Parental genetic distance and combining ability analyses in relation to heterosis in various rice origins

Journal of Crop Science and Biotechnology - Information on parental genetic distance and combining ability is a fundamental prerequisite for hybrid rice breeding. Based on a study of genetic...     

A postmenopause-like model of ovariectomized Wistar rats to identify active principles of Erythrina lysistemon (Fabaceae)

To determine whether the two major compounds of Erythrina lysistemon are active principles accounting for Erythrina estrogenic effects, we used a postmenopause-like model of ovariectomized Wistar rats to evaluate their effects on some menopausal problems. Ovariectomized rats were orally treated either with compound 1 or compound 2 at 1 and 10 mg/kg BW for 28 days. Estradiol valerate served as the reference substance. As results, compounds 1 and 2 displayed estrogen-like effects on the uterus and the vagina, and reduced atherogenic risks by decreasing the two assessed atherogenic parameters, the total cholesterol/HDL-cholesterol ratio and the atherogenic index of plasma.     

Genetic diversity of physic nut (<Emphasis Type="Italic">Jatropha curcas</Emphasis> L.) revealed by SSR markers

Ten microsatellite markers were used to investigate genetic diversity and genetic structure among 32 accessions of Jatropha curcas. Low levels of average genetic diversity were observed (H _E = 0.160). A dendrogram produced by the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) based on Nei’s genetic distances revealed 3 groups among 32 accessions. The genetic differentiation (F _ST ) among two groups was significant (P < 0.01). The model-based Bayesian clustering method indicated that a population structure (ΔK) was separated into two groups. The analysis of molecular variance (AMOVA) showed higher variability (63.753%) among groups than within groups (36.247%). These findings could assist in defining the best method of genetic conservation and studies in breeding programs for genetic improvement of J. curcas.     

Genetic variation of avirulence genes (AVR-Pi9, AVR-Pik,AVR-Pita1) and genetic diversity of rice blast fungus,Pyricularia oryzae,in Thailand

Genetic variation of the rice blast (Pyricularia oryzae) population in Thailand was investigated based on the nucleotide sequence of three avirulence genes, AVR-Pi9, AVR-Pik, and AVR-Pita1. Sixty rice blast isolates were collected from rice-growing areas around Thailand. Gene-specific primers were used to amplify these AVR genes and AVR-Pi9, AVR-Pik, and AVR-Pita1 were detected in 60, 57, and 23 isolates, respectively. Based on the AVR-Pi9 sequences, we identified one rice blast isolate containing an amino acid change from glutamic acid to aspartic acid. Moreover, two rice blast isolates had identical sequences to the rice blast strain originating in Japan, indicating a potential movement of this isolate from Japan to Thailand. Three AVR-Pik alleles were found, including AVR-PikA (3.51%), AVR-PikD (71.93%), and isolates with two copies of AVR-PikD and AVR-PikF (24.56%). AVR-PikA and AVR-PikF are virulent to Thai rice variety Jao Hom Nin. Six haplotypes of AVR-Pita1 were identified with one deletion and 12 amino acid substitutions. This study revealed that different AVR genes in Thai rice blast populations have different levels of genetic variation: AVR-Pi9 and AVR-Pik genes have a relatively low genetic diversity, while the AVR-Pita1 gene has high genetic diversity. We found AVR-Pi9 was not under selection pressure, while AVR-Pita1 was under purifying selection pressure. In addition, geographic location has influenced the distribution of genetic variation of AVR-Pita1. The information obtained from this study is valuable for the future development of breeding strategies for rice blast resistance in Thailand.