Screening for germline mutations in breast/ovarian cancer susceptibility genes in high-risk families in Israel.

We evaluated the clinical utility of screening for mutations in 34 breast/ovarian cancer susceptibility genes in high-risk families in Israel. Participants were recruited from 12, 2012 to 6, 2015 from 8 medical centers. All participants had high breast/ovarian cancer risk based on personal and family history. Genotyping was performed with the InVitae™ platform. The study was approved by the ethics committees of the participating centers; all participants gave a written informed consent before entering the study. Overall, 282 individuals participated in the study: 149 (53 %) of Ashkenazi descent, 80 (28 %) Jewish non-Ashkenazi descent, 22 (8 %) of mixed Ashkenazi/non-Ashkenazi origin, 21 (7 %) were non-Jewish Caucasians, and the remaining patients (n = 10-3.5 %) were of Christian Arabs/Druze/unknown ethnicity. For breast cancer patients (n = 165), the median (range) age at diagnosis was 46 (22-90) years and for ovarian cancer (n = 15) 54 (38-69) years. Overall, 30 cases (10.6 %) were found to carry a pathogenic actionable mutation in the tested genes: 10 BRCA1 (3 non-founder mutations), 9 BRCA2 (8 non-founder mutations), and one each in the RAD51C and CHEK2 genes. Furthermore, actionable mutations were detected in 9 more cases in 4 additional genes (MSH2, RET, MSH6, and APC). No pathogenic mutations were detected in the other genotyped genes. In this high-risk population, 10.6 % harbored an actionable pathogenic mutation, including non-founder mutations in BRCA1/2 and in additional cancer susceptibility genes, suggesting that high-risk families should be genotyped and be assigned a genotype-based cancer risk.

Strigolactones are involved in root response to low phosphate conditions in Arabidopsis.

Strigolactones (SLs) are plant hormones that suppress lateral shoot branching, and act to regulate root hair elongation and lateral root formation. Here, we show that SLs are regulators of plant perception of or response to low inorganic phosphate (Pi) conditions. This regulation is mediated by MORE AXILLARY GROWTH2 (MAX2) and correlated with transcriptional induction of the auxin receptor TRANSPORT INHIBITOR RESPONSE1 (TIR1). Mutants of SL signaling (max2-1) or biosynthesis (max4-1) showed reduced response to low Pi conditions relative to the wild type. In max4-1, but not max2-1, the reduction in response to low Pi was compensated by the application of a synthetic strigolactone GR24. Moreover, AbamineSG, which decreases SL levels in plants, reduced the response to low Pi in the wild type, but not in SL-signaling or biosynthesis mutants. In accordance with the reduced response of max2-1 to low Pi relative to the wild type, several phosphate-starvation response and phosphate-transporter genes displayed reduced induction in max2-1, even though Pi content in max2-1 and the wild type were similar. Auxin, but not ethylene, was sufficient to compensate for the reduced max2-1 response to low Pi conditions. Moreover, the expression level of TIR1 was induced under low Pi conditions in the wild type, but not in max2-1. Accordingly, the tir1-1 mutant showed a transient reduction in root hair density in comparison with the wild type under low Pi conditions. Therefore, we suggest that the response of plants to low Pi is regulated by SLs; this regulation is transmitted via the MAX2 component of SL signaling and is correlated with transcriptional induction of the TIR1 auxin receptor.

Epigenetic Modifications Related to Potato Skin Russeting.

Potato tuber skin is a protective corky tissue consisting of suberized phellem cells. Smooth-skinned varieties are characterized by a clean, shiny appearance compared to the darker hue of russeted potatoes. The rough skin of russeted cultivars is a desired, genetically inherited characteristic; however, unwanted russeting of smooth-skinned cultivars often occurs under suboptimal growth conditions. The involvement of epigenetic modifiers in regulating the smooth skin russeting disorder was tested. We used smooth-skin commercial cultivars with and without the russeting disorder and three lines from a breeding population segregating for russeting. Anatomically, the russet skin showed similar characteristics, whether the cause was environmentally triggered or genetically determined. The old outer layers of the corky phellem remain attached to the newly formed phellem layers instead of being sloughed off. Global DNA methylation analysis indicated a significant reduction in the percentage of 5-methylcytosine in mature vs. immature skin and russet vs. smooth skin. This was true for both the smooth-skin commercial cultivars and the russeted lines. The expression level of selected DNA methyltransferases was reduced in accordance. DNA demethylase expression did not change between the skin types and age. Hence, the reduced DNA methylation in mature and russet skin is more likely to be achieved through passive DNA demethylation and loss of methyltransferase activity.

Strigolactones interact with ethylene and auxin in regulating root-hair elongation in Arabidopsis.

Strigolactones (SLs) or derivatives thereof have been identified as phytohormones, and shown to act as long-distance shoot-branching inhibitors. In Arabidopsis roots, SLs have been suggested to have a positive effect on root-hair (RH) elongation, mediated via the MAX2 F-box. Two other phytohormones, auxin and ethylene, have been shown to have positive effects on RH elongation. Hence, in the present work, Arabidopsis RH elongation was used as a bioassay to determine epistatic relations between SLs, auxin, and ethylene. Analysis of the effect of hormonal treatments on RH elongation in the wild type and hormone-signalling mutants suggested that SLs and ethylene regulate RH elongation via a common regulatory pathway, in which ethylene is epistatic to SLs, whereas the effect of SLs on RH elongation requires ethylene synthesis. SL signalling was not needed for the auxin response, whereas auxin signalling was not necessary, but enhanced RH response to SLs, suggesting that the SL and auxin hormonal pathways converge for regulation of RH elongation. The ethylene pathway requirement for the RH response to SLs suggests that ethylene forms a cross-talk junction between the SL and auxin pathways.