Excellent Agronomic Traits Research Articles

Brassica carinata genome characterization clarifies U's triangle model of evolution and polyploidy in Brassica.

Ethiopian mustard (Brassica carinata) in the Brassicaceae family possesses many excellent agronomic traits. Here, the high-quality genome sequence of B. carinata is reported. Characterization revealed a genome anchored to 17 chromosomes with a total length of 1.087 Gb and an N50 scaffold length of 60 Mb. Repetitive sequences account for approximately 634 Mb or 58.34% of the B. carinata genome. Notably, 51.91% of 97,149 genes are confined to the terminal 20% of chromosomes as a result of the expansion of repeats in pericentromeric regions. Brassica carinata shares one whole-genome triplication event with the five other species in U's triangle, a classic model of evolution and polyploidy in Brassica. Brassica carinata was deduced to have formed ∼0.047 Mya, which is slightly earlier than B. napus but later than B. juncea. Our analysis indicated that the relationship between the two subgenomes (BcaB and BcaC) is greater than that between other two tetraploid subgenomes (BjuB and BnaC) and their respective diploid parents. RNA-seq datasets and comparative genomic analysis were used to identify several key genes in pathways regulating disease resistance and glucosinolate metabolism. Further analyses revealed that genome triplication and tandem duplication played important roles in the expansion of those genes in Brassica species. With the genome sequencing of B. carinata completed, the genomes of all six Brassica species in U's triangle are now resolved. The data obtained from genome sequencing, transcriptome analysis, and comparative genomic efforts in this study provide valuable insights into the genome evolution of the six Brassica species in U's triangle.

Comparative proteomic analysis reveals that the Heterosis of two maize hybrids is related to enhancement of stress response and photosynthesis respectively

BackgroundHeterosis refers to superior traits exhibiting in a hybrid when compared with both parents. Generally, the hybridization between parents can change the expression pattern of some proteins such as non-additive proteins (NAPs) which might lead to heterosis. ‘Zhongdan808’ (ZD808) and ‘Zhongdan909’ (ZD909) are excellent maize hybrids in China, however, the heterosis mechanism of them are not clear. Proteomics has been wildly used in many filed, and comparative proteomic analysis of hybrid and its parents is helpful for understanding the mechanism of heterosis in the two maize hybrids.ResultsOver 2000 protein groups were quantitatively identified from second seedling leaves of two hybrids and their parents by label-free quantification. Statistical analysis of total identified proteins, differentially accumulated proteins (DAPs) and NAPs of the two hybrids revealed that both of them were more similar to their female parents. In addition, most of DAPs were up-regulated and most of NAPs were high parent abundance or above-high parent abundance in ZD808, while in ZD909, most of DAPs were down-regulated and most of NAPs were low parent abundance or below-low parent abundance. Pathway enrichment analysis showed that more of stress response-related NAPs in ZD808 were high parent abundance or above-high parent abundance, and most of PS related NAPs in ZD909 were high parent abundance or above-high parent abundance. Finally, four stress response-related proteins and eight proteins related to PS were verified by PRM, ten of them had significant differences between hybrid and midparent value.ConclusionsEven though every one of the two hybrids were more similar to its female parent at proteome level, the biological basis of heterosis is different in the two maize hybrids. In comparison with their parents, the excellent agronomic traits of hybrid ZD808 is mainly correlated with the high expression levels of some proteins related to stress responses and metabolic functions, while traits of ZD909 is mainly correlated with high expressed proteins related to photosynthesis. Our proteomics results support previous physiological and morphological research and have provided useful information in understanding the reason of valuable agronomic traits.

Purple-fleshed sweet potato genotypes as the ingredients for crisps and noodle making

The presence of anthocyanins in purple-fleshed sweet potato has been intensively promoted as functional foods regarding its high antioxidant activity and essential health benefits. Therefore, a number of attractive and nutritious food products needs to be developed in order to diversify the utilization and increase the consumption. As selected promising purple-flesh sweet potato genotypes have been available, their suitability prepared for different food products needs to be studied. About 12 genotypes of sweet potato with varied purple color intensity or deepness were processed into crispy chips (crisps) and noodles and evaluated their physical properties (yield, lightness, hardness) and sensorial attributes (color, aroma, texture, taste) using a Hedonic test with 20 panelists. The results showed that sweet potato genotypes with purple flesh in combination with yellow/orange or white color, namely MSU 06046-74, Antin 1, and MSU 06044-05 were suitable for crisps making, followed by those with medium purple color, such as Aya Murasaki, MIS 0612-73, MIS 0614-02, MIS 0601-22, and MSU 06014-51. Conversely, sweet potato with deep purple color, namely MSU 06028-71 and MSU 06046-48 were tailored for the ingredients of noodles. This information would be useful for releasing new purple sweet potato varieties in addition to their excellent agronomic traits.

Fertility recovery of wheat male sterility controlled by Ms2 using CRISPR/Cas9.

Fertility recovery of wheat male sterility controlled by Ms2 using CRISPR/Cas9.

Evaluation of cowpea for drought tolerance at seedling stage

Cowpea is a health-promoting diploid legume species [Vigna unguiculata (L.) Walp., 2n = 2x = 22]. The annual cowpea production is 5.4 million tons of dry seed globally. Despite the fact that cowpea is one of the most drought-tolerant crops, some genotypes with excellent agronomic traits such as high yield under sufficient water supplies have been reported to be highly drought-susceptible, thus still requiring the need for breeding drought-tolerant cowpea genotypes. Therefore, the objectives of this study were to evaluate drought tolerance in cowpea at seedling stage and to identify drought-tolerant cowpea genotypes. In this study, a total of 331 cowpea genotypes were evaluated for drought tolerance at seedling stage. The experiment was conducted in a greenhouse and repeated 3 times. Drought tolerance phenotyping was conducted using a previously described methodology and a total of 11 traits were analyzed. The experiment was validated by the use of drought-tolerant and susceptible controls. Results showed that: (1) a large variation in the evaluated traits for drought tolerance was identified among the 331 cowpea genotypes, (2) a high correlation was found for traits such as plant greenness score and tolerance to trifoliate leaf chlorosis under drought stress (r = 0.8), whereas no linear correlation was found for traits such as tolerance to trifoliate leaf chlorosis and unifoliate leaf SPAD chlorophyll under non-drought stress (r = 0.0), (3) a total of 21 genotypes were found to be drought-tolerant across different traits, and (4) country of origins could impact drought tolerance in cowpea. The top performing genotypes were repeated using an independent experiment to further validate the data. The results from this study would be of interest in breeding programs aiming at improving drought tolerance in cowpea.

Transfer of the ph1b gene of ‘Chinese Spring’ into a common wheat cultivar with excellent traits

In wheat/alien species hybrids, pairing homoeologous (Ph1) suppresses the pairing and recombination of wheat and alien chromosomes. Ph1b has been found to be the most effective allele in inducing meiotic homoeologous pairing/recombination and is widely used in gene introgression from wild Triticeae species into wheat. However, due to the poor agronomic traits of the ‘Chinese Spring’ ph1b (CS ph1b) mutant, which is more susceptible to disease, the application of CS ph1b is limited. In this study, we transferred the ph1b gene from the CS mutant to a commercial cultivar Shumai 126 (SM126), which has excellent agronomic traits, by crossing and continuous backcrossing. The results showed that the ph1b was present in 11 lines in the BC2F2 generation and was transferred to SM126. Further study indicated that seven homozygous ph1b mutant allele lines were identified from the BC2F3 generation. Two of these lines, SM126ph1b line 1 and 24, are homozygous at loci encoding high molecular weight glutenin subunits (HMW-GS) and the Wx protein, and the line 24 possesses the excellent agronomic traits of SM126. The results of meiotic metaphase I pairing showed that the SM126ph1b pollen mother cells (PMCs) are slightly higher pairing than the level of the original CSph1b stock. A progeny line of wild cross between wheat and Aegilops sharonensis was crossed with CSph1b and line 24 of SM126ph1b, respectively; the results of ND-FISH further proved that SM126ph1b and CSph1b have same effect on inducing homoeologous pairing/recombination, which will facilitate the use of wheat alien chromosome recombinations in wheat improvement.

Metabolic Engineering a Model Oilseed Camelina sativa for the Sustainable Production of High-Value Designed Oils

Camelina sativa (L.) Crantz is an important Brassicaceae oil crop with a number of excellent agronomic traits including low water and fertilizer input, strong adaptation and resistance. Furthermore, its short life cycle and easy genetic transformation, combined with available data of genome and other “-omics” have enabled camelina as a model oil plant to study lipid metabolism regulation and genetic improvement. Particularly, camelina is capable of rapid metabolic engineering to synthesize and accumulate high levels of unusual fatty acids and modified oils in seeds, which are more stable and environmentally friendly. Such engineered camelina oils have been increasingly used as the super resource for edible oil, health-promoting food and medicine, biofuel oil and high-valued chemical production. In this review, we mainly highlight the latest advance in metabolic engineering towards the predictive manipulation of metabolism for commercial production of desirable bio-based products using camelina as an ideal platform. Moreover, we deeply analysis camelina seed metabolic engineering strategy and its promising achievements by describing the metabolic assembly of biosynthesis pathways for acetyl glycerides, hydroxylated fatty acids, medium-chain fatty acids, ω-3 long-chain polyunsaturated fatty acids, palmitoleic acid (ω-7) and other high-value oils. Future prospects are discussed, with a focus on the cutting-edge techniques in camelina such as genome editing application, fine directed manipulation of metabolism and future outlook for camelina industry development.

Diversity of a Large Collection of Natural Populations of Mango (Mangifera indica Linn.) Revealed by Agro-Morphological and Quality Traits

Collection, characterization and utilization of genetic resources are crucial for developing varieties to meet current and future needs. Although mango is an economically important fruit tree, its genetic resources are still undocumented and are threatened in their natural habits. In this study, the variability of 452 mango accessions from three regions in China (Nujiang, Lancang river and Honghe) was assessed using 41 descriptors including qualitative and quantitative traits, with the aim to identify mango accessions with excellent agronomic and quality traits. To this end, descriptive and multivariate analyses were performed. Based on Shannon–Weaver diversity index, qualitative traits including pericarp color, fruit aroma, flesh color, and fruit flavor recorded the highest variability in the germplasm. Fruit related traits including pulp weight, peel weight, and fruit weight were the most diverse traits in the germplasm with a high coefficient of variation (CV > 40%). Significant differences (MANOVA test, p < 0.000) were observed among the three regions for most of the quantitative traits. Biologically significant and positive correlations were found among agronomically important traits such as fruit weight and pulp weight, fruit weight and edible rate. The hierarchical cluster analysis revealed tree clusters, indicating a low diversity in the germplasm. The majority of the descriptors contributed to the differentiation of the accessions. Accessions with good fruits quality (high fruit weight, pulp weight, and edible rate) were found in Cluster 2. Accessions in this cluster could be used for fruit quality improvement in mango breeding programs. Our study sheds light on the diversity of a large collection of natural mango population in China and provides relevant information for efficient conservation and harnessing of mango genetic resources.

Research Status and Prospect of QTL Mapping for Tillers and Other Traits in Forage Sorghum

Forage sorghum is an important raw material for winemaking and livestock feed. It has many excellent agronomic traits. Its genome-wide sequencing work has been completed. Molecular marker-assisted selection technology is widely used in sorghum breeding work. The number of genetic loci affecting the sorghum agronomic traits has been Be positioned. Tillering, as an important plant type trait, has an important influence on the physiological characteristics of sorghum, such as the tolerance, lodging resistance and light absorption efficiency. At present, considerable progress has been made in gene mapping of plant height, ear length, leaf morphology and other traits of forage sorghum. However, the progress of gene mapping for tillering is relatively slow due to the fact that tillering traits are easily affected by various factors. This study summarized the recent research progress of QTL mapping for tillering traits and other agronomic traits in sorghum, and proposed that some conserved sequences with high homology were retained during the evolution of different crop varieties, which proved that there was correlation between different traits of the same species. In sorghum breeding research, combining genetic engineering breeding with experimental statistics and quantitative genetics can better reveal the contribution of various factors to sorghum agronomic traits, improve breeding efficiency and reduce the loss of human and material resources.

Construction of high-density bin map and QTL mapping of horticultural traits from an interspecific cross between Capsicum annuum and Chinese wild Capsicum frutescens

Chinese wild pepper (Capsicum frutescens L.) acts as a source of genetic variability for cultivated pepper breeding. High-resolution quantitative train locus (QTL) mapping is essential for identifying genetic regions related to important phenotype variation. In this study, a set of 120 F2 populations derived from a cross between cultivar Capsicum annuum ‘007EA’ and the wild relative Capsicum frutescens ‘P1512’ (Chinese wild pepper) were generated, and genotyping was performed with genotyping-by-sequencing. Next, an interspecific high-density genetic map containing 3708 bins was constructed using a sliding window approach. The genetic distance of the total map was 5601.79 cM, and the average interval between bins was 1.51 cM. Based on the genetic map, a QTL analysis of the pepper horticultural traits was performed. A total of 25 significant QTLs controlling nine horticultural traits were detected on 12 linkage groups (LGs), and contributed values of phenotypic variance explained (PVE) ranging from 1.90% to 59.03%, with LOD scores ranging from 4.2 to 24.6. In addition, the QTLs for the main stem length, flowering date and numbers of leaves were observed at the same position. Next, we mapped a set of significant QTLs for yield-related traits and other horticultural traits in pepper, based on a high-density genetic linkage map, using GBS. These genetic map and markers are valuable genomic resources for marker-assisted selection (MAS) of excellent agronomic traits and will provide a basis for further fine mapping and comparative genomics research involving pepper.

Mutation at Different Sites of Metal Transporter Gene OsNramp5 Affects Cd Accumulation and Related Agronomic Traits in Rice (Oryza sativa L.).

OsNramp5 is a key gene involved in the control of the uptake of Cd, Mn, and other metal ions by rice root cells. The functional deficiency of this gene can significantly reduce the accumulation of Cd in rice grains, but the effects of its mutation on agronomic traits such as yield and quality have not been investigated comprehensively yet. In the present study, three Huanghuazhan-based OsNramp5 mutants [LCH1 (Low Cadmium Huanghuazhan 1), LCH2 (Low Cadmium Huanghuazhan 2), and LCH3 (Low Cadmium Huanghuazhan 3)] were obtained using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) technology. The mutation-type analysis showed that LCH1, LCH2, and LCH3 encoded defective OsNramp5 protein sequences containing only 76aa, 176aa, and 266aa, respectively. The determination of metal content and the statistics of related agronomic traits revealed that the functionally deficient OsNramp5 not only significantly reduced the accumulation of Cd in the grains of the mutants but also affected rice yield and quality. However, with the decrease of OsNramp5 mutation degree, its effects on chlorenchyma Mn accumulation, yield, and quality were also diminished. Additionally, we also found that the increase in the concentration of Mn in the soil restored the phenotype of the declined yield and quality due to the functional deficiency of OsNramp5. Our findings provide novel insights into and new materials for breeding rice varieties with low Cd accumulation and excellent agronomic traits under severe Cd pollution environment.

Leucaena cultivars – current releases and future opportunities

Plenary paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.The Leucaena genus is made up of 24 different species (19 diploid and 5 tetraploid species). However, early use of the Leucaena genus in commercial agricultural systems was based entirely upon a very narrow germplasm base. A single genotype of Leucaena leucocephala ssp. leucocephala (‘common’ leucaena) was spread pantropically from its center of origin in Mexico over 400 years ago. Genetic improvement of Leucaena leucocephala began in the 1950s, when vigorous ‘giant’ leucaena (L. leucocephala ssp. glabrata) was identified in Australia and Hawaii. Cultivars such as Hawaiian Giant K8, Peru and El Salvador were selected and promoted for grazing in Australia and multipurpose agroforestry uses throughout the tropics. Plant breeding for improved forage production resulted in the release of cv. Cunningham in 1976 in Australia. These cultivars of ‘giant’ Leucaena leucocephala displayed broad environmental adaptability, with the exception of poor tolerance of cold temperatures (and frost) and acid soils. The outbreak of the psyllid insect pest (Heteropsylla cubana) from Cuba during the 1980s devastated both ‘common’ and ‘giant’ leucaena all around the world. This challenge resulted in renewed interest in lesser-known Leucaena spp. that exhibited tolerance to the pest and in interspecific hybridization as a means of developing new cultivars. Some ‘giant’ leucaena lines exhibited excellent agronomic traits and a degree of tolerance to the psyllid pest and this resulted in the release of new cultivars in Australia (cvv. Tarramba and Wondergraze) and Hawaii (cv. LxL). Since the 1990s, plant breeding programs have sought to develop cultivars with greater psyllid tolerance using interspecific hybridization. This has resulted in the release of cv. ‘KX2-Hawaii’ for timber and forage production, and a backcrossed forage cultivar cv. Redlands (Australia). Both cultivars are based upon interspecific hybridization between L. pallida and L. leucocephala ssp. glabrata. Cold-temperature and acid-soil tolerance have been pursued in South American breeding programs based upon L. diversifolia, without commercial success. The development of sterile Leucaena spp. cultivars is currently underway to nullify the environmental weed potential of all current commercial cultivars. Tolerance to cold temperatures (L. diversifolia, L. pallida, L. pulverulenta and L. trichandra), frost (L. greggii and L. retusa) and psyllids (L. collinsii) exists within the Leucaena genus and may be exploited in future hybridization programs. New genetic analyses and molecular plant breeding techniques have the potential to facilitate further gene transfer between Leucaena spp. for the development of the next generation of multipurpose cultivars.

The Quality Evaluation of Tea (Camellia sinensis) Varieties Based on the Metabolomics

The identification and evaluation of tea [Camellia sinensis (L.) O. Kuntze] germplasm resources are of great significance for tea plant breeding. In recent years, various methods, such as morphology, biochemistry, molecular markers, and sensory evaluation, have been used to evaluate the tea germplasm resources. However, the evaluation of tea germplasms based on metabolomics is rarely reported. In this study, we first measured the main agronomic characters and biochemical components of tea young shoots in spring, and then analyzed the metabolic profiles using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography with tandem mass spectrometry (LC-MS/MS). The results indicate that tea germplasm accessions QN3 and QN38 had excellent agronomic traits with early germination and high yield compared with HM. The biosynthesis of flavonoids in young shoots of QN3 was more vigorous, especially for the biosynthesis of epigallocatechin gallate (EGCG) and epicatechin gallate (ECG). Accession QN3 had highest content of luteoloside, myricetin and rutin, whereas QN38 had highest content of most amino acids. On the basis of sensory quality evaluation, accession QN3 and QN38 all had higher total quality scores. By using these approaches, we found that QN3 and QN38 are excellent breeding materials with high yield and high quality for making green teas. We also believe that the evaluation system constructed by the approaches described here is suitable for the identification of tea germplasms.

Genomic divergence in cotton germplasm related to maturity and heterosis.

Commercial varieties of upland cotton (Gossypium hirsutum) have undergone extensive breeding for agronomic traits, such as fiber quality, disease resistance, and yield. Cotton breeding programs have widely used Chinese upland cotton source germplasm (CUCSG) with excellent agronomic traits. A better understanding of the genetic diversity and genomic characteristics of these accessions could accelerate the identification of desirable alleles. Here, we analyzed 10,522 high-quality single-nucleotide polymorphisms (SNP) with the CottonSNP63K microarray in 137 cotton accessions (including 12 hybrids of upland cotton). These data were used to investigate the genetic diversity, population structure, and genomic characteristics of each population and the contribution of these loci to heterosis. Three subgroups were identified, in agreement with their known pedigrees, geographical distributions, and times since introduction. For each group, we identified lineage-specific genomic divergence regions, which potentially harbor key alleles that determine the characteristics of each group, such as early maturity-related loci. Investigation of the distribution of heterozygous loci, among 12 commercial cotton hybrids, revealed a potential role for these regions in heterosis. Our study provides insight into the population structure of upland cotton germplasm. Furthermore, the overlap between lineage-specific regions and heterozygous loci, in the high-yield hybrids, suggests a role for these regions in cotton heterosis.

Registration of ‘TUFRunner ‘297’ ’ Peanut

‘TUFRunner ‘297” (Reg. No. CV‐135, PI 674183) is a large‐seeded, high‐oleic, runner market‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar developed by the University of Florida, Florida Agricultural Experiment Station, North Florida Research and Education Center near Marianna, FL. It was tested under the experimental designation UF12303 and was approved for release in 2014. TUFRunner ‘297’ has a semiprostrate growth habit, with a tall and prominent center stem and medium green leaves. The testa of TUFRunner ‘297’ seed are tan in color, and the seeds are slightly larger than those of ‘Georgia‐06G’, the dominant cultivar in the southeastern United States (83.7 vs. 76.7 g 100 seed−1, P < 0.0001). TUFRunner ‘297’ was released for its pod yield potential, grading potential, disease resistance, and high‐oleic oil chemistry. Over the 6‐yr period from 2010 to 2015, in three Florida locations, TUFRunner ‘297’ had higher pod yield (7270 vs. 6890 kg ha−1, P = 0.004) than Georgia‐06G. The total sound mature kernels grade of TUFRunner ‘297’ was slightly less than that of Georgia‐06G (77.9 vs. 79.4%, P < 0.0001). TUFRunner ‘297’ also has the benefit of high oleic oil chemistry, in which its oil is 76.6% oleic fatty acid compared with 60.8% for Georgia‐06G (P < 0.001). TUFRunner ‘297’ combines excellent agronomic, grade, disease, and oil chemistry traits and should be beneficial to farmers and manufacturers of peanut foods.

Drought resistance of new synthetic hexaploid wheat accessions evaluated by multiple traits and antioxidant enzyme activity

Drought is a severe threat to wheat production. Synthetic hexaploid wheat (SHW, AABBDD) has great potential for improving resistance to various stresses of bread wheat. The drought resistance of thirty-four new SHWs and a control (bread wheat cultivar Jinmai47) were evaluated under two water regimes, i.e., well watered (WW) and water stressed (WS), in two consecutive years. Compared with the cultivar Jinmai47 under WW conditions, SHWs displayed increased plant height (PH), larger flag leaf area (FLA), longer spikes (SL) and more biomass plant−1 (BMPP), but SHWs displayed fewer grains spike−1 (GNPS) and less thousand-grain weight (TGW), resulting in lower grain yield plant−1 (GYPP) and a lower harvest index (HI). The membership function value of drought resistance (MFVD) analysis and drought resistance index (DI) under the two water regimes revealed six SHW lines (SHW1, SHW3, SHW10, SHW16, SHW21 and SHW34) identified with higher drought resistance. Our results also showed higher activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT), in WS plots than in WW plots. SHWs with higher drought resistance exhibited higher activities of antioxidant enzymes (SOD, POX and CAT) in both WW and WS plots. SHWs exhibiting excellent agronomic traits and increased drought resistance could further be applied to stress resistance studies and wheat breeding programmes.

Molecular Cytogenetic Characterization of Novel Wheat-rye T1RS.1BL Translocation Lines with High Resistance to Diseases and Great Agronomic Traits.

Rye has been used worldwide as a source for the genetic improvement of wheat. In this study, two stable wheat-rye primary T1RS.1BL translocation lines were selected from the progeny of the crossing of the wheat cultivar Mianyang11-1 and a Chinese local rye variety, Weining. These two novel translocation lines were identified by molecular cytogenetic analysis. PCR results, multi-color fluorescence in situ hybridization (MC-FISH), and acid polyacrylamide gel electrophoresis (A-PAGE) indicated that both new translocation lines harbor a pair of T1RS.1BL translocation chromosomes, and have been named RT828-10 and RT828-11, respectively. The cytogenetic results also indicated that the pSc119.2 signals of 5AL were absent in both lines along with the pSc119.2 signals of 4AL of RT828-11. When inoculated with different stripe rust and powdery mildew isolates, both lines expressed high resistance to Puccinia striiformis f. sp. tritici and Blumeria graminis f. sp. tritici pathotypes, which are prevalent in China and are virulent on Yr9 and Pm8. The line RT828-11 also exhibited excellent agronomic traits in the field. The present study indicates that this rye variety may carry untapped variations that could potentially be used for wheat improvement.

Genome-wide indel/SSR scanning reveals significant loci associated with excellent agronomic traits of a cabbage (Brassica oleracea) elite parental line \u201801\u201320\u2019

Elite parental lines are of great significance to crop breeding. To discover unique genomic loci associated with excellent economic traits in the elite cabbage inbred-line ‘01–20’, we performed comparisons of phenotypes as well as whole-genome insertion-deletion/simple sequence repeat loci between ‘01–20’ and each of its five sister lines. ‘01–20’ has a range of excellent agronomic traits, including early-maturing, and improvements in plant type and leaf colour. Eight unique loci were discovered for ‘01–20’ and ‘01-07-258’, another elite line similar to ‘01–20’ at the whole-genome level. In addition, two excellent double-haploid lines derived from a cross of ‘01–20’ also inherited these loci. Based on the quantitative trait locus association results, five of these loci were found to be associated with important agronomic traits, which could explain why the elite parent ‘01–20’ possesses greener outer leaves, a more compact and upright plant-type, rounder head, shorter core length, and better taste. Additionally, some of these loci have clustering effects for quantitative trait loci associated with different traits; therefore, important genes in these regions were analysed. The obtained results should enable marker-assisted multi-trait selection at the whole-genome level in cabbage breeding and provide insights into significant genome loci and their breeding effects.

Estimación de aptitud combinatoria de líneas endogámicas y predicción de híbridos de maíz de alta calidad de proteína, Guatemala, 1988

Yellow grain hybrids of high quality protein can provide a comparative advantage because carotenes found in these materials are more easily taken up compared to normal hybrids. This advantage could provide added benefits within the poultry Industry. In this study, 91 possible crosses coming from 14 endogamic lines from the CIMMYT maize hybrid program were evaluated. The single crosses demonstrated superior adaptation notable in the coastal plain of Guatemala having grain yields approaching 7.0 Mg/ha along with excellent agronomic traits, decreased ear rot and uniform plant type. Superior hybrids demonstrated increased yields (average increase of I Mg/ha) versus the best natural check. Inbred parents 2, 1 and 6 demonstrated the highest values for general combinability and they were also amongst the best specific crosses. The yield levels, agronomic characteristics and the expression of stability in the modified endosperm of the single crosses that can be used as females to produce seed for double and three way crosses, suggests anew production alternative that could enhance the use of yellow grain hybrids of high protein quality in the tropical lowlands of Guatemala.

An intercalary translocation from Agropyron cristatum 6P chromosome into common wheat confers enhanced kernel number per spike.

This study explored 6P chromosomal translocations in wheat, and determined the effects of 6P intercalary chromosome segments on kernel number per wheat spike. Exploiting and utilising gene(s) from wild relative species has become an essential strategy for wheat crop improvement. In the translocation line Pubing2978, the intercalary 6P chromosome segment from Agropyron cristatum (L.) Gaertn. (2n=4x=28, PPPP) carried valuable multi-kernel gene(s) and was selected from the offspring of the common wheat plant Fukuho and the irradiated wheat-A. cristatum 6P disomic substitution line 4844-8. Genomic in situ hybridisation (GISH), dual-colour fluorescence in situ hybridisation (FISH), and molecular markers were used to detect the small segmental 6P chromosome in the wheat background and its translocation breakpoint. Cytological studies demonstrated that Pubing2978 was a T1AS-6PL-1AS·1AL intercalary translocation with 42 chromosomes. The breakpoint was located near the centromeric region on the wheat chromosome 1AS and was flanked by the markers SSR12 and SSR283 based on an F2 linkage map. The genotypic data, combined with the phenotypic information, implied that A. cristatum 6P chromosomal segment plays an important role in regulating the kernel number per spike (KPS). By comparison, the mean value of KPS in plants with translocations was approximately 10 higher than that in plants without translocations in three segregated populations. Moreover, the improvement in KPS was likely achieved by increasing both the spikelet number per spike (SNS) and the kernel number per spikelet. These excellent agronomic traits laid the foundation for further investigation of valuable genes and make the Pubing2978 line a promising germplasm for wheat breeding.