Genetic diversity of gac [Momordica cochinchinensis (Lour.) Spreng] accessions collected from Mekong delta of Vietnam revealed by RAPD markers

Abstract Gac (Momordica cochinchinensis (Lour.) Spreng) (2n = 28) belongs to the Cucurbitaceae family. It is indigenous throughout in Vietnam as well as in South East Asia. To estimate the genetic diversity, 20 gac accessions collected in Mekong river delta were analyzed using 10 RAPD primers. Total of 126 fragments were obtained from ten RAPD primers, with 114 polymorphic fragments, and average of 11.4 fragments per primer. The high level of polymorphism (90.4%) was found across 20 gac accessions. The high est Nei's gene diversity value among gac accessions was H = 0.40, and the lowest was H = 0.29 with a mean of 0.36. The highest Shannon diversity index value among gac accessions was H' = 0.58 and the lowest was H' = 0.46 with an average of 0.53. Cluster analysis for genetic relationship between accessions displayed that 20 gac accessions grouped into four main clusters which genetic distance coefficient ranged from 0.29 to 0.64 and with an average of 0.54. There were defined groups according to their locations. According to these results, RAPD technique can be useful tool in genetic diversity evaluation of gac. The information achieved could also be useful for gac breeding program, cultivar differentiation and conservation

Root architecture, membrane lipid metabolism and associated genes in Rice plants submitted to Aluminium treatment

L'acidité dans le sol, combinée à une toxicité aluminique est le stress environnemental le plus important limitant la production de riz (Oryza sativa L.). Dans ce travail, neuf variétés de riz vietnamien, ainsi que deux variétés de riz connues pour leur résistance/sensibilité à l'aluminium sont discriminées pour la tolérance à l'Al grâce à l'analyse de la croissance et la morphologie des racines en condition de culture hydroponique. Les lipides membranaires et l'expression des gènes liés au métabolisme de ces lipides ont également été analysés. Les résultats ont montré que la toxicité de l'aluminium influence tout le système racinaire du riz, elle inhibe la croissance de la racine principale ainsi que celle des racines latérales, le volume des racines, et le nombre de racines latérales. L'Al s'accumule dans les racines et les feuilles. Cette accumulation d'Al corrèle négativement avec la quantité de calcium, de magnésium et de potassium dans les tissus. L'aluminium diminue la teneur en lipides membranaires dans les racines et les feuilles, et ce d'autant plus que la variété est plus sensible. Dans les feuilles, l'acide gras le plus touché est l'acide linolénique C18 : 3 ; dans les racines, l'acide linoléique C18 : 2. L'aluminium provoque en outre dans les feuilles une diminution très importante de la teneur en monogalactosyl diacylglycerol MGDG, un galactolipide constitutif des membranes thylakoïdales. Dans les racines, c'est la phosphatidylcholine PC, qui diminue le plus. Ces modifications des lipides membranaires sont nettement plus importantes chez la variété de riz sensible que chez la variété tolérante. L'expression des gènes de synthèse est corrélée positivement avec les teneurs des lipides membranaires majeurs. Nos résultats ont montré que les lipides jouent un rôle important dans le maintien de l'intégrité et le fonctionnement des membranes cellulaires, et ont une influence sur la capacité des plantes à résister à la présence de l'aluminium dans le milieuSoil acidity combined with the presence of Aluminium ions is a major environmental stress limiting rice (Oryza sativa) production. In this work, root growth and root morphology of nine vietnamese rice varieties and two IRRI reference varieties (one Al-resistant, one Al-sensitive) were studied in hydroponic conditions. Analysis of membrane lipid composition as well as the expression of genes related to lipid metabolism was also performed. Results showed that Al toxicity influenced negatively the whole root system : Al inhibited the elongation rate of the principal root and the lateral roots ; it decreased the root volume and the number of lateral roots. Al accumulated in root and leaf tissues. Al accumulation was negatively correlated with the amounts of Calcium, Magnesium and Potassium in plant tissues. Membrane lipid contents also decreased in roots and shoots, and these decreases were more important in the sensitive varieties than in the tolerant ones. In the shoots, linolenic acid C18:3 content was mostly affected, and in the roots linoleic acid C18:2. Furthermore, in the leaves Al provoked a large decrease in the main lipid of thylakoid membranes monogalactosyl diacylglycerol MGDG. In the roots, it decreased the phosphatidylcholine PC content. Lipid and fatty acid changes were more pronounced in Al-susceptible varieties than in tolerant ones. The expression of genes related to the biosynthesis of the main m embrane lipids during Al treatment correlated well with the time-course of membrane lipid composition. Our results indicated that lipids could play an important role in the integrity and function of cell membranes, and that they could be implicated in the capacity of plants to tolerate the presence of aluminium toxic ions in the environmen

Étude de l'architecture racinaire, du métabolisme des lipides membranaires et des gènes associés chez le riz Oryza sativa L. dans le cadre de la toxicité aluminique

L'acidité dans le sol, combinée à une toxicité aluminique est le stress environnemental le plus important limitant la production de riz (Oryza sativa L.). Dans ce travail, neuf variétés de riz vietnamien, ainsi que deux variétés de riz connues pour leur résistance/sensibilité à l'aluminium sont discriminées pour la tolérance à l'Al grâce à l'analyse de la croissance et la morphologie des racines en condition de culture hydroponique. Les lipides membranaires et l'expression des gènes liés au métabolisme de ces lipides ont également été analysés. Les résultats ont montré que la toxicité de l'aluminium influence tout le système racinaire du riz, elle inhibe la croissance de la racine principale ainsi que celle des racines latérales, le volume des racines, et le nombre de racines latérales. L'Al s'accumule dans les racines et les feuilles. Cette accumulation d'Al corrèle négativement avec la quantité de calcium, de magnésium et de potassium dans les tissus. L'aluminium diminue la teneur en lipides membranaires dans les racines et les feuilles, et ce d'autant plus que la variété est plus sensible. Dans les feuilles, l'acide gras le plus touché est l'acide linolénique C18 : 3 ; dans les racines, l'acide linoléique C18 : 2. L'aluminium provoque en outre dans les feuilles une diminution très importante de la teneur en monogalactosyl diacylglycerol MGDG, un galactolipide constitutif des membranes thylakoïdales. Dans les racines, c'est la phosphatidylcholine PC, qui diminue le plus. Ces modifications des lipides membranaires sont nettement plus importantes chez la variété de riz sensible que chez la variété tolérante. L'expression des gènes de synthèse est corrélée positivement avec les teneurs des lipides membranaires majeurs. Nos résultats ont montré que les lipides jouent un rôle important dans le maintien de l'intégrité et le fonctionnement des membranes cellulaires, et ont une influence sur la capacité des plantes à résister à la présence de l'aluminium dans le milieuSoil acidity combined with the presence of Aluminium ions is a major environmental stress limiting rice (Oryza sativa) production. In this work, root growth and root morphology of nine vietnamese rice varieties and two IRRI reference varieties (one Al-resistant, one Al-sensitive) were studied in hydroponic conditions. Analysis of membrane lipid composition as well as the expression of genes related to lipid metabolism was also performed. Results showed that Al toxicity influenced negatively the whole root system : Al inhibited the elongation rate of the principal root and the lateral roots ; it decreased the root volume and the number of lateral roots. Al accumulated in root and leaf tissues. Al accumulation was negatively correlated with the amounts of Calcium, Magnesium and Potassium in plant tissues. Membrane lipid contents also decreased in roots and shoots, and these decreases were more important in the sensitive varieties than in the tolerant ones. In the shoots, linolenic acid C18:3 content was mostly affected, and in the roots linoleic acid C18:2. Furthermore, in the leaves Al provoked a large decrease in the main lipid of thylakoid membranes monogalactosyl diacylglycerol MGDG. In the roots, it decreased the phosphatidylcholine PC content. Lipid and fatty acid changes were more pronounced in Al-susceptible varieties than in tolerant ones. The expression of genes related to the biosynthesis of the main m embrane lipids during Al treatment correlated well with the time-course of membrane lipid composition. Our results indicated that lipids could play an important role in the integrity and function of cell membranes, and that they could be implicated in the capacity of plants to tolerate the presence of aluminium toxic ions in the environmentPARIS-EST-Université (770839901) / SudocSudocFranceF

Population genetic structure of a thousand rubber tree accessions from wild Rondonia populations conserved in Vietnam

International audienceNatural rubber is a strategic raw material in many sectors of modern industrial societies and is almost exclusively produced by cultivating rubber trees [Hevea brasiliensis (Willd. ex A. Juss.) Mull. Arg.)]. Breeding of this species focuses mainly on advanced improved varieties developed over a century in Southeast Asia and Africa, but it also relies on genetic diversity available in wild germplasm. In this study, we describe the diversity observed within 1060 accessions originating from the state of Rondonia (Brazil) and conserved ex situ in Vietnam. Available passport data for these accessions indicate their putative distribution throughout seven districts in Rondonia. Genotyping data obtained on these accessions with 15 SSR markers generated 458 different alleles. A principal coordinate analysis enabled a clear separation of accessions from Calama district on the first axis, as well as accessions from Ariquemes and Ji-Parana districts on opposite sides of the second axis. A three-step Bayesian analysis of population structure gave a clearer representation, involving three levels of differentiation. At the first differentiation level, the accessions were divided into two clusters, k1 comprising 42% of the accessions, k2 with 25%, and the remaining 33% being admixed accessions. Further levels of Bayesian analysis enabled to distinguish between accessions from different farms in a same district. A better knowledge of the genetic structure at the infra-Rondonia state level, will help in using this available genetic diversity in future breeding programs

Omega-3 fatty acid desaturase (FAD3, FAD7, FAD8) gene expression and linolenic acid content in cowpea leaves submitted to drought and after rehydration

International audienceMembrane polyunsaturated fatty acids (PUFA) and particularly linolenic acid (18:3, LA) are known to be implicated in plant tolerance to low temperature. Their role in resistance to drought is much less investigated. In this work, three full-length cDNAs corresponding to omega-3 fatty acid desaturases: fad3 (endoplasmic reticulum), fad7 and fad8 (chloroplastic) were isolated from Vigna unguiculata leaves. Two cowpea cultivars, one drought-tolerant, EPACE-1, and one drought-susceptible, 1183, were compared in terms of fad isoform gene expression and leaf LA contents in plants submitted to water stress followed by rehydration. In EPACE-1, LA content in the main leaf polar lipids increased in response to mild water deficit. Severe water deficits induced a decrease in MGDG LA content while those of PC and DGDG continued to increase. Variations in FAD gene expression, matched those in LA contents. In 1183, LA contents decreased in all lipid classes in response to water stress, as did FAD3 and FAD8 gene expression levels. Rehydration after a moderate water stress induced stimulation mostly in FAD3 gene expression in both cvs. LA contents were equivalent to control levels in EPACE-1. In 1183, they were back to control levels in PC shortly after rehydration but remained low in galactolipids. These results suggested that omega-3 FAD activities were involved in the increase in leaf membrane unsaturation, in the drought tolerant plants whereas the sensitive plants lost PUFAs in response to the treatment. The significance of this discrepancy between the two cvs. in terms of adaptation to drought is discussed