Sweetpotato, I. batatas (L.) Lam. (Convolvulaceae), is an important food crop, and breeding efforts are necessary to provide new varieties to overcome pest, disease, and climate challenges and to maintain world food production. Fortunately, there
The sweet potato Ipomoea batatas (L.) Lam. is classified in series Batatas (Choisy) in Convolvulaceae, with 12 other species and an interspecific true hybrid. The phylogenetic relationships of a sweetpotato cultivar and 13 accessions of Ipomoeas in the series Batatas were investigated using the nucleotide sequence variation of the nuclear-encoded β-amylase gene. First, flowers were examined to identify the species, and DNA flow cytometry used to determine their ploidy. The sweetpotato accession was confirmed as a hexaploid, I. tabascana a tetraploid, and all other species were diploids. A 1.1–1.3 kb fragment of the β-amylase gene spanning two exons separated by a long intron was PCR-amplified, cloned, and sequenced. Exon sequences were highly conserved, while the intron yielded large sequence differences. Intron analysis grouped species currently recognized as A and B genome types into separate clades. This grouping supported the prior classification of all the species, with one exception. The species I. tiliacea was previously classified as a B genome species, but this DNA study classifies it as an A genome species. From the intron alignment, sequences specific to both A and B genome species were identified. Exon sequences indicated that I. ramosissima and I. umbraticola were quite different from other A genome species. Placement of I. littoralis was questionable: its introns were similar to other B genome species, but exons were quite different. Exon evolution indicated the B genome species evolved faster than A genome species. Both intron and exon results indicated the B genome species most closely related to sweetpotato (I. batatas) were I. trifida and I. tabascana.
Jacquemontia sandwicensis A. Gray (Convolvulaceae, formerly J. ovalifolia subsp. sandwicensis ) is a prostrate vine endemic to the main Hawaiian Islands. It typically grows along coastal areas, particularly on the leeward sides of the islands
It is well known that crossability within section Batatas is a complex phenomenon because of genetic, cytogenetic and physiological implications. During 1988 to 1991 we investigated the factors involved in crossability. In the 1st stage, self-compatibility was determined/verified in I. cynanchifolia (2x), I. grandifolia (2x), I. triloba (2x), I. x leucantha (2x), I. lacunosa (2x), I. tenuissima (2x), I. ramosissima (2x) and I. cordato-triloba (2x). Additionally, self-incompatibility was verified in I. trifida (2x), I. tiliacea (4x) and I. batatas (4x,6x). It is postulated that sexual compatibility is related to a multiallelic sporophytic incompatibility system. In the second stage, 4,162 cross pollinations between 11 species were performed at La Molina and San Ramon, and 76 interspecific combinations from 110 possible theoretic combinations in a diallelic 11 × 11 design were obtained. Of 76 interspecific combinations, 38 succeded with a crossability rate ranging from 0.01 to 1.00 at La Molina. In San Ramon, of 17 interspecific combinations, 11 were succesfull when estimating crossability from 0.01 to 0.71. Considering the factors affecting crossability, it was found that latitude influences flowering synchrony in progenitors, and in the germination process, and the early death of seedlings is related to an unbalanced genome (embryo/endosperm) relationship. In interspecific crosses, it was shown that I. trifida and I. x leucantha act as “bridge species”.
‘Covington’ is an orange-fleshed, smooth-skinned, rose-colored, table-stock sweetpotato [Ipomoea batatas (L.) Lam.] developed by North Carolina State University (NCSU). ‘Covington’, named after the late Henry M. Covington, an esteemed sweetpotato scientist at North Carolina State, was evaluated as NC98-608 in multiple state and regional yield trials during 2001 to 2006. ‘Covington’ produces yields equal to ‘Beauregard’, a dominant sweetpotato variety produced in the United States, but it is typically 5 to 10 days later in maturity. ‘Covington’ typically sizes its storage roots more evenly than ‘Beauregard’ resulting in fewer jumbo class roots and a higher percentage of number one roots. Total yields are similar for the two clones with the dry matter content of ‘Covington’ storage roots typically being 1 to 2 points higher than that of ‘Beauregard’. ‘Covington’ is resistant to fusarium wilt [Fusarium oxysporum Schlect. f.sp. batatas (Wollenw.) Snyd. & Hans.], southern root-knot nematode [Meloidogyne incognita (Kofoid & White 1919) Chitwood 1949 race 3], and moderately resistant to streptomyces soil rot [Streptomyces ipomoeae (Person & W.J. Martin) Wakswan & Henrici]. Symptoms of the russet crack strain of Sweet Potato Feathery Mottle Virus have not been observed in ‘Covington’. The flavor of the baked storage roots of ‘Covington’ has been rated as very good by standardized and informal taste panels and typically scores as well or better in this regard when compared with ‘Beauregard’.
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).
Sweetpotato, Ipomoea batatas is in the morning glory family, Convolvulaceae, genus Ipomoea, group Batatas. It has many wild Ipomoea relatives that serve as a reservoir of many needed pest and stress-resistance genes. A major barrier to introgression of useful genes is the ploidy gap—sweetpotato is a hexaploid and wild Ipomoeas are diploids and tetraploids. The wild species can be successfully crossed using 2n pollen or by first increasing ploidy by colchicine treatment. The ploidy of such hybrid offpsring can be determined by DNA flow cytometry. My objective was to develop a technique to determine DNA content in Ipomoea and values for DNA content for the major Ipomoea species using the EPIC flow cytometer with a UV detector. Nuclei were extracted and pretreated with cellulase and pectolyase before staining with propidium iodide (PI). A highly linear relationship was found between the DNA content determined by DNA flow cytometry and the ploidy of the closest sweetpotato relatives as determined by chromosome counts. These species were diploid I. trifida, tetraploid I. batatas, and hexaploid I. batatas. DNA content was most similar among other diploid Ipomoea species in the group Batatas and was significantly different in other Ipomoeas not in group Batatas.
. Collection, selection, and evaluation of island-specific phenotypes must be done to meet this demand. The vine Jacquemontia sandwicensis A. Gray (Convolvulaceae) is endemic to the coasts of the Hawaiian Islands. It was formerly classified as a subspecies
, Sclerotium rolfsii ( Gorodecki and Hadar, 1990 ; Mandelbaum et al., 1985 ), and Pythium soilborne mycosis ( Santos et al., 2008 ). C. cneorum L. (silverbush) is a small evergreen Mediterranean subshrub, in the Convolvulaceae family, forming a low mound
during cooking and is not as attractive. The flavor is very mild and almost tasteless. Convolvulaceae. Water spinach ( Ipomoea aquatica ) is a semiaquatic tender perennial from east India that roots very easily at stem nodes. The flowers are usually white