Meta-QTL and Candidate Gene Analyses of Agronomic Salt Tolerance and Related Traits in an RIL Population Derived from .

Breeding salt-tolerant crops is necessary to reduce food insecurity. Prebreeding populations are fundamental for uncovering tolerance alleles from wild germplasm. To obtain a physiological interpretation of the agronomic salt tolerance and better criteria to identify candidate genes, quantitative trait loci (QTLs) governing productivity-related traits in a population of recombinant inbred lines (RIL) derived from were reanalyzed using an SNP-saturated linkage map and clustered using QTL meta-analysis to synthesize QTL information.

Combining Genetic and Transcriptomic Approaches to Identify Transporter-Coding Genes as Likely Responsible for a Repeatable Salt Tolerance QTL in Citrus.

The excessive accumulation of chloride (Cl) in leaves due to salinity is frequently related to decreased yield in citrus. Two salt tolerance experiments to detect quantitative trait loci (QTLs) for leaf concentrations of Cl, Na, and other traits using the same reference progeny derived from the salt-tolerant Cleopatra mandarin () and the disease-resistant donor were performed with the aim to identify repeatable QTLs that regulate leaf Cl (and/or Na) exclusion across independent experiments in citrus, as well as potential candidate genes involved. A repeatable QTL controlling leaf Cl was detected in chromosome 6 (), where 23 potential candidate genes coding for transporters were identified using the genome as reference.

HKT1;1 and HKT1;2 Na Transporters from Play Different Roles in the Plant Na Distribution under Salinity.

Salt tolerance is a target trait in plant science and tomato breeding programs. Wild tomato accessions have been often explored for this purpose. Since shoot Na/K is a key component of salt tolerance, RNAi-mediated knockdown isogenic lines obtained for alleles encoding both class I Na transporters HKT1;1 and HKT1;2 were used to investigate the silencing effects on the Na and K contents of the xylem sap, and source and sink organs of the scion, and their contribution to salt tolerance in all 16 rootstock/scion combinations of non-silenced and silenced lines, under two salinity treatments.

Genetic Control of Reproductive Traits under Different Temperature Regimes in Inbred Line Populations Derived from Crosses between and Accessions.

In the present work, we study the genetic control of reproductive traits under different heat stress conditions in two populations of inbred lines derived from crosses between two accessions and two tomato cultivars (E9×L5 and E6203×LA1589). The temperature increase affected the reproductive traits, especially at extremely high temperatures, where only a few lines were able to set fruits. Even though a relative modest number of QTLs was identified, two clusters of QTLs involved in the responses of reproductive traits to heat stress were detected in both populations on chromosomes 1 and 2.

Role of Na transporters HKT1;1 and HKT1;2 in tomato salt tolerance. I. Function loss of cheesmaniae alleles in roots and aerial parts.

We analyzed the physiological impact of function loss on cheesmaniae alleles at the HKT1;1 and HKT1;2 loci in the roots and aerial parts of tomato plants in order to determine the relative contributions of each locus in the different tissues to plant Na/K homeostasis and subsequently to tomato salt tolerance. We generated different reciprocal rootstock/scion combinations with non-silenced, single RNAi-silenced lines for ScHKT1;1 and ScHKT1;2, as well as a silenced line at both loci from a near isogenic line (NIL14), homozygous for the Solanum cheesmaniae haplotype containing both HKT1 loci and subjected to salinity under natural greenhouse conditions. Our results show that salt treatment reduced vegetative growth and altered the Na/K ratio in leaves and flowers; negatively affecting fruit production, particularly in graft combinations containing single silenced ScHKT1;2- and double silenced ScHKT1;1/ScHKT1;2 lines when used as scion.

Genetic Analysis of Root-to-Shoot Signaling and Rootstock-Mediated Tolerance to Water Deficit in Tomato.

Developing drought-tolerant crops is an important strategy to mitigate climate change impacts. Modulating root system function provides opportunities to improve crop yield under biotic and abiotic stresses. With this aim, a commercial hybrid tomato variety was grafted on a genotyped population of 123 recombinant inbred lines (RILs) derived from , and compared with self- and non-grafted controls, under contrasting watering treatments (100% vs.

Na transporter HKT1;2 reduces flower Na content and considerably mitigates the decline in tomato fruit yields under saline conditions.

Genes encoding HKT1-like Na transporters play a key role in the salinity tolerance mechanism in Arabidopsis and other plant species by retrieving Na from the xylem of different organs and tissues. In this study, we investigated the role of two HKT1;2 allelic variants in tomato salt tolerance in relation to vegetative growth and fruit yield in plants subjected to salt treatment in a commercial greenhouse under real production conditions. We used two near-isogenic lines (NILs), homozygous for either the Solanum lycopersicum (NIL17) or S.

Genetic analysis of tomato root colonization by arbuscular mycorrhizal fungi.

Background And Aims: Arbuscular mycorrhizal fungi (AMF) play an important role in plant nutrition and protection against pests and diseases, as well as in soil structuration, nutrient cycling and, generally speaking, in sustainable agriculture, particularly under drought, salinity and low input or organic agriculture. However, little is known about the genetics of the AMF-plant association in tomato. The aim of this study was the genetic analysis of root AMF colonization in tomato via the detection of the quantitative trait loci (QTLs) involved.

The sodium transporter encoded by the HKT1;2 gene modulates sodium/potassium homeostasis in tomato shoots under salinity.

Excessive soil salinity diminishes crop yield and quality. In a previous study in tomato, we identified two closely linked genes encoding HKT1-like transporters, HKT1;1 and HKT1;2, as candidate genes for a major quantitative trait locus (kc7.1) related to shoot Na /K homeostasis - a major salt tolerance trait - using two populations of recombinant inbred lines (RILs).

Root-to-Shoot Hormonal Communication in Contrasting Rootstocks Suggests an Important Role for the Ethylene Precursor Aminocyclopropane-1-carboxylic Acid in Mediating Plant Growth under Low-Potassium Nutrition in Tomato.

Selection and breeding of rootstocks that can tolerate low K supply may increase crop productivity in low fertility soils and reduce fertilizer application. However, the underlying physiological traits are still largely unknown. In this study, 16 contrasting recombinant inbred lines (RILs) derived from a cross between domestic and wild tomato species ( × ) have been used to analyse traits related to the rootstock-mediated induction of low () or high () vigor to a commercial F1 hybrid grown under control (6 mM, ) and low-K (1 mM, ).

Fruit volatile profiles of two citrus hybrids are dramatically different from those of their parents.

Volatile compounds released from the fruit of two hybrid Citrus genotypes (FxCh90 and FxCh77) were compared to those from their parental varieties, Fortune mandarin and Chandler pummelo. A series of 113 compounds were identified, including 31 esters, 23 aldehydes, 20 alcohols, 17 monoterpenoids, and other compounds. The differences in the volatile profile among these four genotypes were essentially quantitative.

Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+ /K+ homeostasis.

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na(+) ] and [K(+) ] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na(+) -selective class I-HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single-nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2.

Rootstock-mediated changes in xylem ionic and hormonal status are correlated with delayed leaf senescence, and increased leaf area and crop productivity in salinized tomato.

Tomato crop productivity under salinity can be improved by grafting cultivars onto salt-tolerant wild relatives, thus mediating the supply of root-derived ionic and hormonal factors that regulate leaf area and senescence. A tomato cultivar was grafted onto rootstocks from a population of recombinant inbred lines (RILs) derived from a Solanum lycopersicum x Solanum cheesmaniae cross and cultivated under moderate salinity (75 mM NaCl). Concentrations of Na(+), K(+) and several phytohormones [abscisic acid (ABA); the cytokinins (CKs) zeatin, Z; zeatin riboside, ZR; and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC)] were analysed in leaf xylem sap in graft combinations of contrasting vigour.