Editing Pinaceae (section)

== Defense mechanisms ==
External stresses on plants have the ability to change the structure and composition of [[Forest ecology|forest ecosystems]]. Common external stress that ''Pinaceae'' experience are [[herbivore]] and [[pathogen]] attack which often leads to tree death.<ref name=":7">{{Cite journal|last1=Cherubini|first1=Paolo|last2=Fontana|first2=Giovanni|last3=Rigling|first3=Daniel|last4=Dobbertin|first4=Matthias|last5=Brang|first5=Peter|last6=Innes|first6=John L.|date=2002|title=Tree-Life History Prior to Death: Two Fungal Root Pathogens Affect Tree-Ring Growth Differently|jstor=3072253|journal=Journal of Ecology|volume=90|issue=5|pages=839–850|doi=10.1046/j.1365-2745.2002.00715.x|doi-access=free|bibcode=2002JEcol..90..839C }}</ref> In order to combat these stresses, trees need to adapt or evolve defenses against these stresses. ''Pinaceae'' have evolved myriad mechanical and chemical defenses, or a combination of the two, in order to protect themselves against antagonists.<ref name=":1">{{Cite journal|title=Terpenoid biosynthesis and specialized vascular cells of conifer defense. - Semantic Scholar|year=2010|doi=10.1111/j.1744-7909.2010.00910.x|pmid=20074143|s2cid=26043965|last1=Zulak|first1=K. G.|last2=Bohlmann|first2=J.|journal=Journal of Integrative Plant Biology|volume=52|issue=1|pages=86–97|doi-access=free}}</ref> ''Pinaceae'' have the ability to up-regulate a combination of constitutive mechanical and [[Chemical defense|chemical strategies]] to further their defenses.<ref name=":8">{{Cite journal|last1=Franceschi|first1=Vincent R.|last2=Krokene|first2=Paal|last3=Christiansen|first3=Erik|last4=Krekling|first4=Trygve|date=2005-08-01|title=Anatomical and chemical defenses of conifer bark against bark beetles and other pests|journal=New Phytologist|language=en|volume=167|issue=2|pages=353–376|doi=10.1111/j.1469-8137.2005.01436.x|pmid=15998390|issn=1469-8137|doi-access=free}}</ref>

''Pinaceae'' defenses are prevalent in the bark of the trees. This part of the tree contributes a complex defensive boundary against external antagonists.<ref name=":0">Franceschi, V. R., P. Krokene, T. Krekling, and E. Christiansen. 2000. Phloem parenchyma cells are involved in local and distance defense response to fungal inoculation or bark-beetle attack in Norway spruce (''Pinaceae''). American Journal of Botany 87:314-326.</ref> [[Constitutive defense|Constitutive]] and [[Inducible plant defenses against herbivory|induced defenses]] are both found in the bark.<ref name=":0" /><ref name=":6">{{Cite journal|last1=Hudgins|first1=J. W.|last2=Christiansen|first2=E.|last3=Franceschi|first3=V. R.|date=2004-03-01|title=Induction of anatomically based defense responses in stems of diverse conifers by methyl jasmonate: a phylogenetic perspective|journal=Tree Physiology|language=en|volume=24|issue=3|pages=251–264|doi=10.1093/treephys/24.3.251|pmid=14704135|issn=0829-318X|doi-access=free}}</ref><ref name=":9">{{Cite journal|last1=Krokene|first1=P.|last2=Nagy|first2=N. E.|last3=Solheim|first3=H.|date=2008-01-01|title=Methyl jasmonate and oxalic acid treatment of Norway spruce: anatomically based defense responses and increased resistance against fungal infection|journal=Tree Physiology|language=en|volume=28|issue=1|pages=29–35|doi=10.1093/treephys/28.1.29|pmid=17938111|issn=0829-318X|doi-access=free}}</ref>

=== Constitutive defenses ===
[[Constitutive defense]]s are typically the first line of defenses used against antagonists and can include sclerified cells, lignified periderm cells, and secondary compounds such as [[Phenols|phenolics]] and resins.<ref name=":2">{{Cite journal|last=Sampedro|first=L.|date=2014-09-01|title=Physiological trade-offs in the complexity of pine tree defensive chemistry|journal=Tree Physiology|language=en|volume=34|issue=9|pages=915–918|doi=10.1093/treephys/tpu082|pmid=25261122|issn=0829-318X|doi-access=free|hdl=10261/105595|hdl-access=free}}</ref><ref name=":0" /><ref name=":6" /> Constitutive defenses are always expressed and offer immediate protection from invaders but could also be defeated by antagonists that have evolved adaptations to these defense mechanisms.<ref name=":2" /><ref name=":0" /> One of the common secondary compounds used by ''Pinaceae'' are phenolics or polyphenols. These secondary compounds are preserved in [[vacuole]]s of polyphenolic [[Parenchyma|parenchyma cells]] (PP) in the [[Phloem|secondary phloem]].<ref name=":3">{{Cite journal|last1=Nagy|first1=N. E.|last2=Krokene|first2=P.|last3=Solheim|first3=H.|date=2006-02-01|title=Anatomical-based defense responses of Scots pine (Pinus sylvestris) stems to two fungal pathogens|journal=Tree Physiology|language=en|volume=26|issue=2|pages=159–167|doi=10.1093/treephys/26.2.159|pmid=16356912|issn=0829-318X|doi-access=free}}</ref><ref name=":9" />

=== Induced defenses ===
[[Inducible plant defenses against herbivory|Induced defense]] responses need to be activated by certain cues, such as herbivore damage or other biotic signals.<ref name=":2" />

A common induced defense mechanism used by ''Pinaceae'' is resins.<ref name=":4">{{Cite journal|last1=Nagy|first1=Nina E.|last2=Franceschi|first2=Vincent R.|last3=Solheim|first3=Halvor|last4=Krekling|first4=Trygve|last5=Christiansen|first5=Erik|date=2000-03-01|title=Wound-induced traumatic resin duct development in stems of Norway spruce (Pinaceae): anatomy and cytochemical traits|journal=American Journal of Botany|language=en|volume=87|issue=3|pages=302–313|doi=10.2307/2656626|issn=1537-2197|jstor=2656626|pmid=10718991}}</ref> Resins are also one of the primary defenses used against attack.<ref name=":1" /> Resins are short term defenses that are composed of a complex combination of volatile [[Monoterpene|mono]]- (C<sub>10</sub>) and [[sesquiterpene]]s (C<sub>15</sub>) and nonvolatile [[diterpene]] resin acids (C<sub>20</sub>).<ref name=":1" /><ref name=":4" /> They are produced and stored in specialized secretory areas known as resin ducts, resin blisters, or resin cavities.<ref name=":4" /> Resins have the ability to wash away, trap, fend off antagonists, and are also involved in wound sealing.<ref name=":3" /> They are an effective defense mechanism because they have toxic and inhibitory effects on invaders, such as insects or pathogens.<ref name=":5">{{Cite journal|last1=Lewinsohn|first1=Efraim|last2=Gijzen|first2=Mark|last3=Croteau|first3=Rodney|date=1991-05-01|title=Defense Mechanisms of Conifers: Differences in Constitutive and Wound-Induced Monoterpene Biosynthesis Among Species|journal=Plant Physiology|language=en|volume=96|issue=1|pages=44–49|doi=10.1104/pp.96.1.44|issn=0032-0889|pmid=16668184|pmc=1080711}}</ref> Resins could have developed as an evolutionary defense against [[bark beetle]] attacks.<ref name=":4" /> One well researched resin present in ''Pinaceae'' is [[oleoresin]]. Oleoresin had been found to be a valuable part of the [[Pinophyta|conifer]] defense mechanism against [[Biotic stress|biotic attacks]].<ref name=":5" /> They are found in [[Plant secretory tissue|secretory tissues]] in tree stems, roots, and leaves.<ref name=":5" /> Oleoresin is also needed in order to classify conifers.<ref name=":5" />

=== Active research: methyl jasmonate ===
The topic of defense mechanisms within family ''Pinaceae'' is a very active area of study with numerous studies being conducted. Many of these studies use [[methyl jasmonate]] (MJ) as an antagonist.<ref name=":6" /><ref name=":9" /><ref name=":10">{{Cite journal|last1=Fäldt|first1=Jenny|last2=Martin|first2=Diane|last3=Miller|first3=Barbara|last4=Rawat|first4=Suman|last5=Bohlmann|first5=Jörg|date=2003-01-01|title=Traumatic resin defense in Norway spruce (Picea abies): Methyl jasmonate-induced terpene synthase gene expression, and cDNA cloning and functional characterization of (+)-3-carene synthase|journal=Plant Molecular Biology|language=en|volume=51|issue=1|pages=119–133|doi=10.1023/A:1020714403780|pmid=12602896|s2cid=21153303|issn=0167-4412}}</ref> Methyl jasmonate is known to be able to induce defense responses in the stems of multiple ''Pinaceae'' species.<ref name=":6" /><ref name=":10" /> It has been found that MJ stimulated the activation of PP cells and formation of xylem traumatic resin ducts (TD). These are structures that are involved in the release of phenolics and resins, both forms of defense mechanism.<ref name=":6" /><ref name=":9" />

<gallery>
File:Pinceae_Bishop_pine_prickle_cone_pine_pinus_muricata.jpg | Close up of bishop pine cones
File:Pinaceae_Knobcone_Pine_Pinus_attenuata.jpg | Knobcone pine cone
</gallery>