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Mohammad Sadat Hosseini Grouh, Kourosh Vahdati, Mahmoud Lotfi, Darab Hassani, and Nejat Pirvali Biranvand

acid. Flow cytometer analysis. Flow cytometry was used for determination of the ploidy level of samples prepared from leaves of the haploid and diploid (control) in vitro plants. Nuclei were released from 0.5 cm 2 of leaf tissue by chopping with a

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C. K. Chandler and P. M. Lyrene


Guard cells tended to be shortest for diploid species and longest for hexaploids, but there was so much plant-to-plant variation both within ploidy levels (diploid, tetraploid, hexaploid) and within species that guard cell length was not a reliable indicator of ploidy level of individual plants.

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Elliot H. Norden, Paul M. Lyrene, and Jose X. Chaparro

the age of flowering. The purpose of this paper was to describe the ploidy, phenotypes, pollen fertility, and crossing behavior of plants from these and similar crosses. Materials and Methods The seeds from the interspecific crosses were planted on the

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Thomas Ranney* and Thomas Eaker

Information on ploidy levels is extremely valuable for use in plant breeding programs. Fertility, crossability, and heritability of traits are all influenced by ploidy levels. Knowledge of reproductive pathways, including occurrence of apomixes, pseudogamy, and formation of unreduced gametes can also be important information for developing breeding strategies. Although ploidy level can be determined by counting chromosomes, flow cytometry provides a reliable and much faster means for determination of nuclear DNA content and associated ploidy level. Measurement of ploidy levels of seeds (embryo and endosperm) can also provide useful insights into reproductive pathways. The objective of this study was to determine the approximate genome size, estimated ploidy level, and range of reproductive pathways of a diverse collection of flowering crapbapples (Malus spp.). Genome sizes were calculated as nuclear DNA content for unreduced tissue (2C). Results from the taxa included in our survey showed DNA contents ranging from 1.52 to 1.82 for diploids, 2.40 to 2.62 for triploids, and 3.36 to 3.74 pg/2C for tetraploids. Based on these ranges, we identified 43 diploid, 10 triploid, and 4 tetraploid crabapple taxa in this collection. Results from open pollinated seeds and seedlings demonstrated a variety of reproductive pathways including apomixes and unreduced gametes. This research provides information on ploidy levels and reproductive pathways of flowering crabapples and will allow for more systematic and efficient progress in the development of improved cultivars.

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Sandra B. Wilson, Julia Rycyna, Zhanao Deng, and Gary Knox

is dynamic, as we gradually learn more about their reproductive biology, ploidy, phenotypic stability, and long-term consequences. For nearly 2 decades, we have conducted a series of experiments that have evaluated more than 25 heavenly bamboo

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Guo-Gui Ning, Xue-Ping Shi, Hui-Rong Hu, Yan Yan, and Man-Zhu Bao

( Natarella and Sink, 1971 ; Sink, 1973 ; Vanderkrol and Chua,1993 ). Certainly, there have also been no studies in petunia regarding the relationship of ploidy with flower form ( Meyerowitz et al., 1989 ). Currently, breeding for new varieties of double

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Xia Xu, Jiang Lu, and Zhongbo Ren

Ploidy level in grapevines varies, especially since in vitro techniques are employed in the breeding process and after plants are treated with either chemicals or radiation. Detection of ploidy level in grapevines by microscopic chromosome counting is complicated by their high number and the small size of chromosomes. Flow cytometry provides an accurate and rapid method in determining the ploidy level in plant tissue by measuring the nuclear DNA content in living cells and thus is a very useful tool in plant breeding or genetic studies. The objective of this research was to analyze the ploidy level of a selected group of muscadine vines that were different from normal diploid vines in morphology. These grapes were derived from either chemical treatment of known varieties or from controlled/open pollinations. Among the 26 grapevines investigated, 8 were found to be diploids, 11 were tetraploids, and 7 were chimeric aneuploids. Results of this study indicate that flow cytometry is a quick, reliable tool for determining ploidy levels of grapevines.

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A. Tenkouano, J.H. Crouch, H.K. Crouch, and D. Vuylsteke

We attempted to determine ploidy level in the gametophyte and the sporophyte of Musa using pollen and chloroplast characteristics, respectively. In the gametophyte, interploidy differences accounted for 63.8% of the genetic variance for pollen diameter and 87.5% for pollen stainability, the remainder being attributable to intraploidy differences among clones. While pollen count and stainability effectively separated triploid accessions from diploids or tetraploids, they did not discriminate between diploids and tetraploids. In the sporophyte, the relative contributions of interploidy and intraploidy differences to genetic variation in the number of chloroplasts in stomatal guard cells were 70.8% and 29.2%, respectively. Although pollen diameter and chloroplast number increased with ploidy, the use of the sporophytic parameter appears to provide a more satisfactory means of estimating ploidy status in Musa.

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Peggy Ozias-Akins and Robert L. Jarret

The nuclear DNA content of 53 accessions from 24 Ipomoea (Convolvulaceae) species, including four sweetpotato cultivars, was determined by flow cytometry of DAPI-stained nuclei. Ploidy level and DNA content were significantly correlated within the genus, but more highly so within species that contained multiple cytotypes. DNA content of cultivated Z. batatas (L.) Lam. (4.8 to 5.3 pg/2C nucleus) and feral tetraploid I. batatas (3.0 to 3.5 pg/2C nucleus) was estimated from the known DNA content of chicken erythrocytes (2.33 pg), which were used as an internal standard. Tetraploid forms of Z. cordato-triloba Dennstedt also were identified. Ploidy analysis using flow cytometry is rapid and suitable for large-scale experiments such as studying the genetic structure of populations of Z. batatas and related species. Chemical name used: 4′,6-diamidino-2-phenylindole (DAPI).

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S. De Schepper, L. Leus, M. Mertens, E. Van Bockstaele, M. De Loose, P. Debergh, and J. Heursel

Ploidy level was determined for six species and 88 cultivars of the Rhododendron subgenus Tsutsusi. High-resolution flow cytometry of nuclear DNA was performed on macerated plant tissue. All plants analyzed were diploid (2n = 26) with the exception of `Euratom', `Euratom Orange', and `Red Wing', which were triploid (3n = 39), and `Casablanca Tetra', which was found to be a cytochimera: mixoploid (2n + 4n) in the LI and LII, but tetraploid in the LIII. The described method has proven to be useful in screening a large population of rhododendrons. Analysis of different organs and plant tissues was easily accomplished through flow cytometry, and has proven useful in determining the ploidy of different histogenic layers.