Muscadine grapes ( Vitis rotundifolia Michx.) are relatively insect- and disease-resistant native plants and are commonly grown in the southeastern United States to diversify farm operations ( Conner, 2009 ; Silva et al., 1994 ; Striegler et al
Derek W. Barchenger, John R. Clark, Renee T. Threlfall, Luke R. Howard, and Cindi R. Brownmiller
Jiang Lu and Lloyd Schell
Vitis rotundifolia (Muscadine grapes), a native species characterized with multiple resistance to grape diseases and insects, are cultivated throughout the southeastern U.S. for fresh fruit and processing. However, the species falls short of consumer's expectation as fresh fruit due to its seediness and thick skin. However, Vitis vinifera, a predominant Vitis species grown worldwide possesses good fruit characteristics such as seedlessness and edible skin but is susceptible to many diseases. Attempts to produce rotundifolia-vinifera hybrids to combine good fruit quality and disease resistance of both into F1 hybrids have been made by grape breeders for many years. Limited success was only reported when the V. vinifera was used as seed parents. Pollinating seedless vinifera pollen onV. rotundifolia stigma was made in 1993 and 1994. More than 20,000 flowers from 34 cross combinations were pollinated. These crosses were made to see if there is any chance to produce hybrids when muscadine grapes were used as female parent and specifically to introgress the seedlessness from European grapes into muscadine grapes. A few hundred seeds were collected from these crosses and germinated in a greenhouse. Two seedlings were clearly distinguished from the others with morphology intermediate between muscadine and the vinifera grapes, while the rest looked straight muscadine grapes derived from possible contaminated pollination. This conclusion was further confirmed by isozyme and DNA markers. One of the seedlings produced from the cross of `Jumbo' × `Thompson Seedless' grew vigorously and has been setting fruit since 1996. Fruit are mixture of stenospermocarpic and pathonocarpic seedlessness. Fruit setting and pollen viability test indicated that this hybrid is at least partly self-fertile. Many other characteristics of the hybrid, such as leaves, stems, tendrils, time of budbreak, bloom date, and ripen date are intermediate between muscadine and bunch grapes. The hybrid is resistant to Pierce's disease, anthracnose disease, and downy mildew, which are the limited factor to growing V. vinifera in the hot and humid southeastern U.S. This is the first report of a seedless hybrid from V. rotundifolia × V. vinifera.
Derek W. Barchenger, John R. Clark, Renee T. Threlfall, Luke R. Howard, and Cindi R. Brownmiller
Native to the southeastern United States, the muscadine grape ( Vitis rotundifolia Michx.) is commonly grown for its unique flavor, high nutraceutical content, and pest and disease resistance, which is often a limiting factor in the production of
David W. Ramming, Richard L. Emershad, and Ronald Tarailo
Hybridizations between seedless Vitis vinifera L. genotypes and V. rotundifolia (Michx.) were made specifically to introgress the seedless trait into the disease-resistant background of V. rotundifolia. The seedless, gynoecious P79-101 was hybridized with three V. rotundifolia parents, producing a total of 102 ovules. From these ovules, 44 embryos developed, producing 20 plants. Isozyme analyses and morphological traits confirmed that 19 of the plants were hybrids. Sixteen were planted in an experimental vineyard at California State Univ. Fresno. One seedling, C41-5, produced seedless fruit that appeared to be stenospermocarpic based on fruit and aborted seed size. Fruit weight was slightly less than that of `Thompson Seedless' (stenospermocarpic) and at least twice that of parthenocarpic fruit of `Black Corinth' and C41-7, a seeded hybrid with many parthenocarpic fruit. Aborted seeds of C41-5 were larger than, but not significantly different from, those of `Thompson Seedless', while parthenocarpic fruit from `Black Corinth' and C41-7 had aborted seeds that were smaller than those of C41-5. Seed weight of C41-7 averaged almost 10 times that of aborted C41-5 seeds. This is the first report of a stenospermocarpic, seedless hybrid of V. vinifera × V. rotundifolia.
Sudarsono and Ronald G. Goldy
Four muscadine grape (Vitis rotundifolia Michx.) cultivars (Carlos, Noble, Regale, and Tarheel) were evaluated for their ability to be cultured in vitro. Axillary buds were placed on Murashige and Skoog medium as modified by Chee. Different levels of benzylaminopurine [(BA) 0.5 to 10.0 μm], kinetin [(KIN) 0.5 to 5.0 μm], and thidiazuron [(TDZ) 0.5 to 11.3 μm], and different explant positions were evaluated for their effect on in vitro explant establishment and shoot production. Thidiazuron (2.3 to 4.5 μm) alone or in combination with BA (1.0 to 5.0 μm) or KIN (1.0 or 5.0 μm) was effective for establishing axillary buds. Similar levels were also effective for promoting shoot proliferation. Explants originating from the 10 basal nodes of a shoot with at least 25 nodes gave better shoot proliferation than explants originating from the 10 distal nodes. Chemical names used: 6-benzylaminopurine, 6-furfurylaminopu. rine (kinetin):N -phenyl-N'-l,2,3 -thiadiazol-5-y lurea (thidiazuron).
Zhongbo Ren and Jiang Lu
Non-native grape species such as V. vinifera and V. labrusca can not sustain the hot and humid environment of Florida due to their susceptibility to various diseases. Vitis rotundifolia (muscadine grapes) is native to Florida and the southeastern United States and adapted well to this climate condition. They are highly resistant to almost all grape foliage diseases and root pests such as nematode and phylloxera. Theoretically, muscadine grapes may become a valuable rootstock for bunch grapes. Unfortunately, most previous studies found that muscadine grapes were graft-incompatible with bunch grapes by normal grafting techniques. This study was to look for an alternative technique to graft V. vinifera onto muscadine rootstocks. A preliminary study indicated that bunch grape scions were successfully grafted on adult muscadine grapes. Two V. vinifera grape cultivars, `Thompson Seedless' and `Chardonnay', and two muscadine grape cultivars, `Carlos' and `Alachua', were used for this study. The muscadine grapes used as rootstocks are 6-year old field-grown vines and V. vinifera was used as scions. Using the common V-type grafting method was completely failed in more than 150 attempts. We then tried to insert the first-year buds of V. vinifera into 1- to 3-year-old muscadine canes. Surprisingly, the survival rate of the inserting buds was moderately high when `Carlos' was used as the rootstock. `Thompson Seedless'/`Carlos', `Chardonnay'/`Carlos' reached 53% and 33%, respectively. Successful grafting but lower survival rate was also obtained when `Alachua' was used as the rootstock (10% in `Thompson Seedless/`Alachua' and 3% in `Chardonny'/`Alachua'). The average survival rate of `Thompson Seedless' on the muscadine rootstocks was 36%, and `Chardonnay' was 12%. Regardless the cultivar of the scions, buds survived on `Carlos' and `Alachua' rootstocks were 44% and 5%, respectively. Results from this study indicated that V. vinifera grapes could be successfully grafted onto muscadine rootstocks. The survival rate varied depending on cultivars used for both scion and rootstock. It would be very interesting to see if resistance to certain diseases such as the Pierce's disease can be improved in those V. vinifera grape with muscadine roots and trunks derived from this preliminary study.
Yuru Chang, Lorenzo Rossi, Lincoln Zotarelli, Bin Gao, and Ali Sarkhosh
The Muscadine grape ( Vitis rotundifolia L., Vitaceae) is the predominant grape cultivar commonly grown in the southeastern United States, with current markets existing for juice, wine, and fresh fruit ( Duarte Alonso and O’Neill, 2012 ). Most
Patrick J. Conner
The genus Vitis contains two subgenera, Euvitis (bunch grapes) and Muscadinia (muscadine grapes). The muscadine grape, Vitis rotundifolia Michx., is the only commonly cultivated member of the Muscadinia subgenus. Muscadine grapes are
Karen L. Thies and Clinton H. Graves Jr.
A meristem micropropagation system was developed to produce Agrobacterium -free muscadine grape. Meristems were cultured on a modified Woody Plant Medium (mWPM) supplemented with 0.45 μm BAP. After 2 weeks, cultures were transferred to mWPM containing 8.92 μm BAP to enhance shoot proliferation. Propagules were subsequently subdivided and transferred to fresh medium at 2- to 4-week intervals. New shoots were excised and inserted in mWPM supplemented with 0.57 μm IAA to promote root formation. This method has been successfully used to produce Agrobacterium -free plants of muscadine cultivars Carlos, Doreen, Jumbo, Magnolia, and Sterling for research purposes and for a foundation planting in Mississippi. Chemical names used: benzylaminopurine (BAP); indole3-acetic acid (IAA).
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.