The process of abscission results in shedding of plant parts such as leaves, fruit, flowers, and in citrus, shoot tips and entire shoots. Growers must successfully manage abscission in their operations to avoid unnecessary defoliation or loss of yield due to floral abscission or preharvest fruit drop. Conversely, abscission enhancement may be desired during harvest. Yet despite its importance to horticulture, little is known about mechanisms that control abscission. We know that abscission can be induced by ethylene and altered to some extent by auxin. Over the years, many physiological and anatomical events of abscission have been described. For example, cellulase, polygalacturonase and pectin methylesterase genes are induced during abscission, and they are thought to have a role in alteration and depolymerization of middle lamella polysaccharides located in the abscission zone area. Other genes, such as those associated with the process of pathogen resistance, are also induced during abscission. We are interested in using tools of molecular biology to examine abscission-related gene expression prior to organ separation in Florida field-grown Valencia orange (Citrus sinensis L. Osbeck) and greenhouse-grown calamondin (Citrus madurensis Loureiro) citrus trees. Subtractive cDNA library screening and differential display were used to examine gene expression in fruit, leaf and floral abscission zones 6, 24 and 48 h after induction of abscission with 5-chloro-3-methyl-4-nitro-1H-pyrazole or Ethrel® (Rhone-Poulenc, [2-chloroethyl] phosphoric acid). Some isolated cDNAs encoded polypeptides with no significant matches in the database or share significant similarities with unknown proteins isolated from Arabidopsis. Other cDNAs encoded polypeptides with similarity to cell wall modifying proteins such as polygalacturonases and expansin, PR proteins such as chitinase, proteins associated with secondary and xenobiotic metabolism such as amine oxidase, benzoquinone reductase, caffeic acid methyltransferase, phenylalanine ammonia lyase and squalene synthase, and proteins associated with signal transduction such as several serine/threonine kinases. Temporal and spatial expression of these genes and others will be presented. Use of this information to target potential points of abscission control will be discussed.
J.K. Burns, C. Arias, I. Kostenyuk and M. Obraztnova
Yuliya A. Salanenka and Alan G. Taylor
. Lau, S-M. C. Rogers, G. Ray T. 2000 A new method for rapid screening for xenobiotic phloem mobility in plants Aust. J. Plant Physiol. 27 835 843 Wuest, S.B. 2002 Water transfer from soil to seed: The role of vapor transport Soil Sci. Soc. Amer. J. 66
Bhimanagouda S. Patil, G.K. Jayaprakasha and Amit Vikram
bitter gourd hypoglycemic activity involve 1) modulation of xenobiotic metabolism by improving the activity of glutathione and glutathione S-transferase ( Raza et al., 2000 ); 2) stimulation of insulin secretion by β-cells in obese
Martin M. Williams II, Loyd M. Wax, Jerald K. Pataky and Michael D. Meyer
.g., Diebold et al., 2003 ; Morton and Harvey, 1992 ; Stall and Bewick, 1992 ; Williams and Pataky, 2008 ). Although this type of screening identifies hybrids that may be injured from postemergence herbicides, a more comprehensive understanding of the
Chunxian Chen, Paul Cancalon, Carl Haun and Fred Gmitter Jr.
( Uesawa and Mohri, 2008 ; Uesawa et al., 2008 ). P450s are responsible for the first-pass elimination of various xenobiotics including drugs. FCs act on CYP3A4 by a mechanism-based inhibition. After grapefruit juice ingestion, the FCs induce the
Zhengrong Hu, Erick Amombo, Margaret Mukami Gitau, Aoyue Bi, Huihui Zhu, Liang Zhang, Liang Chen and Jinmin Fu
) . Initially, 128 bermudagrass accessions were used in the screening test. The plants were treated with 4 °C for 21 d, and the control was maintained at (30 °C day/25 °C night). Several parameters were determined every week including transpiration rate and