Differential proteomic response of rice (Oryza sativa) leaves exposed to high- and low-temperature stress.

Global mean surface temperature has been predicted to increase by 1.8-4°C within this century, accompanied by an increase in the magnitude and frequency of extreme temperature events. Developing rice cultivars better adapted to non-optimal temperatures is essential to increase rice yield in the future and, hence, understanding the molecular response of rice to temperature stress is necessary. In this study, we investigated the proteomic responses of leaves of 24-day-old rice seedlings to sudden temperature changes. Rice seedlings grown at 28/20°C (day/night) were subjected to 3-day exposure to 12/5°C or 20/12°C (day/night) for low-temperature stress, and 36/28°C or 44/36°C (day/night) for high-temperature stress, followed by quantitative label-free shotgun proteomic analysis on biological triplicates of each treatment. Out of over 1100 proteins identified in one or more temperature treatments, more than 400 were found to be responsive to temperature stress. Of these, 43, 126 and 47 proteins were exclusively found at 12/5, 20/12 and 44/36°C (day/night), respectively. Our results showed that a greater change occurs in the rice leaf proteome at 20/12°C (day/night) in comparison to other non-optimal temperature regimes. In addition, our study identified more than 20 novel stress-response proteins.

Proteomic analysis of temperature stress in plants.

In this review we examine current approaches used for proteomic analysis of temperature stress in plants. Rapid advances in this field in recent years are discussed, including metabolic, chemical and isotopic labeling, and label-free quantitative techniques. These are compared and contrasted with well-established methods such as 2-DE approaches. Examples of applications of various methods are presented, and technical difficulties and limitations of each are also considered. Results of previous studies are examined in detail, and commonly occurring temperature stress response proteins are collated. We conclude that technical advances, and improvements in genome sequence availability, will have an ever increasing impact on our understanding of molecular mechanisms of stress response in plants.

Prevalence of genetic thrombophilic polymorphisms in the Sri Lankan population--implications for association study design and clinical genetic testing services.

We investigated the prevalence of genotypes/alleles of single nucleotide polymorphisms (SNP) and haplotypes defined by them in three genes in which variations are associated with venous thromboembolism in 80 Sinhalese, 80 Sri Lankan Tamils and 80 Moors in the Sri Lankan population and compared the SNP data with that of other populations in Southern India and haplotype data with that of HapMap populations. The genes and polymorphisms investigated were Methylenetetrahydrofolate reductase (MTHFR) - 677C>T (rs1801133), 1298A>C (rs1801131), 1317T>C, 1793G>A (rs2274976); Factor V (F5) - 1691G>A (rs6025) and 4070A>G (rs1800595); and prothrombin (F2) - 20210G>A (rs1799963). The polymorphisms were genotyped using PCR/RFLP methods. The prevalence of the variant alleles of each polymorphism in the Sinhalese, Tamils, and Moors was MTHFR 677T: Sinhalese - 13%, Tamils - 9%, Moors - 9%. 1317T>C: Sinhalese - 0%; Tamils - 0%; Moors - 0%. 1793A: Sinhalese - 19%, Tamils - 19%, Moors - 19%. F5 1691A: Sinhalese - 2%, Tamils - 3%, Moors - 2%. 4070G: Sinhalese - 6%, Tamils - 5%, Moors - 8%. F2 20210A: Sinhalese - 0%, Tamils - 0%, Moors - 0%. The frequencies observed were similar to data from other South Indian populations; the haplotype data showed haplotypes unique to the Sri Lankan population when compared to HapMap populations. rs9651118 was identified as a SNP that splits the haplotypes harbouring the functionally significant 677T allele in the MTHFR gene. This data would be useful in planning genetic association studies in the Sri Lankan population and in deciding on which genetic variants should be tested in a clinical genetic testing service.