HEAT STRESS RESPONSE AND HEAT-SHOCK PROTEIN

IN PLANTSBy

Kelompok 9 : Agatha Maturbongs : 12/337941/PBI/1048

Nurhening Yuni Ekowati : 12/338474/PBI/1069

Plants :Plants as sessile organisms are exposed

persistently changing stress factors. Primary stress such as drought, salinity,

cold and hot temperatures and chemicals are interconnected in their effect on

plants.These factors cause damaged to the plant cell and lead to secondary

stresses such as osmotic and oxidative stresses. Plants adapt morphologically and physiologically and biochemically

How about heat stress?

Active plants growth in mesophile

organisms is 10-40oC. Any

temperature which is under and below that range creates

heat stress on metabolic activities

of plants.

High temperature

morpho-anatomical, physiological and

biochemical changes in plants

Plants growth and development

Reduction in economic yield

Plants heat stress

Heat stress response is a reaction when tissues and cells of an organism were exposed to sudden heat stress.

HS response is initiated by the activation of heat shock factors (HSF) which cause expression of heat shock gene to

synthesis heat shock proteins

Heat shock proteins (HSPs) are spesific protein that are made when cells are briefly exposed to temperature above their

normal growth temperature.

Heat stress respon and HSPs are highly conserved in every organism.

HSPs can also be induced other stressor such as oxidants, toxins, heavy metals, free radicals, and viruses, so they are

sometimes called the “stress protein”

Most heat shock proteins are chaperon, they protecting plants againt stress by reestablishing

normal conformation and thus cellular homeostasis.

HSF is a regulator in HSPs synthesis.

These proteins are grouped in plants into five classes according to their approximate molecular weight :

(1) Hsp100 (2) Hsp90(3) Hsp70(4) Hsp60(5) sHsps

Arabidopsis, the genetic model for studying and manipulating the heat

stress response. Transgenic

overexpression of Arabidopsis

thaliana heat shock transcription factor (HSF) results in a

synthesis of HSPs at normal temperature

and significantly increased basal

thermotolerance.

HSF expression in tomato plant

HSF expression in fruit ripening

Plants and animals share similar mechanisms in the heat shock (HS) response, such as synthesis of the conserved HS proteins (Hsps).

In general they require unique features to cope with heat stress.

Hsa32 is a conserved HS-inducible gene in land plants

The gene responds to HS at the transcriptional level in moss (Physcomitrella patens), Arabidopsis (Arabidopsis thaliana), and rice (Oryza sativa).

Hsa32 Is a Conserved HS-Inducible Gene in Land Plants

Hsa32 Protein Is Synthesized in Response to HS

Charng et al, 2006

Wang et al, 2004

Wang et al, 2004

PUSTAKA Al-wahibi, M. H. 2010. Plant heat-shock protein : a mini review.

Journal of King Sau University xxx: xxx-xxx Baniwal, S. K, K. Bharti1, K. Y. Chan, M. Fauth, A. Ganguli, S.

Kotak, S. K. Mishra, L. Nover, M. Port, K. Scharf, J. Tripp, C. Weber, D. Zielinski and P. V. Koskull-döring. 2004. Heat stress response in plants: a complex game with chaperones and more than twenty heat stress transcription factors. J. Biosci. 29(4) : 471-487

Charng, Yee-yung, Hsiang-chin Liu, Nai-yu Liu, Fu-chiun Hsu, and Swee-suak Ko. 2006. Arabidopsis Hsa32, a Novel Heat Shock Protein, Is Essential for Acquired Thermotolerance during Long Recovery after Acclimation. Plant Physiology, Vol. 140, pp. 1297–1305

Wahid, A., S. Gelani, M. Ashraf, M.R. Foolad. 2007. heat tolerance in plants : an Overview. Environmental and experimental Botany 61 : 199-223

Wang, Wangxia, Basia Vinocur, Oded Shoseyov and Arie Altman. 2004. Role of plant heat-shock proteins and molecular chaperones in the abiotic stress response. TRENDS in Plant Science Vol.9 No.5.

SEKIANDAN

TERIMA KASIH

Pertanyaan-Pertanyaan

1. Bagaimana hubungan antara rusaknya perikarp pada buah tomat? bagaimana kaitannya dengan glisin betain?jawab : kerusakan perikarp pada buah tomat disebabkan oleh adanya cekaman panas yang merusak membran sel. Panas menyebabkan perubahan integritas dan fluiditas membran, serta menyebabkan enzim-enzim yang terdapat di dalam sel terdenaturasi sehingga sel menjadi mati. Selain itu dengan adanya cekaman panas menyebabkan sintesis likopen terganggu dan bahkan tidak terjadi, kemungkinan karena enzim yang terlibat dalam sintesis likopen mengalami denaturasi. sedangkan glisin betain merupakan salah satu protein osmoprotektan , peningkatan konsentrasi glisin betain dalam cekaman panas adalah untuk menjaga homeostasis sel, yaitu dengan menjaga tekanan osmosis di dalam sel.

2. Bagaimana kaitan Hsf yang dioverekspresikan pada tanaman?Jawab : overekspresi Hsf pada tanaman menyebabkan tanaman lebih toleran terhadap cekaman panas.

3. Apakah pada tumbuhan memiliki semua jenis hsp? Jawab: pada 1 jenis tumbuhan tidak memiliki semua jenis hsp, masing-masing tumbuhan memiliki hsp yang berbeda-beda tergantung adaptasi dan stres yang dialaminya. Misalnya Arabidopsis memiliki 18 gen yang mengkode pembentukan Hsp70 dan Hsp90, Hsp100 dimiliki oleh beberapa tanaman antara lain Arabidopsis, kedelai tembakau, padi dan jagung.

4. Hsp di hasilkan di bagian mana saja pada tumbuhan? Jawab : Hsp dihasilkan pada berbagai organel sel, misalnya Hsp70 dihasilkan pada sitosol, kloroplas, dan mitokondria, sedangkan Hsp22 dihasilkan pada retikulum endoplasma.