Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

278
B. Rathinasabapathi and R. Kaur
implicated to have an adaptive role in plant’s tolerance to heat stress (Vierling, 1991;
Klueva et al., 2001). It is believed that HSPs exhibit chaperone functions by assisting
other proteins in proper post-translational folding and maintaining them in a functional
state. Transgenic expression of HSPs has increased the thermotolerance in many instances.
A transgenic approach was successfully used for manipulating HSP expression
and heat tolerance in Arabidopsis (Lee et. al., 1995; Lee and Schöffl, 1996; Prandl
et. al., 1998; Malik et. al., 1999; Queitsch et. al., 2000; Sanmiya et. al., 2004) (Table 6).
Table 6.
Utilization of various heat shock protein families for development of
thermotolerant transgenic plants
Gene Gene action Species Phenotypic References
expression
Hsp70 Heat-inducible Arabidopsis Increased thermo Lee and Schoff
antisense HSP70 tolerance in (1996)
transgenic plants
Hsp17.7 Heat shock protein Carrot Increased or Malik et. al.,
decreased (1999)
thermotolerance
Hsp101 Heat shock protein Arabidopsis Decreased Hong and
thermotolerance in Vierling (2000)
Hsp101-deficient
(hot1) mutant
Hsp101 Heat shock protein Arabidopsis Manipulated Queitsch et. al.,
themotolerance in (2000)
transgenic plants
Transgenic tobacco expressing class I cytosolic small HSP gene, TLHS1 showed
up to two times higher cotyledon opening rates in comparison to the transgenic tobacco
seedlings carrying the TLHS1 gene in antisense orientation at high temperature
stresses of 40 °C and 45 °C for 1 to 4 h (Park and Hong, 2002). Expression of Athsp101
and sHSP17.7 into the basmati rice resulted in higher survival and better growth performance
in the recovery phase following the heat stress (Agarwal et. al., 2003; Murakami
et. al., 2004). Overexpression of certain transcriptional regulators of HSP expression,
like HSF1 and HSF3, triggered plants to constitutively express HSPs for higher basal
thermotolerance (Lee et. al., 1995; Prändl et. al., 1998).