بررسي اثرات 24-اپي‌براسينواستروئيد بر برخي از خصوصيات گياه شنبليله (Trigonella foenum-graecum L.) تحت شرايط تنش دماي بالا

Evaluation of 24-Epi-brassinosteroid effects on some properties of fenugreek (Trigonella foenum-graecum L.) under high temperature stress

ﻫﺪف از اﯾﻦ ﻣﻄﺎﻟﻌﻪ، ﺑﺮرﺳﯽ ﺗﺄﺛﯿﺮ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ ﺑﺮ ﺑﺮﺧﯽ ﺧﺼﻮﺻﯿﺎت ﻓﯿﺰﯾﻮﻟﻮژﯾﮏ ﺷﻨﺒﻠﯿﻠﻪ ﺗﺤﺖ ﺗﻨﺶ دﻣﺎي ﺑﺎﻻ ﺑﻮد. ﺗﯿﻤﺎرﻫﺎي اﯾﻦ آزﻣﺎﯾﺶ ﺷﺎﻣﻞ ﺳﻄﻮح ﻣﺨﺘﻠﻒ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ )ﺻﻔﺮ، دو، ﭘﻨﺞ و 10 ppm(، ﺑﺎزهﻫﺎي زﻣﺎﻧﯽ ﺷﺶ و 24 ﺳﺎﻋﺖ )ﭘﺲ از اﻋﻤﺎل ﺗﻨﺶ دﻣﺎﯾﯽ و ﯾﺎ ﮐﺎرﺑﺮد 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ( و ﺷﺮاﯾﻂ دﻣﺎﯾﯽ )23 درﺟﻪ ﺳﺎﻧﺘﯽﮔﺮاد و ﺗﻨﺶ دﻣﺎي 42 درﺟﻪ ﺳﺎﻧﺘﯽﮔﺮاد( ﺑﻮدﻧﺪ. ﻧﺘﺎﯾﺞ اﯾﻦ ﭘﮋوﻫﺶ ﻧﺸﺎن داد ﮐﻪ ﺗﻨﺶ دﻣﺎي ﺑﺎﻻ، ﻣﻨﺠﺮ ﺑﻪ ﮐﺎﻫﺶ ﻣﺤﺘﻮاي ﮐﻠﺮوﻓﯿﻞ b a و ﮐﻠﺮوﻓﯿﻞ ﮐﻞ، ﮐﺎروﺗﻨﻮﺋﯿﺪ و اﻓﺰاﯾﺶ ﻣﺤﺘﻮاي ﻣﺎﻟﻮنديآﻟﺪﻫﯿﺪ و درﺻﺪ ﻧﺸﺖ اﻟﮑﺘﺮوﻟﯿﺖ ﺷﺪ و ﮐﺎرﺑﺮد 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ در ﻃﻮل ﺗﻨﺶ ﺑﻪﺻﻮرت ﻗﺎﺑﻞ ﺗﻮﺟﻬﯽ ﻣﺎﻧﻊ از ﮐﺎﻫﺶ ﻣﺤﺘﻮي رﻧﮕﯿﺰه و اﻓﺰاﯾﺶ ﻧﺸﺖ اﻟﮑﺘﺮوﻟﯿﺖ ﺷﺪ. ﮐﺎرﺑﺮد ﺳﻄﻮح ﻣﺨﺘﻠﻒ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ در دﻣﺎﻫﺎي ﺑﺎﻻ، ﻣﺤﺘﻮاي ﻣﺎﻟﻮنديآﻟﺪﻫﯿﺪ را ﮐﺎﻫﺶ و ﺗﺤﻤﻞ ﺷﻨﺒﻠﯿﻠﻪ را اﻓﺰاﯾﺶ داد ﮐﻪ اﯾﻦ اﻓﺰاﯾﺶ ﺗﺤﻤﻞ ﺑﻪ دﻟﯿﻞ ﮐﺎﻫﺶ ﭘﺮاﮐﺴﯿﺪاﺳﯿﻮن اﺳﯿﺪ ﻏﯿﺮﭼﺮب ﺑﻮد. ﻓﻌﺎﻟﯿﺖ آﻧﺰﯾﻢﻫﺎي ﮐﺎﺗﺎﻻز، ﮔﺎﯾﺎﮐﻮل ﭘﺮاﮐﺴﯿﺪاز و آﺳﮑﻮرﺑﺎت ﭘﺮاﮐﺴﯿﺪاز در ﺷﺮاﯾﻂ ﺗﻨﺶ اﻓﺰاﯾﺶ ﯾﺎﻓﺖ و ﺳﻄﻮح ﻣﺨﺘﻠﻒ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ ﻣﻨﺠﺮ ﺑﻪ اﻓﺰاﯾﺶ ﺑﯿﺸﺘﺮ ﻓﻌﺎﻟﯿﺖ اﯾﻦ آﻧﺰﯾﻢ-ﻫﺎ ﺗﺤﺖ ﺷﺮاﯾﻂ ﺗﻨﺶ ﺷﺪ. در اﯾﻦ ﭘﮋوﻫﺶ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ ﺑﺎﻋﺚ ﺗﺤﺮﯾﮏ ﺳﯿﺴﺘﻢ دﻓﺎﻋﯽ ﮔﯿﺎه )ﺗﺤﺮﯾﮏ ﺑﯿﺎن ژنﻫﺎي دﺧﯿﻞ در ﺳﺎزوﮐﺎرﻫﺎي دﻓﺎﻋﯽ( و در ﻧﺘﯿﺠﻪ اﻓﺰاﯾﺶ ﻓﻌﺎﻟﯿﺖ آﻧﺰﯾﻢﻫﺎي آﻧﺘﯽاﮐﺴﯿﺪان )آﺳﮑﻮرﺑﺎت ﭘﺮاﮐﺴﯿﺪاز، ﮐﺎﺗﺎﻻز و ﮔﺎﯾﺎﮐﻮل ﭘﺮاﮐﺴﯿﺪاز( ﺷﺪ. در ﻣﺠﻤﻮع ﻧﺘﺎﯾﺞ اﯾﻦ ﺗﺤﻘﯿﻖ ﻧﺸﺎن داد ﮐﻪ 24-اﭘﯽﺑﺮاﺳﯿﻨﻮاﺳﺘﺮوﺋﯿﺪ، ﻓﻌﺎﻟﯿﺖ ژنﻫﺎي دﺧﯿﻞ در ﻓﺘﻮﺳﻨﺘﺰ و ژنﻫﺎي درﮔﯿﺮ در ﺳﯿﺴﺘﻢ دﻓﺎع آﻧﺘﯽاﮐﺴﯿﺪاﻧﯽ ﮔﯿﺎه ﺷﻨﺒﻠﯿﻠﻪ را ﺗﺤﺮﯾﮏ ﻣﯽﮐﻨﺪ و ﺑﺎ ﮐﺎﻫﺶ ﺗﻨﺶ اﮐﺴﯿﺪاﺗﯿﻮ، ﺗﺤﻤﻞ ﺷﻨﺒﻠﯿﻪ را ﻧﺴﺒﺖ ﺑﻪ ﺗﻨﺶ دﻣﺎﯾﯽ ﺑﺎﻻ اﻓﺰاﯾﺶ ﻣﯽدﻫﺪ.

The aim of this study was to investigate the effect of 24-epi-brassinosteroid on some of the physiological properties of fenugreek under high temperature stress. The treatments consisted of 24-epi-brassinosteroid (2, 5 and 10 ppm), different harvest times (6 and 24 h) and high temperature stress (42° C). Results showed that high temperature stress reduced chlorophyll a, b and total chlorophyll and carotenoid contents and increased malondialdehyde content and electrolyte leakage. 24-epi-brassinosteroid treatment during stress significantly prevented carotenoid, chlorophyll a, b and total chlorophyll contents to be deceased. Applying different levels of 24-epi-brassinosteroid (2 and 5 ppm) at high temperatures decreased malondialdehyde and increased fenugreek tolerance, due to the reduced non-fatty acid peroxidation. The activity of catalase, guaiacol peroxidase and ascorbate peroxidase enzymes enhanced in stress condition and application of 2 and 5 ppm 24-epi-brassinosteroid resulted in further increase of these enzymes activity. The application of 24-epi-brassinosteroid resulted in increased defense gene activity and enhanced content of antioxidant enzymes including ascorbate peroxidase, catalase and guaiacol peroxidase by stimulating the plant defense system. Overall, the results of this study showed that 24-epi-brassinosteroid stimulates the activity of genes involved in either photosynthesis or the antioxidant defense system of fenugreek, and fenugreek tolerance to high temperature stress increased, by reducing oxidative stress.