Spikelet Proteomic Response to Combined Water Deficit and Heat Stress in Rice (Oryza sativa cv. N22)

S V Krishna Jagadish,Richard Malo,Sigrid Heuer,John Bennett,Zhongwen W Rang,Peter Q Craufurd,Raveendran Muthurajan

doi:10.1007/s12284-011-9059-x

Abstract

Abstract In future climates, rice crops will be frequently exposed to water deficit and heat stress at the most sensitive flowering stage, causing spikelet sterility and yield losses. Water deficit alone and in combination with heat stress significantly reduced peduncle elongation, trapping 32% and 55% of spikelets within the leaf sheath, respectively. Trapped spikelets had lower spikelet fertility (66% in control) than those exserted normally (>93%). Average weighted fertility of exserted spikelets was lowest with heat stress (35%) but higher with combined stress (44%), suggesting acquired thermo-tolerance when preceded by water-deficit stress. Proteins favoring pollen germination, i.e., pollen allergens and beta expansin, were highly up-regulated with water deficit but were at normal levels under combined stress. The chaperonic heat shock transcripts and proteins were significantly up-regulated under combined stress compared with either heat or water deficit. The importance of spikelet proteins responsive to water deficit and heat stress to critical physiological processes during flowering is discussed.

Highlights

Global warming could pose a serious threat to developing countries, reducing the world"s agricultural gross domestic product by up to 16% by 2020 (Cline 2007)
Significant decline in precipitation in subtropical regions will double the area under rice (Oryza sativa) cultivation affected by water deficit stress (IPCC 2007; Wassmann et al 2009)
In our study, rice cultivar N22 showed a higher tolerance of heat stress acquired because of a preceding water-deficit stress. Tolerance to both heat and a combination of heat and water deficit stress is shown to be unique to N22 and a similar response was not documented with entries known for tolerance to either of the stresses (Rang et al 2011)

Summary

Introduction

Global warming could pose a serious threat to developing countries, reducing the world"s agricultural gross domestic product by up to 16% by 2020 (Cline 2007). The prices of agricultural commodities are predicted to increase by 40% with a 3°C increase in global temperature (Easterling et al 2007). Global climatic models predict an increase in mean surface air temperature 2.0°C to 4.5°C with an increased variability about this mean (IPCC 2007). Significant decline in precipitation in subtropical regions will double the area under rice (Oryza sativa) cultivation affected by water deficit stress (IPCC 2007; Wassmann et al 2009). Wassmann et al (2009) showed through spatial analysis that high-temperature stress during the susceptible reproductive stage may coincide with periods of water deficit in parts of Bangladesh, eastern India, southern Myanmar, and northern Thailand. It is necessary to study and understand the effects of and interactions between water deficit and high temperature at flowering in rice

Methods

Results

Conclusion