Expression and regulation of genes involved in the reserve starch biosynthesis pathway in hexaploid wheat (Triticum aestivum L.)

Reserve starch of cereal crop accounts for about 70%of grain endosperm and acts as an important human carbohydrate resource worldwide.Wheat reserve starch is synthesized by enzymatic machinery in endosperm cells.To identify genes involved in starch biosynthesis,we constructed 30 RNA-Seq libraries of 10 endosperm-development periods and performed expression and localization analyses.Of 166 endosperm-expressed homologs of starch biosynthesis-related genes,74 showed expression correlated with reserve starch accumulation,including 26 with expected subcellular distribution and higher expression than their isoforms.The key proteins SUS3,UGP1,cAGPase,and Bt1-3 formed the main metabolic pathway and contributed the major substrates for starch processing in amyloplasts.Important isoforms,key pathway proteins,and the main carbon flux toward starch formation in the reserve starch biosynthesis pathway were identified.Based on a coexpression analysis,a library of 425 transcription factors was produced to screen for common regulators.TaMYB44 had features of transcription factors and bound to TaSUT1,TaSSIIIa,TaBEIIa,TaISA1,and TaBEIIb promoters in yeast,suggesting that the gene is a pathway regulator.This study sheds light on understanding the mechanism of reserve starch biosynthesis and will be helpful for increasing starch content in wheat endosperm via biotechnological strategies.

A genetic evidence of chromosomal fragment from bridge parent existing in substitution lines between two common wheat varieties

Locating of important agronomic genes onto chromosome is helpful for efficient development of new wheat varieties. Wheat chromosome substitution lines between two varieties have been widely used for locating genes because of their distinctive advantages in genetic analysis, compared with the aneuploid genetic materials. Apart from the substituted chromosome, the other chromosomes between the substitution lines and their recipient parent should be identical, which eases the gene locating practice. In this study, a set of chromosome substitution lines with cv. Wichita （WI） as the recipient parent and cv. Cheyenne （CNN） as the donor parent were studied for the composition of high molecular weight glutenin subunits （HMW-GS） as well as a range of agronomic important traits. Results revealed that the substitution lines of WI（CNN5D）, WI（CNN6A） and WI（CNN7B） had higher plant heights than the two parents of WI and CNN, and WI（CNN3D） had later maturity than the parents. By sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE） and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） analysis, a substitution line WI（CNN5B） was found to contain different HMW-GS patterns from its two parents, in which 1 By9 was replaced by 1 By8 on chromosome 1BL. Simple sequence repeat （SSR） analysis confirmed that the variation on 1BL in WI（CNN5B） was originated from Chinese Spring （CS）. It is concluded that chromosomal fragments from bridge material and donor parent were quite often retained in intracultivaral chromosome substitution lines except the substituting chromosomes.

Effects of a Carbonated Soft Drink on Epitheial Tumor Incidence in Drosophila melanogaster

Diet represents an important risk factor for tumor development and numerous food dyes have been tested for their carcinogenic potential. Caramel IV colorant and its byproduct, the 4-methylimidazole （4-MI）, are part of the composition of cola soft drinks, although in undefined concentration. Considering that this concentration depends on the manufacturing place, we aimed to evaluate the potential carcinogenic activity of cola soft drinks from Brazil, Canada, Egypt and Netherlands, through the test for detection of epithelial tumor clones （warts） in somatic cells of Drosophila melanogaster. We used 72-hour larvae resulting from the crossing of wts/TM3, Sb^1 virgin females and mwh/mwh males. Larvae were exposed to the media containing the cola soft drinks for 48 hours and the analysis was performed in adults after transformation. Cola soft drinks from Brazil significantly induced epithelial tumor in D. melanogaster, while those from Canada, Egypt and Netherlands did not. In fact, the concentration of 4-MI is higher in cola soft drink commercialized in Brazil. Our results highlight the importance of investigating the toxic potential of current drinks, which may correlate with the rising incidence of malignant diseases.