Morphoagronomic characterization and wholegenome resequencing of eight highly diverse wild and weedy S.pimpinellifolium and S.lycopersicum var.cerasiforme accessions used for the first interspecific tomato MAGIC population

The wild Solanum pimpinellifolium(SP)and the weedy S.lycopersicum var.cerasiforme(SLC)are largely unexploited genetic reservoirs easily accessible to breeders,as they are fully cross-compatible with cultivated tomato(S.lycopersicum var.lycopersicum).We performed a comprehensive morphological and genomic characterization of four wild SP and four weedy SLC accessions,selected to maximize the range of variation of both taxa.These eight accessions are the founders of the first tomato interspecific multi-parent advanced generation inter-cross(MAGIC)population.The morphoagronomic characterization was carried out with 39 descriptors to assess plant,inflorescence,fruit and agronomic traits,revealing the broad range of diversity captured.Part of the morphological variation observed in SP was likely associated to the adaptation of the accessions to different environments,while in the case of SLC to both human activity and adaptation to the environment.Whole-genome resequencing of the eight accessions revealed over 12 million variants,ranging from 1.2 to 1.9 million variants in SLC and from 3.1 to 4.8 million in SP,being 46.3%of them(4,897,803)private variants.The genetic principal component analysis also confirmed the high diversity of SP and the complex evolutionary history of SLC.This was also reflected in the analysis of the potential footprint of common ancestors or old introgressions identified within and between the two taxa.The functional characterization of the variants revealed a significative enrichment of GO terms related to changes in cell walls that would have been negatively selected during domestication and breeding.The comprehensive morphoagronomic and genetic characterization of these accessions will be of great relevance for the genetic analysis of the first interspecific MAGIC population of tomato and provides valuable knowledge and tools to the tomato community for genetic and genomic studies and for breeding purposes.

Proline as a biochemical marker in relation to the ecology of two halophytic Juncus species

Aims osmolytes,used for maintaining osmotic balance and as‘osmoprotectants’,are synthesized in plants as a general,con-served response to abiotic stress,although their contribution to stress-tolerance mechanisms remains unclear.Proline,the most common osmolyte,accumulates in many plant species in parallel with increased external salinity and is considered a reliable bio-chemical marker of salt stress.We have measured proline levels in two halophytic,closely related Juncus species under laboratory and field conditions to assess the possible relevance of proline biosynthesis for salt tolerance and therefore for the ecology of these two taxa.Methods Proline was quantified in plants treated with increasing NaCl con-centrations and in plants sampled in two salt marshes located in the provinces of Valencia and alicante,respectively,in southeast spain.Electrical conductivity,pH,Na+and Cl−concentrations were measured in soil samples collected in parallel with the plant material.Important Findings Treatment with NaCl inhibited growth of J.acutus plants in a concentration-dependent manner,but only under high salt conditions for J.maritimus.salt treatments led to proline accumulation in both species,especially in the more salt-tolerant J.maritimus.The results,obtained under laboratory conditions,were confirmed in plants sam-pled in the field.in all the samplings,proline contents were signifi-cantly lower in J.acutus than in the more tolerant J.maritimus growing in the same area.No direct correlation between soil salinity and proline levels could be established,but seasonal variations were detected,with increased proline contents under accentuated water deficit conditions.our results suggest that proline biosynthesis is not only an induced,general response to salt stress but also an important contributing factor in the physiological mechanisms of salt tolerance in Juncus,and that it therefore correlates with the ecology of both species.

Production of Volatile Moth Sex Pheromones in Transgenic Nicotiana benthamiana Plants

Plant-based bioproduction of insect sex pheromones has been proposed as an innovative strategy to increase the sustainability of pest control in agriculture.Here,we describe the engineering of transgenic plants producing(Z)-11-hexadecenol(Z11-16OH)and(Z)-11-hexadecenyl acetate(Z11-16OAc),two main volatile components in many Lepidoptera sex pheromone blends.We assembled multigene DNA constructs encoding the pheromone biosynthetic pathway and stably transformed them into Nicotiana benthamiana plants.The constructs contained the Amyelois transitella AtrΔ11 desaturase gene,the Helicoverpa armigera fatty acyl reductase HarFAR gene,and the Euonymus alatus diacylglycerol acetyltransferase EaDAct gene in different configurations.All the pheromone-producing plants showed dwarf phenotypes,the severity of which correlated with pheromone levels.All but one of the recovered lines produced high levels of Z11-16OH,but very low levels of Z11-16OAc,probably as a result of recurrent truncations at the level of the EaDAct gene.Only one plant line(SxPv1.2)was recovered that harboured an intact pheromone pathway and which produced moderate levels of Z11-16OAc(11.8μg g^(-1) FW)and high levels of Z11-16OH(111.4μg g^(-1)).Z11-16OAc production was accompanied in SxPv1.2 by a partial recovery of the dwarf phenotype.SxPv1.2 was used to estimate the rates of volatile pheromone release,which resulted in 8.48 ng g-1 FW per day for Z11-16OH and 9.44 ng g^(-1 )FW per day for Z11-16OAc.Our results suggest that pheromone release acts as a limiting factor in pheromone biodispenser strategies and establish a roadmap for biotechnological improvements.