Physiological, morphological, biochemical, and genetic responses of alfalfa to salinity

Authors: ACHARYA, BISWA - University Of California; Sandhu, Devinder; Ferreira, Jorge

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/18/2021
Publication Date: 7/18/2021
Citation: Acharya, B., Sandhu, D., Ferreira, J.F.S. 2021. Physiological, morphological, biochemical, and genetic responses of alfalfa to salinity. In: Yu, L.X., Kole, C., editors. The Alfalfa Genome. Switzerland: Springer Nature Switzerland AG. p. 145-157. https://doi.org/10.1007/978-3-030-74466-3_9.
DOI: https://doi.org/10.1007/978-3-030-74466-3_9

Interpretive Summary: Alfalfa is an important forage crop that is grown worldwide due to its perennial nature, wide adaptability, high biomass yield, resistance to multiple cuttings, and tolerance to various biotic and abiotic stresses. Alfalfa has been reported to be moderately tolerant to salinity and can be grown with low quality degraded water. Salinity is a growing threat to global agriculture. Developing new salt-tolerant cultivars may lead to the expansion of alfalfa cultivation to marginal lands. To realize this goal, the understanding of genetic determinants regulating morphological, physiological, and biochemical traits responsible for salinity tolerance in alfalfa is crucial. In this chapter, we describe the effects of salinity on alfalfa growth and development, mechanisms of salinity tolerance in plants, and the current status of the progress toward understanding salinity tolerance in alfalfa. Here we discuss recent advances in understanding genetic components involved in salinity stress and the possibility of manipulation of those in developing new salt-tolerant genotypes that are vigorous and high yielding. This chapter will be useful to plant biologists working in the field of abiotic stresses. Furthermore, alfalfa geneticists and breeders will be able to utilize this information in selecting genetic material tolerant to salt.

Technical Abstract: Alfalfa is an important forage crop known for its perennial nature, high biomass yield, high nutritive value, and its high demand for water. Global reduction in availability of clean water in arid and semi-arid regions is forcing farmers to irrigate with low quality degraded/recycled water, which is generally high in its salt concentration. High salt concentrations in soils not only affect soil properties but also result in reduced plant growth and tissue ion toxicities. Plants employ a wide variety of physiological, anatomical, molecular, and biochemical mechanisms to cope with salinity stress. Because of the self-incompatible and polyploid nature of alfalfa, the genetic dissection of these complex mechanisms is challenging. Understanding of these mechanisms is critical to effectively manipulate underlying genetic determinants for developing salt-tolerant alfalfa genotypes. This chapter focuses on the effects of salinity on alfalfa growth and development, mechanisms of salinity tolerance in plants, and the current status of the progress toward understanding salinity tolerance in alfalfa. Recent salinity studies on growth, biomass yield, photosynthesis, water and ion relationships, nutritive value, and antioxidants provided a clear picture of different component traits involved in salinity stress in alfalfa. Based on these studies on the effects of salinity on alfalfa growth and development and molecular information generated on model plants, tremendous progress has been made to fill the major knowledge gaps in different pathways regulating salt stress responses in alfalfa. This understanding will facilitate the manipulation of some genetic components that would allow alfalfa to thrive under irrigation with recycled/highly-saline waters and expand alfalfa cultivation to marginal lands.