• Journal of Plant Biotechnology
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• v.36 no.4
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• pp.320-326
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• 2009

The carbon dioxide concentration of the atmosphere is projected to increase by almost 50% over the first 50 years of this century. The major cause of this increase is continued combustion of fossil fuels. As a result, the significant changes in climate that have already occurred will be amplified, in particular a global temperature increase. Renewable energy production has a central role to play in abating net $CO_2$ emissions to a level that will arrest the development of global warming. Especially, biomass crops are becoming increasingly important as concerns grow about climate change and the need to replace carbon dioxideproducing fossil fuels with carbon-neutral renewable sources of energy. To succeed in this role, biomass crop has to grow rapidly and yield a reliable, regular harvest. A prime candidate is Miscanthus, or Asian elephant grass, a perennial species that produces over 3 metres of bamboo-like stems in a year. Miscanthus species are typically diploid or tetraploid. Hybrids between species with different ploidy levels result in the highly productive triploid hybrids, M. ${\times}$ giganteus. Here we will detail the Miscanthus characteristics desired of a biomass fuel crop.

• Journal of Life Science
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• v.22 no.7
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• pp.871-879
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• 2012

Polyploids are a potentially important germplasm source in seedless citrus breeding program. Seedlessness is one of the most promising traits of commercial mandarin breeds that mandarin triploid hybrids possess permanently. The formation of new constant triploid hybrids can be recovered through diploid species hybridization from the fusion of divalent gametes at low frequencyor intra-and inter-ploidy crosses. However, extensive breeding work based on small $F_1$ hybrid seeds developed is impossible without a very effective aseptic methodology and ploidy event. In this study, in vitro embryo culture was employed to recover natural hybrids from monoembryonic diploid, open-pollinated mandarin. Flow cytometry was used to determine ploidy level. A total of 10,289 seeds were extracted from 792 fruits having approximately 13 seeds per fruit. Average frequency of small seeds developed was 7.1%, while the average frequency of small seeds per fruit were: 8.9% for 'Clementine' 10.2% for 'Harehime' 2.6% for 'Kamja' 3.1% for 'Pyunkyool' 2.8% for 'Sadookam' and 7.0% for 'Wilking' mandarin. Average size of a perfect seed was $49.52{\pm}0.07mm^2$ ('Clementine') while the small seed measured $7.95{\pm}0.04mm^2$ ('Clementine'), which was about 1/6 smaller than the perfect seed. In total, 731 small seeds were obtained and all of them contained only one embryo per seed. The efficiency of 'Clementine' was 14 times higher than 'Wilking' and more than 109 times higher than 'Pyunkyool'. The basic information on spontaneous polyploidy provides for the hybridization of constant triploids and increases the efficiency of conventional cross.

• FLOWER RESEARCH JOURNAL
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• v.17 no.4
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• pp.279-284
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• 2009

In order to recover fertility from sterile interspecific OA-1 $F_1$ hybrid (Oriental hybrid 'Mero Star' ${\times}$ Asiatic hybrid 'Connecticut King'), various concentrations (0.1, 0.3 and 0.5%) of caffeine were injected directly into flower buds and then confirmed the viability of OA-1 $F_1$ hybrid at the flowering time. After the caffeine treatment, fertilized $F_1$ hybrids were crossed as female with Asiatic hybrid 'Lanzarote' as male. Five plantlets were obtained from seven embryos of 16 pollinated flowers at 0.3% treatment of caffeine while 0.5% treatment of caffeine obtained one plant let and 0.1 % treatment of caffeine plantlet did not produce at all. Thus 0.3% of caffeine treatment was considered as optimum concentration to produce subsequent progenies and the OA-l $F_1$ hybrid treated with caffeine produced 51% of putative 2n gametes. Pollen germination of OA-2 ('Romero Star' ${\times}$ 'Lady Rosa') and OA-3 ('Expression' ${\times}$ 'Lady Rosa') was not differ between temperature treatment alone and in combination with caffeine and temperature treatment. In the reciprocal crosses of OA-1 and Asiatic hybrid 'Lanzarote' or Oriental hybrid 'Sorbonne', A ('Lanzarote') ${\times}$ OA-1 or OA-1 ${\times}$ A crosses showed better results than O ('Sorbonne') ${\times}$ OA-1 or OA-1 ${\times}$ a crosses in plant obtaining. All progenies obtained from A ${\times}$ OA-1 or OA-1 ${\times}$ A crosses were confirmed as triploids by GISH analysis.