Category Archives: Wiley: Plant Breeding

Flavour improvement in early generations of fresh market tomatoes (Solanum lycopersicum): I. Identification of QTL for sensory attributes, physicochemical measurements and volatile compounds

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Abstract

Human sensory analysis is the most appropriate method for assessing the flavour of fresh market tomatoes, but it is very labour and time consuming. Therefore, sensory attributes are often neglected in early generations of breeding programmes and genetic studies, although there is a demand for tomatoes with improved flavour. In this study, the recently developed Breeders' Sensory Test was applied to an F2 mapping population derived from two parents with superior flavour. Sensory attributes, physicochemical measurements, volatiles and fruit weight were assessed in organic low-input and hydroponic cultivation. A linkage map spanning 1070 cM was developed. In total, 71 quantitative trait loci (QTL) were detected for the means of both cultivation systems, 61 for organic and 46 for hydroponic cultivation. A proportion of 27% of the loci were co-localized between both cultivation systems. Nine distinct QTL clusters for flavour-related traits were identified, including a large cluster on chromosome 6 comprising five sensory and nine volatile QTL. The sensory QTL on chromosomes 2, 5, 6, 10 and 11, partly within clusters, are recommended for marker-assisted selection.

Applying unoccupied aerial systems to assess genetic gain from mass selection for tembotrione tolerance in sorghum (Sorghum bicolor)

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Abstract

The post-emergent herbicide options to control grasses in sorghum have historically been limited. Therefore, a mass selection program was implemented to increase the tolerance of sorghum to the broad-spectrum herbicide tembotrione. The objectives of this study are to determine (i) which observation timing and vegetative indices are most effective in assessing sorghum injury to tembotrione using unoccupied aerial system imagery and (ii) if mass selection can be used to increase the tolerance of sorghum to tembotrione. Using an unoccupied aerial system, several vegetative indices, collected at either 14 or 21 days after tembotrione application, accurately measured sorghum injury. Over four cycles of selection, tembotrione tolerance increased in a linear and consistent manner. This demonstrates that mass selection can be used as a strategy for developing herbicide tolerance in crops. The modest, but steady genetic gain indicates both the quantitative nature of the trait and sufficient heritability to improve it. Given further development, tembotrione-resistant sorghum hybrids could provide an effective means of post-emergent weed control for a range of common weeds.

Identifying quantitative trait locus and candidate genes for maize (Zea mays L.) plant architecture traits based on segregating populations constructed by high‐generation sister lines

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Abstract

Leaf length, width and angle are important traits in the architecture of maize plants. Delving into the genetic mechanisms of these traits is of utmost significance for promoting population yield. In this study, we employed the high-generation sister lines PCU and PCM, which have significant differences in leaf morphological traits, as parental entities for the creation of F2 and F2:3 populations. Through quantitative trait locus (QTL) mapping of the traits in the three ear leaves by ICIM, 55 QTL were obtained, with six stable QTL selected across divergent populations. These QTL had physical spans ranging from 0.34 to 44.8 Mbp. Through gene annotation and qRT-PCR, Zm00001d007382, Zm00001d035965, Zm00001d042777 and Zm00001d020641 were predicted as potential candidates for regulating maize plant architecture. The results of this study lay a foundation for analysing the genetic mechanisms of maize plant architecture traits and cloning-related genes.

Mining exotic germplasm for genetic improvement of protein quantity and quality in soybean (Glycine max)

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Abstract

Soybean meal is the main protein source for animal feed, but it has low content of the essential amino acids cysteine (Cys) and methionine (Met). In this research, an exotic germplasm (PI 399000) was crossed with ‘Woodruff’ to develop an F5-derived recombinant inbred line (RIL) population for mapping quantitative trait loci for seed composition. The population was grown in six environments, and protein, oil, Cys, and Met were determined with near-infrared spectroscopy. RILs were genotyped with the SoySNP6K BeadChip, and 1865 SNPs were used for analysis. QTL analysis identified three loci on chromosomes (Chrs) 6, 15 and 17 in at least five environments for protein; two QTLs on Chrs 14 and 17 in all environments for oil; three QTLs on Chrs 3, 6 and 10 for Cys and Met in at least three environments; and two QTLs for seed size on Chrs 17 and 20 in all environments. Stacking of protein and Cys + Met QTLs can increase both traits simultaneously, and 13 breeding lines were identified with improved seed composition. The markers linked to the QTLs can be used to assist the development of cultivars with improved meal quality.

Meiotic pairing and morphological and yield characterisation of three advanced lines of hexaploid tritordeum (×Tritordeum martini)

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Abstract

Hexaploid tritordeum [×Tritordeum martinii A. Pujadas (Poaceae) nothosp. nov.; HchHchAABB] resulted from crosses between wild barley (Hordeum chilense Roem et. Schultz) and durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.]. Tritordeum (HT) presents interesting agronomic traits that can be transferred to cultivated wheat. Through the years, several HT lines were developed and characterised. Genomic stability and fertility are expected for advanced HT lines with multiple self-fertilisation generations. In this work, we analysed the meiotic chromosomal pairing in pollen mother cells (PMCs) of three advanced lines of hexaploid tritordeum (HT9, HT31 and HT67) after fluorescence in situ hybridisation (FISH) performed with genomic DNA from H. chilense and the bread wheat cloned rDNA sequence, pTa71, as probes, and characterised nine morphological and yield-related traits for three consecutive years in adult plants. As expected, all HT lines showed regular meiotic chromosomal pairing, ensuring plant fertility as previously confirmed by the characterisation of morphological and yield-related traits in adult plants of preceding generations. Globally, tritordeum is interesting for wheat breeding and has potential as an alternative crop.

Development and application of a codominant marker of the melon rind colour gene CmAPRR2

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Abstract

Rind colour is an important quality attribute of melon appearance. Identifying target genes and developing functional molecular markers is significant for rind colour breeding in melon. This study involved a genetic analysis of the fruit rind colours of two inbred lines: H185 (with black green melon rind) and H160 (with white rind) alongside a fruit rind colour gene, CmAPRR2. The purpose was to discover the variation sites of the CmAPRR2 gene and develop specific molecular marker for rind colour in melon. The results showed that the black green rind is dominant over white, and single gene controls the colours. A mutation of the G856T base occurred in the eighth exon of the CmAPRR2 coding DNA region in H160, suggesting that this mutation is the key factor for the white rind colour. Thus, a codominant molecular marker, FC, for gene CmAPRR2 was developed and used for molecular identification of 189 F2 individuals. The marker revealed a complete correspondence between genotype and phenotype. Additionally, the marker revealed that the other four white rinds had G856T mutations. This study provides a basis for targeted improvement of melon rind colours, offering a technical means for molecular marker-assisted breeding of melon rind colours.

Fine mapping of sterile genes in soybean (Glycine max [L.] Merril.) based on cross populations between multi‐elite parent and sterile lines ms1 and ms6

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Abstract

The male sterile line of soybean is crucial for hybrid seed production, and has allowed significant advancements in soybean germplasm innovation and yield increase in China. In this study, we created two bulks of sterile plants and collected a natural population consisting of 100 elite soybean germplasms. There were significant phenotypic differences between the sterile and natural populations resulting from flowers and pods. The sterile plants exhibited fleshy spherical pods and large black-green leaves in the maturity stage, while the leaves of the fertile plants fell off. After I2-KI staining, the pollen of the sterile line turned light brown and yellow, while the pollen of the fertile line turned black. On the basis of the SNP sequencing results, the sterility genes were located on eight chromosomes. Additionally, they were fine-mapped to 13 regions on six chromosomes using 72 pairs of SSR markers. Five genes involved in auxin response and pollen development were predicted as candidate genes underlying soybean sterility. These candidate genes for soybean sterility will help with gene cloning and functional analysis and accelerate the widespread use of hybrid seed production and yield increase in soybean grown in cool regions.

Genetic analysis and molecular mapping of fruit‐bearing habit locus (Bh1) in eggplant (Solanum melongena L.)

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Abstract

In eggplant, two kinds of fruit-bearing habits can be observed, that is, cluster and solitary. The fruits grown in cluster are small in size but contribute towards yield and productivity. In this investigation, we have studied the genetics of fruit-bearing habit and identified the SSR markers linked to this trait. Pusa Safed Baingan 1 (cluster bearer) and Pusa Hara Baingan 1 (solitary bearer) having contrasting traits were crossed to generate F1 (20 plants), F2 (215 plants), B1 (73 plants) and B2 (64 plants). Genetic analysis of the trait was carried out using Chi-square test. The segregation of plants in F2 suggested recessive epistasis with ratio of 9:3:4 (solitary: mixed: cluster) indicating involvement of two genes for controlling the fruit-bearing habit. The parental polymorphic 6 SSR markers were used for genotyping F2 plants and co-segregated with the fruit-bearing habit (Bh 1 ) locus in 1:2:1. A linkage map covering 63.86 cm distance was developed, the SSR marker emf11A03 was closest with a distance of 4.37 cm, emk03O04 at 12.5 cm distance, and emf21O06 at 14.5 cm. The physical positions of the SSR markers emb01J19 and emf11A03 flanking Bh 1 gene were located at 4.77 mb position of contig Sme2.5_05721.1 and 5.18 Mb position of contig Sme2.5_00994.1, respectively. The findings in the present study will be helpful in marker-assisted breeding to enhance yield in eggplant.