Genetic effects and genotype × environment interactions for cooking quality traits in Indica-japonica crosses of rice (Oryza sativa L.)

Indica-japonica hybridization is an important approach for developing superior performing hybrids in rice (Oryza sativa L.). In view of the scanty information available on cooking quality characters in indica-japonica crosses, an investigation was undertaken to estimate genetic and genotype × environment variance and covariance components of amylose content, gel consistency and alkali digestion value, and to determine the relative importance of direct genetic effects, maternal genetic effects and cytoplasmic effects in the genetic variations of the three quality characters. Two indica photo-sensitive genic male sterile (PGMS) lines and four japonica varieties were used as parents to make crosses. Genetic model with genotype × environment interactions for triploid endosperm was used for genetic studies of the three cooking quality characters. Variance component analysis revealed that genetic variations of the three characters were mainly attributable to direct additive and maternal additive effects, and the three traits had significant direct and maternal heritabilities. Genotype × environment interactions were mainly dominance × environment (including direct dominance × environment and maternal dominance × environment) and cytoplasm × environment interactions. Environment factors could only affect the expression extent of dominant genes, without changing their directions. Predicted values of genetic effects indicated that the parental lines, ‘VI-70’ and ‘H9304-1’, appeared to be best for amylose content, ‘T 1950’ and ‘Suxuan’ appeared to be best for gel consistency and alkali digestion value. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetics of fertility restoration of ‘Wild Abortive’ cytoplasmic male sterility in rice,Oryza sativa L.

Summary Genetics of fertility restoration in six varieties and breeding lines of rice was studied in Wild Abortive cytoplasmic genetic male sterility system using cytoplasmic male sterile lines V 20 A and IR 54752 A. Fertility evaluation of the plants in F₂ and testcross populations of the crosses of V 20 A with PR 103, PR 106 and PAU 502-94-1, and IR 54752 A with PAU 1124-36-1 and PAU 1126-1-1 revealed that fertility restoration in PR 103, PR 106, PAU 502-94-1, PAU 1124-36-1 and PAU 1126-1-1 was controlled by two independently segregating dominant genes. The two genes appeared to have additive effects; one of them being stronger than the other in imparting fertility restoration. Data on spikelet fertility of the plants in F₂ and testcross populations of V 20 A/UPR 82-1-1 cross showed that fertility restoration in UPR 82-1-1 was controlled by two independently segregating dominant genes which exhibited recessive epistatic interaction.

---

     

Genetic mapping of bph20(t) and bph21(t) loci conferring brown planthopper resistance to Nilaparvata lugens St?l in rice (Oryza sativa L.)

Brown planthopper(BPH) is one of the most serious and destructive insect pests of rice in most rice growing regions of the world. In this study, two major resistance genes against BPH have been identified in an Oryza rufipogon (Griff.) introgression rice line, RBPH54. Inheritance of the BPH resistance in RBPH54 was studied by screening the resistance in parents, F1, F2 and BC1 generations against BPH biotype 2. A population of BC3F2 lines was developed and SSR markers were employed for the gene mapping, and new markers were designed for fine mapping of the resistance genes, while sequence information of BAC/PAC clones was used to construct physical maps of the genes. The results showed that the BPH resistance in RBPH54 was governed by recessive alleles at two loci, tentatively designated as bph20(t) and bph21(t). The locus bph20(t) was fine mapped to the short arm of chromosome 6 about 2.7 cM to the upper marker RM435 and 2.5 cM to lower marker RM540 and in a 2.5 cM region flanked by two new SSR markers BYL7 and BYL8 which were developed in the present study. The other BPH resistance locus bph21(t) was initially mapped to a region 7.9 cM to upper marker RM222 and 4.0 cM to lower marker RM244 on the short arm of chromosome 10. For physical mapping, the bph20(t)-linked markers were landed on BAC/PAC clones of the reference cv., Nipponbare, released by the International Rice Genome Sequencing Project. The bph20(t) locus was physically defined to an interval of about 75 kb with clone P0514G1. Identification and location of these two genes in the present study have diversified the BPH resistance gene pool, which give benefit to the development of resistant rice cultivars, and the linkage PCR-based SSR markers for the bph20(t) and bph21(t) genes would help realize the application of the genes in rice breeding through marker-assisted selection.     

Genetic basis of multiple resistance to the brown planthopper (Nilaparvata lugens St?l) and the green rice leafhopper (Nephotettix cincticeps Uhler) in the rice cultivar ‘ASD7’ (Oryza sativa L. ssp. indica)

The rice cultivar ASD7 (Oryza sativa L. ssp. indica) is resistant to the brown planthopper (BPH; Nilaparvata lugens Stål) and the green leafhopper (Nephotettix virescens Distant). Here, we analyzed multiple genetic resistance to BPH and the green rice leafhopper (GRH; Nephotettix cincticeps Uhler). Using two independent F₂ populations derived from a cross between ASD7 and Taichung 65 (Oryza sativa ssp. japonica), we detected two QTLs (qBPH6 and qBPH12) for resistance to BPH and one QTL (qGRH5) for resistance to GRH. Linkage analysis in BC₂F₃ populations revealed that qBPH12 controlled resistance to BPH and co-segregated with SSR markers RM28466 and RM7376 in plants homozygous for the ASD7 allele at qBPH6. Plants homozygous for the ASD7 alleles at both QTLs showed a much faster antibiosis response to BPH than plants homozygous at only one of these QTLs. It revealed that epistatic interaction between qBPH6 and qBPH12 is the basis of resistance to BPH in ASD7. In addition, qGRH5 controlled resistance to GRH and co-segregated with SSR markers RM6082 and RM3381. qGRH5 is identical to GRH1. Thus, we clarified the genetic basis of multiple resistance of ASD7 to BPH and GRH.     

Breeding of ‘Manten-Kirari’, a non-bitter and trace-rutinosidase variety of Tartary buckwheat (Fagopyrum tataricum Gaertn.)

Here, we developed a new Tartary buckwheat cultivar ‘Manten-Kirari’, whose flour contains only trace amounts of rutinosidase and lacked bitterness. The trace-rutinosidase breeding line ‘f3g-162’ (seed parent), which was obtained from a Nepalese genetic resource, was crossed with ‘Hokkai T8’ (pollen parent), the leading variety in Japan, to improve its agronomic characteristics. The obtained progeny were subjected to performance test. ‘Manten-Kirari’ had no detectable rutinosidase isozymes in an in-gel detection assay and only 1/266 of the rutinosidase activity of ‘Hokkai T8’. Dough prepared from ‘Manten-Kirari’ flour contained almost no hydrolyzed rutin, even 6 h after the addition of water, whereas the rutin in ‘Hokkai T8’ dough was completely hydrolyzed within 10 min. In a sensory evaluation of the flour from the two varieties, nearly all panelists detected strong bitterness in ‘Hokkai T8’, whereas no panelists reported bitterness in ‘Manten-Kirari’. This is the first report to describe the breeding of a Tartary buckwheat cultivar with reduced rutin hydrolysis and no bitterness in the prepared flour. Notably, the agronomic characteristics of ‘Manten-Kirari’ were similar to those of ‘Hokkai T8’, which is the leading variety in Japan. Based on these characteristics, ‘Manten-Kirari’ is a promising for preparing non-bitter, rutin-rich foods.     

Farmers’ management of peanut (Arachis hypogaea L.) diversity,their varietal preference traits and uses in Southern and Central Benin

Journal of Crop Science and Biotechnology - Peanut (Arachis hypogaea L.) is one of the major oilseed legumes contributing to food security in Benin. Unfortunately, several constraints hamper its...     

Use of equilibrium modified atmosphere packaging for preservation of ‘San Antonio’ and ‘Banane’ breba crops (Ficus carica L.)

The purpose of this work was to study the effect of equilibrium modified atmosphere packaging on the stability of ‘San Antonio’ and ‘Banane’ breba fruit during postharvest cold storage by the use of three different microperforated films (1/50 mm, 1/30 mm, and 1/10 mm; ø = 100 μm). Gas composition in the wraps, weight loss, % disorder, and microbial counts were monitored during cold storage for 21 days. The tested microperforated films allowed the extension of cold storage time for brebas, minimizing weight loss and delaying the disorders due to fungal proliferation, especially M50 (1/50 mm). Total soluble solids (TSS), titratable acidity (TA), pH, firmness, and sensory quality were also evaluated. Among the tested microperforated films, M50 showed the best performance in terms of delaying physicochemical senescence processes of fruit. The breba cultivar had an important impact on the extension of cold storage. For ‘San Antonio’ and ‘Banane’ cultivars packaged with microperforated M50, the optimal time of cold storage was 14 and 21 days, respectively.     

Tagging of four fertility restorer loci for wild abortive—cytoplasmic male sterility system in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) using microsatellite markers

Tagging of restorer genes for wild abortive (WA) CMS source by studying a 222 individual plants from a F₂ population of a cross between IR58025A × IR42686R. The restorer line IR42686R that was used in this study had been previously derived through random mating composite population (RMCP) involving 12 parents facilitated by IR36 genetic male sterility. Four Rf genes were tagged to simple sequence repeats (SSR) markers on chromosomes 1, 7, 10, 12 by recessive class analysis. The recombination frequency between a positive marker and Rf locus was calculated using maximum likelihood estimator assuming that all the 46 extremely sterile individual plants were homozygous at the targeted Rf locus. The recombination frequency between the marker and the restorer trait were converted to genetic distances using Kosambi function. A new Rf locus designated as Rf7 on chromosome 12 was found to be linked to RM7003 at a genetic distance of 13.3 cM (LOD 6.12). We report here first, a new molecular marker (RM 6344) linked to Rf4 locus on chromosome 7 that was previously mapped by trisomic analysis. RM443 and RM315 were flanking the Rf3 gene at a genetic distance of 4.4 (LOD 10.29) and 20.7 cM (LOD 3.98) on chromosome 1, respectively. The Rf6 was flanked on both side with SSR markers RM258 and RM591 at a genetic distance of 4.4 (LOD 10.29) and 23.3 cM (LOD 3.39) located on chromosome 10. The random mating composite population is an excellent breeding approach to develop superior restorer lines and for pyramiding different Rf genes of different CMS systems. Rf genes tagged with closely linked SSR markers would be facilitating marker assisted selection (MAS) in hybrid rice breeding program by reducing time and workload for identifying potential restorers. L. Bazrkar and A. J. Ali equally contributed to this work.     

The development of females of the potato root eelworm, (Heterodera rostochiensis Woll.) on ‘tuber-pieces’ of susceptible and resistant potatoes

A method is described for determining the degree of resistance shown by potatoes to a non-aggressive biotype of the potato root eelworm, Heterodera rostochiensis Woll., using tuber slices inoculated with H. rostochiensis larvae. The degree of resistance assessed by this method was found to agree well with the results obtained by root screening. The tuber piece method of testing for resistance could be used when root screening is impracticable or in conjunction with it.     

Characterisation of starch properties and physical characteristics in buckwheat (Fagopyrum esculentum Moench.) mutant lacking accumulation of ‘granule-bound starch synthase a’

The concentration of amylose, which is synthesised using granule-bound starch synthase, affects the physical properties of food. However, no studies have focused on starch properties and physical characteristics of low-amylose buckwheat. Here, we hypothesised that low-amylose buckwheat would be useful to produce new buckwheat products because low-amylose characteristics change the texture of buckwheat food. In this study, we bred relatively low-amylose buckwheat compared to wild type and investigated the causative genes of the traits, starch properties and physical properties of noodles. In the GBSSa mutant, the amylose concentration was lower than that in the wild type. Compared with the wild type, the mutant exhibited the following traits: Amylose concentration decreased by approximately 2%, setback in the Rapid Visco Analyzer decreased by 30 points and the physical characteristics of noodles in the sensory analysis were soft and sticky. These results suggest that this trait may be useful for changing the texture of foods. In addition, the mutant is promising for producing new foods with physical characteristics that are different from those of the wild type.     

Close linkage of a blast resistance gene,Pias(t), with a bacterial leaf blight resistance gene,Xa1-as(t), in a rice cultivar ‘Asominori’

It has long been known that a bacterial leaf blight-resistant line in rice obtained from a crossing using ‘Asominori’ as a resistant parent also has resistance to blast, but a blast resistance gene in ‘Asominori’ has not been investigated in detail. In the present study, a blast resistance gene in ‘Asominori’, tentatively named Pias(t), was revealed to be located within 162-kb region between DNA markers YX4-3 and NX4-1 on chromosome 4 and to be linked with an ‘Asominori’ allele of the bacterial leaf blight resistance gene Xa1, tentatively named Xa1-as(t). An ‘Asominori’ allele of Pias(t) was found to be dominant and difference of disease severity between lines having the ‘Asominori’ allele of Pias(t) and those without it was 1.2 in disease index from 0 to 10. Pias(t) was also closely linked with the Ph gene controlling phenol reaction, suggesting the possibility of successful selection of blast resistance using the phenol reaction. Since blast-resistant commercial cultivars have been developed using ‘Asominori’ as a parent, Pias(t) is considered to be a useful gene in rice breeding for blast resistance.     

Genetic Diversity of Ethiopian Tef [(Eragrostis tef (Zucc.) Trotter] Released and Selected Farmers’ Varieties along with Two Wild Relatives as Revealed by Microsatellite Markers

Journal of Crop Science and Biotechnology - Knowledge on the extent and pattern of diversity in crop species is a precondition for any crop improvement as it helps breeders in determining apt...     

Genetic diversity of feral alfalfa (<Emphasis Type="Italic">Medicago</Emphasis> <Emphasis Type="Italic">sativa</Emphasis> L.) populations occurring in Manitoba,Canada and comparison with alfalfa cultivars: an analysis using SSR markers and phenotypic traits

Feral populations of cultivated crops may act as reservoirs for novel traits and aid in trait movement across the landscape. Knowledge on the genetic diversity of feral populations may provide new insights into their origin and evolution and may help in the design of efficient novel trait confinement protocols. In this study, the genetic diversity of 12 feral alfalfa (Medicago sativa) populations originating from southern Manitoba (Canada) and 10 alfalfa cultivars and a M. falcata germplasm were investigated using eight SSR markers (i.e., microsatellites) and 14 phenotypic traits. We found that the genetic diversity observed in feral populations was similar to the diversity detected among the 10 cultivars. Analysis of molecular variance revealed that there was great genetic variation within (99.8%) rather than between different feral populations. Cluster analysis (unweighted pair-group method using arithmetic average) revealed no differentiation between feral populations and cultivars for neutral loci. High levels of population differentiation for phenotypic traits (and not for neutral markers) suggest the occurrence of heterogeneous selection for adaptive traits. The phenotypic traits we studied did not distinctly separate feral populations from cultivars but there was evidence of natural selection in feral populations for traits including winter survivability, rhizome production, and prostrate growth habit. Our results suggest that feral alfalfa populations need to be considered in the risk assessment of alfalfa containing novel genetically modified (GM) traits. Further, feral alfalfa populations may be regarded as a source of new germplasm for plant improvement.     

Effect of gamma irradiation on the physico-mechanical and chemical properties of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, in non-refrigerated storage conditions

The effects of γ-irradiation doses, 0.04, 0.08, 0.12 and 1 kGy, applied at two different postharvest times (5 and 30 days after harvest), were studied on the textural behaviour (puncture force, shear force, work done to puncture and shear, cohesiveness and gumminess), microstructure, reducing sugar, total sugar and tuber losses of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, during storage at 22 °C (RH: 85–90%). The lowest dose (0.04 kGy) was sufficient to inhibit sprouting in potatoes exposed on day 5 but not in the tubers exposed on day 30. The irradiated, non-sprouted potatoes maintained their appearance during storage. Potatoes irradiated early appeared more sensitive to radiation-induced damage, resulting in excessive loss of tubers at 1 kGy but low doses (up to 0.12 kGy) did not increase the susceptibility of the tubers to rotting. No significant differences between reducing sugar and total sugar contents of the control and low dose irradiated tubers were observed after 120 d. High dose (1 kGy) induced blackening of the bud tissue, increased rotting percentage and poor textural quality. Increasing low doses (up to 0.12 kGy) progressively reduced the textural deterioration in the tubers during storage. The scanning electron micrographs of potatoes irradiated with 0.08–0.12 kGy showed intact cells with rigid cell walls, accounting for the higher textural values registered by the samples. Among the two treatment timings, ‘K. Sindhuri’ irradiated early after harvest (i.e., on day 5) with 0.08–0.12 kGy doses retained higher textural parameters compared to those irradiated after a delay (day 30). The study showed the potential effect of γ-irradiation for enhancing the storage life of potatoes in non-refrigerated storage.     

Chinese melon (<Emphasis Type="Italic">Cucumis melo</Emphasis> L.) diversity analyses provide strategies for germplasm curation,genetic improvement,and evidentiary support of domestication patterns

The genetic diversity of melon market types (Cucumis melo L., 2n = 2x = 24) in China, an important secondary center of diversity, has not been examined. Therefore, reference accessions from India and Africa, Crete/Greece, Japan, Europe, U.S.A., Spain, and 68 Chinese cultigens (fresh-market non-netted thin-skinned; non-netted thick-skinned; netted thick-skinned; and non-netted thin-skinned, and vegetable) were evaluated by using 17 10-mer RAPD primers (32 mapped loci), days to flower, sex expression, lateral-branch number, and fruit number and weight per plant. While Chinese thin-skinned melons differed from vegetable melon types only in sex expression, the U.S. Western Shipping market type reference accession “Top Mark” and Chinese thick-skinned melons were similar for all of the morphological traits examined. The average similarity (Jaccard Coefficient) between any two pairs of accessions examined as estimated by RAPD variation was 0.47 ± 0.14. Within-group genetic similarities ranged between 0.94 (thin-skinned type) and 0.08 (non-netted thick-skinned type). The average/standard deviation, maximum, and minimum similarity between any two Chinese reference accessions was 0.41 ± 0.13, 0.75, and 0.12, respectively. Cluster analysis partitioned accessions into two main branches consisting of Group Cantalupensis and Inodorus reference accessions (clade 1) and Chinese accessions (clade 2). A second cluster analysis partitioned China, India, and Africa accessions into one major group, and accessions from Japan, Europe, and U.S.A. into another. Results indicate that Chinese accessions are a rich source of genetic diversity for plant improvement, and that molecular assessments support previously described theoretical melon domestication patterns constructed from historical and archeological evidence.     

The potential of lentil (<Emphasis Type="Italic">Lens culinaris</Emphasis> L.) as a whole food for increased selenium,iron, and zinc intake: preliminary results from a 3 year study

Micronutrient malnutrition, especially selenium (Se), iron (Fe), and zinc (Zn) deficiency, is a major global health problem. Previous attempts to prevent micronutrient malnutrition through food fortification, supplementation, and enrichment of staple crops has had limited success. Canadian grown lentils are rich in micronutrients Fe (73–90 mg kg⁻¹), Zn (44–54 mg kg⁻¹), Se (425–673 μg kg⁻¹), and have very low concentrations of phytic acid (2.5–4.4 mg g⁻¹). Our preliminary studies using a Caco-2 cell model show that the uptake of Fe from lentils is relatively greater than that of most other staple food crops. Moreover, preliminary results from our human nutrition study in Sri Lanka show an increased trend in blood Se concentration after lentil consumption. This article briefly overviews our previously published results as well as data from international lentil field trials, and describes the potential for biofortified lentil to provide a whole food solution to combat global human micronutrient malnutrition.