of the TGMS system in two-line breeding is laborsaving,timesaving,simple,inexpensive,efficient,and eliminating the limitations of the cytoplasmic male sterility(CMS) system.'AnnongS' is the first discovered and deeply studied TGMS rice lines in China.'AnnongS-1' and 'Y58S',two derivatives of TGMS line AnnongS,were both controlled by a single recessive gene named tms5,which was genetically mapped on chromosome 2.In this study,three populations('AnnongS-1' × 'Nanjing11','Y58S' × 'Q611',and 'Y58S' × 'Guanghui122') were developed and used for the molecular fine mapping of the tms5 gene.By analyzing recombination events in the sterile individuals using a total of 125 probes covering the tms5 region,the tms5 gene was physically mapped to a 19-kb DNA fragment between two markers 4039-1 and 4039-2,which were located on the BAC clone AP004039.After the construction of the physical map between two markers 4039-1 and 4039-2,a member(ONAC023) of the NAC(NAM-ATAF-CUC-related) gene family was identified as the candidate gene of the tms5 gene.

Mechanism of Sterility and Breeding Strategies for Photoperiod/Thermo-Sensitive Genic Male Sterile Rice

To understand the male sterility mechanism of photoperiod/thermo-sensitive genic male sterile [P（T）GMS] lines in rice, the research progress on genetics of photoperiod and/or temperature sensitive genic male sterility in rice was reviewed. A new idea was proposed to explain the sterility mechanism of P（T）GMS rice. The fertility transition from sterile to fertile is the result of cooperative regulation of major-effect sterile genes with photoperiod and/or temperature sensitive genes, but not the so-called pgms gene in P（T）GMS rice. The minor-effect genes, which exhibit accumulative effect on sterility, are the important factors for the critical temperature of sterility transition. The more minor-effect genes the sterile line holds, the lower the critical temperature of sterility transition is. The critical temperature of sterility transition will be invariable if all the minor-effect genes are homozygous. The strategies for breeding P（T）GMS rice were also proposed. The selective indices of critical photoperiod and temperature for sterility transition should be set according to varietal type and ecological region. Imposing selection pressure is a key technology for breeding P（T）GMS rice with lower critical temperature for sterility, and improving the comprehensive performance of the whole traits and combining ability is vital for breeding P（T）GMS rice lines.

Plant Temperature and Its Simulation Model of Thermo-Sensitive Genic Male Sterile Rice

Plant temperature （Tp） and its relations to the microclimate of rice colony and irrigation water were studied using a thermo-sensitive genic male sterile （TGMS） rice line, Pei＇ai 64S. Significant differences in the daily change of temperature were detected between Tp and air temperature at the height of 150 cm （TA）. From 8：00 to 20：00, Tp was lower than TA, but they were similar during 21：00 to next 7：00. The maximum Tp occurred one hour earlier than the maximum TA, though they both reached the minimum at 6：00. Tp fluctuated less than TA. At the same height, during 6：00-13：00, Tp was higher than air temperature （Ta）, and Tp reached the maximum one hour earlier than Ta. During the rest time on sunny day, Tp was close to or even a little lower than Ta. On overcast day, Tp was higher than Ta in the whole day, and both maximized at the same time. In addition, Tp was regulated by solar radiation, cloudage and wind speed in daytime, and by irrigation water at night. The present study indicated that a TA of 29.6℃ was the critical point, at which Tp was increased or decreased by irrigation water. Tp and the difference between water and air temperatures showed a conic relation. Tp fluctuation was also regulated by the absorption or reflection of solar radiation by leaves during daytime and release of heat energy during nighttime. By analysis on correlation and regression simulation, two models of Tp were established.

Molecular Markers and Candidate Genes for Thermo-Sensitive Genic Male Sterile in Rice

The discovery of thermo-sensitive genic male sterility(TGMS) has led to development of a simple and highly efficient two-line breeding system. In this study, genetic analysis was conducted using three F_2 populations derived from crosses between IR68301 S, an indica TGMS rice line, and IR14632(tropical japonica), Supanburi 91062(indica) and IR67966-188-2-2-1(tropical japonica), respectively.Approximately 1:3 ratio between sterile and normal pollen of F_2 plants from the three populations revealed that TGMS is controlled by a single recessive gene. Bulked segregant analysis using simple sequence repeat(SSR) and insertion-deletion(InDel) markers were used to identify markers linked to the tms gene. The linkage analysis based on the three populations indicated that the tms locus was located on chromosome 2 covering the same area. Using IR68301S × IR14632 F_2 population, the results showed that the tms locus was located between SSR marker RM12676 and InDel marker 2gAP0050058. The genetic distance from the tms gene to these two flanking markers were 1.10 and 0.82 cM, respectively.InDel marker 2gAP004045 located between these two markers showed complete co-segregation with the TGMS phenotype. In addition, InDel marker vf0206114052 showed 2.94 cM linked to the tms gene using F_2 populations of IR68301S × Supanburi 91062. These markers are useful tool for developing new TGMS lines by marker-assisted selection. There were ten genes located between the two flanking markers RM12676 and 2gAP0050058. Using quantitative real-time PCR for expression analysis, 7 of the 10 genes showed expression in panicles, and response to temperatures. These genes could be the candidate gene controlling TGMS in IR68301S.

Characterization and fine mapping of RTMS10, a semi-dominant reverse thermo-sensitive genic male sterile locus in rice

The discovery and application of environment-sensitive genic male sterile(EGMS) rice germplasm provide an easy method for hybrid rice breeding and have made great contributions to hybrid rice production. Typically, the photoperiod-and thermosensitive GMS(P/TGMS) lines utilized in two-line hybrid systems are male sterile under long day or/and high temperature but fertile under short day or/and low temperature conditions. However, Yannong S(Yn S), a reverse TGMS(rTGMS) line, is sterile under low temperature(<29℃) and fertile under high temperature(>29.5℃). Here, we report a genetic study on the rTGMS trait in Yn S. Interestingly, the F1 plants of the cross between Yn S and a cultivar, L422, were male sterile at 22℃ and completely fertile at 27℃. Moreover, the segregation ratio of fertile and sterile individuals in Yn S/L422 F2 populations changed from 1:3.05 to 2.95:1 when the ambient temperature increased, showing that the rTGMS trait exhibits semidominance in Yn S. We further found a locus on chromosome 10, termed RTMS10, which controls the rTGMS trait in Yn S. We then finely mapped RTMS10 to a ~68 kb interval between markers ID13116 and ID1318 by Yn S/L422 BC6 F2 populations. A near iso-genic line(NIL) NL1 from the BC6 F3 generation was developed and the pollen of NL1 became abnormal from the meiosis stage under low temperature. In summary, we identified an rTGMS locus, RTMS10, and provided co-segregated markers, which could help to accelerate molecular breeding of rTGMS lines and better understand the rTGMS trait in rice.

Identification of a Cytoplasmic Male Sterile Line NEA in Brassica napus L.and Its Genetic Studies

Male sterile NEA plants were identified in progenies of the radiated 92P x Aggregate-silique in Brassica napus L. in 1993. Their progeny plants from test crossing and open pollination were 100% male sterile. The double-low male sterile lines JL-4 and JL-18 were bred through successive backcrossing of the double -low variety No.4 and No. 18 in Brassica napus L.to NEA. Restorer lines 6720 and 6722 with significant heterosis in F1 were developed. The results from investigating the restoring-ntaintaining relationship and inheritance of the restorer gene indicated that JL-4 and JL-18 were different from both PolCMS and Shan 2A type, and their restorer gene was controlled by a pair of dominant genie genes.

Development and Application of SCAR Markers for Discriminating Cytoplasmic Male Sterile Lines from Their Cognate Maintainer Lines in Indica Rice

The DNAfragments about 1 600 bp were amplified using random amplified polymorphism DNA （RAPD） primer OPAl2 with the templates of mitochondrial DNA of Zhenshan 97A and Zhenshan 97B, and were sequenced. The nucleotide sequences and lengths of the fragments from Zhenshan 97A and Zhenshan 97B showed no difference. The precise length of the fragment was 1 588 bp. Sequence characterized amplification region （SCAR） primers were then developed to discriminate the cytoplasmic male sterile （CMS） lines and their maintainer lines. A specific 1 588 bp fragment could be amplified with SCAR primers, CHI19F2/CHI19R2 and CHI20F3/CHI23R3, in the mitochondrial DNA of Zhenshan 97A, but not Zhenshan 97B. Furthermore, the specific fragment could be also amplified from the total DNA from green leaf tissues of Zhenshan 97A with SCAR primers, but not Zhenshan 97B. With the corresponding primers, the specific fragment could also be amplified from the total DNA of green leaves of other two CMS lines with wild abortive type cytoplasm （CMS-WA）, namely Zhenpin A and Tianfeng A, but not in their maintainer lines. Moreover, using total DNA as template, each of the four pairs of SCAR primers could also be used to amplify the 1 588 bp fragment in CMS-ID （Indonesia paddy type） line 11-32A but not in 11-32B, and the specific fragment was amplified from the DNA of both F1 and F2 seedlings of Shanyou 63. The results of detecting the genetic purity of a man-made mixture of the seeds of Zhenshan 97A using CHI20F3/CHI23R3 were completely consistent with the phenotypes. Taken together, these results indicated that the specific 1 588 bp-fragment amplified by CHI20F3/CHI23R3 was the unique amplification products of CMS mitochondrial DNA, and could be used to distinguish CMS-WA and CMS-ID lines from their corresponding maintainer lines at the seedling stage.

Differences in Nuclear DNA Between Male-Sterile and Male-Fertile Lines of Sorghum bicolor

Cytoplasmic male sterility(cms)is determined by nuclear-cytoplasmic interactions. Up to now, most studies are focused on the comparison of cytoplasmic DNAs of male-sterile lines and male-fertile lines, and analysis of nuclear DNA has not been documented yet. In order to find out the possible difference in nuclear genome of male-sterile line A1 Tx623 and corresponding male-fertile line Tx623 of sorghum, random amplified polymorphic DNA(RAPD)approach was used to analyze their cytoplasmic and nuclear genomes. Total DNAs of them were amplified at first to screen primers, which were able to generate reproducible bands specific to male-sterile line or male-fertile line. Then the selected primers were used to amplify their mitochon-drial DNA(mtDNA)and chloroplast DNA(cpDNA). The origins of all the polymorphic fragments were analyzed. After ruling out those amplified from cytoplasmic DNA, seventeen polymorphic fragments were determined to be amplified from nuclear DNA. These fragments originated from nuclear DNA indicate that differences in sequence exist between the nuclear DNA of male-sterile line and male-fertile line of sorghum, which do not agree with the traditional standpoint that they have identical nucleus.

Comparisons on Genetic Diversity among the Isonuclear-Alloplasmic Male Sterile Lines and Their Maintainer Lines in Rice

Four sets of rice isonuclear-alloplasmic lines including 16 male sterile lines and their maintainer lines were analyzed by using 91 pairs of SSR primers to study the genetic diversity of nuclear genome and their relative relationships. A total of 169 alleles were detected in the 16 lines, with a frequency of polymorphic loci of 53.85% and an average number of alleles per locus of 1.8, and the average gene diversity was 0.228. Four sets of the isonuclear-alloplasmic male sterile lines shared 146 identical alleles, corresponding to 86.39% of the total alleles; meanwhile, there are 23 different alleles among the tested materials, being 13.61% of the total alleles. On average, 78.70% identical alleles and 21.30% different alleles of the total alleles were detected between the isonuclear-alloplasmic male sterile lines and their maintainer lines. There were 53.85% identical alleles and 46.15% different alleles of the total alleles among the homozygous allonucleus male sterile lines. The fingerprints were established for some male sterile lines and maintainer lines. All the materials tested were divided into three groups at the 0.2 genetic distance based on the cluster analysis. Eight lines of Huanong A and Huayu A （including Huanong B and Huayu B） were in the first group, four lines of Kezhen A （including Kezhen B） in the second group, and four lines of Zhenshan 97A （including Zhenshan 97B） in the third group. For the isonuclear-alloplasmic male sterile lines, the similarity coefficient between Y （Yegong） type and WA （wild abortive） type or between CW （Raoping wild rice） and WA type reached 87-98%.

New Temperature Sensitive Genic Male Sterile Lines with Better Outcrossing Ability for Production of Two-Line Hybrid Rice

An investigation was carried out with three newly developed temperature sensitive genic male sterile （TGMS） lines for their floral traits, seed production potential and outcrossing ability in ten cross combinations. In the TGMS lines, fertile pollens had an average diameter of 0.89 mm while the sterile pollens was with 0.02 mm diameter.TS-29-150GY produced the biggest fertile pollens with 0.92 mm and other two lines produced relatively smaller pollens with 0.91 and 0.85 ram. Pollen fertility during the fertility reversion period was an average of 60.7%. TS-29-150GY had the maximum of 66.9% spikelet fertility whereas other two lines （TNAU18S and TNAU60S） had relatively lower spikelet fertility of 27.8% and 26.7%, respectively. Average of 17.00 g of seed yield was obtained in the TGMS lines during the fertility reversion period. TS-29- 150GY had the highest value of 21.20 g of seed yield while TNAU18S and TNAU60S produced 16.6 g and 13.2 g of seed yield, respectively. The low seed production ability of these three TGMS lines was attributed only to the environmental conditions prevailing during the period. All three TGMS lines had considerable outcrossing potential of 41.2%, 24.6% and 25.0%, respectively. The cross combinations viz. TNAU18S/IET21508 （36 g/plant）, TNAU18S/IET21044 （13 g/plant）, TNAU18S/IET21009 （26.5 g/plant）, TNAU60S/CB-09-106 （26.2 g/plant）, TNAU60S/IET21009 （14 g/plant） and TS29-150-GY/DRR 3306 （39.2 g/plant） showed perfect synchronization with acceptable hybrid seed yield, indicating suitability of TGMS system under Indian condition. Based on the outcrossing related traits viz. panicle exertion, angle of glume opening, stigma length and pollen size, TNAU18S was identified as the best, followed by TS-29-150GY.

Influence of Genetic Drift of Restoring Gene (Rf) on Seed Purity of Yuetai A, a Honglian-Type Cytoplasmic Male Sterile Line in Hybrid Rice

The seed samples of Yuetai A, a Honglian （HL） type cytoplasmic male sterile （CMS） line in hybrid rice were investigated to assess the seed purity and to analyze the cause of off-type plants by imitating the biological contaminant to Yuetai A in Nanjing, Jiangsu Province and Lingshui, Hainan Province during 2004-2006. The seed impurity of Yuetai A mainly resulted from the genetic drift of restoring fertility gene （Rt） after biological contamination but not from its sterility unstability. All of the ten maintainer lines, five restorer lines and three thermo-sensitive genic male sterile lines used in the study could pollinate Yuetai A and Yuetai B to produce F1 plants, directly or indirectly resulting in Rf-gene drifting into Yuetai A and generating ＇iso-cytoplasm restoring-generations＇. Furthermore, high outcrossing rate and similar heading date of Yuetai A with many varieties used in rice production might easily result in the biological contamination. After removing all plants with Rf-gene mixed in Yuetai A and preventing Rf-gene drifting into Yuetai A, the seed purity of Yuetai A and Yuetai B had been raised to 100%.

Genetic Mechanism of Dominant Earliness in Kefeng A,a New Rice Cytoplasmic Male Sterile Line

Kefeng A is an early maturing indica cytoplasmic male sterile （CMS） line of rice. Combinations derived from Kefeng A and late maturing indica restorer lines showed dominant earliness to various extents. To understand the genetic basis of dominant earliness, the genotype of photoperiod-sensitive genes in Kefeng A was analyzed using a complete set of heading time near isogenic lines （NILs） EGO to EG7, ER, LR, T65, T65E^b, T65E^bm, T65m, NIL（Hd1） and NIL（Hd4）. Results indicated that Kefeng A contained two dominant photoperiod-sensitive alleles E1 and Se-1^U on E1 and Se-1 loci, respectively, and the genotype of photoperiod-sensitivity genes for heading time in Kefeng A was E1E1e2e2E3E3Se-1^USe-1UEf-1Ef-1. Based on the detected heading time genotype, in combination with the heading time of Kefeng A and the early maturing phenomenon in its derived F1 hybrids, it is speculated that Kefeng A might carry a dominant inhibitor gene Su-E7 for the dominant photoperiod- sensitive gene E1, and a recessive inhibitor gene i-Se-1 for another dominant photoperiod-sensitive gene Se-1. The reason why F1 hybrids from Kefeng A exhibited early maturing was hereby analyzed and the breeding value of dominant earliness related genes in Kefeng A was discussed.

Analysis on Combining Ability for Characters of Male Sterile Lines in Rapeseed(Brassica napus L.)

The male sterile line is very important in the hybrid breeding program of rapeseed. This study was conducted to evaluate the combining ability of many characters of male sterile lines in Brassica napus L. Ten recessive genetic male sterile （RGMS） lines were used as parents to produce 45 single cross hybrids by using a half diallel cross method. These 45 crosses and their 10 parents were evaluated at Guiyang during 2007-2008. The results showed that both general combining ability （GCA） and specific combiing ability （SCA） effects were important for all characters, but additive gene effects were more predominant than non-additive gene effects. Qianyou 8AB and You 2894AB gave respective highly significant GCA effects of 230.94 and 127.65 kg-hm-2 for seed yield. Lines You 2894AB, QH303-4AB, You 157AB and You 2341AB gave highly significant GCA effects for oil content of 0.99, 1.62, 1.20 and 1.53%, respectively. The crosses among lines Qianyou 3AxQianyou 8B, Qianyou 8AxYou 2894B, You 2894AxQianyou 6B, Qianyou 8AxQH303-4B and Qianyou 8Ax Qianyou 6B gave high SCA effects of 616.29, 398.71,356.48, 394.24 and 303.79 kg hm-2 for seed yield, respectively. All these crosses also gave high seed yield indicating that these crosses could be used in the breeding program.

Verification of Glyphosate Resistance, Lepidopteran Resistance and Wide Compatibility of Male Sterile Line E1C4008S in Rice

Weeds and insect pests are two important biotic stresses resulting in yield loss in rice, and wide compatibility is the essential characteristic of breeding inter-subspecific hybrid rice. This study focused on glyphosate resistance, lepidopteran resistance and wide compatibility as well as identification of molecular and some agronomic characteristics of transgenic male sterile line E1 C4008 S. The results indicated that glyphosate resistance gene Epsps^# and lepidopteran resistance gene Cry1 ca^# were transferred into japonica wide compatibility male sterile line 4008 S by Agrobacterium-mediated method, and four independent transformation events named E1 C4008 S-1, E1 C4008 S-2, E1 C4008 S-3 and E1 C4008 S-4 were obtained, in which E1 C4008 S-3 and E1 C4008 S-4 were of single copy insertion. The EPSPS protein contents of E1 C4008 S-3 and E1 C4008 S-4 in different organs were significantly different both in descending order of leaf > stem > root, and ranged from 300.58 to 1410.69 μg/g at the tillering stage. The glyphosate tolerable concentration(dosage) of E1 C4008 S-3 and E1 C4008 S-4 reached at least 16 g/L(54.42 kg/hm^2), and the seeds of E1 C4008 S-4 can germinate normally on the medium containing 1 g/L glyphosate. The CRY1 C protein contents of E1 C4008 S-3 and E1 C4008 S-4 in different organs were significantly different both in descending order of leaf > stem > root, and ranged from 0.62 to 2.43 μg/g at the tillering stage. The larvae mortalities of rice leaf rollers fed on leaves of E1 C4008 S-3 and E1 C4008 S-4 for 5 d were 95.35% and 97.77%, respectively, while the average mortalities of silkworms fed with protein extracts from leaves of E1 C4008 S-3 and E1 C4008 S-4 reached 94.55% and 83.64%, respectively. The results suggested that wide compatibility and evaluated agronomic traits of E1 C4008 S-4 were not significantly changed by insertion of the exogenous genes. Overall, a novel male sterile germplasm with glyphosate resistance, lepidopteran resistance and wide compatibility was verified to be developed in rice.

Introgression of Gene for Non-Pollen Type Thermo-Sensitive Genic Male Sterility to Thai Rice Cultivars

For the two-line hybrid rice system, pol en sterility is regulated by recessive gene that responds to temperature. The recessive gene controlling thermo-sensitive genetic male sterility （TGMS） is expressed when the plants are grown in conditions with higher or lower critical temperatures. To transfer tgms gene（s） control ing TGMS to Thai rice cultivars by backcross breeding method, a male sterile line was used as a donor parent while Thai rice cultivars ChaiNat 1, PathumThani 1, and SuphanBuri 1 were used as recurrent parents. The BC2F2 lines were developed from backcrossing and selfing. Moreover, the simple sequence repeat （SSR） markers were developed for identifying tgms gene and the linked marker was used for assisting selection in backcrossing. The identification lines were confirmed by pol en observation. The results showed the success of introgression of the tgms gene into Thai rice cultivars. These lines will be tested for combining ability and used as female parent in hybrid rice production in Thailand.

Maxie A- a novel cytoplasm male sterile line

The pollen abortion of Maxie A and Zhengshan97 A belong to stainless type with Ksolu-tion.The maiority of Maxie A abortive Pollenstook cireular shape and few was staining abortion