Prezygotic mate selection is only partially correlated with the expression of NaS-like RNases and affects offspring phenotypes.

Nicotiana attenuata styles preferentially select pollen from among accessions with corresponding expression patterns of NaS-like-RNases (SLRs), and the postpollination ethylene burst (PPEB) is an accurate predictor of seed siring success. However, the ecological consequences of mate selection, its effect on the progeny, and the role of SLRs in the control of ethylene signaling remain unknown. We explored the link between the magnitude of the ethylene burst and expression of the SLRs in a set of recombinant inbred lines (RILs), dissected the genetic underpinnings of mate selection through genome-wide association study (GWAS), and examined its outcome for phenotypes in the next generation. We found that high levels of PPEB are associated with the absence of SLR2 in most of the tested RILs. We identified candidate genes potentially involved in the control of mate selection and showed that pollination of maternal genotypes with their favored pollen donors produces offspring with longer roots. When the maternal genotypes are only able to select against nonfavored pollen donors, the selection for such positive traits is abolished. We conclude that plants' ability of mate choice contributes to measurable changes in progeny phenotypes and is thus likely a target of selection

Silencing an N-Acyltransferase-Like Involved in Lignin Biosynthesis in Nicotiana attenuata Dramatically Alters Herbivory-Induced Phenolamide Metabolism

In a transcriptomic screen of Manduca sexta-induced N-acyltransferases in leaves of Nicotiana attenuata, we identified an N-acyltransferase gene sharing a high similarity with the tobacco lignin-biosynthetic hydroxycinnamoyl-CoA:shikimate/quinate hydroxycinnamoyl transferase (HCT) gene whose expression is controlled by MYB8, a transcription factor that regulates the production of phenylpropanoid polyamine conjugates (phenolamides, PAs). To evaluate the involvement of this HCT-like gene in lignin production as well as the resulting crosstalk with PA metabolism during insect herbivory, we transiently silenced (by VIGs) the expression of this gene and performed non-targeted (UHPLC-ESI/TOF-MS) metabolomics analyses. In agreement with a conserved function of N. attenuata HCT-like in lignin biogenesis, HCT-silenced plants developed weak, soft stems with greatly reduced lignin contents. Metabolic profiling demonstrated large shifts (up to 12% deregulation in total extracted ions in insect-attacked leaves) due to a large diversion of activated coumaric acid units into the production of developmentally and herbivory-induced coumaroyl-containing PAs (N',N''-dicoumaroylspermidine, N',N''-coumaroylputrescine, etc) and to minor increases in the most abundant free phenolics (chlorogenic and cryptochlorogenic acids), all without altering the production of well characterized herbivory-responsive caffeoyl- and feruloyl-based putrescine and spermidine PAs. These data are consistent with a strong metabolic tension, exacerbated during herbivory, over the allocation of coumaroyl-CoA units among lignin and unusual coumaroyl-containing PAs, and rule out a role for HCT-LIKE in tuning the herbivory-induced accumulation of other PAs. Additionally, these results are consistent with a role for lignification as an induced anti-herbivore defense

The development of executive function and language skills in the early school years

Background: The developmental relationships between executive functions (EF) and early language skills are unclear. This study explores the longitudinal relationships between children's early EF and language skills in a sample of children with a wide range of language abilities including children at risk of dyslexia. In addition, we investigated whether these skills independently predict children's attention/behaviour skills. Method: Data are presented from 243 children at four time points. Children were selected for being at risk of reading difficulties either because of a family history of dyslexia (FR; N = 90) or because of concerns regarding their language development (LI; N = 79) or as typically developing controls (TD; N = 74). The children completed tasks to assess their executive function and language skills at ages 4, 5 and 6 years. At 6 (T4) and 7 years (T5) parents and teachers rated the children's attention/behaviour skills. Results: There was a strong concurrent relationship between language and EF at each assessment. Longitudinal analyses indicated a considerable degree of stability in children's language and EF skills: the influence of language on later EF skills (and vice versa) was weak and not significant in the current sample. Children's EF, but not language, skills at T3 predicted attention/behaviour ratings at T4/T5. Conclusions: There is a strong concurrent association between language and EF skills during the preschool and early school years, when children with language impairment show persistent EF deficits. Latent variables measuring language and EF show high longitudinal stability with little evidence of significant or strong reciprocal influences between these constructs. EF, but not language, skills predict later ratings of children's attention and behaviour

The evolutionary context for herbivore-induced plant volatiles: beyond the ‘cry for help’

Attacks by herbivores elicit changes in the bouquet of volatiles released by plants. These herbivore-induced plant volatiles (HIPVs) have been interpreted as being indirect defenses. However, given that no studies have yet investigated whether HIPVs benefit the fitness of a plant, their defensive function remains to be established. Moreover, herbivores, pathogens, pollinators and competitors also respond to HIPVs and, in addition, neighbouring plants in native populations also emit volatiles that provide a background odour. These considerations enrich the evolutionary context of HIPVs and complicate predictions about their adaptive value. Molecular advances in our understanding of HIPV signaling and biosynthesis is enabling the creation of HIPV-’mute’ and possibly HIPV-’deaf’ plants. As we discuss here, such plants could be used for unbiased examination of the fitness value of HIPV emissions under natural conditions

Heritability of a quantitative and qualitative protease inhibitor polymorphism in Nicotiana attenuata

Many plant species contain chemical defenses that protect them against herbivores. Despite the benefit of these chemical defenses, not all individuals contain high levels of these compounds. In the native tobacco Nicotiana attenuata we found that plants from three natural populations differed considerably in their ability to produce trypsin protease inhibitors (PIs), which are defensive proteins that reduce herbivore damage to plants. Plants from a Utah (U) population produced high levels, whereas plants from Arizona (A) contained no detectable PI levels. Californian (C) plants had intermediate levels. The PI-producing U and C plants thus differ quantitatively from each other, whereas they both differ qualitatively from PI-deficient A plants. Here we analyze how PI production is inherited in N. attenuata with the ultimate goal of better understanding how the quantitative and qualitative differences between the three populations have evolved. Using a series of classical crossing designs, we determined that the ability to produce PIs is inherited as a dominant Mendelian trait. PI-deficient plants contain two non-functional recessive alleles, whereas heterozygous plants or homozygous dominant plants both are able to produce PIs. Similarly, the level of constitutive PIs may be determined by its genotype, either by an interaction between a functional and a non-functional allele in heterozygotes, or by a factor on the PI allele itself in homozygous C plants. Based on these data and on previous studies with A and U plants we postulate that the PI-deficient A plants may have originated from a mutant that lost its ability to produce PIs. The fitness loss due to reduced herbivore resistance may be offset by the fitness gain associated with increased competitive ability, a trade-off which may maintain this mutation in the Arizona population. [KEYWORDS: Defense polymorphism - diallel cross - functional allele - heritability - Mendelian trait - natural selection]