A Protective Role of Phenylalanine Ammonia-Lyase from Astragalus membranaceus against Saline-Alkali Stress

Abstract

Phenylalanine ammonia-lyase (PAL, E.C.4.3.1.5) catalyzes the benzene propane metabolism and is the most extensively studied enzyme of the phenylpropanoid pathway. However, the role of PAL genes in Astragalus membranaceus, a non-model plant showing high capability toward abiotic stress, is less studied. Here, we cloned AmPAL and found that it encodes a protein that resides in the cytoplasmic membrane. The mRNA of AmPAL was strongly induced by NaCl or NaHCO3 treatment, especially in the root. Overexpressing AmPAL in Nicotiana tabacum resulted in higher PAL enzyme activities, lower levels of malondialdehyde (MDA), and better root elongation in the seedlings under stress treatment compared to the control plants. The protective role of AmPAL under saline-alkali stress was also observed in 30-day soil-grown plants, which showed higher levels of superoxide dismutase (SOD), proline, and chlorophyll compared to wild-type N. Tabacum. Collectively, we provide evidence that AmPAL is responsive to multiple abiotic stresses and that manipulating the expression of AmPAL can be used to increase the tolerance to adverse environmental factors in plants.

Genome-Wide Identification and Expression Profile Analysis of the Phenylalanine Ammonia-Lyase Gene Family in Hevea brasiliensis

“…These findings indicate that some PALs may take part in response to abiotic or biotic stress. Several recent studies have demonstrated this [8,9]. For example, overexpressing of FuPAL1 gene from F. unibracteata enhanced drought tolerance in Arabidopsis [8].…”

“…Many studies have shown that the accumulation of phenylpropanoid compounds was correlated with PAL activity [3][4][5]. PALs have been characterized in rice [6], wheat [7], castor [3], Fritillaria unibracteata [8], Astragalus membranaceus [9], and Panax ginseng [10] because of PAL significance for phenylpropanoid biosynthesis.…”

Improving plant adaptation to soil antimony contamination: the synergistic contribution of arbuscular mycorrhizal fungus and olive mill waste

“…In addition, the observed boost in the content of antioxidant metabolites in treated plants could be related to the higher accumulation of phenylalanine, as shown in Table 4, because of its function and role o as a precursor of numerous metabolites in plant defence systems against environmental stress such as flavonoids, polyphenols, and anthocyanins [57]. Moreover, the responses of phenylalanine and anthocyanins in this study confirm the shifts in the activity of the phenylalanine ammonialyase (PAL) enzyme, especially in OMW-AMF treatment Table 4 The effect of arbuscular mycorrhizal fungus (AMF) and olive mill waste (OMW) on some phenolic acid (mg g −1 DW), flavonoid compound (mg g −1 DW), phenylalanine amino acid (mg g −1 protein), and the activity of phenylalanine amnio lyase (PAL) enzyme (nkatal mg −1 protein) and chalcone synthase (CHS) (nmol mg −1 protein min −1 ) in oat plants 4), which is responsible for catalyzing the deamination of phenylalanine as the foremost and rate-limiting stage of the phenylpropanoid pathway at the regulation point between primary and secondary metabolites [58]. Similarly, Xi et al [4] reported that AMF can maintain the proteins involved in phenylalanine metabolism at a high level under Sb stress and modulate the adverse effects of stress on plant cells.…”

Multifaceted roles of LhWRKY44 in promoting anthocyanin accumulation in Asiatic hybrid lilies (Lilium spp.)

“…The accumulation of anthocyanins in plant vegetative tissues and flowers is affected by internal factors and external environmental factors such as light, temperature, hormones, sugar, etc. [ 24 , 43 ]. WRKY TFs participate in light signaling pathways.…”