title: Differential response of cell-cycle and cell-expansion regulators to heat stress in apple (Malus domestica) fruitlets.
abstract: Temperature is one of the most significant factors affecting physiological and biochemical aspects of fruit development. Current and progressing global warming is expected to change climate in the traditional deciduous fruit tree cultivation regions. In this study, 'Golden Delicious' trees, grown in a controlled environment or commercial orchard, were exposed to different periods of heat treatment. Early fruitlet development was documented by evaluating cell number, cell size and fruit diameter for 5-70 days after full bloom. Normal activities of molecular developmental and growth processes in apple fruitlets were disrupted under daytime air temperatures of 29°C and higher as a result of significant temporary declines in cell-production and cell-expansion rates, respectively. Expression screening of selected cell cycle and cell expansion genes revealed the influence of high temperature on genetic regulation of apple fruitlet development. Several core cell-cycle and cell-expansion genes were differentially expressed under high temperatures. While expression levels of B-type cyclin-dependent kinases and A- and B-type cyclins declined moderately in response to elevated temperatures, expression of several cell-cycle inhibitors, such as Mdwee1, Mdrbr and Mdkrps was sharply enhanced as the temperature rose, blocking the cell-cycle cascade at the G1/S and G2/M transition points. Moreover, expression of several expansin genes was associated with high temperatures, making them potentially useful as molecular platforms to enhance cell-expansion processes under high-temperature regimes. Understanding the molecular mechanisms of heat tolerance associated with genes controlling cell cycle and cell expansion may lead to the development of novel strategies for improving apple fruit productivity under global warming.
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel. Electronic address: vhmoshea@agri.gov.il.
authors.forename: Moshe A
authors.initials: MA
authors.lastname: Flaishman
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel. Electronic address: ypeles@kaiima.com.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Peles
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel. Electronic address: yardenad@volcani.agri.gov.il.
authors.forename: Yardena
authors.initials: Y
authors.lastname: Dahan
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel. Electronic address: shira.milocochav@mail.huji.ac.il.
authors.forename: Shira
authors.initials: S
authors.lastname: Milo-Cochavi
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, P.O. Box 6, Bet-Dagan 50250, Israel. Electronic address: aviadf@kaiima.com.
authors.forename: Aviad
authors.initials: A
authors.lastname: Frieman
authors.affiliation: The Golan Research Institute, University of Haifa, P.O. Box 97, Kazrin 12900, Israel. Electronic address: amosnaor51@gmail.com.
authors.forename: Amos
authors.initials: A
authors.lastname: Naor
mesh_terms: D002453:Cell Cycle; D002455:Cell Division; D049109:Cell Proliferation; D005638:Fruit / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature; D027845:Malus / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D010940:Plant Proteins
keywords: Apple; Cell cycle control genes; Cell expansion control genes; Fruit size; Fruitlet development; Heat-stress