MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition. Drought is a common environmental stress influencing crop growth and development. To date, it has been reported that a number of plant miRNA are involved in drought stress response. In this study, we comparatively investigated drought stress-responsive miRNAs in the root and leaf of bread wheat (Triticum aestivum cv. Sivas 111/33) by miRNA microarray screening. miRNA microarray analysis showed that 285 miRNAs (207 upregulated and 78 downregulated) and 244 miRNAs (115 upregulated and 129 downregulated) were differentially expressed in leaf and root tissues, respectively. Among the differentially expressed miRNAs, 23 miRNAs were only expressed in the leaf and 26 miRNAs were only expressed in the root of wheat growth under drought stress. Upon drought treatment, expression of miR159, miR160, miR166, miR169, miR172, miR395, miR396, miR408, miR472, miR477, miR482, miR1858, miR2118, and miR5049 were found to be significantly differentiated in bread wheat. The regulatory network analysis showed that miR395 has connections with a number of target transcripts, and miR159 and miR319 share a number of target genes. Drought-tolerant and drought-sensitive wheat cultivars showed altered expression pattern upon drought stress in terms of investigated miRNA and their target transcript expression level.

Amylopectin is the principal component of starch. The amylose extender (ae) gene encodes the starch-branching enzyme IIb, which is critical in determining the fine structure of endosperm starch. To determine the relationship between the fine structure of amylopectin and its physical properties, rice mutant lines defective in the ae function with altered fine structure of amylopectin and in combination with the waxy (wx) background were selected for comparative studies with primary wild-type and ae starches. The ae mutant endosperms accumulated a high amylose content starch with long amylopectin chains. The ae and wx ae starches showed no significant difference in the unit chain-length distribution of amylopectin and starch granule morphology. The wx ae starch displayed a higher pasting temperature and higher peak viscosity. The gelatinization peak temperatures of the wx, ae, and wx ae starches were 2.2, 13.1, and 17.1 degrees C higher, respectively, than that of the wild-type starch, and the wx ae starch showed a retrogradation peak with a shorter cooling period than that of ae starch. The raw ae and wx ae starches were almost indigestible by alpha-amylase in vitro. Rats fed the wx ae starch showed slowly increasing blood glucose at a lower level than the rats fed the wx or wild-type starch. These results indicate that the primary structure of the rice wx ae amylopectin with enriched long chains changes the granular structure of the starch, including its crystal structure, and results in resistance to in vitro or in vivo degradation.

Plants are frequently exposed to microorganisms like fungi, bacteria, and viruses that cause biotic stresses. Fusarium head blight (FHB) is an economically risky wheat disease, which occurs upon Fusarium graminearum (Fg) infection. Moderately susceptible (cv. “Mizrak 98”) and susceptible (cv. “Gun 91”) winter type bread wheat cultivars were subjected to transcriptional profiling after exposure to Fg infection. To examine the early response to the pathogen in wheat, we measured gene expression alterations in mock and pathogen inoculated root crown of moderately susceptible (MS) and susceptible cultivars at 12 hours after inoculation (hai) using 12X135K microarray chip. The transcriptome analyses revealed that out of 39,179 transcripts, 3668 genes in microarray were significantly regulated at least in one time comparison. The majority of differentially regulated transcripts were associated with disease response and the gene expression mechanism. When the cultivars were compared, a number of transcripts and expression alterations varied within the cultivars. Especially membrane related transcripts were detected as differentially expressed. Moreover, diverse transcription factors showed significant fold change values among the cultivars. This study presented new insights to understand the early response of selected cultivars to the Fg at 12 hai. Through the KEGG analysis, we observed that the most altered transcripts were associated with starch and sucrose metabolism and gluconeogenesis pathways.

Disproportionating enzyme (D-enzyme) is a 4-αglucanotransferase (EC 2.4.1.25) that cleaves an α-1,4 glucosidic bond of α-1,4 glucan (donor molecule) and transfers the resulting glucan moiety to a non-reducing end of an acceptor molecule by creating a new α-1,4 glucosidic bond. D-enzymes have been identifi ed in a number of plant species and characterized most extensively in potato 1 7) and Arabidopsis, 8,9) but also studied in pea, 10) wheat, 11) germinating barley seed 12) and sweet potato tubers. 13) These studies showed that plant D-enzymes have common reaction characteristics, where the smallest donor molecule is maltotriose, the smallest acceptor molecule is glucose and the smallest transferred glucan unit is maltose. Similar enzymes are also present in bacteria but bacterial 4-α-glucanotransferases are historically called amylomaltases; the term D-enzyme is only used for plant 4-α-glucanotransferases. Bacterial amylomaltases catalyze similar reactions, but differ slightly in substrate and reaction specifi city. 7) Amylomaltase can use maltose as a donor molecule (although maltose is less effective than larger maltooligosaccharides) and can catalyze glucosyl as well as glucanosyl transfer reactions. 7) It should be noted that reported plant D-enzymes cannot use maltose as a donor and never catalyze glucosyl transfers. The D-enzymes described above are now called DPE1 in order to distinguish them from recently identifi ed isoforms, DPE2, which have been characterized in both Arabidopsis 14 16) and potato. 17) Despite their similarity in primary Abstract: This work aims to characterize disproportionating enzyme (DPE1) and its isoform DPE2 in rice. Rice DPE genes (OsDPE1 and OsDPE2) were cloned and expressed in E. coli. The OsDPE1 and OsDPE2 genes encode proteins of 594 and 946 amino acids with a calculated molecular mass of 67 kDa and 108 kDa, respectively. Purifi ed recombinant OsDPE1 and OsDPE2 showed highest activity at around pH 7.0 and pH 6.0 7.0, respectively. The optimum reaction temperature was 30 C for OsDPE1 and 39 C for OsDPE2. Recombinant OsDPE1 disproportionates maltotriose to produce glucose and maltopentaose, and thus shares the defi ning behavior of D-enzymes. In our experiments, recombinant OsDPE2 catalyzed the glucose transfer reaction from maltose to an acceptor molecule such as glycogen. We also characterized the differences between the diurnal transcription profi les of OsDPE1 and OsDPE2 in rice leaves and seeds, and their temporal expression levels in developing rice seeds.

Germination, emergence and seedling growth are considerably restricted by salinity. The study aimed to compare safflower with sunflower during germination and seedling growth for tolerance to salinity. Four safflower cultivars (Asol, Balcı, Linas and Olas) and sunflower hybrids (Esbella, Oliva, Cartago and C-180) were subjected to various NaCl levels (control, 5, 10 and 15 dS m -1 ) and their seedling growth and ion concentration were investigated. Classification for salinity tolerance was performed by a combination of Principal Component (PCA) and Cluster Analysis considering germination percentage (GP), mean germination time (MGT), vigor index (VI), Na + and Na:K ratio in seedlings. The results elicited that genotypes exhibited varying responses to salinity, MGT significantly prolonged and a dramatic reduction in seedling growth of sunflower was observed. The highest seedling fresh weight was observed in Esbella among sunflower and Asol among safflower and, Na + concentration of seedlings increased with increasing salinity levels. The safflower seedlings absorbed a higher Na + than that of sunflower. Safflower cv. Balcı had the highest Na + concentration in seedling and it maintains its ion balance (Na:K ratio) at all levels of NaCl. Cluster analysis revealed that there were two groups for salinity tolerance, and the safflower cultivars were apparently more salt-tolerant than sunflower hybrids.