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J.D. Abbott and L. T. Thetford

Cyromazine is a triazine molecule with insect growth regulator properties being developed for control of Colorado potato beetle (Leptinotarsa decemlineata Say) (CPB) in vegetables. Research presented focuses primarily on results with potato (Solanum tuberosum L.), however, crop safety has been observed in other crops within the Solanaceae. Several trials were conducted in PA and NY during 1991 to examine the rates and timing necessary to control CPB in potatoes. Data from replicated small plot trials and non-replicated large block trials are included. Rates examined ranged 70 to 560 g ai na-1 applied alone or in combination with a pyrethroid or Bt. Comparisons were made with insecticides presently registered for CPB control in potatoes and cyromazine compared quite favorably. Two applications per CPB generation were made, the first at the beginning of CPB egg hatch and a second 7-16 days later for each generation. This application schedule provided excellent (90%) control of CPB larvae. The reduction in larvae also resulted in a reduction in adult CPB and potato leaf area damaged through insect feeding. In the test conducted in PA, an increase in size and number of tubers was observed when plants were treated with cyromazine. -These increases resulted in a 23-28% increase in total yield compared to that obtained from the untreated check plots.

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S. Bergeron, M.-P. Lamy, B. Dansereau, S. Gagne, S. Parent, and P. Moutoglis

While the majority of terrestial plants are colonized in soils by vesicular-arbuscular fungi (AM), that does not mean that these species can form a symbiosis with AM fungi in an artificial substrate under commercial production conditions. The purpose of this study was to identify those plants having a colonization potential. In Mar. 1998, 51 species and cultivars of ornamental plants were inoculated with two vesicular-arbuscular fungi (Glomus intraradices Schenk & Smith, and Glomus etunicatum Becker & Gerdemann; Premier Tech, Rivière-du-Loup, Quèbec). Periodic evaluations of colonization were done 5, 7, 9, 12, and 16 weeks after seeding. More than 59% of these plants tested were shown to have a good colonization potential with G. intraradices. Species belonging to the Compositae and Labiatae families all colonized. Species in the Solanaceae family showed slight to excellent colonization. Several species studied belonging to the Amaranthaceae, Capparidaceae, Caryophyllaceae, Chenopodiaceae, Cruciferae, Gentianaceae, Myrtaceae et Portulaceae families were not colonized. Root colonization with G. etunicatum was not detected on these species and cultivars during this short experimental period.

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Eliezer Louzada, Sonia Del Rio, and Dianren Xia

The development of improved orange and grapefruit varieties via conventional breeding is not possible due their high degree of apomixis. The currently available varieties originated through natural or induced mutation. The development of a alternative breeding method is urgently needed for these citrus group. Microprotoplast Mediated Chromosome Transfer (MMCT) provides a direct way to transfer a very limited portion of the genome (one or more chromosome) from a donor species to a recipient species. In mammalian cells this procedure has been a powerful tool for gene mapping and to study the regulation of gene expression. Until recently, no chemical treatment was known for an efficient induction of microprotoplat in plants. Recently, amiprophosmethyl (APM) and cremart was found to be very efficient for the mass production of microprotoplasts in the Solanaceae family enabling a single chromosome to be transferred from potato to tomato and tobacco. To establish this technology in citrus, the efficiency of APM for the mass induction of microprotoplast from Swiglea glutinosa, a wild relative of citrus, was studied. APM ranging from 16 to 32 μmol was effective on promoting the scattering of the chromosomes and to create multinucleated cells. The microprotoplasts will be used in chromosome transfer experiments.

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H.F. Harrison, J. K. Peterson, and M. Snook

These studies were initiated to investigate severe growth inhibition observed when some vegetable crops were infested with corn spurry (Spergula arvensis L.). Interference by a natural population of the weed reduced the shoot weights of English pea (Pisum sativum L.) and collard (Brassica oleracea L.) by 93% and 72%, respectively. In a greenhouse experiment where light competition by corn spurry was prevented, broccoli (Brassica oleracea L.) shoot weights were reduced by corn spurry, but pea weights were not different from the controls. Homogenized corn spurry shoot tissue incorporated into a greenhouse potting medium inhibited the growth of both species, and a concentration effect was observed. Sequential hexane, dichloromethane, methanol, and 50% aqueous methanol extracts of corn spurry root and shoot tissue were tested for inhibitory activity using millet seed germination and broccoli seedling growth bioassays. Dichloromethane, methanol, and aqueous methanol shoot extracts were inhibitory to broccoli; whereas all shoot extracts inhibited millet germination. Shoot extracts were more inhibitory than root extracts. Further fractionation of the inhibitors using a combination of reversed-phase sephadex LH-20 and silicic acid column chromatographic procedures showed that a major portion of the millet germination inhibition was due to sucrose esters (SE). Preliminary characterization of the esters showed that there were four different SE groups. The major groups contained either octanoic or dodecanoic acid along with butanoic and petanoic acids. All groups inhibited seed germination at concentrations as low as 20 ppm. This is the first report of the SE class of defense chemicals in plant species outside of the solanaceae family.

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Rebecca C. Lough and R.G. Gardner

During the last century Phytophthora infestans (Mont.) de Bary, which causes the devastating disease late blight of tomato and potato, has been controlled with pesticides. Recently, the difficulty of controlling late blight has increased due to the appearance of new strains of P. infestans that are more virulent and are resistant to metalaxyl. Numerous P. infestans resistance genes exist within the Solanaceae; however, most of these are race-specific and have the potential of being overcome. To achieve durable resistance, it may be necessary to utilize multigenic resistance or gene pyramiding. The Lycopersicon hirsutum Kunth accession LA1033 is highly resistant to P. infestans. To incorporate resistance into a useful background, the L. esculentum Miller inbred line NC215E was used as a recurrent parent in backcrossing with L. hirsutum LA1033. A population of 264 BC3F1 plants derived from 11 BC2F2 families was planted at Fletcher and Waynesville, N.C., in July 1998 in a replicated field trial. BC3F2 seed were collected from a single highly resistant BC3F1 plant. The BC3F2 population was tested for resistance using a detached leaf screen. To verify growth chamber test results, BC3F3 seeds were collected from the BC3F2 individuals and were planted in a field trial at Fletcher in July 1999. The ratio of resistant to susceptible progeny fit the expected ratio for an incompletely dominant trait controlled by two loci. To identify molecular markers linked to the resistance loci, DNA was extracted from the highly resistant and susceptible BC3F2 individuals, and bulks of DNA were constructed. The resistant and susceptible bulks were screened with AFLP (amplified fragment length polymorphism) markers. Results of the AFLP study indicate marker linkage to resistance.

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Kenneth L. Deahl, Richard W. Jones, Frances M. Perez, David S. Shaw, and Louise R. Cooke

The oomycete, Phytophthora infestans, is a devastating pathogen of potato worldwide. Several genotypes of P. infestans are able to infect other cultivated and weed species of the family Solanaceae and cause symptoms similar to late blight. Changes in P. infestans populations have stimulated investigations to determine if potato strains from new immigrant populations infect nonpotato hosts more often than those from the older population. Expansion of the effective host range may be one of the mechanisms involved in pathogenic changes in natural populations of P. infestans and to determine its significance, it is necessary to establish if the pathogen strains on nonpotato hosts represent distinct genotypes/populations or are freely exchanging with those on potato. This article reports characterization of P. infestans isolates from four solanaceous hosts (black nightshade, hairy nightshade, petunia, and tomato) growing within and around fields of blighted potatoes in four U.S. locations and one U.K. location and their comparison with isolates collected from adjacent infected potatoes. Isolates were characterized for mitochondrial DNA haplotype, mating type, metalaxyl resistance, allozymes of glucose-6-phosphate isomerase and peptidase, and DNA fingerprint with the RG57 probe. Analysis showed close similarity of the petunia, hairy and black nightshade isolates to potato isolates. However, tomatoes from New Jersey and Pennsylvania, respectively, were infected by two distinct and previously unreported pathogen genotoypes, which had quite different fingerprints from P. infestans isolates recovered from nearby infected potatoes. Potato growers should be aware that both weed and cultivated solanaceous species can be infected with P. infestans and may serve as clandestine reservoirs of inoculum. Because some of these plants do not show conspicuous symptoms, they may escape detection and fail to be either removed or treated and so may play a major role in the introduction and spread of pathogens to new locations.

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Chiwon W. Lee

Velvet flower (Salpiglossis sinuata, Solanaceae) can be used as an excellent demonstration plant for horticultural crop breeding classes. Salpiglossis produces large trumpetlike flowers exhibiting an assortment of corolla colors and pigmentation patterns. The pistil is large (3 to 4 cm or 1.2 to 1.6 inches long) with a sticky stigmatal tip and flowers can be easily emasculated prior to anthesis. The large pollen grains are shed in tetrads which can be separated and placed on the stigmatal surface. It takes eight to nine weeks from seeding to blooming, with a prolific flowering cycle that comes in flushes. Numerous seeds (about 750 per capsule) are obtained in three weeks after self- or cross-pollination. The influences of three genes that control flower color and pigmentation pattern can be conveniently demonstrated with their dominant and recessive alleles. The R gene controls flower color with red (RR or Rr) being dominant over yellow (rr). The D gene controls the density of pigmentation with solid (DD or Dd) color being dominant over dilute (dd) color. Corolla color striping is controlled by the St gene with striped (stst) being recessive to nonstriped (StSt or Stst) pattern. By using diploid lines of genotypes RRDD (red, solid), RRdd (red, dilute), or rrdd (yellow, dilute) and their crosses, students can easily observe a dominant phenotypic expression in the F1 hybrid and the digenic 9:3:3:1 segregation ratio in the F2 progeny. Another gene (C) that controls flower opening can also be used to show its influence on cleistogamous (closed, selfpollinated, CC or Cc) versus normal chasmogamous (open-pollinated, cc) corolla development. In addition, the induction and use of polyploid (4x) plants in plant breeding can also be demonstrated using this species.

Open access

Yi-Chen Chen, Wei-Chun Chang, San-Tai Wang, and Shu-I Lin

Grafting is widely used in the commercial production of cucurbits (Cucurbitaceae) and solanaceous (Solanaceae) vegetables, but seldom in the production of cruciferous vegetables such as cabbage (Brassica oleracea Capitata group). In our study, we developed a tube grafting method for cabbage using the ‘K-Y cross’ cabbage as the scion and ‘Tsuei Jin’ chinese kale (B. oleracea Alboglabra group) as the rootstock (K-Y/TJ), and then used the K-Y/TJ grafted seedlings to identify the best healing conditions. The examined healing conditions included temperature (15, 20, or 25 °C), relative humidity (RH; 75%, 85%, or 95%), and light intensity (high light intensity, 79 to 107 μmol·m–2·s–1; low light intensity, 38.6 to 58.8 μmol·m–2·s–1; or full darkness, 0 μmol·m–2·s–1). Considering all the healing conditions, the K-Y/TJ grafted seedlings healing at 20 °C, 95% RH, and high light intensity exhibited survival rates of up to 96.7% and overall superior seedling quality. ‘K-Y cross’ cabbages were then grafted onto chinese kale rootstocks, and the head traits of all grafted plants were comparable to those of nongrafted and/or self-grafted ‘K-Y cross’ plants. ‘K-Y cross’ plants grafted on ‘Jie Lan’ chinese kale rootstocks had greater ascorbic acid and total soluble solid (TSS) contents than nongrafted and self-grafted ‘K-Y cross’ plants. Overall, this research describes a successful tube grafting method and the optimal healing conditions for grafted cabbage seedlings, which can be used as a tool to improve head quality.

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Camilo Escalante-Magaña, Luis F. Aguilar-Caamal, Ileana Echevarría-Machado, Fátima Medina-Lara, Lucila Sánchez Cach, and Manuel Martínez-Estévez

Water stress is the main factor responsible for decreased productivity, which affects the growth and development of crops. Plants respond to stress by accumulating compatible solutes, which have a key role in osmotic adjustment, thereby resulting in osmoprotection of the plants. The loss of water can increase the concentration of compatible osmolytes and molecules that regulate the plant metabolism. These solutes can be metabolized as sugars (sucrose, fructose, trehalosa), amino acids (proline), an amphoteric quaternary amine (glycine betaine), and other low-molecular-weight metabolites. However, among all these compatible solutes, proline and glycine betaine occur the most. Proline is an amino acid that can accumulate in low concentrations under optimal conditions; however, stress conditions contribute to its increased content. Few data are available regarding the levels of endogenous glycine betaine on Solanaceae, which is considered a nonaccumulator under water deficit conditions. The objective of this research was to evaluate the role of compatible osmolytes, glycine betaine and proline, in Capsicum sp. plants under different water deficit conditions. In this study, the presence of endogenous levels of proline and glycine betaine in two species of pepper (Capsicum chinense var. Genesis and Rex and Capsicum annuum var. Padron) were found. The concentration levels of proline were 362, 292, and 246 μmol·g−1 DW for Genesis, Rex and Padron respectively, and irrigation conditions (rehydration) of proline levels increased to 381, 395, and 383 μmol·g−1 DW at 21 days. However, glycine betaine levels were 30–70 μmol·g−1 DW. The relative water content, electrolyte leakage, and soil water potential were also analyzed; therefore, the information suggests that proline contributes better to tolerance to water deficit in the genus Capsicum after 14 days of water deficit treatment. It seems that the contribution of glycine betaine is less effective than that of proline; therefore, it does not have an important role in osmotic adjustment.

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Robert Lawrence Jarret and Terry Berke

.E. Bianchetti, L.De.Bem 2005 Three new species of Capsicum (Solanaceae) and a key to the wild species from Brazil Syst. Bot. 30 863 871 Bosland, P.W. Bailey, A.T. Iglesias-Olivas, J. 1996 Capsicum