No Correlation of Morpho-Agronomic Traits of Phaseolus vulgaris (Fabaceae) Genotypes and Resistance to Acanthoscelides obtectus (Say) and Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae).

Resistance of common bean (Phaseolus vulgaris) varieties is an important tool to control Acanthoscelides obtectus (Say) and Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae: Bruchinae) worldwide. However, bioassays to characterize the resistance of a genotype can be difficult to perform. Therefore, the current study sought to correlate the morpho-agronomic traits of P. vulgaris genotypes with their resistance to A. obtectus and Z. subfasciatus to facilitate genotype characterization. Bean samples of each genotype were infested with newly emerged insect couples, and the number of adults obtained in each genotype was quantified (value used as a resistance parameter). The resistance index was calculated by dividing the number of adults obtained in each genotype by the one obtained in the cultivar Bolinha, used as the standard for susceptibility. Fifty genotypes were evaluated for A. obtectus and 202 for Z. subfasciatus. All genotypes were characterized according to their resistance to each insect and 18 other morpho-agronomic traits, for a total of 19 descriptors. Principal component analyses did not show any correlation between insect resistance and the morpho-agronomic traits of the genotypes. Further, the thousand seeds weight (TSW), which is indicative of the genotype center of origin was tested considering genotypes from Mesoamerican with low TSW, while those from Andean with high TSW. Thus, the lack of correlation between genotype resistance and TSW indicates that resistance to A. obtectus and Z. subfasciatus in P. vulgaris is not related to the host center of origin.

Common Bean: Experimental Indicator Plant for Citrus leprosis virus C and Some Other Cytoplasmic-Type Brevipalpus-Transmitted Viruses.

Citrus leprosis (CL) caused by Citrus leprosis virus C (CiLV-C) is present in Latin America from Mexico to Argentina, where citrus plants are grown. CiLV-C is transmitted by the tenuipalpid mite, Brevipalpus phoenicis, causing localized lesions on citrus leaves, fruit, and stems. One limitation to study of the virus-vector-host relationship in this pathosystem is the lack of a suitable assay plant. On Citrus spp. used as susceptible hosts, symptoms may take weeks or months to appear after experimental inoculation by viruliferous mites. Common bean (Phaseolus vulgaris) was found to respond with localized necrotic lesions after inoculation with viruliferous B. phoenicis in 5 days. Thus far, 113 tested common bean varieties and lines and some recent accessions of varied genetic background behaved in a similar way. Black bean 'IAC Una' was adopted as a standard test variety. When inoculated leaves were left at 28 to 30°C, the period for the lesion appearance was reduced to only 2 days. Confirmation that the lesions on common bean leaves are caused by CiLV-C were made by transmission electron microscopy, immunofluorescence, enzyme-linked immunosorbent assay, and reverse-transcription polymerase chain reaction specific for CiLV-C. Common bean plants mite-inoculated with some other cytoplasmic-type Brevipalpus-transmitted viruses (BrTVs) (Passion fruit green spot virus, Solanum violaefolium ringspot virus, Ligustrum ringspot virus, and Hibiscus green spot virus) also responded with necrotic local lesions and may serve as test plants for these viruses. Two nuclear types of BrTV (Coffee ringspot virus and Clerodendrum chlorotic spot virus) were unable to produce symptoms on common bean.

Rapid screening of natural products by high-resolution high-temperature gas chromatography.

The crude ethanol extracts from the leaves of three Croton hemiargyrus hemiargyreus plants are fractionated by thin-layer chromatography, yielding five fractions. The fractions and the crude extract are analyzed by high-temperature high-resolution gas chromatography coupled with mass spectrometry (HT-HRGC-MS). Several natural products, including thermolabile components, can be characterized directly in the samples, such as alkaloids, terpenes, flavonoids, acids, alcohols, etc. The cold on-column technique proves to be appropriate for the injection of these thermolabile compounds. HT-HRGC-MS is shown to be a valuable tool and an alternative technique to classical phytochemical procedures for the simple and fast routine analysis of natural products in crude extracts.