Volume 1 Number 2 2007

CONTENTS AND ABSTRACTS

Shuyu Liu, Mitali Banik, Kangfu Yu, Soon J. Park, Vaino Poysa (Canada), Yanan Guan (China) Marker-Assisted Selection (MAS) in Major Cereal and Legume Crop Breeding: Current Progress and Future Directions (pp 74-88)

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Invited Review: With the development of molecular markers in crops, genetic and physical maps have been constructed in several important crops. Genes or QTL conditioning important agronomic traits were mapped onto chromosomes or genetic linkage groups through analyses of mapping populations. This paper reviews the application of marker-assisted selection (MAS) in three major cereal crops, wheat (Triticum aestivum L.), maize (Zea mays L.) and rice (Oryza sativa L.), as well as two legume crops, soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.). The important traits mapped in biotic stresses include resistances to bacterial, viral and fungal diseases; resistances to insects, such as aphids, green bugs, and Hessian flies; and resistance to nematodes. Other traits include tolerance to abiotic factors like drought, high temperature, and soil nutrient deficiency; seed quality and nutrient components; as well as yield and its components. The advantages and disadvantages of using MAS in crop breeding are discussed. This paper is a summary of available MAS strategies and potential application of MAS in tracking more traits in practical breeding. Future utilization of MAS is also discussed. As a review of MAS in five important crops across cereals and legumes, we believe it provides useful information to crop breeders and molecular geneticists.

Fangyun Cheng (China) Advances in the Breeding of Tree Peonies and a Cultivar System for the Cultivar Group (pp 89-104)

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Invited Review: Tree peonies native to China have become an internationalized ornamental plant and are widely cultivated in many countries in Asia, America, Europe and Australia. Breeding starting from domestication of wild plants through selection of bud mutations and seedlings to hybridization has been done for about 1500 years. At present a few thousand cultivars are cultivated globally in gardens or propagated in nurseries, all of which genetically originated from infra- and inter-specific, inter-subsectional and -sectional hybridization and are included in different groups with distinct traits from each other. A cultivar system of tree peonies that considers the origin and diversity of cultivars should theoretically be set up at the base of a cultivar group, and would depend on recent advances from botanical studies and breeding achievements in the last few decades. Such a system composed of 17 cultivar-groups first identified by our work will explain the relationship between species and cultivar groups and among cultivar groups and would benefit tree peony breeding as an important reference for ascertaining breeding strategy and objectives, selecting and matching parents in crossing, and exploring and utilizing valuable genes controlling desirable ornamental traits and resistances. Attempts made in in vitro tissue culture, ovule and embryo culture, somatic embryogenesis and plantlet regeneration are uncovering a promising use of bio-techniques to overcome problematic issues of tree peony breeding such as cross incompatibility, hybrid abortion and sterility, slow growth to flower and difficulties in propagation. Combined with molecular marker-assisted and transgenic breeding, inter-subsectional and -sectional distant hybridization will effectively promote the breeding of tree peonies and undoubtedly bring about more opportunity to release better cultivars. A scientific strategy and an international cooperation on tree peony breeding are very necessary for effective work and objectives to be achieved in the future.

Sobir, Roedhy Poerwanto (Indonesia) Mangosteen Genetics and Improvement (pp 105-111)

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Invited Mini-Review: Mangosteen (Garcinia mangostana L.) originated from natural hybridization of G. malaccensis and G. hombrioniana. Mangosteen is reproduced from adventitious embryos, from which the seed develops without fertilization, i.e. agamospermy or apomixis. Studies on mangosteen flowers revealed that the stamens and pistils developed at an early stage of flower development, however subsequently staminate growth is stunted and aborted. Apomictic reproduction leads to the assumption that mangosteen trees have same genetic properties. However, field evaluation showed variability in several morphological characters, such as tree shape, fruit shape, and petal color. Further studies using DNA markers confirmed genetic variability among the mangosteen population. The variation may have arisen from accumulation of natural mutations. Another hypothesis is that the mangosteen population may have developed from more than a single hybridization of its two wild progenitor species. Crop improvement has been conducted using mutation breeding through application of gamma ray irradiation on seed callus, as well as on cell culture. Early results indicated genetic variability increased three-fold compare to that of natural levels as detected by RAPD analysis.

Bo Zhou, Yuhua Li, Fei Zhao (China), Saneyuki Kawabata (Japan) Recent Progress in Cellular, Biochemical and Genetic Events of Brassica Species (pp 112-118)

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Invited Mini-Review: Brassica species are playing an even more important role in global agriculture and horticulture. To understand the regulation and evolution of Brassica species, the Multinational Brassica Genome Project (MBGP) was initiated and various techniques have been developed to characterize the behaviour of the underlying genes, genomic regulatory networks and associated metabolism. By using cDNA library screening and Rapid Amplification of cDNA Ends (RACE), many functional genes related to metabolism have been identified. cDNA microarrays were applied to determine gene expression profiles. Molecular markers were used in marker-assisted selection and breeding, and transformation technology was applied to the introduction of desirable traits. Moreover, quantitative trait loci (QTL) have been identified for a wide range of morphological, physiological and crop traits in the different Brassica crop types. Many systems and technologies have also been applied to study self-incompatibility and Cytoplasmic male sterility (CMS) in Brassica species. With the development of molecular biology, more and more knowledge at the level of gene expression, biochemistry, metabolism and physiology has been gained in Brassica species. Furthermore, as one of the most commonly grown and widely adapted crops Brassica species have been used as vegetables. We present a techniques review on cellular, biochemical and genetic events in Brassica species.

Suhyoung Park, Soo-Seong Lee, Moo-Kyoung Yoon, IL-Gin Mok, Hyo Guen Park (Korea) Development of Uniform F₁ Hybrid Varieties of Korean Radish Using Self-Incompatibility in Double-Crossing (pp 119-122)

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Original Research Paper: Radish (Raphanus sativus L.) is one of the major vegetables comprising ‘Kimchi’, which is the general term given to a group of fermented vegetables in Korea. The radish for ‘Kimchi’ is different from the European radish, which is used mainly in salads, and will be referred to as ‘Korean radish’ hereafter. Radish possesses self-incompatibility (SI) which prevents self-fertilization by recognizing self-pollen on the stigmatic surface. SI has been effectively used to produce uniform F₁ hybrid seeds; however, SI has caused problems in seed propagation of parental lines. Radish also bears a small number of seeds per pod compared to Chinese cabbage. To produce parental seeds effectively, breeders have made double-crossed (DC) varieties using similar inbreds, even though DC varieties show low uniformity. We have tried to increase seed production and uniformity by using cross-compatible near-isogenic lines (CCNILs). We have modified the single seed descent method by employing DNA markers on the S-locus. Hundreds of inbreds have been developed from two parental sets after one parental cross and five generations of inbreds. In each generation, PCR-based selection has been performed to select SI heterozygotes. We have tried to make inbreds possessing a different SI allele but with other genes fixed. Ways to use CCNILs in radish breeding will be discussed.

V.O. Adetimirin (Nigeria) Relationships among Three Non-Destructive Seedling Vigour Traits in Maize (pp 123-128)

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Original Research Paper: Three non-destructive methods of seedling vigour assessment were compared in a pot experiment and two soil fertility environments in a field experiment. Ten and 23 maize (Zea mays L.) genotypes were evaluated in the pot and field experiments, respectively. The experimental design was a randomized complete block with three replicates. The seedling vigour traits investigated were seedling height, seedling length and vigour score on a scale of 1 to 9 (where 1= excellent vigour; 9 = very poor vigour). Data were collected at 2 and 4 weeks after planting (WAP) in pots, and 4 WAP in the field. The maize genotypes showed genetic variation for the three seedling vigour traits studied. Seedling height, seedling length and vigour score were significantly (P < 0.01) correlated in pots and in the field. Phenotypic correlation ranged from -0.76 to 0.89 in pots and -0.51 to 0.96 in the field while genotypic correlation ranged from -0.91 to -1.04 in pots, and -0.57 to 0.96 in the field. Heritability for the three traits was moderate to high (0.38-0.67) in pots and high in the field (0.71-0.88). Any one of the three traits could, therefore, be used for the assessment of seedling vigour in maize. Vigour score integrates qualitative and quantitative aspects of seedling performance. The ease and rapid nature of its determination place it at advantage over the other two seedling vigour traits.

María Andrea Espósito, Leonardo Andrés Milanesi, Eugenia Alejandra Martin, Vanina Pamela Cravero, Fernando Sebastian López Anido, Enrique Luis Cointry (Argentina) Analysis Based on Morphological, Protein and SRAP Markers in Pea (Pisum sativum L.) (pp 129-134)

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Original Research Paper: Morphological, protein and SRAP markers among fourteen pea varieties (Pisum sativum L) were studied. Data on 15 morphological traits were collected and analyzed. A total of 32 protein bands and 162 polymorphic SRAP fragments were scored. A comparison between morphological and molecular data and morphological and protein data was carried out through a Procrustes Generalized Method. Previously we carried out a Principal Component Analysis (PCA) for morphological data and Principal Coordinates Analysis (PCoA) for the protein and SRAP data. The correlation between SRAP and morphological data was R=0.56 for 2005 and R=0.80 for 2006 showing the highest correlation between both data sets for the second year what presented unfavourable environmental conditions. Meanwhile, the correlation between protein and morphological data was R=0.56 for 2005 and R=0.63 for 2006. These results suggest that exposure to a combination of environmental stresses may increase the expression of genetic variability for productive traits. Genetic diversity is the basis for successful crop improvement and can be estimated by different methods such as protein or molecular markers but DNA markers provide an opportunity to characterize genotypes more precisely than proteins. Molecular markers were significantly correlated with markers based on agronomic traits, suggesting that the two systems give similar estimates of genetic relations among the varieties.

María Andrea Espósito, Leonardo Andrés Milanesi, Eugenia Alejandra Martin, Vanina Pamela Cravero, Fernando Sebastian López Anido, Enrique Luis Cointry (Argentina) Principal Component Analysis Based on Morphological Characters in Pea (Pisum sativum L.) (pp 135-137)

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NO ABSTRACT