Abstract
Stylosanthes guianensis (Aublet) Sw. is a tropical forage legume with soil acidity tolerance and excellent adaptation to infertile soils, but sensitive to chilling. To understand the molecular responses of S. guianensis to chilling, differentially expressed genes between a chilling tolerant mutant 7–1 and the wild type were identified using suppression subtractive hybridization, and eight of them were confirmed and the regulation pattern were analyzed using quantitative reverse transcription PCR (qRT-PCR). Chloroplast protein 12 (CP12) functions to regulate the Calvin cycle by forming a ternary complex with glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK). SgCP12 transcript was induced by chilling in both plants, and higher levels were observed in 7–1 than in the wild type, implying a potential role of SgCP12 in chilling tolerance. To confirm this, transgenic S. guianensis plants over-expressing or down-regulating SgCP12 were generated, respectively. Higher Fv/Fm and survival rate and lower ion leakage were observed in transgenic plants overexpressing SgCP12 as compared with the wild type after chilling treatment, while lower Fv/Fm and survival rate and higher ion leakage were found in SgCP12 antisense plants. SgCP12 overexpression plants showed promoted growth with increased plant height and fresh weight, while the antisense plants exhibited reduced growth with decreased plant height and fresh weight as compared with the wild type. The results indicated that regulation of SgCP12 expression alters plant growth and chilling tolerance in S. guianensis. In addition, higher levels of net photosynthetic rate (Pn), GAPDH and PRK activities were observed in SgCP12 overexpression transgenic plants, while lower levels in antisense plants than in the wild type under both control and chilling conditions, indicating that altered activities of GAPDH and PRK were associated with the changed Pn in transgenic S. guianensis. Our results suggest that SgCP12 regulates GAPDH and PRK activities, Pn, and chilling tolerance in S. guianensis.
Highlights
Temperature is one of the major abiotic stress influencing plant growth and development
Five genes are involved in photosynthesis, including psaE, Chloroplast protein 12 (CP12), CP26, rbcS and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and the other one CAT is stress related
Rubisco is consisted of four large subunits and four small subunits and catalyzes fixation of CO2 by ribulose-1,5-bisphosphate (RuBP). rbcS transcript was induced continuously in both 7–1 and the wild type, and higher level was observed in 7–1 after 48 h of chilling (Figure 1D)
Summary
Temperature is one of the major abiotic stress influencing plant growth and development. Thousands of genes are reprogrammed in expression and multiple metabolic pathways are modified in both temperate and tropical plants in response to low temperature (Fowler and Thomashow, 2002; Krasensky and Jonak, 2012; Zhang et al, 2012). The accumulated ROS may induce gene expression as a second messenger in signal transduction, or result in oxidative damages to photosynthetic apparatus and even lead to plant death if ROS could not be effectively scavenged (Foyer and Noctor, 2009). Stylosanthes guianensis (Aublet) Sw. is a tropical forage legume with soil acidity tolerance and excellent adaptation to infertile soils (Jiang et al, 2005). It is commonly used as a cover crop in southern China as well. The largest group was classified as chloroplast and photosynthesis related genes including CP12 (unpublished data), implying an association of the group of genes with chilling tolerance in S. guianensis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
