Photosynthetic Responses of Canola to Exogenous Application or Endogenous Overproduction of 5-Aminolevulinic Acid (ALA) under Various Nitrogen Levels

Abstract

Limited data are available on the effects of 5-aminolevulinic acid (ALA) on plant photosynthesis in relation to the nitrogen (N) level. In this study, we investigate photosynthetic responses to ALA in canola plants (Brassica napus L.). We used wild-type plants without ALA addition (controls), wild-type plants with exogenous ALA application, and transgenic plants that endogenously overproduced ALA. The plants were grown hydroponically in nutrient solutions with low, middle, and high concentrations of N. Our results indicate that plants in both treatment groups had higher chlorophyll contents and net photosynthetic rates and lower intracellular CO2 concentrations in the leaves, as compared to controls. Furthermore, simultaneous measurement of prompt chlorophyll fluorescence and modulated 820-nm reflections showed that the active photosystem II (PS II) reaction centers, electron transfer capacity, and photosystem I (PS I) activity were all higher in treated plants than controls at all N levels; however, the responses of some photochemical processes to ALA were significantly affected by the N level. For example, under low N conditions only, a negative ΔK peak appeared in the prompt chlorophyll fluorescence curve, indicating a protective effect of ALA on electron donation via activation of the oxygen-evolving complex. Taken together, our findings suggest that ALA contributes to the promotion of photosynthesis by regulating photosynthetic electron transport under various N levels. These findings may provide a new strategy for improving photosynthesis in crops grown in N-poor conditions or reduced N-fertilization requirements.

ALA reverses ABA-induced stomatal closure by modulating PP2AC and SnRK2.6 activity in apple leaves

“…In addition to research on exogenous ALA application, studies on transgenic plants that overproduce endogenous ALA have confirmed its biological functions. When Yhem1 (a yeast Hem1 driven by the Arabidopsis HemA promoter, which is light-inducible) was transformed into higher plants, transgenic tobacco [ 76 , 77 ], strawberry [ 78 ], tomato [ 79 ], and canola [ 80 ] biosynthesized much more endogenous ALA and chlorophyll and had higher photosynthetic rates and energy conversion efficiency than their respective WTs. Yhem1 transgenic Arabidopsis [ 81 ], tomato [ 82 ], and canola [ 83 ] have been demonstrated to be more salt tolerant, and transgenic banana was colder tolerant [ 84 ].…”

Response of Canola productivity to integration between mineral nitrogen with yeast extract under poor fertility sandy soil condition

“…Chl. contents were increased in plants grown under middle and high N conditions as compared with plants grown under low N conditions, which significantly affected photochemical processes 20 . N is a fundamental element for leaf plants, insufficient N supply lead to decreased photosynthetic rate in plants 21 , this occurs to many factors such as a decrease in pigment degradation 22 , reduction in stomatal conductance 23 and a decline in the light and dark reaction of photosynthesis.…”

“…Canola is a nitrophilous plant, wherein a high concentration of NO 3 in the culture media results in higher Chl. contents in the plant leave compared with controls 20 . The Chl.…”

A Comparative Study on the Superiority of AOS DP3-7 Over 5-ALA in Facilitating Pigment Change in Peppers

“…This weight gain could be attributed to the enhanced metabolic activity and improved nutrient assimilation facilitated by the biostimulants 19 . Considering the role of AOS in eliciting defense responses 20 and improving plant vigor 21 , and the influence of 5-ALA on chlorophyll production and energy transfer, it is plausible that these substances improved the photosynthetic efficiency of the plants 22 , thereby leading to an accumulation of biomass. Such findings are particularly significant for the agricultural sector, as they suggest a feasible strategy for increasing yield without compromising, and potentially improving, the quality of the produce.…”