PJB-2019-549
Plant hydraulic conductivity determines photosynthesis in rice under PEG-induced drought stress
Guanglong Zhu, Lifeng Gu, Yu Shi, Huize Chen, Yuqian Liu, Faguang Lu, Zhen Ren, Yue Wang, Haitong Lu, Adnan Tabassum and Guisheng Zhou
Abstract
Photosynthesis (A) plays a key role in maintaining plant carbon balance, but it is sensitive to drought. Both A and plant hydraulic conductivity (Kplant) decrease under water deficit. It is not clearly whether the declined Kplant is more related to root or leaf, whether the decreased A is related to Kplant and/or leaf hydraulic conductivity (Kleaf) and diffusive alone or both diffusive and metabolic impairments decreased A. Two drought-tolerant (DW) contrasting rice genotypes were used to explore the relationship of A, Kplant and Kleaf under PEG induced drought stress (PEG-DS). The results showed that photosynthesis related parameters of A, stomatal conductance (gs), transpiration rate (Tr), maximum Rubisco carboxylation rate (Vcmax), maximum electron transport rate (Jmax), carboxylation efficiency (CE), Kleaf, Kplant and xylem sap flow rate (XSFR) were all decreased significantly under PEG-DS. These decreases were more severe in DW-sensitive genotype IR64 than DW-tolerant genotype Hanyou-3. However, both intercellular CO2 concentration (Ci) and CO2 concentration inside chloroplasts (Cc) were prominently increased in IR64 rather than in Hanyou-3 under PEG-DS. In addition, both gs and gm (mesophyll conductance to CO2) were strongly positively correlated with A (R2=0.98 & 0.71). Photosynthesis of both genotypes were increased with increasing Ci under each treatment. Furthermore, A and gs were significantly correlated with Kplant (R2=0.94 & 0.96) but not with Kleaf, and Kplant was not related to Kleaf. Kplant rather than Kleaf determines photosynthesis in rice under drought conditions, which was mainly attributed to Kplant decreases the stomatal conductance and ultimately lead to decrease in photosynthesis
To Cite this article:
Zhu, G., L. Gu, Y. Shi, H. Chen, Y. Liu, F. Lu, Z. Ren, Y. Wang, H. Lu, A. Tabassum and G. Zhou. 2021. Plant hydraulic conductivity determines photosynthesis in rice under PEG-induced drought stress. Pak. J. Bot., 53(2): DOI: http://dx.doi.org/10.30848/PJB2021-2(14)
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