title: Intracellular Ca(2+) and K(+) concentration in Brassica oleracea leaf induces differential expression of transporter and stress-related genes.
abstract: BACKGROUND
  One of the most important members of the genus Brassica, cabbage, requires a relatively high level of calcium for normal growth (Plant Cell Environ 7: 397-405, 1984; Plant Physiol 60: 854-856, 1977). Localized Ca(2+) deficiency in cabbage leaves causes tip-burn, bringing about serious economic losses (Euphytica 9:203-208, 1960; Ann Bot 43:363-372, 1979; Sci Hortic 14:131-138, 1981). Although it has been known that the occurrence of tip-burn is related to Ca(2+) deficiency, there is limited information on the underlying mechanisms of tip-burn or the relationship between Ca(2+) and tip-burn incidence. To obtain more information on the genetic control of tip-burn symptoms, we focused on the identification of genes differentially expressed in response to increasing intracellular Ca(2+) and K(+) concentrations in B. oleracea lines derived from tip-burn susceptible, tip-burn resistant cabbages (B. oleracea var. capitata), and kale (B. oleracea var. acephala).
  
  
  RESULTS
  We compared the levels of major macronutrient cations, including Ca(2+) and K(+), in three leaf segments, the leaf apex (LA), middle of leaf (LM), and leaf base (LB), of tip-burn susceptible, tip-burn resistant cabbages, and kale. Ca(2+) and K(+) concentrations were highest in kale, followed by tip-burn resistant and then tip-burn susceptible cabbages. These cations generally accumulated to a greater extent in the LB than in the LA. Transcriptome analysis identified 58,096 loci as putative non-redundant genes in the three leaf segments of the three B. oleracea lines and showed significant changes in expression of 27,876 loci based on Ca(2+) and K(+) levels. Among these, 1844 loci were identified as tip-burn related phenotype-specific genes. Tip-burn resistant cabbage and kale-specific genes were largely related to stress and transport activity based on GO annotation. Tip-burn resistant cabbage and kale plants showed phenotypes clearly indicative of heat-shock, freezing, and drought stress tolerance compared to tip-burn susceptible cabbages, demonstrating a correlation between intracellular Ca(2+) and K(+) concentrations and tolerance of abiotic stress with differential gene expression. We selected 165 genes that were up- or down-regulated in response to increasing Ca(2+) and K(+) concentrations in the three leaf segments of the three plant lines. Gene ontology enrichment analysis indicated that these genes participated in regulatory metabolic processes or stress responses.
  
  
  CONCLUSIONS
  Our results indicate that the genes involved in regulatory metabolic processes or stress responses were differentially expressed in response to increasing Ca(2+) and K(+) concentrations in the B. oleracea leaf. Our transcriptome data and the genes identified may serve as a starting point for understanding the mechanisms underlying essential macronutrient deficiencies in plants, as well as the features of tip-burn in cabbage and other Brassica species.
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. leejy@kribb.re.kr.
authors.forename: Jeongyeo
authors.initials: J
authors.lastname: Lee
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. jekim@kribb.re.kr.
authors.forename: Jungeun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. choijp@kribb.re.kr.
authors.forename: Jae-Pil
authors.initials: JP
authors.lastname: Choi
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. lmy1205@kribb.re.kr.
authors.forename: MiYe
authors.initials: M
authors.lastname: Lee
authors.affiliation: Environment-friendly Agriculture Research Division, Gyeongsangnam-do Agricultural Research and Extension Service, Jinju, 660-360, Republic of Korea. goguma99@korea.kr.
authors.forename: Min Keun
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Environment-friendly Agriculture Research Division, Gyeongsangnam-do Agricultural Research and Extension Service, Jinju, 660-360, Republic of Korea. lyh2011@korea.kr.
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, College of Biological Sciences, Chungnam National University, Daejeon, 305-764, Republic of Korea. ykhur@cnu.ac.kr.
authors.forename: Yoonkang
authors.initials: Y
authors.lastname: Hur
authors.affiliation: Department of Horticulture, Sunchon National University, Jeonnam, 540-742, Republic of Korea. nis@sunchon.ac.kr.
authors.forename: Ill-Sup
authors.initials: IS
authors.lastname: Nou
authors.affiliation: Department of Crop Science, College of Agriculture & Life Sciences, Chungnam National University, Daejeon, 305-764, Republic of Korea. supark@cnu.ac.kr.
authors.forename: Sang Un
authors.initials: SU
authors.lastname: Park
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. srmin@kribb.re.kr.
authors.forename: Sung Ran
authors.initials: SR
authors.lastname: Min
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Republic of Korea. kimhr@kribb.re.kr.|Systems and Bioengineering, University of Science and Technology, 217 Gajung-ro, Daejeon, Republic of Korea. kimhr@kribb.re.kr.
authors.forename: HyeRan
authors.initials: H
authors.lastname: Kim
mesh_terms: D001937:Brassica / Q000737:chemistry / Q000235:genetics*; D002118:Calcium / Q000032:analysis*; D003593:Cytoplasm / Q000737:chemistry; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D058977:Molecular Sequence Annotation; D018515:Plant Leaves / Q000737:chemistry* / Q000166:cytology; D011188:Potassium / Q000032:analysis*; D018749:RNA, Plant / Q000235:genetics; D017423:Sequence Analysis, RNA; D013312:Stress, Physiological; D059467:Transcriptome
chemical_list: D018749:RNA, Plant; D011188:Potassium; D002118:Calcium