Expression of 9-kDa non-specific lipid transfer protein genes in developing wheat grain is enhanced by high temperatures but not by post-anthesis fertilizer

Abstract

A survey of EST databases identified 16 9-kDa non-specific lipid transfer proteins (nsLTPs) expressed in developing grain from the US spring wheat Butte 86. Two of the most abundant sequences encoded nsLTPs similar to proteins identified previously by two-dimensional gel electrophoresis/mass spectrometry (2-DE/MS). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) was used to examine the expression of these nsLTPs in developing grain or endosperm produced under controlled temperature and fertilizer regimens. Under a moderate (24 °C/17 °C day/night) temperature regimen, transcripts accumulated late in grain development and achieved highest levels as grain reached maximum dry weight. When high temperature regimens (37 °C/28 °C day/night) were imposed from anthesis or 15 days post-anthesis (DPA) until maturity, maximum transcript levels were as much as 9-fold higher. Post-anthesis fertilizer had relatively small effects on transcript levels. Accumulation profiles for 9-kDa nsLTPs generated by 2-DE were consistent with transcript profiles. The nsLTPs increased 2 to 3.5-fold in amount in endosperm in response to high temperatures but showed little change in response to fertilizer. Flour from grain produced under the high temperature regimens also contained greater amounts of nsLTPs. Increases in the levels of nsLTPs in flour as a result of environmental conditions during grain fill may have important implications for flour quality and allergenic potential.