Involvement of nitric oxide-mediated alternative pathway in tolerance of wheat to drought stress by optimizing photosynthesis

Abstract

NO-mediated alternative pathway plays an important role in protecting wheat seedlings against drought stress through dissipating excessive reducing equivalents generated by photosynthesis. Alternative pathway (AP) has been proven to be involved in responses to various stresses. However, the mechanisms of AP in defense response to drought stress are still lacking. The aims of this work are to investigate the role of AP in drought tolerance and how AP is induced under drought stress using two wheat cultivars with different drought tolerance. Our results showed that Longchun22 cultivar is more tolerant to drought than 98SN146 cultivar. Seedlings exposed to drought led to a significant increase in AP, and it increased more in Longchun22. Furthermore, chlorophyll fluorescence parameters (Fv/Fm, ΦPSII, qP) decreased significantly in drought-treated seedlings, especially in 98SN146, indicating that photoinhibition occurred under drought stress. Pretreatment with SHAM, the malate-oxaloacetate shuttle activity and photosynthetic efficiency were further inhibited in drought-treated seedlings, resulting in more serious oxidative damage as indicated by higher levels of malondialdehyde and hydrogen peroxide. Moreover, NO modulated AP under drought stress by increasing AOX1a expression and pyruvate content. Taken together, these results indicate that NO-mediated AP is involved in optimizing photosynthesis under drought stress by avoiding the over-reduction of photosynthetic electron transport chain, thus reducing reactive oxygen species production and oxidative damage in wheat leaves.

Stem metabolism under drought stress – a paradox of increasing respiratory substrates and decreasing respiratory rates

“…This is supported by studies reporting an increase in glycolytic products in shoots of drought-tolerant wheat genotypes (Guo et al 2018). However, a consistent pattern in the drought response of phosphate sugars and carbon substrates entering the Krebs cycle cannot be extracted from previous studies (de Miguel et al 2016, Wang et al 2016, Zhang et al 2017.…”

NO and ABA Interaction Regulates Tuber Dormancy and Sprouting in Potato

“…NO plays a role in numerous plant physiological processes (Begara-Morales et al, 2019), such as transport (Sun et al, 2018), germination (Liu et al, 2010;Arc et al, 2013a), flowering (Khurana et al, 2011), metabolism (Hasanuzzaman et al, 2018), and senescence (Sun, 2018). Moreover, NO is a significant signaling molecule that regulates the plant response to various nonbiological and biological stresses (Begara-Morales et al, 2018), such as stomatal closure (Zhang et al, 2019), heat stress (Parankusam et al, 2017), disease (Srinivas et al, 2014), drought (Wang et al, 2016), and programmed cell death (Ma et al, 2010). Exogenous NO treatment was reported to break dormancy and promote germination in seeds of three warmseasons C 4 grasses (Sarath et al, 2006).…”

Host genotype-specific rhizosphere fungus enhances drought resistance in wheat

“…We conducted a three-level factorial experiment (drought treatment × plant variety × rhizosphere microbiota type) to investigate whether rhizosphere microbes (control vs. polyethylene glycol [PEG 6000]-treated) could influence morphological traits of the YH and CS varieties from the YL and SQ sites in response to drought stress. The drought treatments comprised treatment with (i) 0% PEG 6000 and (ii) 10% PEG 6000 [ 40 , 67 ]. The plant varieties comprised drought-resistant (YH) and drought-sensitive (CS) wheat plants, and rhizosphere microbiota were generated from soils from the YL and SQ planting areas.…”