3.4 Cross-temperature differentially expressed genes in Heat
Shock Response
We examined patterns of expression in hsp genes to evaluate their
specific contribution to the heat shock response (HSR) in both species.
In both species, we found a significant down-regulation of heat shock
protein genes at temperatures where population growth rate was maximized
(Figure 1B, Figure 4A, 4B). In general, genes encoding for hspshad higher expression at the lowest temperature treatment (20oC) for the heat-tolerant, B. calyciflorus s.s.
and at the highest temperature for the heat-sensitive, B.
fernandoi. Genes encoding for hsp 27 and hsp 70 followed
this pattern. Genes encoding for hsp 10, hsp 40, andhsp 60 were differentially expressed only in B.
calyciflorus s.s. and followed the induction pattern of hsp 70.
Genes encoding for hsp90 beta were up-regulated under the highest
imposed temperature regime in both species. In B. calycifloruss.s., genes encoding for hsp20 were also up-regulated under the
highest imposed temperature (32 oC), following the
induction pattern of hsp90 beta (Figure 4A).