Yu Deyue

Identification, inheritance and QTL mapping of root traits related to tolerance to rhizo-spheric stresses in soybean (G. max (L.) Merr.)

A sample of soybean accessions (Glycine max (L.) Merr.) from Huanghe-Huaihe-Haihe and Middle-Lower Changjiang Valleys in China was used to identify their tolerance to rhizo-spheric stresses, including drought, aluminum toxin and low phosphorus. A total of 15 accessions highly tolerant to at least one of the abiotic stresses were screened out. The correlation between drought tolerance and the relative values of total root length, root volume and dry root weight (relative to dry plant weight) were all significant at 0.01 level, respectively. So did for the correlation between aluminum toxin tolerance and the stress to non-stress ratios of the number of lateral roots, tap root length, total root length, root volume and dry root weight. The inheritance study on the above three root traits related to drought tolerance under segregation analysis indicated that between the two parents of the recombinant inbred line (RIL) population of (Kefeng 1 × Nannong 1138-2), the relative values of dry root weight, total root length and root volume were controlled by two major genes plus polygenes with their major gene heritability values 62.26%–91.81% and polygene heritability values 2.99%–24.75%, respectively, and for the latter two traits, the two major genes linked together with recombination value 4.30% and 1.93%, respectively. The inheritance study on the five root traits related to aluminum toxin tolerance revealed that between the two parents of the recombinant inbred line (RIL) population of (Bogao × NG94-156), the stress to non-stress ratios of lateral root number, tap root length, total root length and dry root weight were controlled by three major genes plus polygenes with their major gene heritability values 80.22%–91.81% and polygene heritability values 3.52%–11.39%, while the stress to non-stress ratio of root volume was controlled by three major genes with their major gene heritability value 93.44%. The (Kefeng 1 × Nannong 1138-2) RIL population was also used for mapping QTLs of relative dry root weight, total root length and root volume related to drought tolerance. Five, three and five QTLs located on Linkage group N6-C2, N8-D1b+W, N11-E and N18-K for each of the three traits, respectively, were identified. Each of the traits appeared to have one locus (Dw1, Rl1, Rv1) with relatively large effect in comparison with their other loci, and the three loci in above parentheses were located in the same region STAS8_3T-STAS8_6T on N6-C2 with a same distance to the flanking markers. Thus, Dw1, Rl1, and Rv1 even might be a same locus and performed as pleiotropic of a same gene. The results between segregation analysis and QTL mapping appeared relatively consistent, therefore could be used for verification each other.

Cloning and characterization of an aldehyde dehydrogenase gene GmALDH3-1 from soybean.

To research the mechanism of soybean reproductive development, we identified a number of flower development related genes in soybean by microarray hybridization. A gene predominately expressed in soybean flowers was chosen for further analysis. Through bioinformatic and RT-PCR approaches, the full-length gene was cloned from soybean flowers. The results of BLAST searching indicated that this gene encoded for an aldehyde dehydrogenase and was named as GmALDH3-1. GmALDH3-1 contains a complete open reading frame of 1485 bp in length, which encodes for a peptide of 494 amino acids. The product encoded by GmALDH3-1 shows 83% similarity and 68% identity with Populus tomentosa PtALDH3, respectively, and 39% and 59% with human ALDH3B. Phylogenetic analysis shows that GmALDH3-1 and other ALDH3 subfamily members are grouped into the same branch and GmALDH3-1 is close to PtALDH3 and Arabidopsis AtALDH3F1. Real-time RT-PCR analysis demonstrated that the highest expression level of GmALDH3-1 occurred in flowers, but the expression of this gene was almost undetectable in leaves and roots. We further analyzed GmALDH3-1 expression during the course of seed development based on publicly available microarray data and found that GmALDH3-1 was highly expressed in the seed endothelium, epidermis, outer integument, and hilum.