Cytogenetics and morphology of the pentaploid hybrid between Brassica napus and Orychophragmus violaceus and its progeny

A pentaploid hybrid plant (2n= 50, AACCO) between Brassica napus (AACC) and Orychophragmus violaceus (OO) showed matroclinous morphology and some patroclinous characters. Cloned progenies were mixoploid, consisting of various cells with 38–53 chromosomes, half of the cells with 50 chromosomes. The 50 chromosomes were mainly paired as 25 bivalents and segregated as 25:25 or 22:28; many other segregations were observed in some cells. Progenies produced by selfing had 38–47 chromosomes. Plants with 38 chromosomes were cytologically stable; in all other plants the chromosome number of individual cells varied between the genotype-specific maximum number and 38, indicating loss of chromosomes during mitosis. The mixoploid plants with 44 chromosomes mainly produced two kinds of mixoploid progenies with 44 and 41 chromosomes, respectively. All plants with 2n= 38 had the same morphology as the parental B. napus and were normal in fertility. These chromosome pairings and segregations in the pentaploid and its progeny support the hypothesis that O. violaceus is a natural polyploid species with a basic chromosome number of 3.     

Pollen-mediated gene flow in an autogamous crop: Foxtail millet (Setavia italica)

Gene How is a key concern associated with the eonlamination of seed multiplication iields and the use of transgenic crops. The release of herbicide-resistant germplasnis and the use of male-sterile varieties make foxtail millet (Sviaria ilalicii) an appropriate material to inves-tigate this concern. Pollen dispersal from pollen donor sources and gene tlow in fertile and male-slerile varieties of fortail millet were investigated in experiments in China and France. Although foxtail millel is mainly autogamous (less than 2% oiitcrossing), pollen from a 5m diameter plot could fertilize a tertile variety up to 24 ni away, and a male-sterile variety up to 40m. Negative exponential and WeibuU fnnctions were used to tit the relationships between percentage and number i.A iubrids per cm of ear with distance from the pollen source. Wind velocity and direction resulted in variations of gene How intensity, but did nol change liie slope ofthe regression equations. Pollen competition for available target ovules was observed up to 2 m away from a 1 m diameter pollen source. The percentage of pollen grains that fertilized ovules outside the pollen donor source was 1.4% of the total pollen grain produetion. For every iflO pollen grains released under lieid conditions 1.5 seeds were produced. The probability funetion of pollen dispersal for one donor plant was calculated. It allowed predictions of gene How accord-ing to lield shapes, estimations of isolation distances to preserve /ariety purity against pollen contamination, and the fornuiiation of efficient male/female ratios Ibr hybrid seed production.     

Critical Discussion on Abortive Interspecific Crosses in Brassica

In most interspecific hybridization among diploid Brassica species (n = 8, 9, 10), few or no hybrids are obtained, and the three crosses of tetraploid (n = 17, 18, 19) by diploid species are usually only partially successful, especially in one of the reciprocal crosses. Such a cross-incompatibility complex is explained in this paper by a polar-nuclei activation (PNA) hypothesis which proposes two reversible functions, a normal reproduction and a sexual barrier, of double fertilization in higher plants. The first, i.e. the relative activating value (AV) of diploid species, was estimated as 1.0–3.5, whereas that of tetraploid species was 2.7–5.2. In addition, crosses with a polar nuclei activation index (AI) of about 15–87 % were compatible but those beyond the two limits were incompatible, 50 % of those showing normal seed development after self-pollination.     

Genetics of Five Seed Esterase Isozymes in Pearl Millet

Inheritance and linkage relationships of pearl millet seed esterase isozymes were studied using; polyacrylamide dise: gel electrophoresis and α-naphthyl acetate as substrate. The Zone of enzyme activity was resolved into five bands. The presence of a band showed complete dominance over its absence. Each one of the bands (1 to 4) was under the control of a single gene. Band five was found to be controlled by three independent loci with duplicate gent action Loci for Est₁, Est₃ and Est₄ Were found to be linked. Est₂ Was independent of this linkage group.     

The Application of TDZ in Enhancing Regeneration of Transgenic Plants

At present, transgenic plants are globally grown. Availability of a reliable regeneration system predominantly from a single transformed cell is the prerequisites for gene transfer, but regeneration is still a key problem （Wenzel, 2006）. The application of genetic modification technology in plants is closely related to the efficiency of the regeneration protocol. Shoot formation is oilen enhanced by the combination of auxins and cytokinins. TDZ （Thidiazuron, N-phenyl-N＇-1,2,3-thiodiazol-5-ylurea）, a non-purine, has been shown to promote differentiation of organized centers of growth in cultured tissues at much lower concentrations, and shoot regeneration occurs with an efficiency comparable to or greater than that of other cytokinins （Fiola et al., 1990）. By addition of TDZ, a series of plants which were difficult to culture in vitro or less sensitive to plants growth regulators obtained somatic embryos and regenerated plants, some of them have become the eminent transformation system for genetic engineering. TDZ has been reported to be very efficient in stimulating adventitious shoot production in several recalcitrant plants. TDZ is considered as a potential growth regulator for in vitro shoot regeneration and somatic embryogenesis of several crops. This review summarized how the new growth regulator TDZ to affect the regeneration of transgenic plants.     

Constructive Approaches to Intellectual Property Complexity in Today＇s Agricultural Technology World

Essential to progress in plant biotechnology for deliverable applications, patent and patent application data must be transparent in order to determine where there is whitespace for innovation.     

An introduction to markers, quantitative trait loci (QTL) mapping and marker-assisted selection for crop improvement: The basic concepts

Recognizing the enormous potential of DNA markers in plant breeding, many agricultural research centers and plant breeding institutes have adopted the capacity for marker development and marker-assisted selection (MAS). However, due to rapid developments in marker technology, statistical methodology for identifying quantitative trait loci (QTLs) and the jargon used by molecular biologists, the utility of DNA markers in plant breeding may not be clearly understood by non-molecular biologists. This review provides an introduction to DNA markers and the concept of polymorphism, linkage analysis and map construction, the principles of QTL analysis and how markers may be applied in breeding programs using MAS. This review has been specifically written for readers who have only a basic knowledge of molecular biology and/or plant genetics. Its format is therefore ideal for conventional plant breeders, physiologists, pathologists, other plant scientists and students.     

Assessment of genetic relationships among Cucumis spp. by SSR and RAPD marker analysis

The first successful production of a sterile interspecific hybrid obtained from a cross between Cucumis hystrix Chakr. (2n = 2x = 24) and Cucumis sativus var. sativus L. (2n =2x = 14), and its subsequent fertility restoration through chromosome doubling provide an effective means for investigating genetic relationships among Cucumis spp. In this study, random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were used to investigate relationships among C. s. var. sativus L., C. s. var. hardwickii (R.) Alef., C hystrix, C. hytivus Chen & Kirkbride (the amphidiploid species from chromosome doubling of the C. sativus x C. hystrix interspecific hybrid, 2n = 38), C. melo (2n =2x = 24) and C. metuliferus Meyer and Naudin (2n =2x= 24). A total of 109 SSR bands and 398 RAPD primed sites were used to calculate Jaccard's distance coefficients for cluster analysis using a unweighted pair‐group method using an arithmetic averaging (UPGMA) algorithm. The genetic relationships identified using SSR and RAPD markers were highly concordant, such that the correlation between SSR and RAPD genetic distance (GD) estimates was r = 0.94. SSR and RAPD analysis of 22 accessions allowed for their grouping into two distinct groups designated as CS and CM. While group CS consisted of 11 C. sativus genotypes, and the C. hytivus and C. hystrix accessions, group CM included six C. melo genotypes and C. metuliferus. The GD values between C. hystrix and C. sativus ascribed by SSR and RAPD matrices were 0.59 and 0.57, respectively. These GDs were smaller than those detected between C. hystrix and C melo (0.87 and 0.70 derived from SSR and RAPD markers, respectively).     

RFLP/AFLP mapping of a brown planthopper (Nilaparvata lugens Stål) resistance gene Bph1 in rice

We have constructed a linkage map of the rice brown planthopper (BPH)resistance gene, Bph1. RFLP and AFLP markers were selected by thebulked segregant analysis and used in the mapping study of 262 F₂sthat were derived from a cross of `Tsukushibare', a susceptible japonica cultivar, and `Norin-PL3', an authentic japonicaBph1-introgression line. Twenty markers were mapped within a 28.9-cMregion containing the Bph1 locus on the long arm of rice chromosome12. Combining the result of segregation analysis of BPH resistance by themass seedling test and that of the markers, the Bph1 locus wasmapped within a 5.8-cM region between two flanking markers. The closestAFLP markers, em5814N and em2802N, was at 2.7 cM proximal to theBph1 locus. Together with the previously constructed high-resolutionmap of bph2 locating the locus at ca. 10 cM proximal to the Bph1 locus, this improved version of the linkage map would facilitatepyramiding these two important BPH resistance genes.     

QTL analysis of cooked rice grain elongation, volume expansion, and water absorption using a recombinant inbred population

The traits of elongation, volume expansion, and water absorption are very important in determining the quality of cooked rice grains. In this study, quantitative trait loci (QTL) analysis of these traits was performed using a recombinant inbred population derived from a cross between two indica cultivars, ‘Zhenshan 97’ and ‘Minghui 63 ,’ which are the parents of the most widely grown hybrid rice in China. Using a linkage map based on 221 molecular marker loci covering a total of 1796 cM, a total of 33 QTLs were identified for the nine traits tested. QTLs were detected on chromosomes 1– 3 , 5– 9 , and 11 , respectively. The QTLs identified included three for cooked rice grain length elongation (chromosomes 2 , 6 , and 11), six for width expansion (chromosomes 1‐ 3 , 6 , 9 , and 11) and two for water absorption (chromosomes 2 and 6). Interestingly, a single QTL located near the wx gene on chromosome 6 seemed to influence all the traits tested for the cooked rice quality.