Natural Variation in 9-Cis-Epoxycartenoid Dioxygenase 3 and ABA Accumulation

Abstract

The stress hormone abscisic acid (ABA) is critical for drought resistance; however, mechanisms controlling ABA levels are unclear. At low water potential, ABA accumulation in the Arabidopsis (Arabidopsis thaliana) accession Shahdara (Sha) was less than that in Landsberg erecta (Ler) or Columbia. Analysis of a Ler 3 Sha recombinant inbred line population revealed a single major-effect quantitative trait locus for ABA accumulation, which included 9-cis-epoxycarotenoid dioxygenase3 (NCED3) as a candidate gene. NCED3 encodes a rate-limiting enzyme for stress-induced ABA synthesis. Complementation experiments indicated that Sha has a reduced-function NCED3 allele. Compared with Ler, Sha did not have reduced NCED3 gene expression or protein level but did have four amino acid substitutions within NCED3. Sha differed from Ler in the apparent molecular mass of NCED3, indicative of altered NCED3 proteolytic processing in the chloroplast. Site-directed mutagenesis demonstrated that substitution at amino acid 271 was critical for the altered NCED3 molecular mass pattern, while the other Sha NCED3 polymorphisms were also involved in the reduced ABA accumulation. Sha did not have a reduced level of thylakoidbound NCED3 but did differ from Ler in the apparent molecular mass of stromal NCED3. As Sha was not impaired in known factors critical for NCED3 function in ABA synthesis (expression, chloroplast import, and thylakoid binding), the differences between Ler and Sha NCED3 may affect NCED3 activity or other factors influencing NCED3 function. These results identify functionally important sites on NCED3 and indicate a complex pattern of NCED3 posttranslational regulation in the chloroplast. During periods of drought stress and reduced water potential (c w), plant endogenous abscisic acid (ABA) levels increase dramatically. Increased ABA controls

Temperature Impacts the Response of Coffea canephora to Decreasing Soil Water Availability

“…Two other interesting ABA signaling related DEGs are two carotenoid dioxygenases (Cc05_g10210, FC = 1.66; Cc08_g05610, FC = −3.36). The gene Cc05_g10210 encodes CcNCED3, a gene involved in ABA synthesis (Kalladan et al 2019) and previously shown to have increased transcript levels in coffee leaves under different water deficits (Simkin et al 2008;Thioune et al 2017). Transcript levels for carotenoid dioxygenase Cc08_g05610, were relatively high initially, dropped significantly as the water deficit increased, then exhibited only a partial recovery after re-watering.…”

Transcriptome Analysis Reveals Potential Roles of Abscisic Acid and Polyphenols in Adaptation of Onobrychis viciifolia to Extreme Environmental Conditions in the Qinghai-Tibetan Plateau

“…Members of the NCED family have been shown to encode key rate-limiting enzymes through the oxidative cleavage of cis -epoxycarotenoids in the ABA biosynthetic pathway to accumulate ABA for further signal transduction in order to resist abiotic stresses [ 84 , 85 , 86 , 87 ]. In recent studies, overexpression of AtNCED3 in Arabidopsis enhanced the drought tolerance by promoting the levels of ABA [ 88 , 89 ]. In rice, the overexpression of OsNCED3 resulted in increased ABA content and promote water stress tolerance of the transgenic plants [ 90 ].…”

Heterologous Expression of Arabidopsis thaliana rty Gene in Strawberry (Fragaria × ananassa Duch.) Improves Drought Tolerance

“…To explore the molecular mechanisms underlying the increased drought tolerance of the transgenic plants heterologously expressing rty, we analyzed the expression of stress-responsive genes during the PEG treatment using an RT-qPCR analysis. Speci cally, we analyzed the expression of the following drought-responsive genes, involved in ABA biosynthesis, catabolism, transport, and signaling: NCED3 (nine cis-epoxycarotenoid dioxygenase 3) [32], ABI1 (ABA insensitive 1) [33], RD29A (responsive to dehydration 29) [34], DREB2A (dehydration responsive element-binding protein 2A) [35], and PP2C (type-2C protein phosphatase) [36]. The expression of RD29A (a stress-responsive marker), and DREB2A (a regulator of many water stress-inducible genes) during PEG treatment was upregulated to a greater extent in the transgenic plants than in the control plants (Fig.…”