Identification and characterization of an expansin gene AsEXP1 associated with heat tolerance in C3 Agrostis grass species

Jichen Xu, Jiang Tian, Faith C. Belanger, Bingru Huang

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62 Scopus citations


Plant tolerance of heat stress involves various changes at physiological and molecular levels. The objective of this study was to examine the expression of a gene encoding expansin protein in relation to heat tolerance in two C 3 grass species and genotypes differing in heat tolerance. Heat-tolerant, thermal Agrostis scabra, adapted to high temperatures in geothermal areas in Yellowstone National Park, was subjected to 20°C (control) or 40°C (heat stress) for 7 d in a growth chamber. Differential display analysis identified that a gene, AsEXP1, encoding an expansin protein, was strongly up-regulated in leaves exposed to heat stress in thermal A. scabra. Virtual northern hybridization and RT-PCR confirmed that AsEXP1 was a heat-inducible gene in leaves. The expression of AsEXP1 was induced at 1 h of plant exposure to heat stress and reached the highest level of expression at 4 h of treatment. A 1.3 kb full-length cDNA of AsEXP1 was isolated, which encodes a 251 amino acid protein. Two ecotypes of thermal A. scabra and 10 genotypes of Agrostis stolonifera (creeping bentgrass), a widely used turfgrass species in cool climatic regions, varying in the level of heat tolerance, were exposed to 40°C for 7 d to examine the level of AsEXP1 expression in relation to heat tolerance. Genetic variation in heat tolerance was evaluated by measuring cell membrane stability, photochemical efficiency, and leaf growth. RT-PCR analysis revealed that the level of AsEXP1 in different genotypes was positively correlated with the level of heat tolerance in both grass species. The results first identified a heat-related expansin gene in grass species and suggest that AsEXP1 may be useful as a molecular marker to select for heat-tolerant grass germplasm.

Original languageEnglish (US)
Pages (from-to)3789-3796
Number of pages8
JournalJournal of Experimental Botany
Issue number13
StatePublished - Oct 2007

All Science Journal Classification (ASJC) codes

  • Physiology
  • Plant Science


  • Agrostis scabra
  • Agrostis stolonifera
  • High temperature
  • Turfgrass


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