Diabetes mellitus is a metabolic disease spreading worldwide that has been reported to worsen the development and progression of other diseases (cancer, vascular diseases and dementia). To establish functional rice lines with anti-postprandial hyperglycaemic effects, we developed mutant rice lines, which lack one or two gene(s) related to starch synthesis, and evaluated their effects. Powder of mutant rice lines or other grains was loaded to rats fasted overnight (oral grain powder loading test). Incremental area under time-concentration curves (iAUC) were calculated with monitored blood glucose levels. Rice lines with anti-postprandial hyperglycaemic effects were separated by cluster analysis with calculated iAUC. A double mutant rice #4019 (starch synthase IIIa (ss3a)/branching enzyme IIb (be2b)), one of the screened mutant rice lines, was fed to Goto-Kakizaki (GK) rats, an animal model for type 2 diabetes, for 5 weeks. Plasma levels of C-peptide, a marker of pancreatic insulin secretion, were measured with ELISA. For in vitro study, a rat pancreatic cell line was cultured with a medium containing rat serum which was sampled from rats fed #4019 diet for 2 d. After 24-h of incubation, an insulin secretion test was performed. Through the oral rice powder loading test, seven rice lines were identified as antidiabetic rice lines. The intake of #4019 diet increased plasma C-peptide levels of GK rats. This result was also observed in vitro. In rat serum added to cell medium, ornithine was significantly increased by the intake of #4019. In conclusion, the mutant rice #4019 promoted pancreatic insulin secretion via elevation of serum ornithine levels.
Grain quality characters of 575 Bangladesh rice cultivars from 7 ecotypes were studied. The cultivars were collected from 6 distinct regions (Rajshahi, Dhaka, Sylhet, Barisal, Khulna and Chittagong) of the country. Significant variation was observed in all the parameters investigated. The range of grain length, width, thickness and weight of 100 grains varied between 5.26 mm and 10.36 mm, 1.76 mm and 3.68 mm, 1.30 mm and 2.54 mm, and between 0.84 g and 3.68 g, respectively. Long grains (7.76-9.00 mm) were found to be present in a maximum number of cultivars. However, based on length/width ratio (grain shape), medium grains (L/W ratio 2.10-3.00) showed the maximum frequency. Grain quality characters varied widely according to ecotypes. The cultivars of Transplanted Aman (T. Aman) ecotype exhibited the highest level of genetic variation. Geographical distribution of grain quality parameters differed according to the regions. Cultivars collected from Khulna region were more diverse than cultivars collected from other regions.
To understand the genetic patterns of the physio-morphological traits for barley grain yield, six-generations (P 1 , P 2 , F 1 , F 2 , BC 1 , and BC 2 ) were used to determine the type of gene action in the four barley crosses. Grain yield showed a strong positive association (r = 0.83 and 1) with Grain Filling Rate in Giza121/RIL1 and Giza126/RIL2 crosses, respectively. The relationship between yield and earliness was not consistent with crosses and positive (r) values were quite low. It should be possible to select early-maturing and high-yielding segregates with high 100-kernel weight. The results indicated that the dominance effect [dd] was more important and greater than the additive effect [aa] and [ad] for most traits. Positive heterosis over the mid-and better-parent was quite similar for the most traits, except for heading and maturity dates, that showed negative heterotic effects. The inbreeding depression was high significant and positive for Grain Filling Rate, chlorophyll contents, Flag Leaf area and 100-kernel weight. On the other hand, it was a negatively significant for the earliness trait (HD, MD, and GFP). The lack of uniformity for estimates of inbreeding depression can be explained by environmental variation and to its influence on the type of gene action. Narrow-sense heritability ranged from 13.3% for Grain Filling Period in Giza12/RIL1 to 66.6% for heading dates in Giza121/RIL2 crosses. Genetic advance estimates were low due to lack of additive variance. The crosses Giza121/RIL1 and Giza126/RIL2 would be of interest in a breeding program, for improving characteristics of earliness, yield, and its components.Keywords: Hordeum vulgare L., type of gene action, heterosis, heritability IntroductionBarley (Hordeum vulgare L.) is a crop with great adaptive potential in many regions of the world. In areas which have only a brief rainy season, growers can obtain a harvest mainly because this crop has advantages in aspects such as salt tolerance, frost tolerance in the early period of development, drought tolerance, etc. Breeding for quantitative traits in early generations is impeded by several factors such as polygenic nature and low heritability of a trait (grain yield, the number of spikes per plant, etc.), linkage, non-additive gene effects and environmental effects (Harlan, 1976).In order to overcome these difficulties, it is necessary to get as much information as possible about the genetic structure of breeding population undergoing selection (Sharma et al., 2003). This means identifying the gene effects that control the inheritance of a trait of interest and contributing to the exploitable genetic variance of the population.Grain yield increase would be effectively rested with the basis of the capabilities of yield components and other closely associated traits. In cereal crops, the upper three leaves on the stem, especially the uppermost leaf, i.e., flag leaf, are the primary source of carbohydrate production. The flag leaf could contribute a large proportion of the carbohydrates...
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