Ernst Cebert

Occurrence of clover stem borer, Languria mozardi (Coleoptera: Languriidae), on canola: a new host record.

Abstract The clover stem borer (CSB), Languria mozardi Latreille (Coleoptera: Languriidae) at various life stages (larva, pupa and adult), was discovered on canola (Brassica napus L.; Brassicaceae) during the 2000-01 growing season; these plantings were part of the canola nursery at Alabama A&M Universitys Winfred Thomas Agricultural Research Station (WTARS) located in northern Alabama. This was the first and, so far, the only record of L. mozardi on canola. Given the wide range of host plants on which CSB has been reported to occur, this North American endemic species may pose a potential threat to canola production in the United States. Although our data showed differential preference for canola cultivars by CSB, damage by this species on canola was negligible. A comprehensive list of plant hosts of L. mozardi is also presented in this report.

Anthocyanin Accumulation in Muscadine Berry Skins Is Influenced by the Expression of the MYB Transcription Factors, MybA1, and MYBCS1

The skin color of grape berry is very important in the wine industry. The red color results from the synthesis and accumulation of anthocyanins, which is regulated by transcription factors belonging to the MYB family. The transcription factors that activate the anthocyanin biosynthetic genes have been isolated in model plants. However, the genetic basis of color variation is species-specific and its understanding is relevant in many crop species. This study reports the isolation of MybA1, and MYBCS-1 genes from muscadine grapes for the first time. They are designated as VrMybA1 (GenBank Accession No. KJ513437), and VrMYBCS1 (VrMYB5a) (GenBank Accession No. KJ513438). The findings in this study indicate that, the deduced VrMybA1 and VrMYBCS1 protein structures share extensive sequence similarity with previously characterized plant MYBs, while phylogenetic analysis confirms that they are members of the plant MYB super-family. The expressions of MybA1, and MYBCS1 (VrMYB5a) gene sequences were investigated by quantitative real-time PCR using in vitro cell cultures, and berry skin samples at different developmental stages. Results showed that MybA1, and MYBCS1 genes were up-regulated in the veràison and physiologically mature red berry skins during fruit development, as well as in in vitro red cell cultures. This study also found that in ripening berries, the transcription of VrMybA1, and VrMYBCS1 in the berry skin was positively correlated with anthocyanin accumulation. Therefore, the upregulation of VrMybA1, and VrMYBCS1 results in the accumulation and regulation of anthocyanin biosynthesis in berry development of muscadine grapes. This work greatly enhances the understanding of anthocyanin biosynthesis in muscadine grapes and will facilitate future genetic modification of the antioxidants in V. rotundifolia.

Molecular Cloning, Characterization, and Expression Analysis of Flavanone 3-Hydroxylase (F3H) Gene during Muscadine Grape Berry Development

Flavonoids are natural antioxidants that include the groups of notable pigments such as anthocyanins and proanthocyanidins. Flavanone 3-Hydroxylase (F3H) is a key enzyme needed for the biosynthesis of flavonoids, the main ingredients of muscadine grape extracts. This study reports the first successful isolation, cloning and characterization of F3H gene from Vitis rotundifolia Michx. The full length cDNA of V. rotundifolia F3H gene (designated as VrF3H) had an open reading frame (ORF) of 1081 bp encoding 364 amino acids with a calculated molecular mass of 40.8kDa as well as an isoelectric point of 5.60. Comparative and in silico analyses revealed that the cloned VrF3H from muscadine grapes has high identity with F3H from other plant species. The deduced VrF3H protein showed similarities with other available plant F3H proteins, and the conserved amino acids ligating ferrous iron and residues participating in 2-oxo-glutarate binding were found in similar positions comparable to other F3Hs. Furthermore, three-dimensional structure modeling showed that F3H protein had the enzyme core consisting of β-sheet, a typical structure shared by all 2-oxoglutarate-dependent dioxygenases including F3Hs. Phylogenetic tree analysis indicated that VrF3H belongs to the Vitis F3H cluster. VrF3H transcripts were found to be abundantly expressed in the in-vitro red cells, veraison and physiologically mature red berries, but not expressed in the skins of the green berries. The isolation and characterization of VrF3H gene will enable further study in the role of VrF3H gene in the biosynthesis of flavonoids in V. rotundifolia.

Prospects for Transgenic and Molecular Breeding for Cold Tolerance in Canola (Brassica napus L.)

Canola is cultivated both during winter and spring seasons in the United States and this exposes the crop to winter kill, frost, and high temperatures, during the reproductive period. The temperatures during winter and spring are known to influence all the crucial steps of the reproductive cycle including gametogenesis, pollination, fertilization and embryogenesis (Angadi, 2000). Winter rapeseed has been successfully grown in the Pacific Northwest, southern Great Plains, Midwest, and southeast regions of the USA. The hardiest cultivars will routinely survive winters in the north east of USA but survival is inconsistent further south (Rife et al., 2001). Winter-grown canola (Brassica napus L.) production is limited mostly by frost and winter-kill in the southern canola-growing regions of the United States (Singh et al., 2008). For instance, the late freeze in 2007 resulted in significant damage to most of the winter canola cultivars at the National Winter Canola Variety Trials in Alabama, U.S. (Cebert and Rufina, 2007). Winter hardiness and freezing tolerance are a major concern for improving production consistency in many regions of the canola growing countries.

Principal Component Analysis and Molecular Characterization of Reniform Nematode Populations in Alabama

U.S. cotton production is suffering from the yield loss caused by the reniform nematode (RN), Rotylenchulus reniformis. Management of this devastating pest is of utmost importance because, no upland cotton cultivar exhibits adequate resistance to RN. Nine populations of RN from distinct regions in Alabama and one population from Mississippi were studied and thirteen morphometric features were measured on 20 male and 20 female nematodes from each population. Highly correlated variables (positive) in female and male RN morphometric parameters were observed for body length (L) and distance of vulva from the lip region (V) (r = 0.7) and tail length (TL) and c′ (r = 0.8), respectively. The first and second principal components for the female and male populations showed distinct clustering into three groups. These results show pattern of sub-groups within the RN populations in Alabama. A one-way ANOVA on female and male RN populations showed significant differences (p ≤ 0.05) among the variables. Multiple sequence alignment (MSA) of 18S rRNA sequences (421) showed lengths of 653 bp. Sites within the aligned sequences were conserved (53%), parsimony-informative (17%), singletons (28%), and indels (2%), respectively. Neighbor-Joining analysis showed intra and inter-nematodal variations within the populations as clone sequences from different nematodes irrespective of the sex of nematode isolate clustered together. Morphologically, the three groups (I, II and III) could not be distinctly associated with the molecular data from the 18S rRNA sequences. The three groups may be identified as being non-geographically contiguous.

Insect Incidence and Damage on Pearl Millet (Pennisetum glaucum) Under Various Nitrogen Regimes in Alabama

Abstract Although pearl millet [Pennisetum glaucum (L.) R. Br.; Poales: Poaceae] is grown extensively on 5 continents and is attacked by various insects at all stages of growth and development, little is specifically known of how yields of this important crop are affected by insect herbivory. This study was conducted in north central Alabama to determine insect occurrence on pearl millet and to determine the levels of damage caused by insects feeding on pearl millet genotypes at different nitrogen rates. The field experiment was laid out following a randomized complete block design with 4 replications in which 4 genotypes and 4 fertilizer levels were arranged in factorial combinations. The pearl millet genotypes consisted of 2 open pollinated lines, ‘2304’ and ‘LHBO8’, and 2 hybrids, ‘606A1*2304’ and ‘707A1*4280’ and fertilization rates used were 0, 40, 80 and 120 kg ha-1 N. Insect samplings were carried out weekly from 61 to 109 days after planting (DAP). Insects in 6 orders and 11 families were found on pearl millet genotypes. Eastern leaf-footed stinkbug (Leptoglossus phyllopus (L.); Hemiptera: Coreidae) was the most prevalent and dominant insect species found followed by the American bird grasshopper (Schistocerca americana Drury; Orthoptera: Acrididae) and the differential grasshopper (Melanoplus differentialis (Thomas: Orthoptera: Acrididae). Population of L. phyllopus was at its peak during the latter part of the growing season from 81 to 109 DAP. Populations of S. americana and M. differentialis declined as crop matured (61 DAP > 66 DAP >75 DAP). Results also showed that leaf and head damage did not differ among genotypes and nitrogen rates tested.