miRNA-based drought regulation in wheat.

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.

Transcriptome analysis of wheat inoculated with Fusarium graminearum.

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.

Structure, physical, and digestive properties of starch from wx ae double-mutant rice.

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.