Identification of the novel recessive gene pi55(t) conferring resistance to Magnaporthe oryzae

The elite rice cultivar Yuejingsimiao 2 （YJ2） is characterized by a high level of grain quality and yield, and resistance against Magnaporthe oryzae. YJ2 showed 100% resistance to four fungal populations collected from Guangdong, Sichuan, Liaoning, and Heilongjiang Provinces, which is a higher frequency than that shown by the well-known resistance （R） gene donor culti- vats such as Sanhuangzhan 2 and 28zhan. Segregation analysis for resistance with F2 and F4 populations indicated the re- sistance of YJ2 was controlled by multiple genes that are dominant or recessive. The putative R genes of YJ2 were roughly tagged by SSR markers, located on chromosomes 2, 6, 8, and 12, in a hulked-segregant analysis using genome-wide selected SSR markers with F4 lines that segregated into 3 resistant （R）： 1 susceptible （S） or 1R：3S. The recessive R gene on chromosome 8 was further mapped to an interval ~1.9 cM/152 kb in length by linkage analysis with genomic position-ready markers in the mapping population derived from an F4 line that segregated into 1R：3S. Given that no major R gene was mapped to this inter- val, the novel R gene was designated as pi55（t）. Out of 26 candidate genes predicted in the region based on the reference genomic sequence of the cultivar Nipponbare, two genes that encode a leucine-rich repeat-containing protein and heavy-metalassociated domain-containing protein, respectively, were suggested as the most likely candidates for pi55（t）.

Searching Development-deficient Genes in Edible Mushroom by Self-crossing

[Objective] This study aimed to investigate the effect of mating factor recombination on the development of edible mushroom,and explore the possibility for using self-crossing to breed sporeless/low sporing mushroom strains.[Method] Selecting Agrocybe salicacola strain YAASM0711 as the self-crossing material,six self-crossed combinations were directionally constructed with single spore growth rate as an indicator,to carry out comprehensive analysis of the qualitative traits（color,deformity and growth characteristics）,quantitative traits（shape,yield,size and number of fruit bodies） and mating types of its self-crossed F1 progenies.[Result] After mating factor recombination,self-crossed single spore progenies showed serious genetic differentiation,the average mycelial growth rate and agronomic traits of inbred progenies were lower than those of the parents.The phenotype in fruiting body formation could be divided into normal fruiting and abnormal fruiting（including abnormal fruiting bodies,sporeless or low sporing fruiting bodies,no fruiting）.To be specific,18% self-crossed strains had superior agronomic traits to the parents,which can be used for selecting predominant strains from self-crossed progeny populations based on different breeding purposes.[Conclusion] The genes controlling mycelial growth rate of single spore were linked with mating factors.The mating factor-recombinant single spore strains could be selected according to the correlation between mating type and growth rate.The fruiting result of self-crossed strains indicated that the genes related to sporeless/low sporing development were recessive.Not only genetic materials harboring development-deficient genes in edible mushroom can be obtained by self-crossing,but also the sporeless/low sporing mutant strains with important application prospects can be bred.

Nutritional Quality of the Maize Combinations with Mutant Gene opaque-2 (o2)

[Objective] This study aimed to investigate the action of mutant gene o2 and its effect on nutritional quality of different maize combinations. [Method] A total of 33 normal maize combinations from 18 inbred lines were compared with 33 combinations including gene o2 from the corresponding o2 near-isogenic lines （o2-NILs）, to study the effect of o2 gene introduction on maize grain quality. [Result] The contents of lysine, protein and oil in o2-NILs were greatly more than that of normal maize combinations. Except for lysine, contents of other 14 amino acids changed when o2 gene was introduced. Contents of aspartic acid, threonine, glycine, isoleucine, histidine, arginine and proline were improved; while contents of serine, glutamic acid, alanine, valine, leucine, tyrosine and phenylalanine were decreased. Correlation analysis showed that contents of aspartic acid, arginine and threonine had the highest correlation with lysine content. Protein and oil contents had higher correlation with lysine content （0.48 and 0.38）. Analysis of 33 o2-NILs revealed that the o2 combinations CAL58×Ji477and CA156×196 showed high comprehensive quality and high yield with greater development potential. [Conclusion] This study will provide theoretical and material basis for improving the quality of temperate maize germplasm by introducing o2 gene.

Genetic Analysis of the Resistance in Six Newly-bred Rice Varieties to the Whitebacked Planthopper,Sogatella furcifera

The paper reports the study on resistance in 6 newly-bred rice varieties, such as Nongxiang 16 and 9234, to the whitehacked planthopper, Sogatella furcifera. In crossing with the susceptible Taichung Native 1 (TN1), the resistance of their F1 and F2 populations and the back-crossed BC1F1 populations have been evaluated. The resistance to 5. furcifera in Zhenongda 6022, 9234 and Zhongjian 96-3 was controlled by a single dominant gene, and by a single recessive gene in Nongxiang 16, R40 and Shuhui 881, respectively. These varieties possessed good agronomical characteristics and could be used in further rice breeding and rice production.

An Improved GA for Combinational Logic Expressions

This paper discusses complete binary trees as chromosomes of Genetic Algorithm (GA), and proposes the concept of dominant and recessive genes. On the base of it, a new crossover operator with the selective ability was designed. Finally experimental results are presented.

Genotyping the Heading Date of Male-Sterile Rice Line II-32A

II-32A, an elite male-sterile line of rice （Oryza sativa L.）, has been widely used for the production of hybrid rice seed In China. Heading date In most combinations using II-32A shows transgressive Inheritance or similarity to the latter parent, but the genotype of II-32A with respect to major genes for heading time Is unknown. This limits the further exploitation of this sterile line In breeding and hybrid seed production. Using a number of major gene heading date Isogenlc lines and heading date QTL near-lsogenic lines, we genetically analyzed II-32B under both long- and short-day conditions. We show that II-32B carries two photoperlod-sensltlve genes, E1 and E3, a recessive late-heading gene, ef-l, and a photoperlod-sensltlve allele, Se-1^u. In addition we Identified In II- 32B a recessive Inhibitor for E1 or Se-1^n and other modified photoperlod-sensltlve genes. The heading-date constitution of II-32A was determined to be E1e2E3Se-1^uef-li-Se-1.