Identification of genes associated with productivity traits and salinity tolerance from activation tagged lines of rice

World-wide crop productivity is hugely impacted by diverse eco-environmental conditions. In the present investigation, activation tagged (AT) lines of rice endowed with improved agronomic attributes have been analyzed for tolerance to salinity stress besides identification of genes associated with these attributes. Under salinity stress conditions, AT lines exhibited increased seed germination rates, improved plant growth and development at vegetative and reproductive stages as compared to wild-type (WT) plants. Furthermore, AT lines disclosed enhanced plant water content, photosynthetic efficiency, stomatal conductance, water use efficiency and maximum quantum yield when compared to WT plants, leading to improved yields and delayed onset of stress symptoms. Moreover, AT lines revealed effective antioxidant systems causing decreased accumulation of reactive oxygen species and delayed salinity stress symptoms compared to WT plants. Reduced accumulation of malondialdehyde with concomitant increases in proline and soluble sugars of AT lines further endorsing their improved stress tolerance levels. TAIL and qRT-PCR analyses of AT lines revealed Ds element integrations at different loci and respective overexpression of identified candidate genes involved in various aspects of plant development and stress tolerance. Accordingly, the AT lines plausibly serve as a rare genetic resource for fortifying stress tolerance and productivity traits of elite rice cultivars. Highlight Activation tagged lines of rice endowed with improved agronomic attributes have been analyzed for tolerance to salinity stress besides identification and expression analysis of genes associated with these attributes.

TCACATCAATCCACTTGCTT-3′ to amplify RFP and 4X enhancer regions, respectively. vector was used as the positive control. rate (%) was computed using the formula: To test the salinity tolerance ability of AT lines during the initial growth stage, 9 GR activity was calculated using 6.22 mM -1 cm -1 extinction coefficient and expressed as 2 5 7 nmol min -1 g -1 FW. The SOD activity of AT lines and WT plants was estimated by 2 5 8 monitoring the inhibition of blue formazane production by means of photochemical reduction 2 5 9 of nitro blue tetrazolium (NBT) according to Beauchamp and Fridovich (1971). One unit of 2 6 0 SOD activity was defined as the amount of enzyme required to inhibit 50% of the NBT photo 2 6 1 reduction and is expressed as U mg protein -1 min -1 . Catalase activity of AT lines and WT 2 6 2 plants was determined as described by Aebi (1984). The enzyme activity in leaf tissues was 2 6 3 calculated using the molar extinction coefficient of H 2 O 2 (36 mM -1 cm -1 ) and expressed as 2 6 4 moles of H 2 O 2 consumed min -1 mg -1 protein. Thermal cycling conditions adopted for TAIL-PCR are represented in Supplementary Table   2 7 8 S1. Tertiary PCR products corresponding to 2° PCR products were excised from the gel, 2 7 9 purified and sequenced using the ABI PRISM 3730 DNA Analyzer System (ABI, USA).

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Flanking sequences were deployed to BLAST against rice genome in the Rice Annotation Data on leaf gas exchange parameters, osmolytes, molecular antioxidants, chlorophyll 2 9 6 content, oxidative stress parameters, biomass and yield of AT lines and WT plants subjected to well-water and salinity stress were represented as mean ± SE. In each stress experiment, 10 test and standard error were carried out using preloaded software in Excel. grain number/plant (Kota et al., 2020). In this report, three AT lines, viz.., A10-Ds-RFP6 attempt has been made to evaluate their salinity tolerance levels at different developmental  corresponding to the RFP expression unit with RFP forward and nos reverse primers AT rice lines disclosed varied responses against salinity stress at different stages Ds-RFP3 revealed higher seed germination rates of 78.59 ± 1.59%, 82.61 ± 2.58% and 79.42 ± 2.61% than that of WT (09.94 ± 2.46%) (Fig. 1A). Two week-old seedlings of AT lines 3 3 1 subjected to 250 mM salinity stress for ten days exhibited higher survival rates and biomass In addition to morphological improvements, significant variations were also observed 3 4 4 in leaf RWC, photosynthetic leaf gas exchange characteristics and maximum quantum yield FW under well-water conditions. However, imposition of salt stress caused significant

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In order to assess the effects of oxidative stress, MDA content was measured in WT WT plants was 28.58 nmol g -1 FW which was higher than the MDA levels recorded in the AT  However, no significant differences were found between AT lines and WT plants in ASA and 4 1 6 TPC contents under well-water conditions. Whereas, under salinity stress, AT lines exhibited 4 1 7 higher ASA (8.58 to 9.04 mg g -1 FW) and TPC (31.52 to 33.82 mg g -1 FW) values when 4 1 8 compared to WT (4.83 and 20.89 mg g -1 FW) plants (Fig. 4E, Fig. 4F). mutants as compared to the WT plants (Fig. 5). The catalase activity of the WT plants and AT lines varied from 0.933 to 1.086 U mg protein -1 min -1 under well-water conditions. (2.459 to 2.849 U mg protein -1 min -1 ) as compared to the low activity of WT (1.587 U mg 4 2 7 protein -1 min -1 ) plants (Fig. 5A). Likewise, significant increase in the activities of SOD lines compared to 2.072 U mg -1 protein and 18.56 nmol min -1 g -1 FW and 0.158 nmol min -1 g -4 3 4 1 FW in WT plants (Fig. 5D, Fig. 5E, Fig. 5F). Ds-RFP3 AT lines, using the arbitrary primer AD-2 and 3′ Ds specific primers downstream (up to 10kb) at the integration site of Ds element in the rice genome (Table 1). repeat and disease resistance RPP13-like protein 1 encoding genes when compared to that of 4 5 4 WT plant (Fig. 6B). Likewise, expression profiles of glutamate decarboxylase, inactive  In the present investigation, AT lines disclosed higher RWC levels under salinity  and its association with increments in biomass yields both under well-water and salinity stress 5 1 7 conditions mainly due to their superior photosynthetic efficiency. Furthermore, improved water and salinity conditions, suggesting that their improved adaptability contributed to 5 2 2 increased productivity under elevated atmospheric CO 2 even when grown under salinity  ( Sekhar et al., 2014Sekhar et al., , 2015. Additionally, salinity stress was found to reduce PS-II efficiency perform on par with the AT mutants under stress conditions.

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In the present study, imposition of salinity stress caused significant increases in the AT lines exhibited increased accumulation of proline under salinity which was found 5 5 0 associated with higher levels of stress tolerance compared to their WT counterparts. Salinity environmental conditions (Gill & Tuteja, 2010;AbdElgawad et al., 2016). In this study, proteasome system (UPS) and endoplasmic reticulum-associated protein degradation (ERAD) OsCDC48 promoted increased tiller number and grain yield. Based on present results, we reported the involvement of acetyltransferases of GNAT family in conferring tolerance to 5 8 5 drought, salinity and cold by controlling the expressions of diverse stress responsive genes.

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Elevated relative expression levels of mov34/MPN/PAD-1 family gene, AT plants indicate their probable involvement in various aspects of plant growth, OsFBDUF17 -F-box and DUF domain containing genes in the AT line could be attributed to 5 9 7 its enhanced tolerance levels to salinity stress conditions. In wheat, it was found that 5 9 8 increased glutamate decarboxylase expression and accumulation of GABA were associated 5 9 9 with higher levels of tolerance to salinity and osmotic stress (AL-Quraan et al., 2013). To sum up, an overview of present results dealing with selected rice AT lines genotypes bestowed with genetic resilience to cope with the challenges of rapid climate-  were later allowed to recover under normal conditions. Data on survival rate (C), total RFP3 are three different AT lines, WT: Wild type. reproductive stages.