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Title: Morpho-physiological parameters affecting iron deficiency chlorosis response in soybean (Glycine max L.)

item VASCONCELOS, MARTA - Universidade Catolica Portuguesa
item Grusak, Michael

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2013
Publication Date: 1/2/2014
Citation: Vasconcelos, M.W., Grusak, M.A. 2014. Morpho-physiological parameters affecting iron deficiency chlorosis response in soybean (Glycine max L.). Plant and Soil. 374:161-172.

Interpretive Summary: Soybean productivity is severely impacted when soil conditions lead to inadequate amounts of available iron. When this occurs, plants suffer from iron deficiency chlorosis (IDC), which appears as yellowing of the leaves and stunted growth. Our goal is to develop soybean cultivars that are less susceptible to IDC, and thus we have tried to learn more about the way that plants tolerate this condition. In this study, we first identified a number of existing cultivars that had been shown to be highly tolerant or highly susceptible of IDC. We measured iron concentrations in young leaves of each cultivar, seed iron concentrations, and assessed each cultivar's capacity for acquiring iron through their roots. These measurements were compared with IDC tolerance ratings. We found that more IDC-tolerant cultivars were those that started with more iron in their seeds, and which could partition more iron to their first leaves. These results will help us to develop new approaches to combat IDC-related declines in productivity in soybean.

Technical Abstract: Iron deficiency chlorosis (IDC) leads to severe leaf chlorosis, low photosynthetic rates, and yield reductions of several million metric tons each year. In order to devise breeding and genetic transformation programs that aim at generating high-yielding and IDC-tolerant soybean lines, it is necessary to better understand the mechanisms that enable tolerant plants to survive under Fe-limiting conditions. An in silico analysis in the USDA soybean collection allowed the identification of a set of novel efficient and inefficient soybean cultivars that can be used in future studies concerning IDC response. Plants were grown in iron-deficient and iron-sufficient conditions, and several IDC-related aspects were studied. No correlation was found between root reductase activity and chlorosis. A negative correlation was found between dry weight of the unifoliolate leaves and chlorosis in the first trifoliate. Chlorosis tolerance was also negatively correlated with stem weight and with iron concentration of the first unifoliolates. It was also positively correlated with the amount of iron in the first trifoliate leaves. Soybean differential chlorosis susceptibility between different accessions is linked to specific morpho-physiological parameters such as leaf size, stem weight, and tissue iron partitioning.