[show abstract][hide abstract] ABSTRACT: Plant or soil water status are required in many scientific fields to understand plant responses to drought. Because the transcriptomic response to abiotic conditions, such as water deficit, reflects plant water status, genomic tools could be used to develop a new type of molecular biomarker. Using the sunflower (Helianthus annuus L.) as a model species to study the transcriptomic response to water deficit both in greenhouse and field conditions, we specifically identified three genes that showed an expression pattern highly correlated to plant water status as estimated by the pre-dawn leaf water potential, fraction of transpirable soil water, soil water content or fraction of total soil water in controlled conditions. We developed a generalized linear model to estimate these classical water status indicators from the expression levels of the three selected genes under controlled conditions. This estimation was independent of the four tested genotypes and the stage (pre- or post-flowering) of the plant. We further validated this gene expression biomarker under field conditions for four genotypes in three different trials, over a large range of water status, and we were able to correct their expression values for a large diurnal sampling period.
Plant Cell and Environment 05/2013; · 5.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: Verticillium wilt caused by Verticillium albo-atrum and Verticillium dahliae is responsible for yield losses in many economically important crops. The capacity of pathogenic fungi to adapt to new host plants is a well-known threat to the durability of existing resistant crop varieties. In the present work 25 Medicago truncatula genotypes from a core collection and six Verticillium albo-atrum and Verticillium dahliae strains were used to study the potential of non-host Verticillium strains isolated from different plant species to infect this legume plant. The experiment was designed as factorial with randomised complete blocks, and with three repetitions. The wilt symptoms caused by Verticillium albo-atrum and Verticillium dahliae were determined every 3 days during 30 days after inoculation of ten-day-old plantlets and scored on a disease index scale from 0 to 4. Disease severity was quantified by maximum symptom scores and area under the disease progress curves . Highly significant differences were observed among plant genotypes, fungal strains and their interactions. The correlation between maximum symptom score and area under the disease progress curve was 0.86. The most severe symptoms were caused by the alfalfa strain Verticillium albo-atrum-V31-2 and the least severe by Verticillium dahliae JR2, as shown by by mean values obtained on the 25 genotypes. M. truncatula genotype TN8.3 was the most susceptible genotype when the mean values obtained with the 6 fungal strains was considered, whereas F11013-3, followed by F83005.9 and DZA45.6 were highly resistant to all strains studied. The results can be used to choose parents for studying the genetics of resistance in Medicago truncatula to Verticillium strains with different levels of aggressiveness.
European Journal of Plant Pathology 01/2013; · 1.61 Impact Factor
[show abstract][hide abstract] ABSTRACT: The objective of the present research was to map QTLs associated with agronomic traits such as days from sowing to flowering,
plant height, yield and leaf-related traits in a population of recombinant inbred lines (RILs) of sunflower (Helianthus annuus). Two field experiments were conducted with well-irrigated and partially irrigated conditions in randomized complete block
design with three replications. A map with 304 AFLP and 191 SSR markers with a mean density of 1 marker per 3.7cM was used
to identify QTLs related to the studied traits. The difference among RILs was significant for all studied traits in both conditions.
Three to seven QTLs were found for each studied trait in both conditions. The percentage of phenotypic variance (R
2) explained by QTLs ranged from 4 to 49%. Three to six QTLs were found for each yield-related trait in both conditions. The
most important QTL for grain yield per plant on linkage group 13 (GYP-P-13-1) under partial-irrigated condition controls 49% of phenotypic variance (R
2). The most important QTL for 1,000-grain weight (TGW-P-11-1) was identified on linkage group 11. Favorable alleles for this QTL come from RHA266. The major QTL for days from sowing
to flowering (DSF-P-14-1) were observed on linkage group 14 and explained 38% of the phenotypic variance. The positive alleles for this QTL come from
RHA266. The major QTL for HD (HD-P-13-1) was also identified on linkage group 13 and explained 37% of the phenotypic variance. Both parents (PAC2 and RHA266) contributed
to QTLs controlling leaf-related traits in both conditions. Common QTL for leaf area at flowering (LAF-P-12-1, LAF-W-12-1) was detected in linkage group 12. The results emphasise the importance of the role of linkage groups 2, 10 and 13 for studied
traits. Genomic regions on the linkage groups 9 and 12 are specific for QTLs of leaf-related traits in sunflower.
KeywordsSunflower–Recombinant inbred lines–QTL–Partial-irrigation–Agronomic traits
[show abstract][hide abstract] ABSTRACT: Identifying the connections between molecular and physiological processes underlying the diversity of drought stress responses in plants is key for basic and applied science. Drought stress response involves a large number of molecular pathways and subsequent physiological processes. Therefore, it constitutes an archetypical systems biology model. We first inferred a gene-phenotype network exploiting differences in drought responses of eight sunflower (Helianthus annuus) genotypes to two drought stress scenarios. Large transcriptomic data were obtained with the sunflower Affymetrix microarray, comprising 32423 probesets, and were associated to nine morpho-physiological traits (integrated transpired water, leaf transpiration rate, osmotic potential, relative water content, leaf mass per area, carbon isotope discrimination, plant height, number of leaves and collar diameter) using sPLS regression. Overall, we could associate the expression patterns of 1263 probesets to six phenotypic traits and identify if correlations were due to treatment, genotype and/or their interaction. We also identified genes whose expression is affected at moderate and/or intense drought stress together with genes whose expression variation could explain phenotypic and drought tolerance variability among our genetic material. We then used the network model to study phenotypic changes in less tractable agronomical conditions, i.e. sunflower hybrids subjected to different watering regimes in field trials. Mapping this new dataset in the gene-phenotype network allowed us to identify genes whose expression was robustly affected by water deprivation in both controlled and field conditions. The enrichment in genes correlated to relative water content and osmotic potential provides evidence of the importance of these traits in agronomical conditions.
PLoS ONE 01/2012; 7(10):e45249. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of the present study was to map quantitative trait locus (QTLs) associated with percentage of seed protein, oil and fatty acids content under different conditions in a population of recombinant inbred lines (RILs) of sunflower. Three independent field experiments were conducted with well-, partial-irrigated and late-sowing conditions in randomized complete block design with three replications. High significant variation among genotypes is observed for the studied traits in all conditions. Several specific and non-specific QTLs for the aforementioned traits were detected. Under late-sowing condition, a specific QTL of palmitic acid content on linkage group 6 (PAC-LS.6) is located between ORS1233 and SSL66_1 markers. Common chromosomic regions are observed for percentage of seed oil and stearic acid content on linkage group 10 (PSO-PI.10 and SAC-WI.10) and 15 (PSO-PI.15 and SAC-LS.15). Overlapping occurs for QTLs of oleic and linoleic acids content on linkage groups 10, 11 and 16. Seven QTLs associated with palmitic, stearic, oleic and linoleic acids content are identified on linkage group 14. These common QTLs are linked to HPPD homologue, HuCL04260C001. Coincidence of the position for some detected QTLs and candidate genes involved in enzymatic and non-enzymatic antioxidants would be useful for the function of the respective genes in fatty acid stability.
AFRICAN JOURNAL OF BIOTECHNOLOGY 11/2010; 9:6768-6782. · 0.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of this study was to identify genomic regions controlling seed protein content, kernel and hull weights, and seed density in water-stress conditions in sunflower (Helianthus annuus L.). The experiments consisted of a split-plot design (water treatment and recombinant inbred lines) with three blocks in two environments (greenhouse and field). High significant variation was observed between genotypes for all traits as well as for water treatment x genotype interaction. Several specific and nonspecific QTLs were detected for all traits under well-watered and water-stress conditions. Two SSR markers, ORS671_2 and HA2714, linked to protein content were identified that have no interaction with water treatments in greenhouse conditions. We also detected the E35M60_4 marker associated with kernel weight that had no interaction with water treatments. A specific QTL for protein content was detected with important phenotypic variance (17%) under water-stress conditions. Overlapping QTLs for protein content and seed density were identified in linkage group 15. This region probably has a peliotropic effect on protein content and seed density. QTLs for protein content colocated with grain weight traits were also identified.
[show abstract][hide abstract] ABSTRACT: A set of sunflower recombinant inbred lines (RILs) was used to study agronomical traits under greenhouse and field conditions each with two water treatments and three replications. The difference among RILs was significant for all the traits studied in all conditions; and water treatment × RILs interaction was also observed for most of the traits in both field and greenhouse conditions. Because of the low rate of drought stress, this part of field data are not informative. Several quantitative trait loci (QTLs) were identified for yield-related traits with the percentage of phenotypic variance explained by QTLs (R2) ranging from 4% to 40%. Several QTLs for grain yield per plant (GYP) under four water treatments were identified on different linkage groups, among which two were specific to a single treatment (GYPN.4.1, GYPI.7.1). Three QTLs for GYP were overlapped with several QTLs for drought-adaptative traits detected in our previous study (Poormohammad Kiani et al. 2007b). The whole results do highlight interesting genomic regions for marker-based breeding programmes for drought tolerance in sunflower.
[show abstract][hide abstract] ABSTRACT: This study was conducted to identify physiological traits associated with cold tolerance in sunflower and to identify the genomic regions involved in their variation. A population of 98 recombinant inbred lines (RILs) and their two parents were sown in the field as usual sowing date (control) and one or two months earlier (long-term low temperature treatments). A trait commonly used to underlying cold tolerance related to the degree of membrane damage, as well as traits associated with growth capacity (chlorophyll content, potential photochemical efficiency of photosystem II and plant dry weight) and finally those reflecting acclimation mechanism to stress conditions (osmotic potential at full turgor, and specific leaf area) have been investigated at early development stages. Significant differences were observed among the three sowing dates for all traits. Chlorophyll content and specific leaf area are genetically associated with cold tolerance. Genetic gains were observed for chlorophyll content and osmotic potential traits in some of early sowing dates, which suggest that they could be used for cold tolerance in breeding programs. QTL analyses show that several putative genomic regions are involved in the variation of the physiological traits studied under low temperature. Major QTLs for cold tolerance associated with SSR markers such as ORS331_2 for the cell membrane stability should be checked in several environments to see if they can be used in marker-assisted selection programs.
[show abstract][hide abstract] ABSTRACT: The objectives of the present research were to determine the effects of water stress on seed-quality traits and to map QTLs controlling the studied traits under two different water treatments in a population of sunflower recombinant inbred lines (RILs). Two experiments were conducted in greenhouse and field conditions, each with well-watered and water-stressed treatments. The experiments consisted of a split-plot design (water treatment and RIL) with three blocks. Analyses of variance showed significant variation among genotypes, and a water treatment x genotype interaction was also observed for most of the traits. Two to 15 QTLs were found, depending on trait and growth conditions, and the percentage of phenotypic variance explained by the QTLs ranged from 5% to 31%. Several QTLs for oil content overlapped with QTLs for palmitic and stearic acid contents in all four conditions. An overlapping region on linkage group 3 (QTLs 2.OC.3.1 and 4.SA.3.1) was linked to an SSR marker (ORS657). A principal component analysis was performed on four fatty acid traits. Two principal components, P1 and P2, were used for QTL analysis. This method improved the ability to identify chromosomal regions affecting the fatty acids. We also detected the principal-component QTLs that did not overlap with the fatty acid QTLs. The results highlight genomic regions of interest in marker-based breeding programmes for increasing oil content in sunflower.
[show abstract][hide abstract] ABSTRACT: The quantitative trait loci (QTL) controlling chlorophyll fluorescence parameters were analysed in a population of recombinant inbred lines (RILs) developed from the cross between PAC2 and RHA266. Four chlorophyll fluorescence parameters, namely the potential photochemical efficiency of photosystem II (PSII) electron transport (ΦP), the actual efficiency of PSII electron transport (ΦPSII), non-photochemical fluorescence quenching (NPQ) and the proportion of closed PSII traps (1-qP), were measured under well-watered and water-stressed conditions in 45-day-old plants at stage near flower bud formation. A large genetic variation and transgressive segregation was observed for the traits studied under two water treatments. Results showed that the progressive water stress did not cause long-term down-regulation of photosynthesis apparatus (ΦP); but it reduced actual efficiency of PSII electron transport (ΦPSII). QTL analysis showed that several putative genomic regions are involved in the total variation of chlorophyll fluorescence parameters under two water treatments. In the present study, among the 26 QTLs detected under well-watered conditions, five were shown to be constitutive by QTL-by-water treatment (environment) interaction. Most of the QTLs were specific for one condition, demonstrating that the genetic control of the expression of the traits related to photosynthesis differed under different water conditions. In several cases, one QTL was found to be associated with more than one trait. The results showed also overlapping QTLs for some of the chlorophyll fluorescence parameters and plant water status traits identified in our previous research work; mainly on linkage groups 7 and 16. It appears from the present and the previous studies that markers linked to these traits might be useful for drought tolerance selection in sunflower, after being validated in another genetic background.
[show abstract][hide abstract] ABSTRACT: Genotypic variation for water status and gas exchange parameters under different water treatments (well-watered and water-stressed plants before and after rehydration) were investigated in a population of recombinant inbred lines (RILs) of sunflower (Helianthus annuus L.). Afterwards, four RILs and parental lines presenting contrasting responses to dehydration and rehydration were selected to determine the differential expression of four water-stress associated genes: aquaporin, dehydrin, leafy cotyledon1-like protein and fructose-1,6 bisphosphatase. Water stress revealed a high genetic variability for water status and gas exchange parameters when compared with well-watered genotypes. Genetic gain when selected RILs were compared with the best parent was significant for most traits due to transgressive segregation. QTL mapping and graphical genotyping showed that RILs carrying different genomic regions for some QTLs presented also physiological different characteristics as well as gene expression patterns. The expression level of aquaporin genes in leaves of four RILs and their parents was down regulated by water stress and was associated with relative water content (RWC). Down-regulation was also associated with genomic regions having alleles with negative effects on plant water status. The level of dehydrin transcripts increased in leaves of all studied RILs in response to water stress. Transcript accumulations of dehydrin and leafy cotyledon1-like genes, likely involved in protective tolerance processes, were not correlated directly with plant water status or QTL effects. Down-regulation of fructose-1,6 bisphosphatase was observed under water stress. Net photosynthesis rate (P(n)) and the fructose-1,6 bisphosphatase gene expression levels were associated mainly after rehydration. This phenomenon indicates an association between physiological response to water stress and differential expression of water-stress related genes.
Theoretical and Applied Genetics 02/2007; 114(2):193-207. · 3.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: The goals of the present research were to develop an integrated and high density genetic-linkage map using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers on a population of 123 F9 recombinant inbred lines (RILs) and to identify QTLs involved in the genetic control of water status traits and osmotic adjustment under well-watered and water-stressed conditions. A map with 304 AFLP and 191 SSR markers with a mean density of one marker per 3.7 cM was constructed. Our physiological experiment consisted of a split-plot design with three blocks. The main plot consisted of water treatments (well-watered and water-stressed) and subplot contained 78 RILs and parental lines. Water deficit was induced in 45-day-old plants at stage near flower bud formation for a period of 12 days. After 12 days of differential watering, water status traits (leaf water potential, relative water content, turgor potential, osmotic potential and osmotic potential at full turgor) as well as osmotic adjustment (OA) were evaluated. The effects of water treatment, RIL and ‘RIL × water treatment’ were significant. QTL analysis showed that several putative genomic regions are involved in the total variation of water status traits under two water treatments. Among 24 QTLs detected under well-watered conditions, 5 (about 21%) were also detected in the water-stressed treatment. The percentage of phenotypic variance explained by the QTLs ranged from 6% to 29%. Among the eight QTLs detected for OA, four of them (50%) were co-located with the QTLs for turgor potential (Ψt) on linkage group 4 (OA.4.1), with the QTL for osmotic potential at full turgor (ΨsFT) in well-watered RILs on linkage group 12 (OA.12.2), and with QTLs of several traits on linkage group 5 (OA.5.1 and OA.5.2). The four other QTLs for OA (50%) were very specific. The major QTL for OA on linkage group 5 accounted for 29% of the phenotypic variation, which is overlapped also with the QTLs for several water status traits. However, the QTLs were identified in greenhouse conditions and the usefulness of these QTLs for marker-assisted selection should therefore be evaluated under field conditions, and validated in other genetic backgrounds.
[show abstract][hide abstract] ABSTRACT: Sunflower is a valuable crop in dry conditions already removed on poor soils without irrigation. Sunflower is considered well-adapted to drought, although systematic analyses of the physiological bases of it, and purposeful attempts to breed for greater drought tolerance are still limited. Crop modellers and geneticists have developed a vision of their roles in plant breeding from their own perspective. However, to improve breeding efficiency, interdisciplinary collaboration becomes increasingly important. Opportunities for collaboration between crop modellers, ecophysiologists and geneticists are explored in this article, to propose powerful tool to resolve genotype x environment interactions. Several views of the integration of physiological responses will be discussed. The first looks at basic responses and considers how linkages can be strengthened by genotype or management (e.g., early sowing). The second introduces simulation modelling as a way to study genotype x environment interactions. The article focuses on significant progress to the study of sunflower and to the integration of knowledge to assist plant improvement and crop management.