Aluminium Stress Tolerance in Legumes under Acidic Soils: Mechanisms and Methods – A Review

Author: Mayurakshee Mahanta, Noren Singh Konjengbam*, Andrean Allwin Lyngdoh and Reginah Pheirim

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Abstract

Being one of the most abundant elements in earth’s crust, Aluminium (Al) is ubiquitously present in the soil, mostly in unavailable forms at neutral or near neutral soil pH. However, under acidic soil conditions, when pH drops below 5, Al solubilizes into phytotoxic forms, adversely affecting root growth, vigor and productivity of plants, causing 25–80% yield reduction in cultivated crops. Legumes are an important component of human diet and an essential component of the ecosystem. Being highly sensitive to soil acidity, legumes are highly affected by Al toxicity, which is a major constraint for legumes production in acidic soils. Acidic soils predominate the tropical and subtropical regions of the world. In order to extend legume production in acidic soils, there arises a need to understand Al toxicity and develop suitable methods for combating Al toxicity stress. Thus, the present paper reviews Al toxicity-its nature and tolerance mechanisms, screening methods, genetics and breed

Keywords

Al toxicity, legumes, root re-growth, organic acids, inheritance, mapping.

Conclusion

Al toxicity is one of the prime limitations of crop production in acidic soils, especially at pH below 5.0 where Al becomes phytotoxic and inhibits plant root growth. In addition to its adverse effect in the plant root system, Al also leads to disruptions in cellular redox homeostasis, oxidative stress, increased ROS production, lipid peroxidation and nutrient imbalances. Al induced accumulation of callose in the root tips and inhibition of root growth are used as important biomarkers for screening Al tolerance in plants cultured under hydroponics. Plants have evolved numerous mechanisms to tolerate Al toxicity stress, most importantly the secretion of organic acids like malate, citrate, oxalate etc., which chelates the Al ions externally in the rhizosphere, or internally in the cytosol of the plants, thus preventing its toxic effects on the plants. High level of genetic variability has been observed for Al tolerance in legumes and QTLs identified for Al tolerance in major legumes may

References

INTRODUCTION Legumes particularly pulses are an essential component of human diet, contributing significant amounts of protein in addition to carbohydrates, and several vitamins and minerals. Through their unique property of fixing atmospheric nitrogenby the process of biological nitrogen fixation in symbiotic association with Rhizobium bacteria, legumes improve soil fertility and the functioning of ecosystems, thus also forming an important component of different cropping systems. With more than 78.3 million, ha of land planted to legumes, these species provide over 35% of the world’s protein intake (Werner and Newton 2005). India is the largest producer of pulses in the world, with around 25% share in the global production, contributing around 19.3 million tonnes (ESI, 2015) but with a very low average productivity of 764 kg/ha (Pooniya et al. 2015). Acid soils, also known as ultisols or oxisols, classified by a pH of 5.5 or lower are widely distributed in the tropical and subtr

How to cite this article

Mayurakshee Mahanta, Noren Singh Konjengbam, Andrean Allwin Lyngdoh and Reginah Pheirim (2022). Aluminium Stress Tolerance in Legumes under Acidic Soils: Mechanisms and Methods – A Review. Biological Forum – An International Journal, 14(1): 1538-1548.