Physiological Responses of Ocimum basilicum, Salvia officinalis, and Mentha piperita to Leaf Wounding

Abstract

The investigation about the leaf wounding effect on plant physiological procedures and on leaf pigments content will contribute to the understanding of the plants’ responses against this abiotic stress. During the experiment, some physiological parameters such as photosynthesis, transpiration and stomatal conductance as well as the chlorophyll and anthocyanin leaf contents of Ocimum basilicum, Salvia officinalis, and Mentha piperita plants were measured for about 20–40 days. All the measurements were conducted on control and wounded plants while in the latter, they were conducted on both wounded and intact leaves. A wide range of responses was observed in the wounded leaves, that is: (a) immediate decrease of the gas exchange parameters and long-term decrease of almost all the measured variables from O. basilicum, (b) immediate but only short-term decrease of the gas exchange parameters and no effect on pigments from M. piperita, and (c) no effect on the gas exchange parameters and decrease of the pigments content from S. officinalis. Regarding the intact leaves, in general, they exhibited a similar profile with the control ones for all plants. These results imply that the plant response to wounding is a complex phenomenon depending on plant species and the severity of the injury.

The Effect of Leaf Wounding on Basil Plants of Different Developmental Stages

“…In the vegetative plants, the photosynthetic decrease was eliminated on day 2 and reappeared on day 3, while it was constant during both the budding and flowering wounding treatments. The aforementioned findings in the vegetative plants are in accordance not only with previous results on vegetative wounded basil plants [ 4 ], but also with findings on Arabidopsis thaliana (L.) Heynh. plants that were six weeks old, which presented a significant decrease 2 h after leaf wounding, but photosynthesis increased to the control level 24 h after wounding [ 3 ].…”

“…Despite the observed differences between the examined developmental stages of the Greek basil plants, in general, the wounded leaves exhibited a decrease in the photosynthetic rate compared to both the intact and control leaves ( Figure 1 ). A decrease in carbon assimilation in the remaining leaf tissues after mechanical or herbivory wounding was revealed more often than an increase or a lack of change [ 22 ], although the plant species may be important for the type of photosynthetic response [ 4 ]. The wound-induced decrease in the photosynthetic rate was not consistent throughout the vegetative stage ( Figure 1 a), but it was unambiguous when wounding was imposed during budding ( Figure 1 b), and especially during the flowering stage ( Figure 1 c).…”

“…Moreover, carbon skeletons are also required for the synthesis of new molecules [ 2 , 24 ]. Considering that sucrose and starch are the most common substrates for accomplishing these requirements, the intact leaves of wounded plants may operate as source organs, showing an increased photosynthetic rate not only compared to that of the wounded leaves, but sometimes even in comparison with the leaves of control plants [ 4 ]. Thus, in certain developmental stages, intact leaves may fulfill the energy and carbon demands of the wounded leaves and demonstrate increased sink strength, especially in the vicinity of the wounded tissue.…”

“…Mechanical or herbivory wounding causes injuries or tears and results in localized cell death, loss of water and solutes, and disruption of the vascular system [ 2 ]. Consequently, it affects a wide range of physiological processes, such as photosynthesis, transpiration, and respiration [ 3 , 4 ]. Moreover, leaf injury, even that caused by a mechanical force, not only leads to structural and physiological damage, but can also be a potential threat as a gateway for pathogen invasion [ 5 ].…”

Systemic Expression of Genes Involved in the Plant Defense Response Induced by Wounding in Senna tora

“…On the other hand, the GO and KEGG terms involved in the photosynthesis process were negatively modulated after wounding ( Figure 2 C,E). Reduction of photosynthetic activity by biotic and abiotic stresses has been reported [ 28 , 29 ]. In addition, the indoleacetic acid metobolism and borate transport were the major GO terms inhibited by wounding in S. tora leaves ( Figure 2 C).…”