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%.

Solutions to Insecurity Problems in Seed Production of Two-line Hybrid Rice

The insecure problems of seed production have seriously hampered the healthy and sustainable development of two-line hybrid rice.The safety issues on seed production of two-line hybrid rice and current research situation were pointed out in this paper.The three main reasons for unsafety in seed production of twoline hybrid rice were unsuitable site selection,high critical sterility-inducing temperature and the drift of critical temperature.In this paper,strategies and measures were put forward based on many years of practice.It could minimize the risk in seed production of two-line hybrid rice by selecting dual-purpose genic male sterile line with lower critical sterility-inducing temperature and long lower temperature resistant time.Based on the climate data and climatic demands of the ＂three safe-periods＂ in seed production,a new idea for determining appropriate bases and periods for seed production was proposed by using computer technology,which solved the aimless selection of sites and periods for the seed production of two-line hybrid rice.Besides,we established a system of single plant selection and identification method and original seed propagation with cyclic cold water,which could reduce the generation number of original seed propagation in seed production and avoid the drift of critical sterility-inducing temperature.This paper improved the seed production safety in the three aspects of seed nature,seed source and seed production site.

Analysis of Heterosis, Combining Ability and Heritability of Cadmium Content in Brown Rice of Three-line Indica Hybrid Rice

Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.

Characterization of Reverse Thermo-sensitive Genic Male Sterile Lines in Cold Regions of China

Yannong S, a reverse thermo-sensitive genic male sterile （TGMS） line, is sterile at high temperature and fertile at low temperature. In the present study, the fertility of Yannong S and the japonica reverse TGMS lines derived from it was in- vestigated in Harbin, Heilongjiang from 2013 to 2015. The results showed that Yan- nong S was completely male sterile in July and August （the hottest months of the year in Harbin）, and the seed setting rate of bagged panicles was 0. We also in- ferred that the critical temperature for inducing the sterility of Yannong S was higher than 28 ℃. Most of the japonica reverse TGMS lines derived from Yannong S were completely aborted in July and August, with a seed setting rate of 0. It can be con- cluded that the reverse TGMS lines derived from Yannong S are genetically stable lines that have a long period of sterility in cold regions, so they may be the ideal genetic materials for the development and in-situ seed production of japonica hybrid rice.

Thoughts and Practice on Some Problems about Research and Application of Two-Line Hybrid Rice

The main problems about research and application of two-line hybrid rice were reviewed, including the confusing nomenclature and male sterile lines classification, the unclear characteristics of photoperiod and temperature responses and the unsuitable site selection for male sterile line and hybrid dce seed production. In order to efficiently and accurately use dual-purpose genic male sterile lines, four types, including PTGMS （photo-thermo-sensitive genic male sterile rice）, TGMS （thermo-sensitive genic male sterile rice）, reverse PTGMS and reverse TGMS, were proposed. A new idea for explaining the mechanism of sterility in dual-purpose hybrid rice was proposed. The transition from sterile to fertile was involved in the cooperative regulation of major-effect sterile genes and photoperiod and/or temperature sensitive ones. The minor-effect genes with accumulative effect on sterility were important factors that affected the critical temperature of sterility transfer. In order to make better use of dual-purpose lines, the characterization of responses to photoperiod and temperature of PTGMS should be made and the identification method for the characterization of photoperiod and temperature responses of PTGMS should also be put forward. The optimal ecological site for seed production could be determined according to the historical climate data and the requirements for the meteorological conditions during the different periods of seed production.

Innovation and development of the third-generation hybrid rice technology

The breeding and large-scale application of hybrid rice contribute significantly to the food supply worldwide.Currently,hybrid seed production uses cytoplasmic male sterile(CMS)lines or photoperiod/thermo-sensitive genic male sterile(PTGMS)lines as female parent.Despite huge successes,both systems have intrinsic problems.CMS systems are mainly restricted by the narrow restorer resources that make it difficult to breed superior hybrids,while PTGMS systems are limited by conditional sterility of the male sterile lines that makes the propagation of both PTGMS seeds and hybrid seeds vulnerable to unpredictable climate changes.Recessive nuclear male sterile(NMS)lines insensitive to environmental conditions are widely distributed and are ideal for hybrid rice breeding and production,but the lack of effective ways to propagate the pure NMS lines in a large scale renders it impossible to use them for hybrid rice production.The development of"the third-generation hybrid rice technology"enables efficient propagation of the pure NMS lines in commercial scale.This paper discusses the establishment of"the thirdgeneration hybrid rice technology"and further innovations.This new technology breaks the limitations of CMS and PTGMS systems and will bring a big leap forward in hybrid rice production.

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%.

水稻不育系泰丰A创制及其优良品质性状遗传基础研究

针对杂交稻“高产难优质”的瓶颈问题,基于杂种优势群与优势模式,选择华南地区高配合力、高异交率保持系博B和优质丝苗米亲本米31以及长江流域优质抗病早稻浙9248作为育种亲本进行复合杂交,通过穿梭种植生态加压表型鉴定与室内品质鉴定相结合的方法,育成了粒型细长、整精米率高、食味佳的“三高一优”不育系及其保持系泰丰A/B。截至2023年,用泰丰A配组育成泰丰优208、泰优390、泰优1002和泰优398等优质杂交稻共计92个。其中,80.4%的米质达到国(部)标优质3级以上标准,18个品次获得国家或省级优质稻食味鉴评金奖和银奖,2个品种被农业农村部认定为超级稻,较好解决了杂交稻“高产难优质”的“卡脖子”问题。此外,对控制泰丰A/B重要品质性状的QTLs(基因)进行了分析,发现位于第3、5、6和7号染色体上的gs3、GW5TFB、WxTFB和GW7TFB基因或其所在的染色体区段是泰丰A/B品质表现优异的重要遗传基础。

小麦光温敏核雄性不育系BS366和BS1086杂种一代结实率研究

为了解小麦光温敏核雄性不育系BS366和BS1086的育性恢复状况,评估恢复系人工定向改良对其恢复能力的效果,在不育生态区对以55份定向改良的恢复系和33份非改良恢复系(常规小麦)为父本配制的杂种一代的结实率进行了分析。结果表明,BS366和BS1086杂种一代结实率变化范围为15.42%~140.34%和20.28%~119.07%(国际法),平均结实率分别为73.02%和72.21%,二者差异不显著,说明2份母本的育性恢复能力差异不显著。BS366和BS1086杂种一代结实率主要分布于40%~110%和60%~100%间,BS1086杂种一代结实率分布更为集中。BS366和BS1086与改良父本的杂种一代平均结实率分别为84.45%和78.97%,与非改良父本的杂种一代平均结实率分别为53.97%和60.95%,改良父本的平均恢复力高于非改良父本,表明定向改良有利于提高恢复系的恢复力。BS366和BS1086与相同父本的杂种一代结实率差异在-41.66%~61.93%之间,表明相同父本对不同母本的育性恢复力存在差异。BS366和BS1086与相同改良父本的杂种一代中有61.82%的结实率差异分布于-10%~20%之间,与相同非改良父本的杂种一代中有51.52%的结实率差异在-30%~0%之间,表明同一改良父本对不同母本的育性恢复力差异小于非改良父本。BS366与14份父本、BS1086与7份父本的杂种一代结实率高于对照,其中父本14YH261、14YH551、SD036与2份母本杂种一代的结实率均高于对照,说明具有可用恢复力的父本不仅数量极少,而且对不同母本的恢复力存在较大差异。杂种一代主茎穗的平均结实率极显著大于分蘖穗。因此,建议对不同母本分别开展强恢复力的恢复系筛选,并以中选强恢复系为亲本进行定向改良,有效增加杂种一代结实率达对照水平的组合数量,为获得更多强优势杂交组合奠定基础。

从一道高考题谈利用雄性不育系生产杂交种子

以一道利用雄性不育系生产杂交种子的高考题引发的思考为切入点,阐明利用雄性不育系批量生产杂交种子的技术原理,提出利用转基因技术生产杂交种的技术要点仍是选育不育系、保持系和恢复系并年年留种,为生物学教学提供有价值的参考。

水果萝卜杂交一代新品种‘青脆2号’的选育

青脆2号是以雄性不育系秀252513161A为母本,自交系天716152为父本配制而成的水果型萝卜杂交一代新品种。其植株生长势旺,肉质根顺直、圆柱形,平均根长23.5 cm、横径6.5 cm;外皮绿色,光滑细腻,根痕少;肉质浅绿色,质地脆,味甜;品质优,耐贮藏,维生素C含量258.2 mg/kg,可溶性糖含量5.93%,蛋白质含量1.22%,粗纤维含量0.68%,还含有钙、铜、铁、钾、镁、锰、钠、磷、锌等多种矿物质元素;单根质量约710 g,平均667 m^(2)产量高达5396.5 kg;抗病性强,表现中抗黑腐病、抗霜霉病、抗芜菁花叶病毒病(TuMV)。适宜我国北方地区秋露地和秋延后保护地栽培。

光/温敏核不育系的不育机理及两系杂交稻的发展与展望

本文回顾了中国两系杂交水稻的发展历史;介绍了两系法中光/温敏型核不育系遗传资源的发现和选育;总结了植物中光温敏型雄性不育的遗传学和细胞学机制;并对水稻两系法中光/温敏型雄性不育系的遗传资源优化及育种策略提出了建议。

优质籼型光温敏核不育系荃时S的选育与应用

介绍了荃时S的选育过程、特征特性、配组应用及繁殖技术要点。荃时S是以银312S为母本,与配合力好的优良恢复系YR0822杂交,采用系谱法选育而成的籼型光温敏核不育系,具有育性转换起点温度较低、不育性稳定、异交率高、抗倒伏、米质优等特点,2021年通过安徽省农作物品种审定委员会组织的专家技术鉴定。该不育系与恢复系银泰香占配制的籼型两系杂交水稻品种时两优泰香具有中抗稻瘟病、米质达部标优1级、丰产等特点,并获得2022年(第四届)安徽省优质稻品种食味品质籼稻金奖,2022年通过国家农作物品种审定委员会审定。

以淡绿叶为标记的籼型光—温敏核不育系M2S的选育

以淡绿叶标记基因系ＩＧＭ１９与籼型光－温敏核不育系８９０２５杂交，再用８９０２Ｓ回交１次，通过多代选育获得了带淡绿色叶隐性标记性状，且育性转换特性与８９０２Ｓ明显不同的籼型光－温敏核不育系Ｍ２Ｓ。在杭州（３０°０５’Ｎ）自然条件下，Ｍ２Ｓ具有连续３０ｄ以上的不育期（不育度＞９９．５％），在秋季正常情况下，结实率可达５１．８％。人工气候箱控制条件下，Ｍ２Ｓ在短日适温时结实正常，在长日（１５．０ｈ）与所有处理温度（３０．１℃、２４．１℃和２３．１℃）、高温（３０．１℃）与所有处理日长（１５．０ｈ、１４．０ｈ和１２．５ｈ）的光温组合下均完全不育或高度不育。结实率的方差分析结果表明，其育性转换的温度效应和光周期效应均不显著，仅光温工作效应显著，属典型的光温互作雄性不育系。Ｍ２Ｓ本身较稳定的不育性和带有隐性淡绿色叶的标记性状将有利于在两系法杂交水稻中应用。

12个粳稻新不育系的配合力及利用价值评价

以12个新育成的BT型粳稻不育系和8个恢复系为亲本,采用p×q不完全双列杂交(NCⅡ)设计,对其F1代13个农艺性状的配合力进行了分析。除单株穗数的特殊配合力方差不显著外,所有性状的一般配合力方差和特殊配合力方差均达到极显著水平。所测性状主要受亲本一般配合力的影响,主穗实粒数、结实率、单株产量和收获指数受组合特殊配合力的作用较突出。穗长、穗颈长、结实率和收获指数受不育系的影响较大,其余性状均受恢复系的影响较大。亲本一般配合力和组合特殊配合力是相互独立的。一般配合力和特殊配合力与杂种优势呈极显著正相关。不育系以六盐A、丹阳941A、98G26A、99-9A、香粳8016A和95122A较好,有较大的应用潜力;恢复系以C418、J16、晚161和C76较好。

青麻叶结球白菜雄性不育系的转育

利用核型雄性不育系 3A作为不育源 ,以青麻叶材料黑 2 2 7为目标亲本 ,经过杂交、自交、兄妹交、测交等转育手段 ,将雄性不育基因转育到青麻叶结球白菜上 ,获得了青麻叶类型雄性不育系S10 ,其不育株率和不育度均为 10 0 % ,蜜腺正常 ,结籽正常 ,农艺性状与青麻叶类型结球白菜基本相同。对育成的雄性不育系S10进行了配合力测定 。

携带白化转绿型叶色标记光温敏核不育系玉兔S的选育及其特征特性

以我国主栽的籼型光温敏核不育系培矮 6 4S为起始材料 ,利用 30 0Gy的6 0 Co γ射线辐照干种子 ,经多代选择选育了一个携带白化转绿型叶色标记的新型不育系玉兔S。该不育系苗期性状明显比原亲本培矮 6 4S差 ,但成熟期的主要农艺性状、育性特征、配合力、抗病性及稻米品质均与培矮 6 4S相仿。补偿性生理机制研究表明 ,在分蘖、拔节和开花阶段玉兔S叶绿体内腺苷酸激酶和RuBP羧化酶的活性要比培矮 6 4S高。遗传研究表明 ,白化转绿型突变性状受单隐性基因控制 ,并在幼苗阶段特异性表达。对不育系玉兔S在两系杂交水稻生产中的应用前景作了讨论。

我国三系杂交稻主要不育系的微卫星标记多样性和遗传结构分析

选取均匀分布在水稻12条染色体上的48对SSR引物，对28份我国杂交水稻主要不育系进行了多样性和遗传结构分析。在所分析的48个位点中，多态性位点41个，多态性位点百分率（P）为85．4％；每1个位点平均等位基因数（A）为3．5，变幅2～6个；平均基因多样性指数（HP）和平均多态性信息含量指数（PIC）分别为0．40和0．36。AMOVA分析表明，不育系遗传变异主要存在于各选育时期内，时期间的遗传变异仅占总变异的3．3％，且未达到显著水平。基于模型的遗传结构分析表明，我国三系杂交稻主要不育系多数含有相近血缘，背景单一。

中国大豆雄性不育和杂种优势利用研究进展与问题分析

杂种优势利用是大幅度提高大豆产量的有效措施之一,我国的大豆杂种优势利用研究开始于20世纪80年代中期,经过20多年的研究探索,我国在大豆杂种优势利用研究领域总体上处于国际前列。在世界上率先育成了大豆质核互作"三系",开展了大规模杂种优势测定研究,育成了数个大豆杂交种,对大豆杂交制种技术进行了广泛研究,取得重要进展。然而,杂交大豆的产业化进程仍较缓慢,还存在一系列问题亟待解决。文章总结我国在大豆雄性不育和杂种优势利用研究方面所取得的重要进展,对存在的主要问题进行了分析,并对今后的研究策略提出了建议。