Shoot and root characteristics of four peach tree [Prunus persica (L.) Batsch (Peach Group)] growth habits (compact, dwarf, pillar, and standard) were studied. In compact trees, leaf number (1350/tree) was twice, but leaf area (6 cm2/leaf) was half that of pillar and standard trees. The number of lateral branches in compact trees (34) was nearly three times more than in pillar and standard trees. Leaf area index (total one-side leaf area per tree divided by the canopy cross-sectional area of the tree) of pillar trees was greater than compact, dwarf, and standard trees (13 compared with 4, 4, and 3, respectively) due to a narrower crown diameter. Dwarf trees were distinct with few leaves (134/tree) and less than half the roots of the other growth habits. Compact trees produced more higher order lateral (HOL) roots than pillar and standard trees. More second order lateral (SOL) roots were produced by compact than standard trees (1.2 vs. 0.8 SOL roots per centimeter first order lateral root). Pillar trees had higher shoot: root dry weight (DW) ratios (2.4) than compact and standard trees (1.7 for both) due to lower root DWs. Root topology was similar among compact, pillar, and standard peach trees but root axes between branch junctions (links) were significantly longer in compact trees. Compact trees had more and longer HOL roots in roots originating near the root collar (stem-root junction) (i.e., more fibrous roots) and this appeared to correlate with more lateral branches in the canopy. These results indicate significant differences in root as well as shoot architecture among growth habits that can affect their use as scion or rootstock cultivars.
Thomas Tworkoski and Ralph Scorza
Georges T. Dodds and Pamela M. Ludford
Chilling-injury symptoms on the surface of eight cultivars or lines of tomato (Lycopersicon esculentum Mill.) fruit were mapped with respect to subtending locules. Mature-green (MG) fruit were chilled at SC for 10 to 25 days and then ripened to red ripe at 20C. Mature-green fruit showed a major portion of injury over subtending locules and on the stem end. The location of injury corresponded with the regions that were the last to ripen. The injuries of immature-green (IG) fruit treated in a similar manner were different from those of MG fruit both in appearance and in distribution.
E.J. Parks, J.W. Moyer, and J.H. Lyerly
Fluorescent amplified fragment length polymorphism (F-AFLP) and microsatellites (SSRs) were used to evaluate new guinea impatiens (Impatiens hawkeri W. Bull) cultivars. Ninety-five quality-selected polymorphic fragments from 10 F-AFLP+3 primer combinations were used to evaluate 100 cultivars representing a variety of colors, forms, and breeding programs. Jaccard similarities and unweighted pair-group method of the arithmetic average (UPGMA) clustering formed a dendrogram with three cultivar groups, to a large extent clustering the cultivars by breeder with a high cophenetic correlation coefficient. A small insert genomic library was created and 442 kb of new guinea impatiens sequence was screened for repetitive motifs, resulting in 14 microsatellite markers. A subset of 46 cultivars representing five commercial breeding companies and 11 cultivar series was selected for microsatellite analysis. Seven loci were polymorphic, with two to six alleles per locus. Although both methods were equally effective in distinguishing the cultivars from one another, the topologies of the dendrograms for the two methods were different. The topology of the AFLP dendrogram reflected possible relationships based on cultivar series and breeding company, while the SSR dendrogram did not. The objectives of this research were to develop and validate both F-AFLP and SSR methodologies for new guinea impatiens, identify markers that can be reliably used for fingerprinting, and create a database for future cultivar comparisons.
James M. Bradeen, Inga C. Bach, Mathilde Briard, Valérie le Clerc, Dariusz Grzebelus, Douglas A. Senalik, and Philipp W. Simon
A sample of 124 Daucus carota L. accessions, including cultivated carrot [D. carota ssp. sativus (Hoffm.) Arcangeli] and related wild subspecies, using a variety of molecular markers was examined. Represented within the samples were wild accessions from 18 countries, 14 of 16 major root types of European origin, and examples of major North American and Asian cultivated carrot types. Amplified fragment length polymorphism (AFLP) and inter-simple sequence repeat (ISSR) markers revealed extensive variation within D. carota. Although cultivated carrot and wild D. carota subspecies can cross freely, cultivated and wild carrots clustered separately, supporting the possibility that human selection for desirable horticultural traits has artificially reduced gene flow between cultivated and wild forms. Our analyses support the likelihood that North American D. carota populations arose due to introduction of weedy materials rather than escape of cultivated forms. With the exception of wild vs. cultivated types, no genetic alliances were evident in dendrogram topology. Furthermore, between and even within nonmapped marker classes, dendrogram topology predictions were not consistent. Generally poor correlations among root types, geographic origin, mitochondrial, plastid, and specific nuclear diversity and AFLP/ISSR data were also observed. We concluded that genetic diversity in carrot is extensive and relatively nonstructured in nature.
James A. Schrader and William R. Graves
Alnus maritima (Marsh.) Muhl. ex Nutt. is a rare woody plant species that exists as three subspecies found in widely disjunct locations in the United States. Although there is a growing interest in the phytogeography, ecology, conservation, and landscape potential of this species, the phylogeny of A. maritima has not yet been resolved by using molecular methods. We have combined a relatively new method of genome fingerprinting, ISSR-PCR, and the automated imaging capabilities of GeneScan technology to investigate the molecular systematics of A. maritima. Based on the molecular evidence from 108 ISSR loci, we confirm that the three disjunct populations of A. maritima have diverged sufficiently to be classified as subspecies. Our molecular phylogeny of the three subspecies of A. maritima agreed in topology with a phylogeny produced from morphological data and showed that subsp. oklahomensis is the most distinct of the three subspecies and was the first to diverge. The simultaneous analysis of molecular and morphological data provides a detailed and balanced phylogeny reconstruction for the three subspecies. Our results support the theory that A. maritima originated in Asia, migrated into North America across the Bering land bridge, and was established over a large range in the New World before being forced into its present meager disjunct distribution.
Meryem Ipek, Ahmet Ipek, and Philipp W. Simon
Garlic (Allium sativum L.) is an asexually propagated crop that displays much morphological diversity. Studies which have assessed garlic diversity with isozymes and randomly amplified polymorphic DNA (RAPD) markers generally agreed with the morphological observations but sometimes failed to discriminate clones. To discriminate among closely related garlic clones in more detail, we introduced amplified fragment-length polymorphism (AFLPs) to evaluate the genetic diversity and phenetic relatedness of 45 garlic clones and three A. longicuspis clones and we compared AFLP results with RAPD markers and isozymes. Three AFLP primer combinations generated a total of 183 polymorphic fragments. Although similarities between the clusters were low (≥0.30), some clones within the clusters were very similar (>0.95) with AFLP analysis. Sixteen clones represented only six different banding patterns, within which they shared 100% polymorphic AFLPs and RAPD markers, and likely are duplicates. In agreement with the results of other investigators, A. longicuspis and A. sativum clones were clustered together with no clear separation, suggesting these species are not genetically or specifically distinct. The topology of AFLP, RAPD, and isozyme dendrograms were similar, but RAPD and isozyme dendrograms reflected less and much less polymorphism, respectively. Comparison of unweighted pair group method with arithmetic averaging (UPGMA) dendrograms of AFLP, RAPD, and isozyme cluster analyses using the Mantel test indicated a correlation of 0.96, 0.55, and 0.57 between AFLP and RAPD, AFLP and isozyme, and RAPD and isozyme, respectively. Polymorphic AFLPs are abundant in garlic and demonstrated genetic diversity among closely related clones which could not be differentiated with RAPD markers and isozymes. Therefore, AFLP is an additional tool for fingerprinting and detailed assessment of genetic relationships in garlic.
Francisca López-Granados, M. Teresa Gómez-Casero, José M. Peña-Barragán, Montserrat Jurado-Expósito, and Luis García-Torres
network will learn the existing relationship between the two by means of a learning algorithm. This learning will materialize in the network's topology and in the value of its connections. Once the neural network has learned to carry out the desired
Li Yingzhi, Cheng Yunjiang, Tao Nengguo, and Deng Xiuxin
, 2000 ). In maximum parsimony analysis, we first treated gaps as missing data, and then treated them as fifth state to determine whether there were any phylogenetic topology differences between the two methods. Maximum likelihood analysis. In
Omar Carrillo-Mendoza, Wayne B. Sherman, and José X. Chaparro
“twigginess” of stone fruit trees. Various types of plant growth models that integrate plant topology and plant geometry to study plant architecture are available ( Fourcaud et al., 2008 ). Another means to portray plant architecture is the development of
Xiaomeng Li, Rangjin Xie, Zhenhua Lu, and Zhiqin Zhou
the chloroplast data resulted in a single most parsimonious tree of length 51 steps [ Fig. 1 ; consistency index (CI) = 0.980, retention index (RI) = 0.995]. The topologies of the phylogenetic trees based on MP and NJ (data not shown) analyses were