Comparative Physiological and Molecular Analyses of Two Contrasting Flue-Cured Tobacco Genotypes under Progressive Drought Stress

Abstract

Drought is a major environmental factor that limits crop growth and productivity. Flue-cured tobacco (Nicotiana tabacum) is one of the most important commercial crops worldwide and its productivity is vulnerable to drought. However, comparative analyses of physiological, biochemical and gene expression changes in flue-cured tobacco varieties differing in drought tolerance under long-term drought stress are scarce. In this study, drought stress responses of two flue-cured tobacco varieties, LJ851 and JX6007, were comparatively studied at the physiological and transcriptional levels. After exposing to progressive drought stress, the drought-tolerant LJ851 showed less growth inhibition and chlorophyll reduction than the drought-sensitive JX6007. Moreover, higher antioxidant enzyme activities and lower levels of H2O2, Malondialdehyde (MDA), and electrolyte leakage after drought stress were found in LJ851 when compared with JX6007. Further analysis showed that LJ851 plants had much less reductions than the JX6007 in the net photosynthesis rate and stomatal conductance during drought stress; indicating that LJ851 had better photosynthetic performance than JX6007 during drought. In addition, transcriptional expression analysis revealed that LJ851 exhibited significantly increased transcripts of several categories of drought-responsive genes in leaves and roots under drought conditions. Together, these results indicated that LJ851 was more drought-tolerant than JX6007 as evidenced by better photosynthetic performance, more powerful antioxidant system, and higher expression of stress defense genes during drought stress. This study will be valuable for the development of novel flue-cured tobacco varieties with improved drought tolerance by exploitation of natural genetic variations in the future.

Transcriptome Profiling, Biochemical and Physiological Analyses Provide New Insights towards Drought Tolerance in Nicotiana tabacum L.

“…In agreement with our results, [46,47] evidenced that drought stress cause reduction in plant fresh and dry weight in tobacco and tomato plants. Our results are in line with many reports that have stated that drought-tolerant varieties could maintain higher growth than drought-sensitive ones [23].…”

“…Changes of leaf water potential in response to the drought stress were evaluated in various genotypes as shown in Figure 2D, the three varieties showed a clear decrease during 72 h of the drought stress. These findings are supported by [23], as drought stress decreased LWP.…”

“…However, presently, drought stress has become a limiting factor for its growth and development. In recent years, different approaches, such as physiological, transcriptomics and metabolomics, have been used in various studies, which highlighted the importance of disease resistance, abiotic stresses tolerance and drought tolerance in both transgenic and non-transgenic tobacco plants [20][21][22][23][24]. Similarly, other studies also put light on the role of various pathways such as plant hormones signal transduction pathway, proline metabolism pathway, starch and sucrose metabolism pathway etc.…”

Comparative Physiological, Biochemical and Transcript Response to Drought in Sorghum Genotypes

“…1D-F). Previous reports have showed that drought stress induced higher H 2 O 2 accumulation, lipid peroxidation and EL in drought-sensitive maize, barley and tobacco genotypes than that in drought-tolerant genotypes [17,30,31]. Similarly, the results from this study indicate that the sorghum genotypes PI 585453, PI 585456 and PI 585452 suffered greater cell membrane damage than other genotypes and demonstrate a possible correlation to drought sensitivity.…”

Overexpression of the Maize Sulfite Oxidase Increases Sulfate and GSH Levels and Enhances Drought Tolerance in Transgenic Tobacco

“…At the moment, soil moisture content was progressively reduced to around 20%. The soil moisture was measured daily using a Soil Moisture Meter (ECA-SW1, TuoPu Bio Co., China) as described previously ( Su et al, 2017 ). And then, these stressed plants were re-watered.…”