**4. Final considerations**

provides the information that will be used by genetic breeding in the search for cultivars re‐

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

Zhang et al*.* (2011) [58] evaluated the responses of cultivars tolerant and susceptible to the fun‐ gus *Phytophthora sojae* by means of two-dimensional electrophoresis. The authors observed 46 proteins being expressed (Figure 11), among which only 11% were related to plant defense.

In addition, proteomic studies that deal with seed development also play an essential role [62]. The data obtained may help to interpret the function of genes that determine protein concentration, considered as a key characteristic for genetic breeding of soybeans. Moreover, differential proteomic analyses designed to describe the changes that occur from maturation to senescence in organs and organelles have been reported. There is also already a soybean proteome database, providing information on the proteins involved in the soybean response

**Figure 11.** Identification of 26 and 20 protein spots from Yudou25 (A) and NG6255 (B), respectively. The numbers

with arrows indicate the differentially expressed protein spots. Ip and Mr are shown on the gels [58].

**Figure 10.** profile of aluminum regulated-proteins in PI 416937 72 h posttreatment [56].

to stress caused by drought, salinity and, principally, flooding [63].

sistant to various diseases.

Relationships

544

In light of the above, proteomics in soybean studies contributes to diverse biotechnological applications, with its approach proving to be fundamental. Its use in the search for superior soybean materials has the purpose of comparing and contrasting genotypes for a deter‐ mined type of stress and identifying the proteins that respond to the stress by means of changes in their levels of expression. The identification of these molecules and their respec‐ tive functions will allow direction of breeding work, which should continue only with those that perform roles related to the characteristic of stress tolerance.

For that reason, it is essential to cross proteomic data with information also gathered from genomics, transcriptomics and metabolomics so as to check the correlation of the candidate proteins with the desired characteristic. The following stage aims to evaluate these proteins (genes) in regard to their segregation for the characteristic of interest or quantitative trait lo‐ cus (QTL), that is, determine how much each one of them contributes to the characteristic of tolerance. Finally, the selected genes may be integrated in marker assisted selection (MAS) or in genetic transformation programs.
