Judith K Brown

Hadjistylli, M., SA.Schwartz, JK. Brown, and GK. Roderick. 2014. Isolation and characterization of nine microsatellite loci from the sweetpotato whitefly Bemisia tabaci biotype B. Insect Science (accepted).

Abstract:

The fine structure of the mouthparts of the whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), was examined by scanning and transmission electron microscopy. Adult whitefly mouthparts are similar to those of other homopterans, especially aphids, being composed of the labrum, the labium, and the stylets. The stylet bundle is the feeding organ of the whitefly and is composed of 2 mandibular stylets and 2 maxillary stylets. Mandibular stylets, which are located on the outer aspect of the stylet bundle, each contain 2 dendrites. The tips of the mandibular stylets are curved inward, and there are barb-like ridges on the lateral aspects, which probably function in piercing and cutting plant tissues and in anchoring the stylets in the tissues. The maxillary stylets are not innervated and are interlocked to form 2 separate compartments, the food canal and salivary canal. At the distal end of the interlocked maxillary stylets, there is a small depression, which may allow for mixing of the salivary canal and food canal components. Movement of the B. tabaci stylets during feeding is discussed in comparison with other homopterans. © 1995.

Varsani, A., Martin, D.P., Navas-Castillo, J., Moriones, E., Hernández-Zepeda, C., Idris, A.M., Murilo, F., Zerbini, F.M., and Brown, J.K. 2014. Revisiting the classification of curtoviruses based on genome-wide pairwise identity. Arch. Virol. 159: 1873-1882.

Abstract:

There are measurable differences between whitefly populations from different biogeographic backgrounds. These differences influence the capacity of B. tabaci (Hemiptera: Homoptera: Aleyrodidae) populations to vector WFT geminiviruses and are seen in whitefly host range phenotypes and host preferences that affect the ability and efficiency of whitefly mediated geminivirus transmission to and from certain hosts. Also suggestive of differences between populations are variable levels of fecundity, and that females do not mate with males from (putatively) genetically distinct populations.

PMID: 18621976;PMCID: PMC2528111;Abstract:

A silencing vector for cotton (Gossypium hirsutum) was developed from the geminivirus Cotton leaf crumple virus (CLCrV). The CLCrV coat protein gene was replaced by up to 500 bp of DNA homologous to one of two endogenous genes, the magnesium chelatase subunit I gene (ChlI) or the phytoene desaturase gene (PDS). Cotyledons of cotton cultivar 'Deltapine 5415' bombarded with the modified viral vectors manifested chlorosis due to silencing of either ChlI or PDS in approximately 70% of inoculated plants after 2 to 3 weeks. Use of the green fluorescence protein gene showed that replication of viral DNA was restricted to vascular tissue and that the viral vector could transmit to leaves, roots, and the ovule integument from which fibers originate. Temperature had profound effects on vector DNA accumulation and the spread of endogenous gene silencing. Consistent with reports that silencing against viruses increases at higher temperatures, plants grown at a 30°C/26°C day/night cycle had a greater than 10-fold reduction in viral DNA accumulation compared to plants grown at 22°C/18°C. However, endogenous gene silencing decreased at 30°C/26°C. There was an approximately 7 d delay in the onset of gene silencing at 22°C/18°C, but silencing was extensive and persisted throughout the life of the plant. The extent of silencing in new growth could be increased or decreased by changing temperature regimes at various times following the onset of silencing. Our experiments establish the use of the CLCrV silencing vector to study gene function in cotton and show that temperature can have a major impact on the extent of geminivirus-induced gene silencing. © 2008 American Society of Plant Biologists.