, 1990 ). Somatic embryogenesis plays an important role in micropropagation, genetic manipulation, cryopreservation, induced mutagenesis, and germplasm conservation in plants ( Sharma et al., 2012 ; Vahdati et al., 2008 ). In general, somatic
Mohammad Sadat-Hosseini, Kourosh Vahdati, and Charles A. Leslie
Tracie K. Matsumoto, Francis T.P. Zee, Jon Y. Suzuki, Savarni Tripathi, James Carr, and Bruce Mackey
has a detrimental impact in Hawaii on both commercial production and germplasm conservation. Although tolerance but not genetic resistance to PRSV has been reported in the Carica germplasm, PRSV-resistant plants have been achieved by genetic
Boling Liu, Hongzhou Fang, Chaorong Meng, Ming Chen, Qingdong Chai, Kai Zhang, and Shijuan Liu
with lines, which are known as the window-leaved plants ( Krulik, 1980 ). Thus, this micropropagation protocol could facilitate in the propagation of H. turgida for commercial cultivation, as well as germplasm conservation. Literature Cited Amoo, S
Angela Baldo, Larry Robertson, and Joanne Labate
Cultivated tomato varieties are genetically extremely similar. We identified 764 Unigenes with potential single nucleotide polymorphisms (SNPs) among more than 15 cultivars from public expressed tomato data. By sequencing regions from 53 of these Unigenes in two to three cultivars, we discovered an unexpected wealth of nucleotide polymorphism (62 SNPs and 12 indels in 21 Unigenes). This included a high proportion of predicted nonsynonymous nucleotide (17 of 33 SNPs in exons) and nonconservative amino acid (6 of 16 nonsynonymous SNPs) changes. We hypothesize that five of these regions are associated with introgressions from wild relatives. Identifying polymorphic, expressed genes in the tomato genome will be useful for both tomato improvement and germplasm conservation.
Antonieta N. Salomão and Rosângela C. Mundim
The effects on germination of two lots of Carica papaya seed of dehydration at 25 °C, followed by exposure to -20 °C or -196 °C, were evaluated with and without gibberellic acid (GA3) treatment. In the absence of GA3 treatment, dehydration increased subsequent germination only in seed lot 1 when moisture content (m.c.) was reduced from 59% to 6.0% and 5.3%. In seed lot 2, dehydration followed by exposure to -196 °C increased germination compared with dehydration alone. Treatment with GA3 enhanced germination rate in all treatments. Dehydration to 5.3% (lot 1) or 6.9% and 6.8% m.c. (lot 2), followed by exposure to subzero temperatures and treatment with GA3, were the most favorable combined treatments to enhance papaya seed germination. The results suggest that papaya seed presents an orthodox behavior, permitting germplasm conservation in conventional and cryogenic genebanks.
Don J. Durzan and M.D. Durzan
Prospects for the establishment of joint-ventured agribusiness in developing countries are a function of international agreements, local risk conditions, business networks, and banking systems that are willing to support the innovative transfer, protection, assessment, and commercialization of biotechnology. The integration of biotechnology will occur only if truly convincing practices emerge that enhance biodiversity and the competitiveness of sustainable production, utilization, and marketing cycles. Integration also depends on agreements on intellectual property rights, plant protection, trade and tariffs, price stabilization, and non-trade-distorting policies. These policies deal with broad issues in research, pest and disease control, environmental quality, germplasm conservation, resource retirement programs, and even with crop and disaster insurance. Measures derived from these policies will apply to novel processes and to organisms that have been genetically engineered and approved for release into the environment. For developing countries, much more attention will have to be paid to biological diversity and sustainable balances among intercropped agriforest and horticultural production systems. Balances should be compatible with regional and local customs and practices before genetically engineered “green goods and services” are introduced in the marketplace. Recombinant DNA technologies are currently better-suited to deal on a “gene-by-gene” basis, with commodity surpluses and material conversions involving more concentrated and industrialized processes than with field plantations of genetically engineered, complex, and long-lived crops that may require considerable adaptive plasticity. In most countries with developing economies, the integration of recombinant DNA technology represents a “special problematique” involving politico- and socioeconomic and environmental factors. Barriers to transfer and integration may involve evolving international agreements, public acceptance, resource over-exploitation, environmental degradation, rapid insect and disease resistance, contaminated water and food supplies, reduced quality of life, labor quality, corruption, crime, farmers' rights, germplasm conservation, and lack of protection of intellectual property, among other factors. Hence, the timing and mode of transferring biotechnology needs considerable impact assessment on a case-by-case basis.
Mario Crespo, James Nienhuis, Jan Tivang, and Paul Skroch
Knowledge of relative genetic distance among genotypes is useful in a breeding program because it permits organization of germplasm resources. Genetic distance (GD) was estimated among 113 faba bean, Vicia faba L. genotypes, which included three botanical varieties from different geographical areas around the world. The genotypes included 87 accessions from Bolivia, 14 accessions from the Middle East and North Africa, five accessions from Australia, and seven commercial varieties from Europe. Twenty-three RAPD primers were scored yielding four to 13 polymorphic bands resulting in a total of 165 bands. Our objective was to determine genetic relationships among accessions and cultivars as measured by RAPD markers. The genetic relationships were estimated using the ratio of discordant to total bands scored. A multidimensional scaling (MDS) plot indicated four clusters corresponding to: i) European commercial cultivars; ii) the Middle East, North Africa, and Australian accessions; iii) the Bolivian highland landraces; and iv) the Bolivian collection maintained in a valley environment. A permutation test confirmed the four clusters (P < 0.01). Sampling variance results indicated that a CV of 10% could be obtained with as few as 148 bands between groups. Selection and drift appears the main cause of divergence of two populations in the Bolivian faba bean collection. The results of this study indicated that RAPDs are a powerful tool for evaluation of germplasm conservation methods in faba bean.
Xianqin Qiu, Hao Zhang, Hongying Jian, Qigang Wang, Ningning Zhou, Huijun Yan, Ting Zhang, and Kaixue Tang
Roses are one of the economically most important groups of ornamental plants. The internal transcribed spacers (ITS) of the nuclear ribosomal DNA and the chloroplast gene matK were used to investigate the genetic diversity and genetic relationships among Rosa germplasm including 39 wild species, 21 old garden roses, and 29 modern cultivars. Three dendrograms based on ITS and matK clustering data indicated that 1) 39 wild genotypes were consistent with their classification into botanical sections with only a few exceptions; 2) most of the wild genotypes were separated from rose cultivars. However, three sections, Synstylae, Chinenses, and Rosa, that contributed to the modern roses generally gathered together with almost all old garden and modern roses on the molecular level; and 3) the relationships between cultivated roses as inferred by ITS and matK sequences do not correlate with horticultural groups. Results demonstrated that both sequence techniques can contribute to clarifying the genetic relationships of rose accessions and germplasm conservation to enhance the ornamental and economic value of rose.
Juan J. Ruiz, Santiago García-Martínez, Belén Picó, Muquiang Gao, and Carlos F. Quiros
We studied the genetic variability of some traditional tomato (Lycopersicon esculentum L. Mill.) cultivars of Spain, and established their relationships using both simple sequence repeats (SSR) and sequence related amplified polymorphism (SRAP) markers. These included cultivars from different locations of three main types, Muchamiel, De la pera, and Moruno. Additionally we tested two other local cultivars, `Valenciano' and `Flor de Baladre', plus a small sample of commercial cultivars and a few wild species. Both types of markers resolved the cultivars from different groups, but SSR failed to distinguish some of those classified under the same group. All the De la pera cultivars clustered together by genetic similarity with the SRAP markers. The other traditional cultivars, which are grown in a wider geographic range, formed a more diffuse group, which included the commercial cultivar Roma. The Mexican cultivar Zapotec, a breeding line, and the virus-resistant commercial hybrid `Anastasia' were the most distant of all the cultivars. The latter hybrid had higher similarity to the wild species due to introgressed segments from them carrying the resistance genes. Similar results were observed for SSR markers but with a lower level of resolution. This information would be useful to facilitate tomato germplasm conservation and management efforts.
Tim Rinehart, Cecil Pounders, and Brian Scheffler
Crapemyrtles (Lagerstroemia) are deciduous shrubs or trees with prolific summer flowers. Their popularity is due in large part to low maintenance requirements in sunny climates, wide range of growth habits, disease resistance, and bark characteristics, as well as having a long flowering period (up to 120 days). Once well-established, they are extremely tolerant to heat and drought. Lagerstroemia was first introduced to the southern U.S. from southeast Asia more than 150 years ago, and is comprised of at least 80 known species. Most modern cultivars are L. indica and L. fauriei hybrids. L. speciosa is a tropical crapemyrtle with very large flowers, but lacks cold hardiness. It is a vigorous plant, but only when grown in Hardiness zones 9 or 10. We recently established microsatellite markers for Lagerstroemia and evaluated their utility for verifying interspecific hybrids. Here we verify F1 hybrids between L. indica `Tonto', `Red River', and L. speciosa. We also genotyped two commercially available L. speciosa hybrids. Currently, we are using crapemyrtle SSRs for cultivar identification and germplasm conservation. Future research includes marker-assisted breeding to produce powdery mildew and flea beetle resistant cultivars, as well as improved growth habit and fall foliage color.