Rootstock Alleviates Salt Stress in Grafted Mulberry Seedlings: Physiological and PSII Function Responses

Abstract

This study investigated the effect of NaCl stress on Na+ and K+ absorption and transport by roots, nitrogen and phosphorus content in leaves, PSII photochemical activity and reactive oxygen species (ROS) in leaves of mulberry own-root seedlings and grafted seedlings. To determine the response, own-root seedlings of a high yielding mulberry cultivar, Tieba mulberry (Morus alba L.), and the grafted seedlings, obtained by using Qinglong mulberry with high salt tolerance as rootstock and Tieba mulberry as scion, were used. The Na+ content in roots and leaves of grafted seedlings was significantly lower than that in own-root seedlings under salt stress; while K+ content in roots and leaves of grafted seedlings was significantly higher than that in own-root seedlings. The root activity in grafted seedlings was significantly higher than that in own-root seedlings, as well as the content of nitrogen, phosphorous and water. PSII photochemical activity in leaves of grafted seedlings was less significantly affected by salt stress compared to own-root seedlings. The electron transport at the acceptor side of PSII from QA to QB was less affected by salt stress, which resulted in a significantly lower ROS content in leaves of grafted seedlings than that of own-root seedlings. Therefore, grafting high-yielding and good-quality Tieba mulberry with salt tolerant Qinglong mulberry as rootstock showed a relatively high salt tolerance. This may be because (1) the root system of rootstock presented high Na+ resistance and has selective absorption capacity for Na+ and K+ (2) the root system of rootstock prevented excess Na+ from being transported to aerial parts in order to reduce adverse effects of Na+ (3) the root system of rootstock had enhanced root activity under salt stress, which accelerated water and nutrient absorption (4) the leaves of grafted seedlings had higher PSII photochemical activity and electron transport rate compared with those of own-root seedlings under salt stress, which effectively reduced ROS burst mediated by photosynthesis and reduced oxidative damage.

Improving Photosynthetic Capacity, Alleviating Photosynthetic Inhibition and Oxidative Stress Under Low Temperature Stress With Exogenous Hydrogen Sulfide in Blueberry Seedlings

“…However, the change of V K is not only affected by injury on the PSII donor side, but also by damage on PSII acceptor side. When the injury on the acceptor side is greater than that on the donor side, V K does not increase significantly (Zhang et al, 2018c;Zhang et al, 2019b). Therefore, although the electron transfer from Q A to Q B on the PSII acceptor side of blueberry leaves was inhibited by low temperature, low temperature had little effect on the oxygen-evolving complex of the PSII donor side as V K did not change.…”

Exogenous melatonin improves salt tolerance in tomato by regulating photosynthetic electron flux and the ascorbate–glutathione cycle

“…The radiation that was used to activate photosynthesis was 600 μmol m −2 s −1 (saturation light). The air temperature and humidity were 25°C and 50-60 %, respectively (Zhang et al 2018). Concentration of CO 2 was changed at 3 min intervals in a sequence of 1600, 1200, 1000, 800, 600, 400, 300, 200, 150, 100, and 0 μmol mol −1 .…”

Special issue in honour of Prof. Reto J. Strasser - Effects of exogenous abscisic acid on the photosynthetic function and reactive oxygen species metabolism of tobacco leaves under drought stress

“…However, the change of VK was affected by both the damage to the donor side of PSII and by damage to its acceptor side. When the degree of damage to the acceptor side was greater than the degree of damage to the donor side, VK would no longer significantly increase (Xu et al 2018, Zhang et al 2018d. Therefore, in this study, the effect of PSII on the donor side under drought stress might have been caused by the insensitivity of the oxygen-evolving complex to drought stress or by excessive damage on the acceptor side.…”