title: Salt-responsive mechanisms in chromosome segment substitution lines of rice (Oryza sativa L. cv. KDML105).
abstract: Two chromosome segment substitution lines of Khao Dawk Mali 105 (KDML105) rice that carry quantitative trait loci for drought tolerance located on chromosome 8 (DT-QTL8) designated CSSL8-94 and CSSL8-116 were investigated for co-expression network and physiological responses to salinity compared to their parents (KDML105; drought and salt sensitive recurrent parent, and DH103; drought tolerant QTL donor). These CSSL lines show different salt-response traits under salt stress (CSSL8-94 shows higher tolerance than CSSL8-116) and possess different segments of DT-QTL8. To identify specific biological process(es) associated with salt-stress response, co-expression network analysis was constructed from each DT-QTL segment. To evaluate differential physiological mechanisms responding to salt stress, all rice lines/cultivar were grown for 21 d in soils submerged in nutrient solutions, then subjected to 150 mM NaCl for 7 d. Physiological parameters related to co-expression network analysis (photosynthetic parameters) and salt responsive parameters (Na(+)/K(+) ratio, proline content, malondialdehyde and ascorbate peroxidase activity; EC1.11.1.1) were investigated along with the expression analysis of related genes. Physiological responses under salt stress particularly photosynthesis-related parameters of CSSL8-94 were similar to DH103, whereas those of CSSL8-116 were similar to KDML105. Moreover, expression levels of photosynthesis-related genes selected from the co-expression networks (Os08g41460, Os08g44680, Os06g01850, Os03g07300 and Os02g42570) were slightly decreased or stable in CSSL8-94 and DH103 but were dramatically down-regulated in CSSL8-116 and KDML105. These differential responses may contribute to the photosynthesis systems of CSSL8-94 being less damaged under salt stress in comparison to those of CSSL8-116. It can be concluded that the presence of the specific DT-QTL8 segment in CSSL8-94 not only confers drought tolerant traits but also enhances its salt tolerant ability.
authors.affiliation: Salt-tolerant Rice Research Group, Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Noppawan
authors.initials: N
authors.lastname: Nounjan
authors.affiliation: Rice Gene Discovery Laboratory, BIOTEC, NSTDA, Kasetsart University, Kamphaeng Saen Campus, Nakorn Pathom 73140, Thailand.
authors.forename: Jonaliza L
authors.initials: JL
authors.lastname: Siangliw
authors.affiliation: Rice Gene Discovery Laboratory, BIOTEC, NSTDA, Kasetsart University, Kamphaeng Saen Campus, Nakorn Pathom 73140, Thailand.
authors.forename: Theerayut
authors.initials: T
authors.lastname: Toojinda
authors.affiliation: Center of Excellence in Environment and Plant Physiology, Department of Botany, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Supachitra
authors.initials: S
authors.lastname: Chadchawan
authors.affiliation: Salt-tolerant Rice Research Group, Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand. Electronic address: piythe@kku.ac.th.
authors.forename: Piyada
authors.initials: P
authors.lastname: Theerakulpisut
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics*; D055864:Droughts; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010788:Photosynthesis; D011188:Potassium / Q000378:metabolism; D040641:Quantitative Trait Loci / Q000235:genetics*; D054712:Salinity; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological
chemical_list: D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium
keywords: Co-expression network; Drought tolerance QTL; Photosynthesis; Rice; Salt stress