Genetic Analysis of the First Female Flower Node and the First Male Flower Node in Bitter Gourd

Exploring genetic mechanism of the first female flower node and the first male flower node in bitter gourd has practical significance for formulating breeding strategy. In this article, a cross was made between CN19-1 and Thai4-6, and the F2segregation population was also constructed through F1selfing. The genetic characteristics of the first female flower node and the first male flower node were analyzed by adopting the major gene plus polygene mixed genetic model. The data analysis results showed that the first female flower node and the first male flower node were continuous distribution in the F2segregation population. E-2 model was the most suitable model for the genetic analysis of the first female flower node and the first male flower node. The additive effect values of the 2 pairs of major genes controlling the first female flower node were 2.722 and 1.862 8 respectively, the dominant effect values were-2.721 6 and-0.171 8, respectively. The additive effect value of polygene was-0.839 2, and the dominant effect value of polygene was 2.225 4. The heritability of major genes and polygene were 83.73% and 1.54%, respectively. The additive effect values of the 2 pairs of major genes controlling the first male flower node were 17.746 9 and 3.972, respectively, the dominant effect values were 5.191 6 and-3.972, respectively. The additive effect value of polygene was-20.530 5, and the dominant effect value was-4.141 4. The heritability of major genes and polygene was 92.34% and 4.7%, respectively. This study could provide a theoretical basis for bitter gourd breeding.

Genetic Analysis of Notched Grain in Rice水稻腹缺米的遗传分析

调查了1366份水稻品种和品系,腹缺米的发生频率为5.63%,腹缺米频率与粒重的相关r=+0.6195。1978、1979和1981年,用腹缺米和饱满米配制了17个组合,F_1、F_2和 BF的分析发现,腹缺米受两对显性互补基因控制,环境条件只影响腹缺米的程度。这种障碍在早期世代进行连续选择即可消除。

Longitudinal genetic analysis of growth-related traits in red swamp crayfish Procambarus clarkii (Girard)

The red swamp crayfish,Procambarus clarkii,is an economically important species especially in China.Their exoskeleton places serious constraints on growth and culture management.Their growth is achieved through intermittent molting/ecdysis.The longitudinal genetic dynamics for growth-related traits at different ecdysial points in P.clarkii has been unclear to date.In this study,conditional genetic analysis was carried out for growth-related traits(body weight,body length,chela length,and cephalothorax length)based upon a mixed genetic model with conditional additive,dominance,and genotype by environment effects in P.clarkii.A complete diallel cross was made among three geographic populations of P.clarkii for the genetic mating design.Results of the conditional genetic analysis showed that from 4 th molt to 9 th molt the conditional additive variations were increased significantly whereas the conditional non-additive genetic variations(dominance and genotype by environment interaction)were decreased significantly for these growth-related traits.This indicated that lots of new expression of additive effect genes for body weight,body length,chela length,and cephalothorax length occurred during ontogeny,and environment played a signifi cant role in the expression of genes affecting these growth-related traits.Growth of the four traits was mainly affected by non-additive genetic effects in early developmental stage(prior to 4 th molt).The cumulative conditional additive variation for the growth-related traits from 4 th molt to 9 th molt accounted for a large majority of the total conditional additive variations from 2 nd molt to 9 th molt,indicating that this period was very important for the growth of this species.Using the conditional analysis method,dynamics of growth-related traits during an important ontogenetic phase of red swamp crayfish was uncovered.Our results provide valuable insights into refining production of this species.

Identification, Genetic Analysis and Mapping of Resistance to Phytophthora sojae of Pm28 in Soybean

Phytophthora sojae Kanfman and Gerdemann （P. sojae） is one of the most prevalent pathogens and causes Phytophthora root rot, which limits soybean production worldwide. Development of resistant cultivars is a cost-effective approach to controlling this disease. In this study, 127 soybean germplasm were evaluated for their responses to Phytophthora sojae strain Pm28 using the hypocotyl inoculation technique, and 49 were found resistant to the strain. The hypocotyl of P1, P2, F1, and F2：3 of two crosses of Ludou 4 （resistant）×Youchu 4 （susceptible） and Cangdou 5 （resistant）×Williams （susceptible） were inoculated with Pm28, and were used to analyze the inheritance of resistance. The population derived from the cross of Ludou 4×Youchu 4 was used to map the resistance gene （designated as Rps9） to a linkage group. 932 pairs of SSR primers were used to detect polymorphism, and seven SSR markers were mapped near the resistance gene. The results showed that the resistance to Pm28 in Ludou 4 and Cangdou 5 was controlled by a single dominant gene Rps9, which was located on the molecular linkage group N between the SSR markers Satt631 （7.5 cM） and Sat_186 （4.3 cM）.

Genetic Analysis and Molecular Mapping of a Novel Chlorophyll-Deficit Mutant Gene in Rice

A rice etiolation mutant 824ys featured with chlorophyll deficiency was identified from a normal green rice variety 824B. It showed whole green-yellow plant from the seedling stage, reduced number of tillers and longer growth duration. The contents of chlorophyll, chlorophyll a, chlorophyll b and net photosynthetic rate in leaves of the mutant obviously decreased, as well as the number of spikelets per panicle, seed setting rate and 1000-grain weight compared with its wild-type parent. Genetic analyses on F1 and F2 generations of 824ys crossed with three normal green varieties showed that the chlorophyll-deficit mutant character was controlled by a pair of recessive nuclear gene. Genetic mapping of the mutant gene was conducted by using microsatellite markers and F2 mapping population of 495R/824ys, and the mutant gene of 824ys was mapped on the short arm of rice chromosome 3. The genetic distances from the target gene to the markers RM218, RM282 and RM6959 were 25.6 cM, 5.2 cM and 21.8 cM, respectively. It was considered to be a new chlorophyll-deficit mutant gene and tentatively named as chill（t）.

Genetic Analysis and Primary Mapping of pms4, a Photoperiod-Sensitive Genic Male Sterility Gene in Rice (Oryza sativa)

To understand the genetic characteristics of a new photoperiod-sensitive genic male sterile line Mian 9S, some reciprocal crosses were made between Mian 9S and six indica rice materials, Yangdao 6, Luhui 602, Shuihui 527, Mianhui 725, Fuhui 838 and Yixiang 1B. Genetic analysis results suggested that the photoperiod-sensitive genic male sterility （PGMS） of Mian 9S was controlled by a single recessive nuclear gene. Thus, the F2 population derived from the cross of Yangdao 6/Mian 9S was used to map the PGMS gene in Mian 9S. By using SSR markers, the PGMS gene of Mian 9S was mapped on one side of the markers, RM6659 and RM1305, on rice chromosome 4, with the genetic distances of 3.0 cM and 3.5 cM, respectively. The gene was a novel PGMS gene and designated tentatively as pms4. In addition, the application of the pms4 gene was discussed.

Genetic Analysis and Mapping of TWH Gene in Rice Twisted Hull Mutant

A mutant with twisted hulls was found in a breeding population of rice （Oryza sativa L.）. The mutant shows less grain weight and inferior grain quality in addition to twisted hulls. Genetic analysis indicated that the phenotype of mutant was controlled by a single recessive gene （temporarily designated as TW（H）. To map the TWH gene, an F2 population was generated by crossing the twh mutant to R725, an indica rice variety with normal hulls. For bulked segregant analysis, the bulk of mutant plants was prepared by mixing equal amount of plant tissue from 10 twisted-hull plants and the bulk of normal plants was obtained by pooling equal amount tissue of 10 normal-hull plants. Two hundred and seven pairs of simple sequence repeat （SSR） primers, which are distributed on 12 rice chromosomes, were used for polymorphism analysis of the parents and the two bulks. The TWH locus was initially mapped close to the SSR marker RM526 on chromosome 2. Therefore, further mapping was performed using 50 pairs of SSR primers around the marker RM526. The TWH was delimited between the SSR markers RM14128 and RM208 on the long arm of chromosome 2 at the genetic distances of 1.4 cM and 2.7 cM, respectively. These results provide the foundation for further fine mapping, cloning and functional analysis of the TWH gene.

Morphogenesis,Anatomical Observation and Primary Genetic Analysis of a Multi-glume Floral Organ Mutant in Rice

A multi-glume （mg） mutant was obtained by screening the T-DNA inserted mutant pool. Anatomical observation revealed that the florets of the mutant showed elongated leafy paleas/lemmas and palea/lemma-like structures, just like multi-glumes. Among the 215 observed florets of the mutant, 14.27% were failed to produce pistil and stamens, 23.72% showed extra floret generated on the same rachilla, while 62.01% consisted of one to nine stamens and one to three pistils in a single floret. On the other hand, in some cases the transparent bulged vesile-like tissue could be observed at the basis of filament. The mutant showed glumaceous Iodicules, which prevented the florets from opening in natural conditions, while the absolute male and female sterility was an obvious character of the current mutant. Observation on the process of floral organ morphogenesis by a scanning electron microscopy （SEM） indicated that no phenotype difference in floret primordia was found between the wild-type and the mutant. Meanwhile, for the mutant, the beginning of stamen and pistil primordial differentiation was later than the wild type and the palea/lemma-like structure continued to differentiate after the formation of normal palea and lemma. Furthermore, in the mutant the asymmetrical division of floral primordial caused variation in the number of stamens and pistils. Therefore, the genetic analyses indicated that the mutation phenotype was a recessive trait controlled by a single gene and co-segregated with the T-DNA. Based on the phenotypic characteristics, it could be deduced that the mutant was the result of homeotic conversion from the function of the class E genes in ABCD model.

Distribution of Grain Hardness in Chinese Wheats and Genetic Analysis

A hundred winter wheat and 41 spring wheat cultivars and advanced lines were used to investigate the distribution of grain hardness in Chinese wheats and correlations between grain hardness and other kernel traits. P1, P2, F1 , F2 and F3 from three crosses, i. e. , Liken2/Yumai2, 85Zhong33/Wenmai6 and 85Zhong33/95Zhong459 were sown to study the genetics of grain hardness. Significant correlation was observed between hardness measured by Single Kernel Characteristic System 4100 (SKCS 4100) and Near Infrared (NIR) Spectroscopy, r ranging from 0.85 to 0.94. Chinese wheat is a mixed population in terms of hardness, ranging from very soft to very hard. For autumn-sown wheat, on average, grain hardness decreases from north to south and spring-sown wheat is dominant with hard type. Hardness is negatively associated with flour color, and its associations with flour yield and ash content differ in winter and spring wheats. Grain hardness is controlled by a major gene and several minor genes with additive effect mostly, but dominant effect is also observed, with heritability of 0.78.

Genetic Analysis and Mapping of an Enclosed Panicle Mutant Locus esp1 in Rice (Oryza sativa L.)

A mutant was isolated from the M2 of 60Co-T ray mutagenized male-fertility restorer line Zao-R974 in rice. The mutant showed pleiotropic phenotypes including dwarfism, delayed heading time, short and partially enclosed panicles, short uppermost internode, decreased grain and secondary branch numbers per panicle, and partially degenerated spikelets. The mutant was named as espl （enclosed shorter panicle 1）. Genetic analysis indicated that the mutant phenotype was controlled by a recessive locus. Spraying exogenous GA~ did not rescue the panicle enclosure. Using an F2 and a BC, population of the cross between espl and a japonica cultivar Nipponbare, we mapped the ESP1 locus to a region of-260 kb on chromosome 11. This result provides a basis for further map-based cloning of the ESP1 locus.

Genetic Analysis and Molecular Mapping of Light-Sensitive Red-Root Mutant in Rice

The light-sensitive red-root mutant, designated as HG1, was newly observed from an indica rice variety, Nankinkodo, when seedlings were grown with roots exposed to natural light. The root color of the mutant began to turn slight-red when the roots were exposed to the light at the intensity of 29 ）Jmol/（m^2·s）, then turned dark-red at the light intensity of 180 pmol/（m^2·s）, suggesting that the root color of the mutant was evidently sensitive to light. Furthermore, genetic analysis showed that the character of light-sensitive red-root of the HG1 mutant was controlled by a single dominant gene, tentatively designated as Lsr. With simple sequence repeat markers, Lsrgene was located between the markers RM252 and RM303 on chromosome 4 with the genetic distances of 9.8 cM and 6.4 cM, respectively. These results could be useful for fine mapping and cloning of Lsrgene in rice.

Genetic Analysis and Molecular Mapping of Novel White Striped Leaf Mutant Gene in Rice

A new white striped leaf mutant wsll was discovered from Nipponbare mutated by ethyl methanesulfonate. The mutant showed white striped leaves at the seedling stage and the leaves gradually turned green after the tillering stage. The chlorophyll content of wsll was significantly lower than that of wild-type during the fourth leaf stage, tillering stage and booting stage. The numbers of chloroplast, grana and grana lamella were reduced and the thylakoids were degenerated in wsll compared with wild type. Genetic analysis showed that the wsll was controlled by a single recessive gene. Molecular mapping of the wsll was performed using an F2 population derived from wsll/Nanjing 11. The wsll was finally mapped on the telomere region of chromosome 9 and positioned between simple sequence repeat markers RM23742 and RM23759 which are separated by approximately 486.5 kb. The results may facilitate map-based cloning of wsll and understanding of the molecular mechanism of the regulation of leaf-color by WSL1 in rice.

Genetic Analysis of Early Generation Stability in Rice

The mechanism of early generation stability （EGS） in rice was studied via genetic analysis. Three types of crosses were made, namely between EGS varieties, EGS and conventional rice variety, and conventional rice varieties. The genetic analysis was based on the stable lines in F2 population. The stable lines may appear from some combinations of EGS rice crossing with each other and EGS rice crossing with conventional varieties at different frequencies, but stable lines didn＇t appear in conventional varieties crossing with conventional varieties. Genetic analysis results indicated that the EGS phenomena should just exist in special rice materials, and the frequency of stable lines was closely related to the EGS traits of parents. The EGS traits were neither qualitative nor quantitative traits, and they were controlled by neither dominant genes nor recessive genes. The EGS traits might be inherited by F1 single plant, and the traits of F3 and F4 were corresponded to those of F2 population, i.e. F3 and F4 lines derived from non-segregating F2 showed uniform agronomic traits, and those from segregating F2.did not. The agronomic traits of EGS lines were consistent with those of F1 single plant. On the other hand, when EGS lines occurred, the segregating lines in Mendelian manner were also observed in all F2 population of the same combination. It was suggested that the reason why the stable strains occurred might be a special factor to control （open/close） gene at the beginning of cell division in zygote, resulting in closing mitosis and opening somatic reduction. The somatic reduction of zygote resulted in recombination and homozygosity forming in F1 single plant, and some lines with uniform agronomic traits were observed in some lines of F2 population.

Genetic Analysis and Molecular Mapping of Two SMV-Resistance Traits in Soybean:Adult-Plant Resistance and Resistance to Seed Coat Mottling

Soybean mosaic virus （SMV） could lead to adult-plant system diseases, and cause mottling of soybean seeds. Genetic analysis and molecular mapping were conducted using an F2 population and derived F3 families from two crosses of Dongnong 3C624 （susceptible）x Dongnong 8143 （resistant） and Dongnong 3C628 （susceptible）× Tie 6915 （resistant）. Simple sequence repeat （SSR） markers with bulked segregation analysis （BSA） were used to conduct genetic mapping of the resistance to SMV1 in the segregating populations. The results indicated that resistance to SMV1 in adultplants and the resistance to seed coat mottling in Dongnong 8143 and Tie 6915 was separately controlled by one single dominant gene. The two dominant genes were identified to be linked on the MLG F by Mendel＇s genetics and SSR genetic mapping. The order and distance of markers DPRSMV1 and DSRSMV1 were Sat 229-6.9 cM-DSRSMV1-4.6 cM-Sat_317-3.6 cM-DPRSMV1-5.2 cM-Satt335. The order and distance of markers TPRSMV1 and TSRSMV1 was Satt160-16.1 cM-TPRSMV1-7.3 cM-Satt516-2.0 cM-TSRSMV1-4.5 cM-Sat_133. This research provides the useful information for breeders to select the two types of SMV resistance simultaneously in soybean breeding through molecular marker-assisted selection （MAS）.

Genetic Analysis and Mapping of Dominant Minute Grain Gene Mi3(t) in Rice

Grain size, determined chiefly by grain length, is one of the main factors affecting the grain yield in rice production. To study the trait of rice grain size, F1 and F2 populations were developed from crosses Shuhui 881/Y34 and Shuhui 527/Y34, and genetic analysis for minute grain was performed. The F1 populations showed minute grains, and grain size segregations in the two F2 populations were both in accordance with the ratio of 3：1, indicating that minute grain in Y34 was controlled by a completely dominant gene. By using the F2 population from Shuhui 881/Y34, this dominant gene, tentatively designated as Mi3（t）, was mapped based on SSR markers in the interval between RM282 （genetic distance of 5.1 cM） and RM6283 （genetic distance of 0.9 cM） on the short arm of chromosome 3.

Genetic Analysis of Major and Minor Gene(s) Resistant to Stripe Rust in Important Resource Wheat Line Jinghe891-1

Inheritance of line Jinghe891-l resistant to pathotype of Puccinia striiformis in two patterns of temperature (Normal: day 18℃ /night 10℃ , High: day 24℃ /night 15℃ )was studied in this paper. The results showed that there were at least two pairs of dominant major genes and one pair of recessive minor genes in Jinghe 891-1. The two pairs of major genes that conferred resistance to CY31 were allelic or linked closely with resistance gene in Jubilejna Ⅱ , Kangyin655 and T. spelta Album. They were novel resistance genes and were inherited in a repeated or independent mode. The minor genes, which could modify the major genes, were sensitive to temperature and conferred resistance to all pathotypes of Puccinia striiformis in China. It is recommended that this line can be used as an important resource stock.

Identification and Genetic Analysis of Gall Midge Resistance in Rice Germplasm 91-1A2

Resistance to rice gall midge in rice germplasm 91-1A2 was identified and genetically analyzed F1s of rice population were derived from 91-1A2 which crossed with rice materials Jinggui, TN1, W1263 （Gm1）, IET2911 （Gm2）, BG404-1 （gm3）, OB677 （Gm4）, ARC5984 （Gm5） and Duokang 1 （Gm6） as a male parent. The resistance of all parental lines and F1, BC1F1 and F2 populations to rice gall midge was identified. The results showed that 91-1A2 and all F1s were resistant to Chinese rice gall midge biotype IV. The segregation ratio of resistant plants to susceptible ones in BC1F1 and F2 were accorded with 1：3 and 9：7 rules by X2 test, suggesting that the resistance of 91-1A2 to Chinese rice gall midge biotype IV was controlled by two dominant genes which were new resistance genes, non-allelic to the known rice gall midge resistance genes.

Phylogenetic Analysis of Citrus tristeza virus Isolates of Wild Type Citrus in China

The genetic variation and phylogenetic relationships of Citrus tristeza virus （CTV） isolates collected from Chinese wild type citrus were analyzed by comparing the sequences of nine genomic regions （p23, p20, p13, p18, p25, p27, POL, HEL and k17） with the CTV isolates of cultivated citrus from different countries. The results showed that the divergence pattern of genomic RNA of the CTV isolates from wild type citrus was similar to that of other isolates from cultivated citrus, the 3′ proximal region was relatively conserved, and the 5′ proximal region had greater variability. The nine genomic regions of CTV isolates analyzed were found to have been under purifying selection in the evolution process. Phylogenetic analysis showed that the eleven Chinese wild CTV isolates were located at different clades and did not relfect their geographical origins, suggesting genetic diversity among the Chinese wild CTV populations. These results will aid in the understanding of molecular evolution of the Chinese CTV populations.

Genetic analysis of morphological index and its related taxonomic traits for classification of indica

The Cheng index distinguishes indica andjaponica rice based on six taxonomic traits.This index has been widely used for classifi- cation of indica and japonica varieties in China.In this study,a double haploid(DH)popula-tion derived from anther culture of ZYQ8/JX17 F,a typical inter-subspecies hybrid,was used to investigate the six taxonomictraits,i.e.leaf hairiness(LH),color of hullwhen heading(CHH),hairiness of hull(HH),length of the first and second panicle internode(LPI),length/width of grain(L/W),andphenol reaction(PH).The morphological in- dex(MI)was also calculated.Based on themolecular linkage map constructed from this

Dynamic genetic analysis for body weight and main length ratio in turbot Scophthalmus maximus

The objective of this study was to estimate genetic parameters of body width(BW)to body length(BL)ratio(BW/BL)and of body weight traits(BWT)in turbot,and to elucidate the genetic mechanism of the two traits during ontogeny by dynamic genetic analysis.From 3 to 27 months,BW,BL and BWT of each communally stocked fish were measured every 3 months.The BW/BL ratio was measured at different sampling ages.A twotrait animal model was used for genetic evaluation of traits.The results showed that the heritability values of BW/BL ratio ranged from 0.2168 to 0.3148,corresponding to moderate heritability.The BWT heritability values ranged from 0.2702 to 0.3479 corresponding to moderate heritability.The heritability of BW/BL ratio was lower than that of BWT,except at 3 months of age.Genetic correlation between BW/BL ratio and BWT decreased throughout the measurement period.Genetic correlations were higher than the phenotypic correlations.The current results for estimating genetic parameters demonstrate that the BW/BL ratio could be used as a phenotypic marker of fast-growing turbot,and the BW/BL ratio and BWT could be improved simultaneously through selective breeding.