Nitrogen Starvation and Nitrate or Ammonium Availability Differently Affect Phenolic Composition in Green and Purple Basil

Abstract

Basil (Ocimum basilicum L.) comprises green and purple cultivars, worldwide cultivated and appreciated for high contents of rosmarinic acid and anthocyanins, respectively. Although nitrogen (N) fertilization is needed for high yields, in basil it could have detrimental effects on the accumulation of phenolic compounds. In this study, plants of the cultivars ‘Italiano Classico’ (green) and ‘Red Rubin’ (purple) were grown in hydroponics and subjected to different nutritional treatments, consisting in N starvation, and nitrate (NO3−) or ammonium (NH4+) nutrition. Plant growth and nutritional status, estimated by the contents of NO3−, NH4+, and amino acids in roots and leaves, were evaluated and put in relation with quality traits of basil leaves, such as chlorophyll content, antioxidant capacity, total phenols, the activity of phenylalanine ammonia-lyase, and the concentrations of individual (poly)phenolic acids and flavonoids. This study reveals that N starvation, as well as the availability of the two inorganic N forms, differently affect the phenolic composition in the two cultivars. Compared to plants grown in NO3− availability, in NH4+ availability, green basil showed a higher content of (poly)phenolic acids, while in purple basil, an increase in the contents of anthocyanins was detected. Overall, the study suggests that the management of NH4+ supply could contribute to enhance crop quality in hydroponics, and provides new knowledge about the relationship between N nutrition and phenolic metabolism in basil.

The Effect of Nitrogen Input on Chemical Profile and Bioactive Properties of Green- and Red-Colored Basil Cultivars

“…Regardless the level of N input, Mitikas was the most productive genotype with a total above-ground plant fresh weight on average 68%, 102%, and 120% higher than Red Basil, Dark Opal, and Basilico Rosso. Similar results were reported by the authors [ 29 ] comparing Italian Classic green basil with Red Rubin basil grown in soilless system. Green basil response to N input was also characterized by a higher quadratic coefficient compared to the other varieties tested, suggesting a higher response to N inputs.…”

“…These results are in agreement with the findings of Nguyen and Niemeyer [ 13 ] who examining the phenolic profile of Sweet Thai, Dark Opal, and Genovese basil in response to increasing N levels observed significantly higher levels of phenolic compounds and especially of rosmarinic acid at the lower levels of N in Dark Opal and Genovese basil. Similarly, Prinsi et al [ 29 ] recorded an increase of rosmarinic and total phenolic acids content in green and red basil grown in a hydroponic system after N starvation for 5 days before harvest.…”

Biochemical and Proteomic Changes in the Roots of M4 Grapevine Rootstock in Response to Nitrate Availability

“…Among them, a decrease in chalcone isomerase (#106), an enzyme that catalyzes the isomerization of naringenin chalcone to naringenin flavanone in the flavonoid pathway, was observed. This result agrees with the well-known reduction in phenylpropanoid metabolism occurring after NO 3 − resupply to N-starved plants [ 26 , 51 , 52 , 53 , 54 ]. At the same time, we observed an increase in trans-resveratrol di-O-methyltransferase (#41), which suggests different effects on specific traits of the phenylpropanoid metabolism.…”

Oxidative Status and Antioxidative Response to Fusarium Attack and Different Nitrogen Levels in Winter Wheat Varieties

“…Our findings are in accordance with previous studies in which decreased content of photosynthetic pigments under nitrogen-deficient conditions were found [ 3 , 36 ]. Low nitrogen level induces inhibition of photosynthesis and reduces photosynthetic capacity, which consequently inhibits plant growth and development [ 37 , 38 ].…”