Quantitative trait loci (QTLs) analysis of palm oil fatty acid composition in an interspecific pseudo-backcross from Elaeis oleifera (HBK) Cort,s and oil palm (Elaeis guineensis Jacq.)

IATE Axe 4 : Biotechnologie microbienne et enzymatique des lipides et des agropolymèresWe chose an Elaeis interspecific pseudo-backcross of first generation (E. oleifera x E. guineensis) x E. guineensis to identify quantitative trait loci (QTLs) for fatty acid composition of palm oil. A dense microsatellite linkage map of 362 loci spanned 1.485 cM, representing the 16 pairs of homologous chromosomes in the Elaeis genus from which we traced segregating alleles from both E. oleifera and E. guineensis grandparents. The relative linear orders of mapped loci suggested the probable absence of chromosome rearrangements between the E. oleifera and E. guineensis genomes. A total of 19 QTL associated to the palm oil fatty acid composition were evidenced. The QTL positions and the species origin as well as the estimated effects of the QTL marker alleles were in coherence with the knowledge of the oil biosynthesis pathway in plants and with the individual phenotypic correlations between the traits. The mapping of chosen Elaeis key genes related to oleic acid C18:1, using intra-gene SNPs, supported several QTLs underlying notably FATA and SAD enzymes. The high number of hyper-variable SSR loci of known relative linear orders and the QTL information make these resources valuable for such mapping study in other Elaeis breeding materials

Biotecnología y selección de la palma de aceite: la Palma Dorada del futuro

Los marcadores de ADN, la secuenciación con sistemas NGS, la manipulación genética y las tecnologías de cultivo in vitro, combinadas con la caracterización fenotípica de alta tecnología, ponen al alcance de los cultivadores las variedades que desearían cultivar sin que hubieran podido imaginar siquiera que fuese posible sembrarlas. Se espera que las variedades de palma de aceite sufran muchos cambios desde el día de hoy hasta el año 2050, por medio de una selección biotecnológica de las especies E. guineensis y E. oleifera. La productividad de la palma de aceite está ligada estrechamente a su potencial fisiológico. El determinismo genético completamente dilucidado de la morfología de la fertilidad del fruto permite que existan nuevas variedades que solo contengan pulpa, tales como las pisifera fértiles y tenera partenocárpicos. El bajo crecimiento del tallo y la voluminosidad reducida logran que las palmas se cultiven en menos hectáreas de tierra, lo cual genera una cosecha menos costosa. La reducción de la frecuencia de cosecha (tan baja como una vez al mes) será posible gracias al no desprendimiento de frutos. La baja actividad de lipasa en la pulpa de los frutos maduros garantizará la producción de un aceite de palma sin ácidos libres significativos en los racimos entregados a las plantas extractoras, lo cual asegurará la producción en campo sin incurrir en pérdidas económicas. Las variedades con hasta 90 % de ácido oleico entrarán al mercado y este novedoso aceite de palma “aceitunado” se venderá a precios marcadamente más competitivos para la mesa de la mayoría de las personas del mundo, destronando así al mercado privilegiado del aceite de oliva mediterráneo, de mayor costo. El imperio del cultivo de palma de aceite ha expandido sus territorios a lo largo de América del Sur gracias a las variedades interespecíficas resistentes a la enfermedad de la Pudrición del cogollo, a la vez que se preservan considerablemente la mayoría de los bosques naturales al convertir los grandes pastizales en palmares

A rubber tree's durable resistance to Microcyclus ulei is conferred by aqualitative gene and a major quantitative resistance factor

The components of genetic resistance from the Hevea brasiliensis cultivar MDF 180 against South American Leaf Blight (SALB) caused by Microcyclus ulei were investigated by QTL mapping. MDF 180 has already been described as a cultivar with a high level of partial and long-lasting resistance. The resistance of progeny individuals from a cross between a susceptible cultivar and MDF 180 was assessed both under controlled conditions of inoculation by three M. ulei isolates and under natural infection in a field trial. Genetic maps of the two parents of this progeny were mainly established based on microsatellites and AFLP markers. No resistance QTL were found in the susceptible parent. In the resistant parent, we identified a qualitative gene responsible for the resistance against isolates from French Guiana and a major quantitative resistance factor determining the resistance against isolates from the state of Bahia (Brazil). The qualitative resistance gene was denominated M15md and was located in the linkage group g15. Four minor resistance QTLs were also identified, two of which showed an epistatic interaction with M15md. The durability of the resistance of MDF 180 is discussed in light of these data

Diversity in Expression Patterns and Functional Properties in the Rice HKT Transporter Family1[W]

Plant growth under low K+ availability or salt stress requires tight control of K+ and Na+ uptake, long-distance transport, and accumulation. The family of membrane transporters named HKT (for High-Affinity K+ Transporters), permeable either to K+ and Na+ or to Na+ only, is thought to play major roles in these functions. Whereas Arabidopsis (Arabidopsis thaliana) possesses a single HKT transporter, involved in Na+ transport in vascular tissues, a larger number of HKT transporters are present in rice (Oryza sativa) as well as in other monocots. Here, we report on the expression patterns and functional properties of three rice HKT transporters, OsHKT1;1, OsHKT1;3, and OsHKT2;1. In situ hybridization experiments revealed overlapping but distinctive and complex expression patterns, wider than expected for such a transporter type, including vascular tissues and root periphery but also new locations, such as osmocontractile leaf bulliform cells (involved in leaf folding). Functional analyses in Xenopus laevis oocytes revealed striking diversity. OsHKT1;1 and OsHKT1;3, shown to be permeable to Na+ only, are strongly different in terms of affinity for this cation and direction of transport (inward only or reversible). OsHKT2;1 displays diverse permeation modes, Na+-K+ symport, Na+ uniport, or inhibited states, depending on external Na+ and K+ concentrations within the physiological concentration range. The whole set of data indicates that HKT transporters fulfill distinctive roles at the whole plant level in rice, each system playing diverse roles in different cell types. Such a large diversity within the HKT transporter family might be central to the regulation of K+ and Na+ accumulation in monocots