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1

Expression patterns of convergently overlapping Arabidopsis thaliana gene pairs OHP-NDP1 and OHP2-MES14

100%

Stawski K. , Banach M. , Goc A.

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nr 1

2

Arabidopsis cyclin-dependent kinase gene CDKG;2 is involved in organogenic responses induced in vitro

86%

Zabicki P. , Kuta E. , Tuleja M. , Rataj K. , Malec P.

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nr 1

EN

The Arabidopsis CDKG;2 gene encodes a putative cyclin-dependent Ser/Thr protein kinase of unknown biological function. This gene shows structural similarity to animal and human cyclin-dependent (PITSLRE) kinases. This study used the homozygous knockout cdkg;2 mutant based on T-DNA insertional line SALK_090262 to study the effect of mutation of the CDKG;2 gene on explant response and in vitro plant regeneration. For callus induction and proliferation, hypocotyls and cotyledons of 3-day-old seedlings of cdkg;2 and A. thaliana ecotype Col-0 were cultured on solid MS medium supplemented with 2,4-D (2 mg l-1). Organogenesis was induced after callus transfer on MS + TDZ (0.5 mg l-1). The initiation time of callus and shoot induction differed between the mutant and control cultures. Shoot regeneration after callus transfer on MS + TDZ was delayed in cdkg;2 (31 days versus 7 days in Col- 0). Shoots formed on callus derived from Col-0 hypocotyls but not on cotyledon-derived callus; in cdkg;2, shoots developed on both callus types. Mutant shoots did not form roots, regenerants were dwarfed, and inflorescences had small bud-like flowers with a reduced corolla and generative organs. Abnormalities observed during cdkg;2 organogenesis suggest a role of CDKG;2 as a regulator of adventitious root initiation.

3

Threshold change in expression of GFP-FABD2 fusion protein during development of Arabidopsis thaliana leaves

86%

Labuz J. , Krzeszowiec W. , Gabrys H.

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nr 2

4

Photoinduction of seed germination in Arabidopsis thaliana is modulated by phototropis

86%

Jedynak P. , Mysliwa-Kurdziel B. , Turek E. , Malec P.

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nr 1

EN

Light exposure is an important environmental factor which breaks seed dormancy in many plant species. Phytochromes have been identified as playing a crucial role in perception of the light signal that releases seed germination in Arabidopsis. Phototropins (Phot1, Phot2) are blue/UV-photoreceptors in plants which mediate phototropic responses, chloroplast relocation, hypocotyl growth inhibition and stomata opening. We studied germination under different light conditions in Arabidopsis Phot1-null and Phot2-null mutants and in a double phot1phot2 mutant. Germination of single phot1 and phot2 mutants in darkness was much lower than in wildtype (WT) seeds, whereas double phot1phot2 mutant lacking both functional phototropins germinated at frequency comparable to WT seeds, irrespective of light and temperature conditions. Light treatment of imbibed seeds was essential for effective germination of phot1, irrespective of low-temperature conditioning. In contrast, cold stratification promoted dark germination of phot2 seeds after imbibition in dim light. Low germination frequency of phot1 seeds under low light intensity suggests that the presence of functional Phot1 might be crucial for effective germination at these conditions. The lower germination frequency of phot2 seeds under continuous light suggests that Phot2 might be responsible for stimulating germination of seeds exposed to direct daylight. Thus, the phototropin system may cooperate with phytochromes regulating the germination competence of seeds under different environmental conditions.

5

Plant metallothineins: putative functions identified by promoter analysis in silico

86%

Dabrowska G. , Mierek-Adamska A. , Goc A.

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tom 54

|

nr 2

EN

Metallothioneins are low-molecular-weight proteins capable of covalently binding heavy metal ions due to the presence of many cysteine residues in their sequences. We analyzed the predicted amino acid sequences of 19 metallothionein (7 from Arabidopsis thaliana and 12 from Oryza sativa) and their promoter sequences in silico in order to determine the potential regulatory cis-elements present in the promoters of metallothionein genes, from which it is possible to determine the putative functions of these genes. The PlantCARE and PLACE databases provided information about the putative regulatory elements in the metallothionein promoters. Metal response element sequences were found in the promoters of eleven O. sativa and two Arabidopsis metallothionein genes. Copper response elements were identified in both model plants, usually in many copies, particularly in O. sativa. Both the high cysteine content and the presence of metal response motifs in the promoters support the suggestion that metallothioneins play a key role in metal detoxification. The most common putative element in the analyzed promoters was CIRCADIAN, which was present in five A. thaliana and eight O. sativa sequences. The methyl jasmonate response sequence, root-specific expression element and drought response element were found only in O. sativa metallothioneins. Light and low temperature response elements, biotic and abiotic stress elements, an abscisic acid-responsive element and an ethylene-responsive element occur in selected metallothionein promoters of both species. A few promoters have putative organ- and cell-specific regulatory elements. The presence of many different motifs in the promoters of the Arabidopsis and O. sativa genes implies that metallothioneins are general stress response proteins with many important functions in plants, including regulation of their normal development and adaptation to changing environmental conditions.

6

Reduced fertility and meiotic abnormalities in late generations of telomerase-deficient Arabidopsis thaliana

72%

Puizina J. , Samanic I.

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nr 1

EN

Here we report the consequences of telomere erosion in Arabidopsis thaliana, studied by examining seed and pollen production and the course of male meiosis through the last five generations (G5–G9) of telomerase-deficient Arabidopsis mutants. We used a previously described mutant line in which telomerase activity was abolished by T-DNA insertion into the TERT gene encoding telomerase reverse transcriptase. Reduced fertility accompanied by morphological abnormalities occurred in G6, which produced on average 35 seeds per silique (vs. 43 in wild type) and worsened in G7 (30 seeds) and G8 (14 seeds), as did the morphological abnormalities. The last generation of tert mutants (G9) did not form reproductive organs. Analysis of meiosis indicated that the main cause of reduced fertility in the late generation tert mutants of Arabidopsis was the numerous chromosomal end-to-end fusions which led to massive genome rearrangements in meiocytes. Fusion of meiotic chromosomes began in G5 and increased in each of the next generations. Unpaired chromosomes (univalents) were observed in G7 and G8. The study highlights some differences in the meiotic consequences of telomere shortening between plant and animal systems.

7

Expression pattern of Arabidopsis thaliana pollen- and embryo-specific promoter in transgenic tobacco plants

72%

Jopcik M. , Matusikova I. , Moravcikova J. , Libantova J.

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nr 1

8

Arabidopsis thaliana - modelowa roslina nie tylko w biologii molekularnej

58%

Maluszynska J.

|

1997

|

tom 31

7-16

9

System naczyniowy dojrzalej luszczyny Arabidopsis thaliana [L.] HEYNH.

51%

Weiss H. , Trzaski L.

|

1997

|

tom 31

30-48

10

Morphological characters of fruits and seeds of some Arabidopsis thaliana transparent testa [tt] mutants

44%

Karcz J. , Miszta A.

|

1997

|

tom 31

56-65

11

Evaluation of plant regeneration ability in culture of immature embryos of different Arabidopsis thaliana [L.] HEYNH. genotypes

44%

Gaj M. D. , Ledwon U. , Gaj M.

|

1997

|

tom 31

66-73

12

Wplyw mutagenow [MNH, promieniowania gamma] na efektywnosc kalusowania i regeneracji roslin w kulturze in vitro eksplantatow lisci Arabidopsis thaliana [L.] HEYNH.

36%

Gaj M. D. , Czaja G.

|

1997

|

tom 31

84-91