Salicylic Acid Enhances Adventitious Root and Aerenchyma Formation in Wheat under Waterlogged Conditions.

Murali Krishna Koramutla,Belay T Ayele,Pham Anh Tuan

doi:10.3390/ijms23031243

Murali Krishna Koramutla, Belay T Ayele + Show 1 more

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https://doi.org/10.3390/ijms23031243

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Abstract

The present study investigated the role of salicylic acid (SA) in regulating morpho-anatomical adaptive responses of a wheat plant to waterlogging. Our pharmacological study showed that treatment of waterlogged wheat plants with exogenous SA promotes the formation axile roots and surface adventitious roots that originate from basal stem nodes, but inhibits their elongation, leading to the formation of a shallow root system. The treatment also enhanced axile root formation in non-waterlogged plants but with only slight reductions in their length and branch root formation. Exogenous SA enhanced the formation of root aerenchyma, a key anatomical adaptive response of plants to waterlogging. Consistent with these results, waterlogging enhanced SA content in the root via expression of specific isochorismate synthase (ICS; ICS1 and ICS2) and phenylalanine ammonia lyase (PAL; PAL4, PAL5 and PAL6) genes and in the stem nodes via expression of specific PAL (PAL5 and PAL6) genes. Although not to the same level observed in waterlogged plants, exogenous SA also induced aerenchyma formation in non-waterlogged plants. The findings of this study furthermore indicated that inhibition of ethylene synthesis in SA treated non-waterlogged and waterlogged plants does not have any effect on SA-induced emergence of axile and/or surface adventitious roots but represses SA-mediated induction of aerenchyma formation. These results highlight that the role of SA in promoting the development of axile and surface adventitious roots in waterlogged wheat plants is ethylene independent while the induction of aerenchyma formation by SA requires the presence of ethylene.

Highlights

Wheat (Triticum aestivum L.) is an important cereal crops world-wide; its production is adversely affected by several abiotic stress factors including waterlogging, which causes approximately 15–20% of the yield loss in annual wheat crop production [1].Waterlogging significantly reduces the diffusion rate of oxygen through the soil, leading to the occurrence of hypoxic or anoxic conditions [2]
To gain insights into the role of Salicylic acid (SA) in mediating morpho-anatomical adaptations to waterlogging, this study examined the effect of exogenous SA on the formation of adventitious roots and root aerenchyma in waterlogged wheat plants, and investigated changes in the expression patterns of SA biosynthesis genes and endogenous SA levels in the root, and basal stem nodes that produce adventitious roots in response to waterlogging
This study investigated the role of SA in regulating morpho-anatomical adaptive responses to waterlogging in wheat

Summary

Introduction

Wheat (Triticum aestivum L.) is an important cereal crops world-wide; its production is adversely affected by several abiotic stress factors including waterlogging, which causes approximately 15–20% of the yield loss in annual wheat crop production [1].Waterlogging significantly reduces the diffusion rate of oxygen through the soil, leading to the occurrence of hypoxic or anoxic conditions [2]. To cope with waterlogging-induced oxygen deficient conditions, plants develop several morphological and anatomical adaptive responses such as the formation of adventitious roots and root aerenchyma that improve oxygen availability to the roots [3]. Waterlogging induced development of adventitious roots in upland cereal crops such as wheat is often associated with aerenchyma formation [4,5]. With respect to abiotic stresses, SA plays an important role in mitigating the adverse effects of drought, cold, heat and salinity in many plant species including wheat [6,8]. Studies on Arabidopsis and mung bean have demonstrated the role of SA in the formation of adventitious roots under normal growing conditions [9,10,11]. Exogenous application of SA and its synthetic derivative, acetyl SA, has been shown to have positive effects on several morphological traits in the shoot system including plant height, number of tillers, flag leaf area, number of spikes per plant and number of grains per spike [12,13]

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