Guang-Hua He

Prediction of hybrid grain yield performances in Indica Rice (Oryza sativa L.) with effect-increasing loci

One hundred and fifty-one rice hybrids produced in two sets of half-dialell crosses and their parents (13 cytoplasmic male sterile lines and 19 restorers) were used to predict the F1 performances of seven yield traits through the parental genetic distances (GD) based on SSR markers. The positive loci (PL) and effect-increasing loci (IL), which were screened from SSR polymorphic loci by the F1 traits of 32 parents, together with total loci (TL), were utilized to estimate parental GD and the models were found to predict the traits of hybrids derived from different parents, fixed parents, and different environments, respectively. The results were as follows: (1) 550 polymorphic loci were detected from 174 SSR markers: a dendrogram based on these loci could separate all the sterile and restorer lines used in the present study, which indicated that parental genetic diversity of F1 was large; (2) the correlations between F1 traits and parental GDs based on IL ranged from 0.61 to 0.87 with a mean of 0.76, and they were higher than those on TL or on PL; (3) predictions based on IL for F1 traits (except grain weight per plant) derived from different environments were ideal, but worse for F1 traits derived from different parents; and (4) IL was more effective than TL and PL in predicting traits of F1 with fixed parents, and predictions for fixed restorer combinations were more effective than those for fixed sterile line combinations. These results should facilitate molecular prediction for hybrid yield and other traits by means of both elite sterile and restorer lines.

Genetic Analysis and Gene Mapping of a Novel Rolled-Leaf Mutant rl12(t) in Rice

Abstract Leaf is an important organ for photosynthesis. Moderate leaf rolling could facilitate structure improvement of plant population and enhance light-use efficiency, which is important in breeding for ideotype plants. A rolled leaf mutant temporarily named rl12(t) , was obtained from the rice ( Oryza sativa L.) restorer line Jinhui 10 treated with ethyl methyl sulphonate (EMS). In the mutant, the newly developing leaves of the mutant did not roll, the upper 1/3 section of mature leaves was curled, and the older mature leaves were rolled completely. The pigment contents of the mutant increased significantly. The cytoplasmic male sterile (CMS) line Xinong 1A with flat leaves was crossed with the rl12(t) mutant to produce F 1 and F 2 populations. Genetic analysis indicated that the mutant was controlled by a single dominant gene. Gene rl12(t) was finally located on chromosome 10 between SWU-1 and SWU-2 with the genetic distances of 1.5 and 0.2 cM, respectively. Because no genes for rolled leaf trait have been previously located on this chromosome, RL12(t) should be a novel and unique dominant gene for rolled leaf.

Identification and Gene Mapping of a multi-floret spikelet 1 (mfs1) Mutant Associated with Spikelet Development in Rice

Abstract In this study, a rice spikelet mutant, multi-floret spikelet 1 ( mfs1 ), which was derived from ethylmethane sulfonate (EMS)-treated Jinhui 10 ( Oryza sativa L. ssp. indica) exhibited pleiotropic defects in spikelet development. The mfs1 spikelet displayed degenerated the empty glume, elongated the rachilla, the extra lemma-like organ and degraded the palea. Additionally, mfs1 flowers produced varied numbers of inner floral organs. The genetic analysis revealed that the mutational trait was controlled by a single recessive gene. With 401 recessive individuals from the F 2 segregation population, the MFS1 gene was finally mapped on chromosome 5, an approximate 350 kb region. The present study will be useful for cloning and functional analysis of MFS1 , which would facilitate understanding of the molecular mechanism involved in spikelet development in rice.

YGL9, encoding the putative chloroplast signal recognition particle 43 kDa protein in rice, is involved in chloroplast development

The nuclear-encoded light-harvesting chlorophyll a/b-binding proteins (LHCPs) are specifically translocated from the stroma into the thylakoid membrane through the chloroplast signal recognition particle (cpSRP) pathway. The cpSRP is composed of a cpSRP43 protein and a cpSRP54 protein, and it forms a soluble transit complex with LHCP in the chloroplast stroma. Here, we identified the YGL9 gene that is predicted to encode the probable rice cpSRP43 protein from a rice yellow-green leaf mutant. A phylogenetic tree showed that an important conserved protein family, cpSRP43, is present in almost all green photosynthetic organisms such as higher plants and green algae. Sequence analysis showed that YGL9 comprises a chloroplast transit peptide, three chromodomains and four ankyrin repeats, and the chromodomains and ankyrin repeats are probably involved in protein-protein interactions. Subcellular localization showed that YGL9 is localized in the chloroplast. Expression pattern analysis indicated that YGL9 is mainly expressed in green leaf sheaths and leaves. Quantitative real-time PCR analysis showed that the expression levels of genes associated with pigment metabolism, chloroplast development and photosynthesis were distinctly affected in the ygl9 mutant. These results indicated that YGL9 is possibly involved in pigment metabolism, chloroplast development and photosynthesis in rice.

Additive effects and epistasis effects of QTL for plant height and its components using single segment substitution lines (SSSLs) in rice.

Plant height is a typical quantitative trait that is liable to be influenced by genetic backgrounds and environments.As a novel research material,single segment substitution lines and double segment pyramiding lines in rice will make QTL identifica-tion and epistasis analysis more accurate because of diminishing the interference of genetic backgrounds among plants.In this study,Detection of QTLs controlling plant height and its components and analysis of epistasis effects were done with 16 secon-dary single segment substitution lines and 15 double segment pyramiding lines derived from crossing of primary SSSLs by ran-domized blocks design.The main results showed that 11 QTLs were detected and distributed on chromosomes 4,6,and 10,of which three QTLs controlling plant height,one QTL coffering length of the first inernode from the top,two QTLs harboring length of the second internode from the top,two QTLs for length of the third internode from the top and three QTL controlling length of the fourth internode from the top were included.Twenty-three digenic interactions were detected for plant height and its components,of which 7 interactions occurred between two loci both not having main effects on the traits,and 16 interactions each involved one locus having a main effect at the single-locus level and another locus that did not show significant effect at the sin-gle-locus level.The results indicated that both additive effects of QTL and epistasis effects between QTLs were important genetic components.Efficiency of QTLs identification and epistasis effects analysis between QTLs could be improved using secondary single segment substitution lines and double segment pyramiding lines derived from crossing of primary single segment substitu-tion lines.

Analysis of Phenotype and Physiology of Leaf Apex Dead Mutant ( lad ) in Rice and Mapping of Mutant Gene: Analysis of Phenotype and Physiology of Leaf Apex Dead Mutant ( lad ) in Rice and Mapping of Mutant Gene

叶片作为植物的主要光合作用场所，研究其早衰机制对提高作物的经济产量具有非常重要的意义。本研究报道了一个来自EMS诱变优良恢复系缙恢10号的新水稻叶尖早衰突变体 lad (leaf apex dead)，其叶尖在第5片叶抽出前呈正常状态，当第5叶完全抽出之后前5叶的叶尖变黄并最终枯死；随后的叶子在完全抽出后，叶尖也逐渐变黄并枯死。对该突变体的生理生化分析发现，其叶绿素含量、可溶性蛋白含量明显下降，SOD酶活性异常。其株高、叶长、粒数等也都显著降低。经遗传分析，该突变性状受一对隐性单基因控制，利用分子标记将该基因定位于第11染色体SSR标记SWU11-19和SWU11-5之间，遗传距离为13 cM，并且与SSR标记SWU11-25和SWU11-27共分离。本研究结果为该基因的进一步克隆和功能研究奠定了良好基础。

Identification and Gene Mapping of Rice Early Senescent Leaf (e s l 3) Mutant

Leaf early senescence can directly decrease crop photosynthesis, yield and quality. Therefore, the identifications of mutants with early senescence and its gene function play key roles in crop genetic improvement. A mutant with early senescent leaf blades, named as esl3, was identified from an EMS-induced progeny in the restorer line Jinhui 10. The middle-upper leaf in mutation displayed a brown and withered phenotype from seedling stage to maturity. Correspondingly, the chlorophyll content and net photosynthetic rate declined in the abnormal leaves while enhanced in the normal green part of leaves compared with the wild type. Agronomic traits, such as panicle number, panicle length, grains per panicle, 1000-grain weight, plant height and weight of dry matter, were reduced significantly or very significantly except for seed setting rate as compared with those of wild type. Genetic analysis showed the senescence was controlled by a recessive nuclear gene. Using 391 mutation individuals in a F2 generation of Nipponbare/esl3, ESL3 was mapped between SSR marker RM19085 and InDel marker Ind05-2 on the chromosome 5 with physical distance 91 kb including 14 annotated genes. These results provide a foundation for the further gene cloning and functional analysis of ESL3 gene.

Transgenic Rice Lines Harboring McCHIT1 Gene from Balsam Pear ( Momordica charantia L.) and Their Blast Resistance: Transgenic Rice Lines Harboring McCHIT1 Gene from Balsam Pear ( Momordica charantia L.) and Their Blast Resistance

稻瘟病是危害水稻的最严重病害之一，探索利用外源基因提高水稻抗稻瘟病水平对现代育种具有重要意义。本研究从T 2 代起逐代增加抗性选择压，采用苗期人工混合接种和病圃田自然诱发等鉴定方法，对转基因水稻后代进行稻瘟病抗性鉴定和筛选，在T 5 代获得了7个稻瘟病抗性极显著增强的转 McCHIT1 基因水稻稳定株系。通过7个生理群26个生理小种的115个稻瘟病有效单孢菌株苗期抗谱测定，这7个株系的抗病频率为52.2%~61.4%，比受体对照缙恢35 (36.8%)高16个百分点以上，主要增加了对ZE群生理小种的抗性，提高了对ZG群、ZF群和优势种群ZB群生理小种的抗性。C36-2-1、C21-6-2、C21-3-1等3个株系的结实率达80%以上，是丰抗结合较好的转 McCHIT1 基因株系。 McCHIT1 基因具有广谱抗性，将其遗传转化水稻，采用“逐代增加选择压，抗中选抗”的方法，可筛选出稻瘟病抗性优良、抗谱明显拓宽、产量性状较好的转基因稳定株系。

Identification and Molecular Mapping of Stripe Leaf Mutant st ( t ) in Rice ( Oryza sativa L.): Identification and Molecular Mapping of Stripe Leaf Mutant st ( t ) in Rice ( Oryza sativa L.)

A stripe leaf mutant temporarily designated as st(t) was discovered in the progeny of an excellent indica restorer line Jinhui10 seed by treatment of EMS (ethyl methane sulfonate) in Rice Research Institute of Southwest University. The st(t) mutant displayed the variegated leaves at three-leaf stage, the variegation developed the white irregular line stripe from elongating stage to the maturation. Compared with the wild type, the mutant decreased the chlorophyll content and increased the carotenoid content significantly. Cells structure was detected by Transmission Electron Microscopic (TEM), and the results indicated that there was no difference between the wild type and the green parts of the st(t), both of them could develop normal chloroplast; in the white parts of the st(t), cells developed abnormally contained irregular stromal lamellae, aberrant thylakoids and more osmiophilic granules. Genetic analysis suggested that the mutational characters were controlled by one nuclear recessive gene. Xinong 1A was crossed with the st(t) and 1 500 mutants from the F2 population were used for gene mapping. Finally, St(t) gene was mapped between SSR marker RM19745 and RM19762 on the chromosome 6, the genetic distances were 0.07 cM and 0.27 cM respectively and the physical distance was 345 kb according to indica rice 9311. This result provides a foundation of map-based cloning of St(t) gene as well as its molecular marker-assisted breeding.

Additive and Epistasis Effects of Quantitative Trait Loci for Plant Height and Its Components in Single Segment Substitution Lines of Rice

Abstract To detect quantitative trait loci (QTLs) for plant height and its components in rice (Oryza sativa L.) as well as their gene action, 16 secondary single segment substitution lines (SSSLs) and 15 double segment pyramiding lines (DSPLs) with Huajingxian 74 background were used as mapping populations. A total of 11 QTLs were identified on chromosomes 4, 6, and 10, containing 3 for plant height, 1 for the first internode from the top, 2 for length of the second internode from the top, 2 for length of the third internode from the top, and 3 for length of the fourth internode from the top. Furthermore, 23 pairs of digenic interactions were detected for plant height and the other 5 traits. Among them, 7 interactions occurred between 2 loci without obvious effects on the traits, and 16 interactions each involving 1 locus with and another without main effect at the single-locus level. The results suggest that both additive effect of QTL and epistasis effect between QTLs play important roles in the heritance of plant height and its components. Secondary SSSLs and DSPLs derived from crosses of primary SSSLs are favorable in improving efficiencies of QTL identification and epistasis effect analysis.