Interspecific Chromosome Substitution Lines as Genetic Resources for Improvement,Trait Analysis and Genomic Inference

The genetic base that cotton breeders commonly use to improve Upland cultivars is very narrow.The AD-genome species Gossypium barbadense,G.tomentosum,and G.mustelinum are part of the primary germplasm pool,too,and constitute genetic reservoirs of genes for resistance to abiotic stress,pests,and pathogens,as well as agronomic and fiber traits.     

Use of lnterspecific Hybrids in the Texas A&M University Cotton Improvement Laboratory

Integrating alleles from Gossypium species into G.hirsutum is important for the enhancement of genetic variability and for creating polymorphism useful in molecular mapping studies.     

Chromosome Substitution Lines:Useful Genomic Resources in Cotton

The genus Gossypium is a very diverse one with about 50 species.However,a very narrow germplasm base is presently being used for genetic improvement of Upland cotton.The wild tetraploid cotton species are reservoirs of important genes for pest and disease resistance,and for improved agronomic and fiber traits.Two of the most important forces impeding Upland cotton improvement are" 1)the paucity of information about genes that control important traits,and 2) the need for extensive usage of diverse germplasm.     

Gossypium Germplasm Resources

The genetic variability residing in diploid andtetraploid species of the Gossypium genusrepresents a large,under-utilized resource incurrent cotton improvement efforts.Geneticdiversity in elite germplasm is reported to benarrow.Actual diversity on the land isnarrower,due to preferential mass planting ofsuccessful cultivars and breeding techniques that     

A Genetic Potential of Gossypium L. Genus, Its Importance and a Practical Use

Among crops the most valuable for themankind,cotton(Gossypium L.genus)occupiesan important place.On the latest scientific datain the composition of the genus there are 50species(Fryxell,1992,et al),growing on 5continents of the world.Biomorphologicdiversity of cotton is the richest source of genetic     

Comparative Genetics of Floral Morphology in Diploid and Allotetraploid Gossypium

The cultivated Gossypium A genome diploid species G.arboreum and G.herbaceum and the allotetraploid species G.hirsutum and G.barbadense share common morphology for various floral traits,which offers an ideal system in which to investigate genetic mechanisms that differentiate diploid and tetraploid genomes.For example,knowing how a single phenotype behaves in the diploids,and comparing the same trait with different dosage effects in the tetraploids,may provide a means to study inter- and intra-genomic interactions in the polyploid genome.     

Comparative Transmission Genetics of Introgressed Chromatin in Gossypium Species

Wild relatives and un-adapted germplasm of crop species harbors several adaptive traits.Introgression of genes for economic and adaptive traits brings in novel genetic variation into the gene pools of many crops including cotton.We compared patterns of introgression into polyploid Gossypium hirsuture from its sister G.tomentosum,and from G.barbadense representing a different clade tracing to the same polyploidization.Advanced-generation populations,resulting from recurrent backcrossing to G.hirsutum,show a paucity of G.tomentosum alleles and severe deficiencies of homozygotes.     

Identification of Quantitative Trait Loci Controlling Seed Physical and Nutrient Traits in Cotton

Cotton (Gossypium spp.) is the leading fiber crop,and an important source of the important edible oil and protein meals in the world.Complex genetics and strong environmental effects hinder much progress in seed quality trait breeding in cotton.The use of molecular markers will improve our understanding of the genetic factors conferring seed quality traits,and it is expected to assist in selection of superior genotypes.     

Agrobacterium-meditated Genetic Transformation of an Upland Cotton (Gossypium hirsutum cv Coker 310) Using a Novel Bt Gene Cry 2Ac

The development of transgenic cotton varieties resistant to bollworms has been a major success of applying plant genetic engineering technology to agriculture,evidenced by phenomenal increase in the cultivable area under (B.thuringiensis) Bt cotton in recent years worldwide.Of late,there are reports of insects developing resistance against the most commonly used Bt toxin CrylAc.Hence,there is an urgent need to broaden the source of resistance by employing new genes in order to reduce the chances of insects developing Bt resistance.Keeping this objective in view,cotton (Gossypium hirsuturn cv Coker 310) plants expressing a novel insecticidal crystal protein Cry2Ac were developed in the present study.     

Genetic Diversity and Relationships among Diploid and Tetraploid Cotton Using RAPD Markers

Gossypium species (+49) represent a vast resource of genetic diversity for improvement of cultivated cotton.To determine intra- and inter-specific genetic diversity and relationships,we employed 30 RAPD random detainer primers on twenty eight cotton accessions from 2 diploid cultivated species (G.arboreum,G.herbaceum) and 2 tetraploid cultivated species (G.hirsuturn,G.barbadense).     

Chromosome Substitution Lines in Cotton Improvement

Presently cotton breeders are confronting seriouschallenges due to the extensive use of narrowgenetic base in Upland cotton,Gossypiumhirsutum.Unique germplasm that incorporatesnew alleles must be developed to provideimproved genetic potential for yield,pest anddisease resistance.Tetraploid species such as G.barbadense,G.tomentosum,and G.mustelinum     

Eukaryotic Translation Initiation Factors Shape RNA Viruses Resistance in Plants

Viruses are representative of a global threat to agricultural production. Genetic resistance is the preferred strategy for the control of viral infection and against loss of crop yield. Viral protein synthesis requires host cellular factors for translating their viral RNAs, and for regulating their replication and cell to cell systemic movement. Therefore, the viruses are dependent on cellular translation factors. Mutations in the gene encoding eIF4E and eIF4G or their isoforms, eIFiso4 E, eIFiso4 G and eIF2Bβ have been mapped as a source of plant potyvirus while other genus of plant virus recessive resistance genes in many species are originated from these loci. Some of other plant translation factors, such as eIF3,eIF4 A-like helicases, eEF1A and eEF1B, which are required in interacting with viral RNAs and regulating various aspects of the infection cycle,have also been identified. Here, we summarized the mechanisms utilized by RNA viruses of eukaryotic plants and the essential roles of e IFs in virus infection. Moreover, we discussed the potential of e IFs as a target gene in the development of genetic resistance to viruses for crop improvement. This review highlighted newly revealed examples of abnormal translational strategies and provided insights into natural host resistance mechanisms that have been linked to 3 cap-independent translational enhancer activity.     

Breeding by Design-High Throughput Phentyping

Plant evolution under domestication has lead to increased productivity, but at the same time it narrowed the genetic basis of crop species. A major objective in modem breeding is to return to the wild ancestors of crop plants and employ some of the diversity that was lost during domestication for the improvement of agricultural yields. Most of the genetic variation present in wild species has a negative effect on the adaptation of plants to agricultural environments, hence the challenge is to identify and utilize the rare advantageous traits in breeding program. To enhance the rate of progress of breeding based on wild species resources we developed a population of tomato segmental introgression lines （ILs-congenics）. The ILs are comprised of marker-defined genomic regions taken from the green fruited wild species S. pennellii and introduced （through genetic crosses） onto the genetic background of the elite inbred variety M82 （Eshed and Zamir, 1995）. The ILs constitute an ＇exotic library＇ where the entire wild species genome was partitioned among 76 lines each carrying a single homozygous introgressed segment. Implementation of this resource for quantitative trait loci （QTL） mapping is based on the nearly isogenic nature of the lines such that any phenotypic difference between M82 and an IL, or the hybrid of M82 with an IL （ILH）, is attributable to the S. pennellii genomic segments.     

Major Results and Research Challenges in Cotton Molecular Genetics at CIRAD (France)

CIRAD (Montpellier,France) develops research activities centered on tropical and sub-tropical agricultural systems.Among others crops,cotton is the focus of a series of research programs in different disciplines from economics to breeding.Major areas in genetics and breeding relate to (1) genetic diversity,(2) eultivar development through classical and molecular breeding,and (3) applied genomics.An important but under-exploited reservoir of genetic diversity exists within the genus Gossypium.     

Uniqueness of the Gossypium mustelinum Genome Revealed by GISH and 45S rDNA FISH

Gossypium mustelinum [-(AD)4"] is one of five tetraploid species in Gossypium.Three pairs of nucleolar organizer regions (NOR) in (AD)4 were detected by FISH with 45S rDNA as a probe,they also were observed with genomic DNA (gDNA) from Gossypium D genome species as probes.Of the three NORs or GISH-NORs,one was super-major and other two were minor,which was distinctly different from other tetraploid cottons.     

QTL Analysis of Fiber Yield and Quality and Resistance to Verticillium Wilt Using Gossypium hirsutum and G.barbadense Advanced Backcross Populations

To introgress elite QTL alleles of Gossypium barbadense L.for fiber yield and quality and resistance to Verticillium wilt into G.hirsutum L.,enlarge the genetic base of G.hirsutum,and provide new germplasm resources for the variety development,the cultivars Zhongmiansuo 36,G.hirsutum,and Hai 1,G.barbadense,were used as recurrent and donor parent,respectively,to produce BC1 F1,BC1S1,and BC2F1 populations.QTL analyses of fiber quality,yield-related,Key words: interspecific backcrosss; AB-QTL; fiber quality; yield; Verticillium wilt resistance     

Collection,Evaluation,and Utilization of Cotton Germplasm in China

A total of 8193 accessions,including 6822 Gossypium hirsutum,350 G.hirsutum race (sub-spe-cies),385 of G.barbadense,378 of G.arboreum,17 of G.herbaceum and 41 wild species,of cotton germplasm are now maintained in China.This germplasm is kept in Beijing National Long-term Genebank and Anyang Cotton Medium-term Genebank.Live plants of the wild species are kept in Cotton garden at Hainan Island.     

Research and Application Perspective of Stay-green Mutants

Stay-green mutants of all botanical species have similar phenotypic features.The senescence is delayed,and chlorophyll degradation is blocked or slowed.Nevertheless,the molecular mechanism of stay-green in these mutants is quite different owing to different genetic basis.The authors summarize the progresses in research on the physiological and biochemical behaviors(mostly concentrated on the enzyme-catalyzed metabolic pathway of chlorophyll),hereditary features and molecular biological aspects in various stay-green mutants.They also describe the importance of stay-green mutation to the research of chlorophyll metabolism,leaf senescence,photosynthesis and other physiological processes in plants,as well as the perspective of exploiting the advantages of these mutants in many aspects of agriculture.Among the many types of stay-green mutants,the most promising and significant can be the functional Type A and Type B which are distinguished for their increased yields and improved resistance against stresses.Furthermore,thorough understanding of changes in the molecular mechanism of stay-green is a potential access to consummately solving the presenility problem of crops.     

Recent Progresses in the Studies of Genetic Engineering for Cold Resistance in Plants

Low temperature is one of abiotic stresses limiting the geographical location suitable for growing corps and periodically account for significant losses in plant productivity, so it's important for agriculture to improve the cold resistance of corps. Many plants can acquire increased frost tolerance after a period of exposure to low, non-freezing temperature through a complex adaptive process called cold acclimation. In the past ten years, with the great advance in the researches of molecular mechanism of cold acclimation, the studies of genetic engineering for cold resistance in plants have also been carried out extensively. Currently, there are two kinds of genes used in plant cold-resistant genetic engineering, Which are protective genes and regulating genes. Many studies indicate both kinds of genes have good prospect for improving the cold resistance of plants. However, there are also many problems in this field to be solved immediately.     

Identification of QTLs Affecting Yield and Fiber Properties in Chromosome 16 in Cotton Using Substitution Line

Gossypium hirsutum L., one of the twocultivated tetraploid species in cotton,ischaracterized by its high yield and wideadaptation,while G.barbadense L.,anothercultivated one,by its super fiber properties.Substitution line in which one pair of intact