Water Status Related Root-to-Shoot Communication Regulates the Chilling Tolerance of Shoot in Cucumber (Cucumis sativus L.) Plants

Abstract

Although root-to-shoot communication has been intensively investigated in plants under drought, few studies have examined root-to-shoot communication under chilling. Here we explored whether root-to-shoot communication contributes to the chilling-light tolerance of cucumber shoots and clarified the key signal involves in this communication. After leaf discs chilling-light treatment, the photoinhibitions of Photosystem I (PSI) and Photosystem II (PSII) were similar in leaf discs of two cucumber varieties (JY-3 and JC-4). When the whole plants, including roots, were chilled under light, the photosynthetic performances in JC-4 leaves decreased more seriously than that in JY-3 leaves. However, when the water status of leaves was maintained by warming roots or floating the attached leaves on water, the PSII activity and amount of PSI in the leaves of the two varieties were similar after chilling-light treatment. In addition, the differences of PSII activities and amount of PSI between the two varieties under whole plant chilling-light treatment were independent of ABA pretreatment. Above results indicate that (1) the better water status in leaves under chilling contributes to the higher chilling tolerance of JY-3; (2) the water status, rather than an ABA signal, dominates root-to-shoot communication under chilling and the chilling tolerance of cucumber shoot.

Characterization of photosynthetic gas exchange in leaves under simulated adaxial and abaxial surfaces alternant irradiation

“…Although some recent reports have investigated dynamic photosynthesis under fluctuating irradiance 22 , the majority of studies were performed on leaves that were irradiated on the adaxial surface 12 13 14 15 16 17 . Abaxial surface irradiation and ad-ab-alt irradiation, which is ubiquitous in the field, have been neglected 11 .…”

“…Unfortunately, previous studies examining the photosynthetic performance of leaves were performed using adaxial surface irradiation121314151617. Less attention has been paid to the photosynthetic performance of leaves under abaxial surface irradiation conditions918, and no attention has been given to investigating the photosynthetic gas exchange of leaves under ad-ab-alt irradiation.…”

“…Consequently, to understand photosynthesis under natural conditions, we need to understand photosynthesis under adaxial and abaxial surfaces alternant irradiation conditions (ad-ab-alt irradiation). Unfortunately, previous studies examining the photosynthetic performance of leaves were performed using adaxial surface irradiation 12 13 14 15 16 17 . Less attention has been paid to the photosynthetic performance of leaves under abaxial surface irradiation conditions 9 18 , and no attention has been given to investigating the photosynthetic gas exchange of leaves under ad-ab-alt irradiation.…”

Ultraviolet-B Radiation (UV-B) Relieves Chilling-Light-Induced PSI Photoinhibition And Accelerates The Recovery Of CO2 Assimilation In Cucumber (Cucumis sativus L.) Leaves

“…PSI is more stable than PSII under most abiotic stresses, such as high-light and high-temperature conditions 9 11 . However, when chilling-sensitive plants experience chilling-light stress 12 13 14 15 , or under the sequence of saturation pulses 16 17 18 , PSI becomes the primary photoinhibition site. Unlike PSII, which can quickly recoversfrom damage 18 19 20 , the recovery of the damaged PSI is quite slow and may be irreversible, even under optimum conditions 13 20 .…”

“…The electron transfer from PSII has been shown to be necessary for PSI photoinhibition 13 14 15 21 . Specifically, blocking the electron transfer from PSII to PSI with DCMU prevents the PSI photoinhibition induced by chilling-light conditions or fluctuating light 13 22 .…”