Comparative transcriptome analysis reveals higher expression of stress and defense responsive genes in dwarf soybeans obtained from the crossing of G. max and G. soja.

BACKGROUND: Plant height is an important component of plant architecture and significantly affects crop breeding practices and yield. Dwarfism in plants prevents lodging and therefore it's a desired trait in crops. OBJECTIVE: To find differentially expressed genes to classify and understand the regulation of genes related to plant growth in mutant dwarf soybeans, which appeared in the F5 generation. METHODS: We obtained a few segregated dwarf soybeans in the populations derived from the crossing of Glycine max var. Peking and Glycine soja var. IT182936 in an F5 RIL population. These dwarf soybeans may be useful genetic resources for plant breeders, geneticists and biologists. Using the Illumina high-throughput platform, transcriptomes were generated and compared among normal and dwarf soybeans in triplicate. CONCLUSION: We found complex relationship of the expressed genes to plant growth. There were highly significantly up-/downregulated genes according to the comparison of gene expression in normal and dwarf soybeans. The genes related to disease and stress responses were found to be upregulated in dwarf soybeans. Such over-expression of disease resistance and other immune response genes can be targeted to understand how the immune genes regulate the response of plant growth. In addition, photosynthesis-related genes showed very low expression in dwarf lines. The transcriptome expression and genes classified as related to plant growth may be useful resources to researchers studying plant growth.

Novel allelic variant of Lpa1 gene associated with a significant reduction in seed phytic acid content in rice (Oryza sativa L.).

In plants, myo-inositol-1,2,3,4,5,6-hexakisphosphate (InsP6), also known as phytic acid (PA), is a major component of organic phosphorus (P), and accounts for up to 85% of the total P in seeds. In rice (Oryza sativa L.), PA mainly accumulates in rice bran, and chelates mineral cations, resulting in mineral deficiencies among brown rice consumers. Therefore, considerable efforts have been focused on the development of low PA (LPA) rice cultivars. In this study, we performed genetic and molecular analyses of OsLpa1, a major PA biosynthesis gene, in Sanggol, a low PA mutant variety developed via chemical mutagenesis of Ilpum rice cultivar. Genetic segregation and sequencing analyses revealed that a recessive allele, lpa1-3, at the OsLpa1 locus (Os02g0819400) was responsible for a significant reduction in seed PA content in Sanggol. The lpa1-3 gene harboured a point mutation (C623T) in the fourth exon of the predicted coding region, resulting in threonine (Thr) to isoleucine (Ile) amino acidsubstitution at position 208 (Thr208Ile). Three-dimensional analysis of Lpa1 protein structure indicated that myo-inositol 3-monophosphate [Ins(3)P1] could bind to the active site of Lpa1, with ATP as a cofactor for catalysis. Furthermore, the presence of Thr208 in the loop adjacent to the entry site of the binding pocket suggests that Thr208Ile substitution is involved in regulating enzyme activity via phosphorylation. Therefore, we propose that Thr208Ile substitution in lpa1-3 reduces Lpa1 enzyme activity in Sanggol, resulting in reduced PA biosynthesis.