Genetic analysis of cold-tolerance of photosynthesis in maize

Abstract

The genetic basis of cold-tolerance was investigated by analyzing the quantitative trait loci (QTL) of an F2:3 population derived from a cross between two lines bred for contrasting cold-tolerance using chlorophyll fluorescence as a selection tool. Chlorophyll fluorescence parameters, CO2 exchange rate, leaf greenness, shoot dry matter and shoot nitrogen content were determined in plants grown under controlled conditions at 25/22 degrees C or 15/13 degrees C (day/night). The analysis revealed the presence of 18 and 19 QTLs (LOD > 3.5) significantly involved in the variation of nine target traits in plants grown at 25/22 degrees C and 15/13 degrees C, respectively. Only four QTLs were clearly identified in both temperatures regimes for the same traits, demonstrating that the genetic control of the performance of the photosynthetic apparatus differed, depending on the temperature regime. A major QTL for the cold-tolerance of photosynthesis was identified on chromosome 6. This QTL alone explained 37.4 of the phenotypic variance in the chronic photoinhibition at low temperature and was significantly involved in the expression of six other traits, including the rate of carbon fixation and shoot dry matter accumulation, indicating that the tolerance to photoinhibition is a key factor in the tolerance of maize to low growth temperature. An additional QTL on chromosomes 2 corresponded to a QTL identified previously in another population, suggesting some common genetic basis of the cold-tolerance of photosynthesis in different maize germplasms.

QTL studies reveal little relevance of chilling-related seedling traits for yield in maize

“…The position of this QTL was co-localized with a QTL for photosynthesisrelated traits detected in the late-sown plants of the mapping population at the seedling stage ). This QTL was also found in seedlings grown at 25°C in growth chambers (Fracheboud et al 2004). At the seedling stage too, the allele for good photosynthetic performance under warm conditions was inherited from the chilling-sensitive parent.…”

“…A dent maize (Zea mays L.) mapping population in the F 2:3 generation, consisting of 226 families derived from the cross ETH-DH7 and ETH-DL3, was used in the present QTL experiment (for details, see Fracheboud et al 2004). The source material was derived from the actual breeding population of the Swiss DSP (Delley Samen und PXanzen AG, Delley, Switzerland).…”

“…These maps and their associated technology have been used successfully for a number of quantitative trait loci (QTL) analyses. A number of papers deal with the chilling tolerance of maize seedlings (Fracheboud et al 2002(Fracheboud et al , 2004Hund et al 2005;Jompuk et al 2005;Pimentel et al 2005;Presterl et al 2007). Once the signiWcance of these QTLs for chilling tolerance has been veriWed, it should become possible to pyramiding the favorable alleles into elite germplasm through marker-assisted selection (MAS).…”

“…Since these lines were selected solely on the basis of chilling tolerance of photosynthesis they are a unique material to identify genetic loci associated with chilling tolerance of photosynthesis by QTL analysis. In previous studies, we have examined this material in respect to chilling tolerance at the seedling stage under controlled conditions (Fracheboud et al 2004) and in the Weld ). These studies revealed major QTLs for chilling tolerance of photosynthesis which were stable across cold environments.…”

QTL for chlorophyll fluorescence of barley plants grown at low oxygen concentration in hydroponics to simulate waterlogging

“…Tolerant plants seem to be able to maintain or conserve energy, but also escape mechanisms are common (Hattori et al 2009;van Veen et al 2013). Chlorophyll fluorescence is widely accepted as an indicator of the activity of PSII, which is involved in electron transport in plant photosynthesis and is particularly sensitive to stresses (Fracheboud et al 2004;Guo et al 2008;Gu et al 2012). Various fluorescence parameters have been found to be closely correlated with carbon assimilation under different stresses in rice (Guo et al 2008), lucerne (Smethurst and Shabala 2003), soybean (Yin et al 2010), wheat ) and maize (Fracheboud et al 2004), as well as grain yield in barley (Bertholdsson 2013) and, under optimal conditions intriticale (Hura et al 2009).…”