Hybrid Parental Lines Research Articles

Similarity of 26 New Released Rice Varieties and Rice Parental Hybrids Based on 36 SSR Markers

More than 200 rice varieties had been released in Indonesia, but the genetic variability among those released varieties was suspected to be relatively low. Molecular markers, especially SSR could be used as a tool to disect the distinctness among rice genotypes, albeit phenotipically similar varieties. The technique could also be used to prove the authenticity of a variety. This research was aimed to obtain DNA fingerprinting data of new released rice varieties and hybrid parental lines using SSR markers. A total of 26 rice genotypes consisted of three upland, ten irrigated, five swampy rice varieties, along with eight hybrid parental lines were used in this experiments. The DNA was extracted from young leaf samples using CTAB modified method and was amplified with 36 SSR markers linked to important rice traits which spread accross the 12 rice chromosomes. The experiment was conducted in Plant Breeding Laboratory of Indonesian Center for Rice Research (ICRR) during 2012. The results showed that PIC value of the genotypes were mostly at medium level of the genetic diversity with the average value of 0.4451. The phylogenetic analysis showed that at the genetic distance of 10%, the genotypes were separated into 9 groups, i.e. Inpago 6, Inpara 5, and BH33d each stood alone while (Inpara 1, Inpara 2 , and Inpara 3); (Inpari 18 and Inpari 19, Inpago 4, Inpago 5, and Inpara 4); (Inpari 11, Inpari 12, Inpari 13, Inpari 14, Inpari 15, Inpari 16, Inpari 17, and Inpari 20); (GMJ6B, B6, and IR79156B); (PK21, BH95E, Bio9, and R14) each belong to one group. The grouping of the genotypes in this study seemed to follow the adaptation type to agro ecosystems. The hybrid parental lines tended to stay in different group from the inbred varieties. The application of these 36 SSR markers was able to distinguish among 26 genotypes rather distinctly.The use of more markers should give more powerful data to distinguish among genotypes.

Exploitation of beneficial alleles from maize (Zea mays L.) landraces to enhance performance of an elite variety in water stress environments

Yield losses of maize due to drought stress (DS) in environments with limited rains can reach 100 %. Introgression of favorable alleles from diverse landraces into adapted elite varieties will improve performance, hence reducing losses. The objective of this study was to assess the performance of BC populations under DS and multiple locations (ML) after introgression of alleles from diverse maize landraces into an elite variety. Twelve backcross (BC1F2) populations together with their recurrent parent (TZLCOMP4C1) and a commercial hybrid (Oba Super1) were evaluated under DS, well watered (WW) conditions during the dry season, and in seven ML trials in Nigeria. Significant differences were observed among genotypes for all traits except for ear aspect score under DS conditions. Grain yield and most agronomic traits measured were highly significant (p < 0.001) under WW conditions and across ML trials. In DS, eight of the 12 BC1F2 populations had similar mean grain yield compared to their recurrent parent. Four of these populations produced 3–7 % more grains than the recurrent parent. Yield improvement was accompanied by reduced barrenness, days to flowering, plant height and ear placement, and good plant and ear aspect scores. The eight BC1F2 populations should be subjected to recurrent selection under controlled DS, while four other BC1F2 populations with low grain yields could be subjected to additional backcross to increase frequency of favorable alleles for improved performance in stress environments. The resulting improved populations can be invaluable source materials for developing drought tolerant varieties and parental lines of hybrids.

English

A field experiment was conducted with sunflower hybrid KBSH- 1 parental lines with six monthly sowings to predict the number of days to be staggered between the parental lines to achieve a synchronized flowering based on meteorological parameters. The regression study was made using the different heat unit concepts. The regression co-efficient between the phenophases and the derived weather parameters growing degree days (GDD), relative temperature disparity (RTD), helio thermal units (HTU) and photo thermal units (PTU) clearly indicated the variability between male and female lines with reference to the three phenophases studied. Among the phenophases, highly significant co-efficient was obtained for days to button formation and 50% flowering. Hence, from the study it was concluded that the computed regression equation could be employed to adopt suitable staggering to achieve proper synchronization to get higher seed filling and yield in sunflower hybrid KBSH-1 seed production. &nbsp; Key words:&nbsp;Sunflower, hybrid parental lines, heat unit concepts, synchronization, flowering, equation.

Abstract 4913: Investigation of the in vitro differentiation ability of hybrid cell clones derived from spontaneous cell fusion events between murine breast cancer cells and murine mesenchymal stem cells.

Abstract We have previously shown that murine breast cancer cell lines are capable of acquiring malignant attributes through cell fusion with stem cell lines in vitro. Hybrid cell clones emerged from spontaneous fusion events in a co-culture model showed an increased resistance against chemotherapeutic substances together with a higher proliferation rate and genetic alterations compared to their parental cell lines. Since solid tumors, including breast cancer, have pronounced heterogeneity of cell populations, cell fusion between cancer cells and tumor infiltrating immune cells as well as stem cells is one mechanism how tumor cells could acquire new properties. With relation to the importance of cell fusion in tumor heterogeneity and progression the objective of this study was to characterize and investigate if hybrid cell clones arised from spontaneous fusion events between hygromycin resistant murine 67NR-Hyg mammary carcinoma cells and puromycin resistant murine bone marrow derived stem cells (BMDCs) from Tg(GFPU)5Nagy/J mice to maintain their ability to differentiate into the neural and osteogenic lineage. Dual hygromycin/puromycin resistant mBMDC/67NRHyg cells originated by cell fusion were confirmed by a dual drug selection procedure and PCR analysis to examine an overlap of parental markers. BMDCs are generally defined as self-renewable, multipotent progenitor cells with the ability to differentiate into several mesenchymal lineages. Differentiation was performed by cultivating the cell clones and parental cell lines under appropriate conditions to an established neural and osteogenic differentiation protocol, respectively. Our results revealed through molecular and biochemical analyses that hybrid cell clones and parental cell lines were positive for neuronal as well as osteogenic markers. Differentiation of hybrid cell clones into the osteogenic lineage was associated with expression of osteocalcin, bone sialoprotein II and collagen type I alpha 1 and increasing alkaline phosphatase activity, while differentiation into neuronal lineage was concomitant with expression of neurofilament M, GAD67 and class III beta-tubulin. In conclusion, our data show that hybrid cell clones are able to differentiate into specialized cells from both osteogenic and neuronal lineages. These stem cell properties indicate that cell clones derived from cell fusion events maintain abilities of the parental cell lines. Citation Format: Marieke Mohr, Kurt S. Zaenker, Thomas Dittmar. Investigation of the in vitro differentiation ability of hybrid cell clones derived from spontaneous cell fusion events between murine breast cancer cells and murine mesenchymal stem cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4913. doi:10.1158/1538-7445.AM2013-4913

SYNTHETIC VARIETIES DERIVED FROM SINGLE OR DOUBLE CROSSES?

The use of synthetic varieties (SVs) derived from single (SynSC) or double (SynDC) crosses is a way of avoiding the high seed cost of hybrid maize (Zea mays L) and onion (Allium cepa L.) varieties, among others. In addition, these SVs could be used to more economically predict the genotypic means (GMs) of the SVs derived from the hybrid parental lines (SynL). It is known, however, that the inbreeding coefficients (ICs) of the SynL, SynSC, and SynDC derived from the same lines can differ, but the reason why is unknown. This lack of knowledge makes it difficult for the breeder to improve the representation of the SynL through the SynDC and SynSC and thereby to improve the estimation of the SynL GM. The objective of this study was to determine the reason why the SynL, SynSC, and SynDC can differ. From unrelated L lines whose IC is FL, L/2 single (SCs) and L/4 double crosses (DCs) were derived; and each line, SC, and DC were represented by m individu- als. By randomly mating each set of parents, the SynL, SynSC, and SynCD were formed. It was found that the genotypic arrays of the three SVs differ because with the same 4 initial lines the number of non-identical by descent genes contributed to the genotypic array is larger as fewer lines are involved in a parent [lines (1), single crosses (2), and double crosses (4)]. Thus, the ICs of SynL and SynDC are the smallest and largest, respectively; and it is expected that the GMs show the opposite ordering. In addition, as m and FL are smaller the differences among the genotypic arrays of the SVs are larger. On the contrary, when the L lines are pure, the genotypic arrays of SynL and SynSC are equal, and their IC must be equal as well. To be equal to SinL, SynDC requires, in addition, a large m. However, even with FL < 1, as m is larger the genotypic arrays of SynSC and SynDC tend to the genotypic array of SynL, although slowly, particularly for SynDC.

Development of a scoring scale for powdery mildew (Golovinomyces cichoracearum (DC.) V.P. Heluta) disease and identification of resistance sources in cultivated and wild sunflowers

Powdery mildew incited by Golovinomyces cichoracearum has become a serious problem on sunflower in India during the past 2–3 years. Genetic resistance in the released cultivars and the parental lines of hybrids is rather limited. Hence, screening of about 420 accessions comprising of wild Helianthus species, interspecific derivatives, core germplasm, inbred lines and few exotic accessions was done under natural field conditions for 2 years and further confirmed by screening under artificial inoculation conditions. PCR analysis using primers specific to powdery mildew causing genera gave a 391 bp band which confirmed the pathogen as G. cichoracearum. Seven different screening methods were tested which induced infection, but dusting of spores on to the healthy leaves proved to be convenient and more effective method of infection. Based on the differential response of the accessions derived from diverse genetic backgrounds, a scale for obtaining reliable estimates of the disease has been devised. Among different cultivar germplasm accessions, the disease severity index (DSI) ranged from 15 to 100 and area under disease progression curve (AUDPC) ranged from 95 to 648. Among the four groups of cultivated sunflower accessions tested, DSI and AUDPC was in the order of exotic lines < interspecific derivatives < inbred lines < core germplasm. Reliable sources of resistance to the pathogen were identified in four annual wild species (H. argophyllus, H. agrestis, H. debilis, H. praecox), six perennials (H. angustifolius, H. atrorubens, H. rigidus, H. salicifolius, H. pauciflorus and H. resinosus), two interspecific derivatives (HIR-1734-2, RES-834-3) and two exotic lines (PI 642072, EC-537925).

Mapping of the ms8 male sterility gene in sweet pepper (Capsicum annuum L.) on the chromosome P4 using PCR-based markers useful for breeding programmes

AbstractThe nuclear male sterility gene ms8 is expected to facilitate the production of sweet pepper (Capsicum annuum L.) hybrids as it provides means for hybridization without the labor-intensive hand emasculation of female inbred lines. The development of molecular markers linked to ms8 locus will help the breeding practice for the selection of hybrid parental lines. In this study, F2 population resulting from a cross between the sweet pepper male sterile line 320 and the male fertile variety Elf was used to identify DNA markers linked to the ms8 locus. With the use of RAPD–BSA technique, seven markers linked to the ms8 locus were found. Four of them were converted into SCAR markers. In addition, two COSII/CAPS markers linked to the ms8 locus were identified. Comparative mapping with reference pepper maps indicated that the ms8 locus is located on the lower arm of the pepper chromosome P4. Identified markers are useful for molecular breeding, however, at present markers tightly linked to ms8 locus are still lacking. Identification of molecular markers linked to the ms8 locus and determination of its chromosomal localization are useful for fine mapping and also provide the perspective for ms8 gene cloning.

Diversity analysis using ISSR markers for resistance to shoot pests in sorghum

Shoot flies and stem borers are key shoot pests that destabilize the yield of sorghum [Sorghum bicolor (L.) Moench] across the semi-arid tropics of Asia and Africa. Progress in building up genetic resistance through breeding programs is slow, which can be attributed to the moderate levels of resistance conferred by the resistance sources in use. Genetic diversity analysis of resistant and elite genotypes is essential in designing breeding programs for resistance to the above pests. In the present study, the genetic diversity of seven genotypes resistant to shoot fly and/or stem borers, a susceptible control genotype and two susceptible elite hybrid parental lines was analyzed using PCR amplification product differences revealed by 26 ISSR primers. Cluster analysis based on ISSR markers resulted in two major groups, (i) resistance sources, and (ii) the susceptible control and hybrid parental lines. It was interesting to note that (a) the susceptible elite hybrid parents and susceptible control were genetically similar, and (b) resistance sources were genetically diverse as a group, offering the possibility that they may have diverse resistance mechanisms. Two improved resistance sources, which are products of crosses between durra race resistance sources and agronomically elite caudatum race materials, bridged two sub-groups of resistance sources. A primer (UBC827) showed the highest PIC value (0.98), thus detecting to the highest level of polymorphism. (AC)n-based primers detected higher levels of polymorphism than others used in this study, and can be recommended for future use. Incorporation of multiple resistant sources in crossing, and pyramiding of genes for resistance in the subsequent generations would help in improvement of shoot fly and stem borer resistance in the elite lines. Breeding strategies to utilize these resistant lines are discussed.

Purification of Sahdyari rice hybrid parental lines through paired crosses for nucleus seed production

The availability of genetically pure and good-quality seed is a primary prerequisite for exploiting the potential of hybrids. Lack of purity in parental lines and improper isolation conditions in seed production result in poor hybrid seed quality. Chinese scientists reported that, with every 1% decrease in the purity of hybrid seed, the eventual yield loss in F1 hybrids would be about 100 kg ha-1 (Sharma 1995). In 1998, RARS-Karjat identified and released a rice hybrid from the cross IR58025A/BR827-35-3-1-1-1R-Sahdyari- for commercial cultivation in Maharashtra State. Maintaining or improving the purity of the parental lines of Sahdyari was a major challenge. Thus, efforts were made to purify the three parental lines of Sahdyari through paired crosses.

Application of SSR markers for molecular characterization of hybrid parents and purity assessment of ICPH 2438 hybrid of pigeonpea [Cajanus cajan (L.) Millspaugh

With an objective of achieving a breakthrough in the productivity of pigeonpea, a hybrid breeding technology based on elements of the cytoplasmic-nuclear male-sterility (CMS) system and partial natural out-crossing has recently been developed. However, there is no molecular diversity information available on parental lines of hybrids being generated at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). This study deals with the use of 148 simple sequence repeat (SSR) markers, including 32 novel markers reported here for the first time, on 159 A (cytoplasmic male sterile), B (maintainer) and R (fertility restorer) lines. In total, 41 (27.7%) markers showed polymorphism with 2 to 6 (average 2.6) alleles and 0.01 to 0.81 (average 0.34) polymorphism information content (PIC) value. Of these polymorphic markers, 22 SSR markers showed polymorphism between A (ICPA 2039) and R (ICPR 2438) lines of the commercial hybrid (ICPH 2438); however, only 21 of these SSR markers showed the same profile between A (ICPA 2039) and B (ICPB 2039) lines. Finally, two SSR markers, CCB4 and CCttc006, were found most suitable for purity assessment of hybrid seeds of the ICPH 2438 hybrid. The utility of these two diagnostic SSR markers has been demonstrated by using seed lots of this hybrid from two sources, ICRISAT and Mahabeej. It is anticipated that molecular diversity information generated on parental lines of hybrids under development, and identification of the two most suitable markers for testing the purity of hybrid seeds of ICPH 2438, will facilitate the pigeonpea hybrid breeding programme.

Prospects of breeding biofortified pearl millet with high grain iron and zinc content

AbstractDevelopment of crop cultivars with elevated levels of micronutrients is being increasingly recognized as one of the approaches to provide sustainable solutions to various health problems associated with micronutrient malnutrition, especially in developing countries. To assess the prospects of this approach in pearl millet (Pennisetum glaucum), a diverse range of genetic materials, consisting of 40 hybrid parents, 30 each of population progenies and improved populations, and 20 germplasm accessions, was analysed for grain iron (Fe) and zinc (Zn) content, deficiencies of which adversely affect human health. Based on the mean performance in two seasons at ICRISAT, Patancheru, India, large variability among the entries was found, both for Fe (30.1–75.7 mg/kg on dry weight basis) and Zn (24.5–64.8 mg/kg). The highest levels of grain Fe and Zn were observed in well‐adapted commercial varieties and their progenies, and in the parental lines of hybrids, which were either entirely based on iniari germplasm, or had large components of it in their parentage. There were indications of large within‐population genetic variability for both Fe and Zn. The correlation between Fe and Zn content was positive and highly significant (r = 0.84; P &lt; 0.01). These results indicate that there are good prospects of simultaneous selection for both micronutrients, and that selection within populations, especially those with the predominantly iniari germplasm, is likely to provide good opportunities for developing pearl millet varieties and hybrid parents with significantly improved grain Fe and Zn content in pearl millet.

Achievements and bottlenecks in developing sunflower hybrids for Uganda

Sunflower (Helianthus annuus L.) has become the most important oil crops in Uganda. The area under production has increased dramatically since the mid 1990s. In the 1970s and 1980s, sunflower breeding research was based on evaluating imported hybrids. This did not show any impact in commercial production. Recent evaluation of hybrids led to the release of PAN 7351 from South Africa which is now in full production and being imported by Mukwano Seed Company. Serere Agricultural Research Institute (SAARI) received a few hybrid parental lines for hybrid development. Some bottlenecks like branching and fertility of female lines led to slow development of hybrids from these parental lines. A few crosses have been made and yields of over 2,000 kg/ha have been attained. Uganda is now in position to produce her own hybrid seed.

Molecular mapping of gene Gm-6(t) which confers resistance against four biotypes of Asian rice gall midge in China

The Chinese rice cultivar Duokang #1 carries a single dominant gene Gm-6(t) that confers resistance to the four biotypes of Asian rice gall midge (Orseolia oryzae Wood-Mason) known in China. Bulked segregant analysis was performed on progeny of a cross between Duokang #1 and the gall midge-susceptible cultivar Feng Yin Zhan using the RAPD method. The RAPD marker OPM06(1400) amplified a locus linked to Gm-6(t). The locus was subsequently mapped to rice chromosome 4 in a region flanked by cloned RFLP markers RG214 and RG163. Fine mapping of Gm-6(t) revealed that markers RG214 and RG476 flanked the gene at distances of 1.0 and 2.3 cM, respectively. Another gall midge resistance gene, Gm-2, mapped previously to chromosome 4, is located about 16 cM from Gm-6(t), to judge by data from a segregating population derived from a cross between Duokang #1 and the Indian cultivar Phalguna that carries Gm-2. We developed a PCR-based marker-assisted selection kit for transfer of the Gm-6(t) gene into Ming Hui 63 and IR50404, two parental lines commonly used in hybrid rice production in China. The kit contains PCR primer pairs based on the terminal sequences of the RG214 and RG476 clones. Polymorphism between Duokang #1 and the hybrid parental lines was found at these markers after digestion of the PCR products with specific restriction endonucleases. The kit will accelerate introduction of gall midge resistance into hybrid rice in China.

Nectar quality in open-pollinated, pol CMS hybrid, and dominant SI hybrid oilseed summer rape

Nectar sugar composition and temporal patterns of nectar sugar production were examined in oilseed summer rape (Brassica napus L. ssp. oleifera (Metzg.)) from six open-pollinated, eight pol cytoplasmic male-sterile (CMS) hybrid and seven dominant self-incompatible (SI) hybrid cultivars at three field plot sites in Manitoba. The total sugar content of nectar samples was measured by the Dreywood anthrone reaction for total carbohydrate, and simple sugar composition was determined using an enzymatic bioanalysis for D-glucose, D-fructose and sucrose. Hybrid and open-pollinated cultivar flowers had similar sugar content. Mean total sugar content per flower also did not vary among hybrid breeding systems when compared within individual weeks of the bloom period or within daily sampling periods. However, for all cultivars, total nectar sugar content per flower was lower during the 08:00 and 11:00 h sampling periods and increased to maximum levels during the 14:00 and 16:00 h sampling periods. Significant differences in nectar sugar content were also found in relation to the bloom phenology of the cultivars. Cultivars produced the greatest amount of sugar per flower during the first 2 wk of the bloom period, then sugar production decreased in the third and fourth weeks. Nectar sugar ratios from all cultivars averaged approximately 1:1 glucose:fructose. Nectar glucose content among cultivars was similar but, among breeding systems, CMS cultivars tended to have lower amounts of glucose than SI or open-pollinated cultivars. Selecting for higher total sugar content may produce nectars more attractive to foraging honeybees (Apis mellifera L.), thereby ensuring adequate pollination of hybrid parental lines and F1 hybrid plants. Selecting for lower nectar glucose will produce honeys with more desirable granulation characteristics. Overall, the production and quality of nectar sugar in oilseed rape hybrids are similar to those of open-pollinated cultivars, and are not likely to adversely affect the pollinating activities of honeybees or their potential for honey production. Key words: oilseed summer rape, Brassica napus, honeybees, Apis mellifera, nectar, simple sugars

Sunflower ( Helianthus ) Resistance to a Stem Weevil, Cylindrocopturus adspersus (Coleoptera: Curculionidae)

Sunflower species ( Helianthus ) were evaluated for resistance to a stem weevil, Cylindrocopturus adspersus (LeConte). In greenhouse tests, foliar feeding by C. adspersus adults was significantly less in 11 of 18 annual and in 13 of 34 perennial species tested than in commercial hybrid ‘894’. The number of C. adspersus larvae recovered was significantly lower in eight annual and all perennial species than in hybrid 894. Significantly fewer larvae of C. adspersus occurred in 27 perennial species of Helianthus in the field during 3 consecutive years (1981–1983) than occurred in nearby wild H. annuus L. or hybrid 894. However, the number of C. adspersus larvae found in F1 progeny of interspecific crosses between the wild species and cultivated hybrid parental lines in the field was equivalent to the number of larvae found in the cultivated parents.