Učinak toplotnog stresa na razvoj i klijanje peluda

undergraduate thesis

• Title (english): The heat stress effect on pollen development and germination
• Author: Vedrana Šlipogor
• Mentor: Željka Vidaković Cifrek (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2009, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Povišena temperatura ima značajan učinak na sve biljne organe i sve razvojne faze u životu biljke. Osobito je važan učinak na razvoj peluda i ženskih reproduktivnih organa, klijanje peludne mješinice i uspješnost stvaranja ploda. U biljaka izloženih toplotnom stresu mijenjaju se metabolički procesi, usporava sinteza normalnih staničnih proteina, neki se proteini degradiraju, a svi ti procesi događaju se u svrhu uspostavljanja termotolerancije. Posebna karakteristika metabolizma u uvjetima toplotnog stresa je sinteza čitavog seta proteina induciranih stresom, koji omogućavaju funkcioniranje stanice u uvjetima visokih temperatura. Pelud je osjetljiv na povišene temperature, iako ima karakterističnu strukturu koja ga štiti od brojnih okolišnih utjecaja. Peludno zrno razvija peludnu mješinicu koja kroz tučak klije prema sjemenom zametku vršnim rastom i pomoću vrlo složene stanične regulacije. Razlog nemogućnosti oplodnje često je abnormalnost klijanja peludne mješinice ili neuspješnost klijanja peluda na tučku. Zato je nužno istraživati utjecaj vanjskih faktora kao što je temperatura na fiziologiju, dinamiku i molekularne mehanizme klijanja peluda. Rezultati studija pokazali su da se proces klijanja peluda mijenja u trenutku povišenja temperature iznad optimalne, nakon čega se smanjuje brzina rasta, vijabilnost ili postotak uspješne oplodnje. Zanimljivo je da toplotni stres različito djeluje na muške i ženske reproduktivne organe. Postoje podaci da od svih biljnih tkiva toplotni stres ne utječe na ekspresiju HSP jedino u peludi. Međutim, u literaturi se o toj temi nalaze kontradiktorni podaci pa se negdje navodi i postojanje ekspresije HSP u peludi. O konkretnom problemu malo je dostupnih podataka, pa bi se u tom području trebalo provesti više istraživanja koja bi integrirala molekularne mehanizme klijanja, fiziološki odgovor peludi na toplotni stres i ekspresiju određenih staničnih i proteina toplotnog stresa.

Abstract (english)

Increased temperature is an important factor that has impact on the living world. In plants, temperatures can affect pollen and female reproductive organs development, pollen tube growth and fruit ripening. Plants adjust their metabolic processes, decrease the rate of normal cellular proteins’ synthesis, degrade some proteins in order to be more termotolerant to heat stress. Synthesising the set of heat shock proteins is a special plants characteristic, which allows normal cell functions in high temperatures conditions. Pollen is heat-sensitive, although it has a specific structure that protects it from harmful environment conditions. Pollen grain grows into pollen tube allowing tip growth and complex cellular regulations all the way to embrio sac. The reason for unsuccessful pollination is often abnormality of the pollen tube or failure in pollen germination on stigma. The aim of this work was to determine influence of high temperature on physiology, dynamics and molecular mechanisms of pollen germination and growth. Results of recent studies showed that percentage of pollen germination, pollen tube growth rate and successful pollination rate are decreasing under influence of increased temperature. Heat stress differently affects male and female reproductive organs. The only plant organ that does not synthesise heat shock proteins under heat stress is pollen, although there are contradictory data in the literature. There is little information available about this problem, so there should be more scientific studies which would integrate data about pollen tube germination and its molecular mechanisms, physiological responses to heat stress and expression of certain cellular and heat shock proteins.

• Keywords: toplotni stres; pelud
• Keywords (english): heat stress; pollen
• Language: croatian
• URN:NBN: urn:nbn:hr:217:535596
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-03-21 10:29:56