The promoter of phytoene synthase, the first specific enzyme of carotenoid biosynthesis, shows two main regulatory regions: a G-box-containing region located near the TATA box, and a TATA box distal region containing the cis-acting element ATCTA, which mediates strong basal promoter activity. This second element was also present in the promoter of phytoene desaturase, the next step of the carotenoid pathway, suggesting a common regulatory mechanism. In this work, we demonstrate that AtRAP2.2, a member of the APETALA2 (AP2)/ethylene-responsive element-binding protein transcription factor family, binds to the ATCTA element. In Arabidopsis (Arabidopsis thaliana) leaves, AtRAP2.2 transcript and protein levels were tightly controlled as indicated by unchanged transcript and protein levels in T-DNA insertion mutants in the AtRAP2.2 promoter and 5# untranslated region and the lack of change in AtRAP2.2 protein levels in lines strongly overexpressing the AtRAP2.2 transcript. Homozygous loss-of-function mutants could not be obtained for the AtRAP2.2 5# untranslated region T-DNA insertion line indicating a lethal phenotype. In AtRAP2.2 overexpression lines, modest changes in phytoene synthase and phytoene desaturase transcripts were only observed in root-derived calli, which consequently showed a reduction in carotenoid content. The RING finger protein SEVEN IN ABSENTIA OF ARABIDOPSIS2 (SINAT2) was identified as an AtRAP2.2 interaction partner using a two-hybrid approach. The structure of SINAT2 and related proteins of Arabidopsis show homology to the SEVEN IN ABSENTIA protein of Drosophila that is involved in proteasome-mediated regulation in a variety of developmental processes. The action of SINAT2 may explain the recalcitrance of AtRAP2.2 protein levels to change by altering AtRAP2.2 transcription.

Botryosphaeria spp. recently have been identified as important grapevine pathogens worldwide. To date, Botryosphaeria rhodina has been the only species associated with cankers on Vitis vinifera in California. A field survey of 166 vineyards in 21 counties was conducted in order to determine the occurrence of other Botryosphaeria spp. in California. In all, 1,735 samples of cankered trunks, cordons, and spurs were collected. Botryosphaeria spp. were the most common fungi isolated from grapevine cankers in California. Morphological identification along with phylogenetic analysis of the internal transcribed spacer region (ITS1-5.8S-ITS2) of the nuclear ribosomal DNA (rDNA) and a partial sequence of the β-tubulin gene showed that at least seven Botryosphaeria spp. occur on grapevines in California: B. australis, B. dothidea, B. lutea, B. obtusa, B. parva, B. rhodina, and B. stevensii. Botryosphaeria spp. were found in grapevine cankers in all grape-growing regions surveyed in California, whereas incidence and distribution varied with location. Grapevine cankers in California have been associated mainly with Eutypa dieback. However, the frequent recovery of Botryosphaeria spp. from cankers in this study indicates that the role of these fungi in grapevine health needs to be more carefully considered.

Xylella fastidiosa is a Gram-negative, xylem-inhabiting, plant-pathogenic bacterium responsible for several important diseases including Pierce's disease (PD) of grapevines. The bacteria form biofilms in grapevine xylem that contribute to the occlusion of the xylem vessels. X. fastidiosa haemagglutinin (HA) proteins are large afimbrial adhesins that have been shown to be crucial for biofilm formation. Little is known about the mechanism of X. fastidiosa HA-mediated cell-cell aggregation or the localization of the adhesins on the cell. We generated anti-HA antibodies and show that X. fastidiosa HAs are present in the outer membrane and secreted both as soluble proteins and in membrane vesicles. Furthermore, the HA pre-proteins are processed from the predicted molecular mass of 360 kDa to a mature 220 kDa protein. Based on this information, we are evaluating a novel form of potential resistance against PD by generating HA-expressing transgenic grapevines. INTRODUCTIONXylella fastidiosa, a Gram-negative, xylem-inhabiting bacterium, causes economically important plant diseases including Pierce's disease (PD) of Vitis vinifera grapevines (Hopkins, 1989) and citrus variegated chlorosis in citrus trees (Rossetti et al., 1990). X. fastidiosa is transmitted by numerous xylem-feeding insects such as sharpshooters and spittlebugs (Hewitt et al., 1946). Once introduced by their vectors, the bacteria multiply in the xylem of infected plants and form microcolonies and three-dimensional biofilms that cause blockage of the xylem vessels. These blockages are thought to be the major cause of the development of symptoms that are similar, but not identical, to water stress and eventually result in the death of the grapevines (Hopkins, 1989; Thorne et al., 2006). X. fastidiosa was the first plant-pathogenic bacterium to have its genome sequenced (Simpson et al., 2000;Van Sluys et al., 2003). The comparatively small genome (2.5 Mb) may explain X. fastidiosa's limited niches, occupying only the insect foregut and the plant xylem. In both locations, the bacteria are exposed to high turbulence, an environment low in nutrients, and host defence responses (O'Toole et al., 1999). These conditions make the formation of a bacterial biofilm a key element in X. fastidiosa survival and replication (de Souza et al., 2003;Guilhabert & Kirkpatrick, 2005;Rodrigues et al., 2008). Biofilm formation in X. fastidiosa is thought to be a sequential process in which planktonic cells attach to host surfaces, self-aggregate with other cells and form a biofilm matrix which consists of exopolysaccharides, proteins and probably DNA (Guilhabert & Kirkpatrick, 2005;Lin, 2009;Roper et al., 2007). The first step in biofilm formation, attachment to host surfaces, is mediated by several different factors, including fimbrial and afimbrial adhesins on the bacterial surface (Li et al., 2007). Fimbrial adhesins can be divided into two classes: long (1-5.8 mm) type IV pili encoded by pil genes, and short (0.4-1.0 mm) type I pili encoded by the fim operon (Meng et al., ...