Dry Breeding and Dry Planting Techniques for Indica Hybrid Rice in Karst Mountain Areas of Gejiu City

Based on the arable land situation in Gejiu City,upland dry planting of indica hybrid rice is being expanded in Karst mountain areas with a rainfall of over 1400 mm and an altitude of 1100-1600 m to develop grain production.This paper gives a specific description of hybrid rice upland dry seedling technology,upland transplanting technology,fertilization technology,field management,weed prevention and control technology,and disease and pest control.

Artificial selection of the Green Revolution gene Semidwarf 1 is implicated in upland rice breeding

Semidwarf breeding has boosted crop production and is a well-known outcome from the first Green Revolution. The Green Revolution gene Semidwarf 1(SD1), which modulates gibberellic acid(GA) biosynthesis, plays a principal role in determining rice plant height. Mutations in SD1 reduce rice plant height and promote lodging resistance and fertilizer tolerance to increase grain production. The plant height mediated by SD1 also favors grain yield under certain conditions. However, it is not yet known whether the function of SD1 in upland rice promotes adaptation and grain production. In this study, the plant height and grain yield of irrigated and upland rice were comparatively analyzed under paddy and dryland conditions. In response to dryland environments, rice requires a reduction in plant height to cope with water deficits. Upland rice accessions had greater plant heights than their irrigated counterparts under both paddy and dryland conditions, and appropriately reducing plant height could improve adaptability to dryland environments and maintain high grain yield formation. Moreover, upland rice cultivars with thicker stem diameters had stronger lodging resistance, which addresses the lodging problem. Knockout of SD1 in the upland rice cultivar IRAT104 reduced the plant height and grain yield, demonstrating that the adjustment of plant height mediated by SD1 could increase grain production in dryland fields. In addition, an SD1 genetic diversity analysis verified that haplotype variation causes phenotypic variation in plant height. During the breeding history of rice, SD1 allelic mutations were selected from landraces to improve the grain yield of irrigated rice cultivars, and this selection was accompanied by a reduction in plant height. Thus, five known mutant alleles were analyzed to verify that functional SD1 is required for upland rice production. All these results suggest that SD1 might have undergone artificial positive selection in upland rice, which provides further insights concerning greater plant height in upland rice breeding.

Germplasm and molecular breeding in horticultural crops

Horticulture is an important part of agricultural planting and production, which is of great significance for enriching human nutrition and beautifying and transforming the human living environment. At present, the area of horticultural crops in China is about 40 million ha, accounting for about onefourth of the national crop planting area, while the production of primary agricultural products is 1 billion tons, and the output value accounts for more than half of the total output value of the planting industry.

Genomic dissection of widely planted soybean cultivars leads to a new breeding strategy of crops in the post-genomic era

Soybeans specially the widely planted cultivars have been dramatically improved in agronomic performance and is well adapted to local planting environments after long-time domestication and breeding.Uncovering the unique genomic features of popular cultivars will help to understand how soybean genomes have been modified through breeding.We re-sequenced 134 soybean cultivars that were released and most widely planted over the last century in China.Phylogenetic analyses established that these cultivars comprise two geographically distinct sub-populations:Northeast China (NE) versus the HuangHuai-Hai River Valley and South China (HS).A total of 309 selective regions were identified as being impacted by geographical origins.The HS sub-population exhibited higher genetic diversity and linkage disequilibrium decayed more rapidly compared to the NE sub-population.To study the association between phenotypic differences and geographical origins,we recorded the vegetative period under different growing conditions for two years,and found that clustering based on the phenotypic data was closely correlated with cultivar geographical origin.By iteratively calculating accumulated genetic diversity,we established a platform panel of cultivars and have proposed a novel breeding strategy named "Potalaization"for selecting and utilizing the platform cultivars that represent the most genetically diversity and the highest available agronomic performance as the "plateau"for accumulating elite loci and traits,breeding novel widely adapted cultivars,and upgrading breeding technology.In addition to providing new genomic information for the soybean research community,the "Potalaization"strategy that we devised will also be practical for integrating the conventional and molecular breeding programs of crops in the post-genomic era.

Breeding against mycorrhizal symbiosis:Modern cotton (Gossypium hirsutum L.) varieties perform more poorly than older varieties except at very high phosphorus supply levels

Cotton (Gossypium hirsutum L.) is an importantfiber cash crop,but its root traits related to phosphorus (P) acquisition,including mycorrhizal root traits,are poorly understood.Eight cotton varieties bred in northwestern China that were released between 1950 and 2013 were grown in pots with or without one arbuscular mycorrhizal fungal (AMF) species(Funneliformis mosseae) at three P supply levels (0,50 and 300 mg P as KH_(2)PO_(4)kg^(-1)).Eleven root traits were measured and calculated after 7 wk of growth.The more recent accessions had smaller root diameters,acquired less P and produced less biomass,indicating an (inadvertent) varietal selection for thinner roots that provided less cortical space for AMF,which then increased the need for a high P fertilizer level.At the two lower P levels,the mycorrhizal plants acquired more P and produced more biomass than non-mycorrhizal plants (3.2 vs.0.9 mg P per plant;1.8 vs.0.9 g biomass per plant at P_(0);14.5 vs.1.7 mg P per plant;and 4.7 vs.1.6 g biomass per plant at P_(50)).At the highest P level,the mycorrhizal plants acquired more P than non-mycorrhizal plants (18.8 vs.13.4 mg per P plant),but there was no difference in biomass (6.2 vs.6.3 g per plant).At the intermediate P level,root diameter was significantly positively correlated with shoot biomass,P concentration and the P content of mycorrhizal plants.The results of our study support the importance of the outsourcing model of P acquisition in the root economics space framework.Inadvertent varietal selection in the last decades,resulting in thinner roots and a lower benefit from AMF,has led to a lower productivity of cotton varieties at moderate P supply (i.e.,when mycorrhizal,the average biomass of older varieties 5.0 g per plant vs.biomass of newer varieties 4.4 g per plant),indicating the need to rethink cotton breeding efforts in order to achieve high yields without very high P input.One feasible way to solve the problem of inadvertent varietal selection for cotton is to be aware of the trade-offs between the root do-it-yourself strategy and the outsourcing towards AMF strategy,and to consider both morphological and mycorrhizal root traits when breeding cotton varieties.

Pre-Breeding Genetic Diversity Assessment of Tomato(Solanum lycopersicum L.)Cultivars Based on Molecular,Morphological and Physicochemical Parameters

Appropriate knowledge of the parental cultivars is a pre-requisite for a successful breeding program.This study characterized fruit yield,quality attributes,and molecular variations of ten tomato cultivars during three consecutive generations under greenhouse conditions.Peto 86,Castle Rock,and Red Star cultivars showed the highest fruit yield(kg/plant),total phenolic compounds(TPC),and sap acidity.Principal component analysis categorized the evaluated fruit yield into three groups based on their quality attributes.A robust positive correlation appeared among traits inside each group.A positive correlation was likewise noticed between the first and the second groups.However,a negative correlation was detected between the first,the second and the third group.Molecular profiling,using seven inter-simple sequence repeat(ISSR)primers,produced 60 loci,including 49 polymorphic loci.The molecular analysis also pinpointed the highest genetic similarity(0.92)between P73 and Moneymaker,while the lowest genetic similarity(0.46)was observed between Castle Rock and Moneymaker.The cultivars P73 and Moneymaker showed the lowest genetic distance(2.24),while the highest genetic distance(5.92)was observed between Super Marmand and Peto86,on the one hand,and between Castle Rock and Moneymaker,on the other hand.The chemical analysis of fruit sap indicated the highest levels of TPC,total flavonoids,anthocyanin,ascorbic acid and total soluble solids in Peto 86 and Castle Rock cultivars.Phylogeny analysis of tomato cultivars based on morphological and molecular attributes indicated four distinct clades.Peto 86,Castle Rock,and Red star cultivars can be recommended for the tomato hybridization breeding programs in the future,with other tomato cultivars as potentially high-yielding parents.

Chemical Composition and Ruminal Digestibility of Ceratoides, a Salt-tolerant Perennial Plant,at Different Years

It has been proposed that salt-tolerant plant could be used as a feed resource for ruminants whereby salt would be removed from salinized land (Asian -Aust. J. Anim. Sci. (2002) 15:998 -1001). Ceratoides arborescens (Losinsk.) Tsien et C. G. Ma is known as a drought-and salt-tolerant plant,a kind of shrubs, growing in semi-arid land of Inner Mongolia. Because the covering effect of the perennial plant as a mulch over the soil might be expected, the optimum covering effect would be obtained after the growth period.The perennial plant produces seeds around summer and end its growth thereafter. Nutrient value of the perennial salt-tolerant plant, however,had not been reported in flowering period at different year. It is necessary to know the ruminal degradability of the plants of each growing year in order to determine the regimen to diet for ruminants. The present experiment,therefore,was undertaken to analyze the digestibility and chemical composition of Ceratoides arborescens as feed for ruminants.

Preliminary Study of Mutation Breeding Combining Heavy Ion Beam Irradiation and Plant Tissue Culture in Taraxacum kok-saghyz

Rubber dandelion(Taraxacum Kok-saghyz,TKS)is a valuable alternative source of natural rubber,thus it is very important and urgent to breed new varieties to increase the biomass or natural rubber content in its roots.

Improving the phenotypic expression of rice genotypes:Rethinking “intensification” for production systems and selection practices for rice breeding

Intensification in rice crop production is generally understood as requiring increased use of material inputs: water, inorganic fertilizers, and agrochemicals. However, this is not the only kind of intensification available. More productive crop phenotypes, with traits such as more resistance to biotic and abiotic stresses and shorter crop cycles, are possible through modifications in the management of rice plants, soil, water, and nutrients, reducing rather than increasing material inputs. Greater factor productivity can be achieved through the application of new knowledge and more skill, and(initially) more labor, as seen from the System of Rice Intensification(SRI), whose practices are used in various combinations by as many as 10 million farmers on about 4 million hectares in over 50 countries. The highest yields achieved with these management methods have come from hybrids and improved rice varieties, confirming the importance of making genetic improvements. However,unimproved varieties are also responsive to these changes, which induce better growth and functioning of rice root systems and more abundance, diversity, and activity of beneficial soil organisms. Some of these organisms as symbiotic endophytes can affect and enhance the expression of rice plants' genetic potential as well as their phenotypic resilience to multiple stresses, including those of climate change. SRI experience and data suggest that decades of plant breeding have been selecting for the best crop genetic endowments under suboptimal growing conditions, with crowding of plants that impedes their photosynthesis and growth, flooding of rice paddies that causes roots to degenerate and forgoes benefits derived from aerobic soil organisms, and overuse of agrochemicals that adversely affect these organisms as well as soil and human health. This review paper reports evidence from research in India and Indonesia that changes in crop and water management can improve the expression of rice plants' genetic potential, thereby creating more productive and robustphenotypes from given rice genotypes. Data indicate that increased plant density does not necessarily enhance crop yield potential, as classical breeding methods suggest. Developing cultivars that can achieve their higher productivity under a wide range of plant densities—breeding for density-neutral cultivars using alternative selection strategies—will enable more effective exploitation of available crop growth resources. Density-neutral cultivars that achieve high productivity under ample environmental growth resources can also achieve optimal productivity under limited resources, where lower densities can avert crop failure due to overcrowding. This will become more important to the extent that climatic and other factors become more adverse to crop production. Focusing more on which management practices can evoke the most productive and robust phenotypes from given genotypes is important for rice breeding and improvement programs since it is phenotypes that feed our human populations.

The apple REFPOP—a reference population for genomics-assisted breeding in apple

Breeding of apple is a long-term and costly process due to the time and space requirements for screening selection candidates.Genomics-assisted breeding utilizes genomic and phenotypic information to increase the selection efficiency in breeding programs,and measurements of phenotypes in different environments can facilitate the application of the approach under various climatic conditions.Here we present an apple reference population:the apple REFPOP,a large collection formed of 534 genotypes planted in six European countries,as a unique tool to accelerate apple breeding.The population consisted of 269 accessions and 265 progeny from 27 parental combinations,representing the diversity in cultivated apple and current European breeding material,respectively.A high-density genome-wide dataset of 303,239 SNPs was produced as a combined output of two SNP arrays of different densities using marker imputation with an imputation accuracy of 0.95.Based on the genotypic data,linkage disequilibrium was low and population structure was weak.Two well-studied phenological traits of horticultural importance were measured.We found marker–trait associations in several previously identified genomic regions and maximum predictive abilities of 0.57 and 0.75 for floral emergence and harvest date,respectively.With decreasing SNP density,the detection of significant marker–trait associations varied depending on trait architecture.Regardless of the trait,10,000 SNPs sufficed to maximize genomic prediction ability.We confirm the suitability of the apple REFPOP design for genomics-assisted breeding,especially for breeding programs using related germplasm,and emphasize the advantages of a coordinated and multinational effort for customizing apple breeding methods in the genomics era.

Mapping and validation of the epistatic D and P genes controlling anthocyanin biosynthesis in the peel of eggplant (Solanum melongena L.) fruit

Fruit color is an important trait inf luencing the commercial value of eggplant fruits.Three dominant genes(D,P and Y)cooperatively control the anthocyanin coloration in eggplant fruits,but none has been mapped.In this study,two white-fruit accessions(19141 and 19147)and their F2 progeny,with 9:7 segregation ratio of anthocyanin pigmented versus non-pigmented fruits,were used for mapping the D and P genes.A high-density genetic map was constructed with 5270 SNPs spanning 1997.98 cM.Three QTLs were identified,including two genes on chromosome 8 and one on chromosome 10.Gene expression analyses suggested that the SmANS on chromosome 8 and SmMYB1 on chromosome 10 were the putative candidate genes for P and D,respectively.We further identified(1)a SNP leading to a premature stop codon within the conserved PLN03176 domain of SmANS in 19141,(2)a G base InDel in the promoter region leading to an additional cis-regulatory element and(3)a 6-bp InDel within the R2-MYB DNA binding domain of SmMYB1,in 19147.Subsequently,these three variations were validated by PARMS technology as related to phenotypes in the F2 population.Moreover,silencing of SmANS or SmMYB1 in the purple red fruits of F1(E3316)led to inhibition of anthocyanin biosynthesis in the peels.Conversely,overexpression of SmANS or SmMYB1 restored anthocyanin biosynthesis in the calli of 19141 and 19147 respectively.Our findings demonstrated the epistatic interactions underlying the white color of eggplant fruits,which can be potentially applied to breeding of eggplant fruit peel color.

Breeding polyploid Populus:progress and perspective

Populus is a genus of 25−30 species of deciduous flowering plants in the family Salicaceae,which are primarily planted in short-rotation planations for producing timber,pulpwood,wooden products as well as bioenergy feedstock;they are also widely planted in agricultural fields and along roadsides as shelter forest belts for windbreak,decoration,and reduction of pollutants and noise.Moreover,their fast-growth and good adaptation to marginal lands enable them to provide some critical ecosystem services at various phytoremediation sites for land restoration and reclaimation.Thanks to their important roles,breeding for fast growing poplar trees has been one of the most important objectives for nearly a century.One of the most demonstrated,documented achievements in this aspect is polyploid breeding,especially triploid breeding.This paper critically reviews the various techniques used in inducing triploid plants,including natural 2n formation,artificial induction of 2n male and female gemmates through chemical or physical treatments,trait characterization of the triploid and tetraploid breeding populations,unveiling the molecular mechanisms underpinning the significantly improved traits,and identification and selection of the best triploid progenies.This review also recapitulated the challenges and strategies facing the future of triploid breeding in Populus,including amelioration of 2n gamete induction techniques and efficiency,selection of the best parents and identification of the best progrenies,utilization of the huge amount of genomic,transcriptomic,proteomic,metabolomic,and other omics data for selecting parents for improving target traits.

Breeding and Cultivation Technique of Ditian 6

Ditian 6 is super sweet corn hybrid. Its parents are inbred line 201-2 and 769 respectively. It was certificated by Variety Certification Committee of Shanxi Province in 2013. Ditian 6 participated in regional trials of Shanxi Province in 2010 and 2011. The average fresh ear yield is 14257. 5 kg / ha. Its growth period is 81 d,belonging to the early variety. It has obvious advantages if it is early cultivated. The kernel is yellow,and the quality reaches a high level. In the early or late market,it has significant economic benefits. The variety has strong resistance to disease and adversity,with wide adaptability,high and stable yield. It can be planted in the areas where accumulated temperature is above 2300℃.

Advances in Transgenic Vegetable and Fruit Breeding

Vegetables and fruits are grown worldwide and play an important role in human diets because they provide vitamins, minerals, dietary fiber, and phytochemicals. Vegetables and fruits are also associated with improvement of gastrointestinal health, good vision, and reduced risk of heart disease, stroke, chronic diseases such as diabetes, and some forms of cancer. Vegetable and fruit production suffers from many biotic stresses caused by pathogens, pests, and weeds and requires high amounts of plant protection products per hectare. United States vegetables farmers are benefiting from growing transgenic squash cultivars resistant to Zucchini yellow mosaic virus, Watermelon mosaic virus, and Cucumber mosaic virus, which were deregulated and commercialized since 1996. Bt-sweet corn has also proven effective for control of some lepidopteran species and continues to be accepted in the fresh market in the USA, and Bt-fresh-market sweet corn hybrids are released almost every year. Likewise, transgenic Bt-eggplant bred to reduce pesticide use is now grown by farmers in Bangladesh. Transgenic papaya cultivars carrying the coat-protein gene provide effective protection against Papaya ring spot virus elsewhere. The transgenic “Honey Sweet” plum cultivar provides an interesting germplasm source for Plum pox virus control. Enhanced host plant resistance to Xanthomonas campestris pv. musacearum, which causes the devastating banana Xanthomonas wilt in the Great Lakes Region of Africa, was achieved by plant genetic engineering. There are other vegetable and fruit crops in the pipeline that have been genetically modified to enhance their host plant resistance to insects and plant pathogens, to show herbicide tolerance, and to improve features such as slow ripening that extends the shelf-life of the produce. Consumers could benefit further from eating more nutritious transgenic vegetables and fruits. Transgenic plant breeding therefore provides genetically enhanced seed embedded technology that contributes to integrated pest management in horticulture by reducing pesticide sprays as well as improving food safety by minimizing pesticide residues. Furthermore, herbicide-tolerant transgenic crops can help reducing plough in fields, thereby saving fuel because of less tractor use, which also protects the structure of the soil by reducing its erosion. Transgenic vegetable and fruit crops could make important contributions to sustainable vegetable production and for more nutritious and healthy food. Countries vary, however, in their market standards of acceptance of transgenic crops. Biotechnology products will be successful if clear advantages and safety are demonstrated to both growers and consumers.

Cost and accuracy of advanced breeding trial designs in apple

Trialing advanced candidates in tree fruit crops is expensive due to the long-term nature of the planting and labor-intensive evaluations required to make selection decisions.How closely the trait evaluations approximate the true trait value needs balancing with the cost of the program.Designs of field trials of advanced apple candidates in which reduced number of locations,the number of years and the number of harvests per year were modeled to investigate the effect on the cost and accuracy in an operational breeding program.The aim was to find designs that would allow evaluation of the most additional candidates while sacrificing the least accuracy.Critical percentage difference,response to selection,and correlated response were used to examine changes in accuracy of trait evaluations.For the quality traits evaluated,accuracy and response to selection were not substantially reduced for most trial designs.Risk management influences the decision to change trial design,and some designs had greater risk associated with them.Balancing cost and accuracy with risk yields valuable insight into advanced breeding trial design.The methods outlined in this analysis would be well suited to other horticultural crop breeding programs.

Characterization of the petiole length in soybean compact architecture mutant M657 and the breeding of new lines

Phenotypic screening of soybean germplasm suitable for high planting density is currently the most viable strategy to increase yield. Previous studies have shown that soybean varieties with dwarf features and a short petiole often exhibit a compact plant architecture which could improve yield through increased planting density, although previously reported short petiole accessions were ultimately not usable for breeding in practice. Here, we established a method to assess petiole length and identified an elite mutant line, M657, that exhibits high photosynthetic efficiency. The agronomic traits of M657 were evaluated under field conditions, and appeared to be stable for short petiole across seven locations in northern, Huang–Huai, and southern China from 2017 to 2018. Compared with the Jihuang 13 wild type, the mutant M657 was shorter in both petiole length and plant height, exhibited lower total area of leaf, seed weight per plant and 100-seed weight, but had an increased number of effective branches and the growth period was prolonged by 2–7 days. Using M657 as a parental line for crosses with four other elite lines, we obtained four lines with desirable plant architecture and yield traits, thus demonstrating the feasibility of adopting M657 in breeding programs for soybean cultivars of high density and high yield.