The relationships among iron‐stress response, iron‐efficiency and iron uptake of plants

Abstract

The relationships among iron‐stress response, iron‐efficiency and iron uptake in plants is discussed. The literature concerning the relationships among iron‐stress response and iron‐efficiency or chlorosis resistance in plants is confusing. Not all plants which exhibit a classical iron‐stress response in nutrient solution culture are more resistant to chlorosis than plants which do not. The term “iron‐efficiency”; has different meanings for different researchers. For example, there are statements in the literature that monocots are “iron‐inefficient”; based on results of laboratory experiments which show a lack of iron‐stress response. Incongruently, separate studies are done using “iron‐efficient”; varieties of sorghum, oats or other monocots. We suggest that the term iron‐deficiency chlorosis (IDC) resistance be used for observations regarding field‐grown plants.

There is still a debate about whether or not iron must be reduced before being transported across the root cell plasmalemma. There is much evidence to support the hypothesis of “obligatory reduction”; of Fe‐III to Fe‐II during the enhanced rate of iron uptake by iron‐stressed plants. However, there is also evidence supporting the contention that iron can be absorbed as a metal complex in toto by plants which are not iron‐stressed or which do not exhibit an enhanced rate of iron uptake in response to iron‐stress. Further research is needed to resolve this debate.

Key words:

• Iron
• Chlorosis
• Iron‐Efficiency
• Reduction
• Iron Nutrition
• Iron‐Stress
• IDC‐Resistance
• Iron Uptake