Genetic Components of Root Architecture Remodeling in Response to Salt Stress.

Salinity of the soil is highly detrimental to plant growth. Plants respond by a redistribution of root mass between main and lateral roots, yet the genetic machinery underlying this process is still largely unknown. Here, we describe the natural variation among 347 accessions in root system architecture (RSA) and identify the traits with highest natural variation in their response to salt.

Capturing Arabidopsis root architecture dynamics with ROOT-FIT reveals diversity in responses to salinity.

The plant root is the first organ to encounter salinity stress, but the effect of salinity on root system architecture (RSA) remains elusive. Both the reduction in main root (MR) elongation and the redistribution of the root mass between MRs and lateral roots (LRs) are likely to play crucial roles in water extraction efficiency and ion exclusion. To establish which RSA parameters are responsive to salt stress, we performed a detailed time course experiment in which Arabidopsis (Arabidopsis thaliana) seedlings were grown on agar plates under different salt stress conditions.

Role of Na+, K+, Cl-, proline and sucrose concentrations in determining salinity tolerance and their correlation with the expression of multiple genes in tomato.

One of the major abiotic stresses affecting agriculture is soil salinity, which reduces crop yield and, consequently, revenue for farmers. Although tomato is an important agricultural species, elite varieties are poor at withstanding salinity stress. Thus, a feasible way of improving yield under conditions of salinity stress is to breed for improved salt tolerance.

Identification of a resistance gene Rpi-dlc1 to Phytophthora infestans in European accessions of Solanum dulcamara.

Initial screening of 14 Solanum dulcamara accessions enabled the identification of individuals resistant and susceptible to Phytophthora infestans. Crosses between contrasting genotypes resulted in three F(2)-BC(1) populations segregating for resistance to late blight in a laboratory assay and under field conditions. Genetic profiling of one of these populations using 128 AFLP primers generated three markers linked to the resistant phenotype.

Abscisic acid levels in tomato ovaries are regulated by LeNCED1 and SlCYP707A1.

Although the hormones, gibberellin and auxin, are known to play a role in the initiation of fruits, no such function has yet been demonstrated for abscisic acid (ABA). However, ABA signaling and ABA responses are high in tomato (Solanum lycopersicum L.) ovaries before pollination and decrease thereafter (Vriezen et al.

The Solanum lycopersicum auxin response factor 7 (SlARF7) regulates auxin signaling during tomato fruit set and development.

Auxin response factors (ARFs) are encoded by a gene family of transcription factors that specifically control auxin-dependent developmental processes. A tomato ARF gene, homologous to Arabidopsis NPH4/ARF7 and therefore designated as Solanum lycopersicum ARF7 (SlARF7), was found to be expressed at a high level in unpollinated mature ovaries. More detailed analysis of tomato ovaries showed that the level of SlARF7 transcript increases during flower development, remains at a constant high level in mature flowers, and is down-regulated within 48 h after pollination.

Changes in tomato ovary transcriptome demonstrate complex hormonal regulation of fruit set.

Plant hormones are considered to be important mediators of the fruit developmental signal after pollination. The role of phytohormones in tomato (Solanum lycopersicum) fruit set was investigated here. Transcriptome analysis of ovaries was performed using two complementary approaches: cDNA-amplified fragment length polymorphism (AFLP) and microarray analysis.

Expression and localization of calreticulin in tobacco anthers and pollen tubes.

The developmental expression pattern and localization of calreticulin were studied in Nicotiana tabacum L. anthers, pollen and pollen tubes. High transcript and protein levels were detected throughout anther development.

Lipid transfer proteins enhance cell wall extension in tobacco.

Plant cells are enclosed by a rigid cell wall that counteracts the internal osmotic pressure of the vacuole and limits the rate and direction of cell enlargement. When developmental or physiological cues induce cell extension, plant cells increase wall plasticity by a process called loosening. It was demonstrated previously that a class of proteins known as expansins are mediators of wall loosening.

STIG1 controls exudate secretion in the pistil of petunia and tobacco.

The lipid-rich, sticky exudate covering the stigma of solanaceous species such as tobacco (Nicotiana tabacum) and petunia (Petunia hybrida) contains several proteins, of which only some have been characterized to date. Proteome analysis of the stigmatic exudate in both species revealed the presence of a cysteine-rich, slightly acidic 12-kD protein called stigma-specific protein 1 (STIG1). In both tobacco and petunia, Stig1 is highly expressed at the mRNA level in very young and developing flowers, whereas hardly any Stig1 transcript is detected in mature flowers.

PIP1 and PIP2 aquaporins are differentially expressed during tobacco anther and stigma development.

Several processes during sexual reproduction in higher plants involve the movement of water between cells or tissues, such as occurs during dehiscence of the anther and hydration of the pollen grain after it is deposited on a stigma. To get more insight in these processes, a set of putative aquaporins was cloned and it was found that at least 15 are expressed in reproductive organs, which indicates that the control of water flow is important for reproduction. Functional studies in Xenopus laevis oocytes using two of the cDNAs showed that NtPIP2;1 is an efficient aquaporin, whereas NtPIP1;1 is not.

Pollination modulates expression of the PPAL gene, a pistil-specific beta-expansin.

Using differential screening we isolated a pistil-specific cDNA clone corresponding to a 1.2 kb mRNA and encoding a 32.5 kDa protein.