Sirex noctilio infestation led to inevitable pine death despite activating pathways involved in tolerance

Defense-related metabolome traits in pine species after infestation by Sirex noctilio are largely unknown, despite, in most cases, trees being overwhelmed. Using LC-MS-based untargeted metabolomics, we revealed the systemic metabolic changes induced by this insect in 14-year-old Pinus radiata trees, the most affected species worldwide. An immediate metabolome alteration was expressed in needles after infestation, including the up-regulation of flavonols, flavan-3-ols, oxyneolignans, auxins, proline, and tryptophan, among others. The flavan-3-ols (catechin and procyanidin B1) suggested a rapidly induced photoprotection mechanism aided by diverting proline as an alternative substrate for respiration to compensate for the progressive chlorosis that degrades photosystems. Meanwhile, glutathione, glutamate, and ascorbate levels significantly dropped in needles, which may indicate the critical oxidative stress that trees had to face since the onset of the infestation. They were not fully replenished after long-term infestation, and redox homeostasis was probably not achieved, compromising tree survival. Nevertheless, a huge auxins overexpression detected in needles throughout the infestation may reflect tolerance against the premature senescence caused by the woodwasp venom. In contrast, the metabolome of wood tissues remained initially unchanged, although it seems to collapse after three months. Overall, the metabolomics strategy adopted in this work evidenced its usefulness in uncovering the fundamental roles of plants' chemical defense that govern interactions with specific stressors.

Thermopriming-associated proteome and sugar content responses in Pinus radiata embryogenic tissue

Improving the capacity of plants to face adverse environmental conditions requires a deep understanding of the molecular mechanisms governing stress response and adaptation. Proteomics, combined with metabolic analyses, offers a wide resource of information to be used in plant breeding programs. Previous studies have shown that somatic embryogenesis in Pinus spp. is a suitable tool not only to investigate stress response processes but also to modulate the behaviour of somatic plants. Based on this, the objective of this study was to analyse the protein and soluble sugar profiles of Pinus radiata embryonal masses after the application of high temperatures to unravel the mechanisms involved in thermopriming and memory acquisition at early stages of the somatic embryogenesis process. Results confirmed that heat provokes deep readjustments in the life cycle of proteins, together with a significant reduction in the carbon-flux of central-metabolism pathways. Heat-priming also promotes the accumulation of proteins involved in oxidative stress defence, in the synthesis of specific amino acids such as isoleucine, influences cell division, the organization of the cytoskeleton and cell-walls, and modifies the levels of free soluble sugars like glucose or fructose. All this seems to be regulated by proteins linked with epigenetic, transcriptional and post-transcriptional mechanisms.

Ultrasonic guided wave measurement in a wooden rod using shear transducer arrays

Research related to acoustic/ultrasonic guided wave testing in wood is still at an early stage. This paper describes the first study to perform ultrasonic guided wave measurements in a wooden rod using arrays of shear transducers. Enhancement of either longitudinal L(0,1) or torsional T(0,1) wave modes and suppression of other modes was able to be achieved using these arrays. At low frequencies, it was found that the L(0,1) wave mode had a similar speed to that obtained using the traditional resonance and time of flight methods. The torsional T(0,1) wave mode has not been used before for non-destructive testing of wood. Since it is non-dispersive, it would appear to be suitable for wood property estimation and structural health monitoring of wooden structures. These results indicate that ultrasonic guided wave testing techniques have strong potential to be used to provide improved measurement of wood properties and structural health monitoring of wooden structures.

Genomic selection for non-key traits in radiata pine when the documented pedigree is corrected using DNA marker information

Background

Non-key traits (NKTs) in radiata pine (Pinus radiata D. Don) refer to traits other than growth, wood density and stiffness, but still of interest to breeders. Branch-cluster frequency, stem straightness, external resin bleeding and internal checking are examples of such traits and are targeted for improvement in radiata pine research programmes. Genomic selection can be conducted before the performance of selection candidates is available so that generation intervals can be reduced. Radiata pine is a species with a long generation interval, which if reduced could significantly increase genetic gain per unit of time. The aim of this study was to evaluate the accuracy and predictive ability of genomic selection and its efficiency over traditional forward selection in radiata pine for the following NKTs: branch-cluster frequency, stem straightness, internal checking, and external resin bleeding.

Results

Nine hundred and eighty-eight individuals were genotyped using exome capture genotyping by sequencing (GBS) and 67,168 single nucleotide polymorphisms (SNPs) used to develop genomic estimated breeding values (GEBVs) with genomic best linear unbiased prediction (GBLUP). The documented pedigree was corrected using a subset of 704 SNPs. The percentage of trio parentage confirmed was about 49% and about 50% of parents were re-assigned. The accuracy of GEBVs was 0.55–0.75 when using the documented pedigree and 0.61–0.80 when using the SNP-corrected pedigree. A higher percentage of additive genetic variance was explained and a higher predictive ability was observed when using the SNP-corrected pedigree than using the documented pedigree. With the documented pedigree, genomic selection was similar to traditional forward selection when assuming a generation interval of 17 years, but worse than traditional forward selection when assuming a generation interval of 14 years. After the pedigree was corrected, genomic selection led to 37–115% and 13–77% additional genetic gain over traditional forward selection when generation intervals of 17 years and 14 years were assumed, respectively.

Conclusion

It was concluded that genomic selection with a pedigree corrected by SNP information was an efficient way of improving non-key traits in radiata pine breeding.

Genomic selection for non-key traits in radiata pine when the documented pedigree is corrected using DNA marker information

BACKGROUND

Non-key traits (NKTs) in radiata pine (Pinus radiata D. Don) refer to traits other than growth, wood density and stiffness, but still of interest to breeders. Branch-cluster frequency, stem straightness, external resin bleeding and internal checking are examples of such traits and are targeted for improvement in radiata pine research programmes. Genomic selection can be conducted before the performance of selection candidates is available so that generation intervals can be reduced. Radiata pine is a species with a long generation interval, which if reduced could significantly increase genetic gain per unit of time. The aim of this study was to evaluate the accuracy and predictive ability of genomic selection and its efficiency over traditional forward selection in radiata pine for the following NKTs: branch-cluster frequency, stem straightness, internal checking, and external resin bleeding.

RESULTS

Nine hundred and eighty-eight individuals were genotyped using exome capture genotyping by sequencing (GBS) and 67,168 single nucleotide polymorphisms (SNPs) used to develop genomic estimated breeding values (GEBVs) with genomic best linear unbiased prediction (GBLUP). The documented pedigree was corrected using a subset of 704 SNPs. The percentage of trio parentage confirmed was about 49% and about 50% of parents were re-assigned. The accuracy of GEBVs was 0.55-0.75 when using the documented pedigree and 0.61-0.80 when using the SNP-corrected pedigree. A higher percentage of additive genetic variance was explained and a higher predictive ability was observed when using the SNP-corrected pedigree than using the documented pedigree. With the documented pedigree, genomic selection was similar to traditional forward selection when assuming a generation interval of 17 years, but worse than traditional forward selection when assuming a generation interval of 14 years. After the pedigree was corrected, genomic selection led to 37-115% and 13-77% additional genetic gain over traditional forward selection when generation intervals of 17 years and 14 years were assumed, respectively.

CONCLUSION

It was concluded that genomic selection with a pedigree corrected by SNP information was an efficient way of improving non-key traits in radiata pine breeding.