Response of regulation of resistance genes, reactive oxygen species, and antioxidant enzymes to salicylic acid treatments in drought tolerant rice

M. Ubaidillah¹², F. Oktaviani², M.A. Mufadilah¹, S. Avivi¹, N. Thamrin¹, A. Indrawati¹, A.N. Puspito², K.M. Kim³ and S. Hartatik¹*

¹1University of Jember, Faculty of Agriculture, Study Program of Agronomy,
Jember Regency, East Java 6812, Indonesia
²University of Jember, Faculty of Agriculture, Study Program of Magister Biotechnology, Jember Regency, East Java 6812, Indonesia
³Division of Plant Biosciences, School of Applied BioSciences, College of Agriculture and Life Science, Kyungpook National University, Daegu, South Korea
*Correspondence: srihartatik.faperta@unej.ac.id

Abstract:

Drought is one of the most important issues in crop production which may disrupt physiological processes and biochemical metabolism in rice plants, including the emergence of plant resistance gene expression such as OsAB13 and OsLEA, the formation of ROS (Reactive Oxygen Species), namely hydrogen peroxide (H₂O₂), as well as the emergence of gene expression related to antioxidant enzyme activity such as OsAPX1, OsCATA, Mn-SOD, Cu/Zn-SOD, and APX Cytosolic. Besides the emergence of plant resistance gene expression, ROS, and changes in gene expression related to antioxidant enzymes, rice plants also produce salicylic acid which acts as an endogenous signal to activate plant resistance gene responses and can encourage plant resistance responses such as antioxidant enzyme activity. The treatments in this study included: control, 15% PEG 6000, 15% PEG 6000 + SA 1 mM, and SA 1 mM. The results showed that the interaction between treatments and rice plant varieties significantly affected plant height, root length, total chlorophyll, and H₂O₂ content. The expression of the OsAPX1, OsCATA, Mn-SOD, and Cu/Zn-SOD genes increased in the 15% PEG 6000 treatment compared to the control. In the 15% PEG 6000 + SA 1 mM treatment, there was an increase in gene expression of APX Cytosolic, Cu/Zn-SOD, and OsCATA compared to the 15% PEG 6000 treatment. The OsLEA is expressed in Siakraya and Sertani 1 as an indicator of resistance to drought stress, and the OsAB13 is expressed in Indragiri, Sertani 1, and Siakraya varieties as an indicator of resistance to drought stress.

Key words:

and rice plants, antioxidant enzymes, drought stress, reactive oxygen species, resistance genes

Molecular discovery of new allele associated with loose smut resistance gene Ut-X in spring wheat

I.S. Draz¹*, A.K. Darwish², M.S. Abou-Elseoud², A.A. Elassal² and D.A. Komeil²

¹Agricultural Research Centre, Institute of Plant Pathology Research, Department of Wheat Disease Research, Eg12619 Giza, Egypt
²University of Alexandria, Faculty of Agriculture, Department of Plant Pathology, El-Shatby, EG21545 Alexandria, Egypt
*Correspondence: dr.ibrahim_draz@yahoo.com

Abstract:

Genes of resistance to loose smut incited by the fungus Ustilago tritici (Pers.) Rostr. are still unknown in the Egyptian spring wheat. Loose smut incidence (LSI) was assessed in ten wheat cultivars through a two-year field trial during 2018–2020. All of the tested cultivars exhibited various percentages of susceptibility (> 10–70% LSI) to the disease except cultivar Misr-3 which exhibited resistance. The most susceptible cultivars were Sakha-93 (60%), Giza-168 (42.1%), and Misr-2 (34.28%). However, the resistant cultivar Misr-3 recorded the least LSI amounting to 5%. The wheat cultivars were screened by the SCAR marker (Xcrc4.2) to identify the presence/absence of loose smut resistance gene Ut-X. Molecular data revealed that the SCAR marker (Xcrc4.2) generated two alleles in cultivars with PCR fragments size of 800-bp and ≃ 200-bp. The favorable allele 800-bp was generated only in the resistant Egyptian cultivar ‘Misr-3’ and the resistant check cultivar ‘Biggar’, indicating the presence of the gene. Meanwhile, another allele ≃ 200-bp was generated in seven Egyptian cultivars, Giza-168, Giza-171, Misr2, Sakha-93, Gemmeiza-12, N-95, and Shandweel-1, indicating the absence of the resistant gene. This is the first study to report resistance genes to loose smut in Egyptian spring wheat, by detecting Ut-X in cultivar Misr-3. In addition, the study documented the first report of another allele ≃ 200-bp associated with SCAR marker (Xcrc4.2). Findings also revealed that the race-specific resistance gene Ut-X confers effective resistance to local U. tritici races, including race T10 which could be widely incorporated in breeding programs to control the disease.

Key words: