Editing Brassicaceae (section)

== Ecology ==
Brassicaceae are almost exclusively [[Entomophily|pollinated by insects]]. A chemical mechanism in the pollen is active in many species to avoid [[self-pollination|selfing]]. Two notable exceptions are exclusive [[Cleistogamy|self-pollination in closed flowers]] in ''[[Cardamine chenopodifolia]]'', and wind pollination in ''[[Pringlea antiscorbutica]]''.<ref name=BioDis /> Although it can be cross-pollinated, ''[[Alliaria petiolata]]'' (garlic mustard) is [[self-fertile]]. Most species reproduce sexually through seed, but ''[[Cardamine bulbifera]]'' produces [[Gemma (botany)|gemmae]] and in others, such as ''[[Cardamine pentaphyllos]]'', the coral-like roots easily break into segments, that will grow into separate plants.<ref name=BioDis /> In some species, such as in the genus ''[[Cardamine]]'', seed pods open with force and so catapult the seeds quite far. Many of these have sticky seed coats, assisting long-distance dispersal by animals, and this may also explain several intercontinental dispersal events in the genus, and its near global distribution. Brassicaceae are common on [[serpentine soil|serpentine]] and [[Dolomite (mineral)|dolomite]] rich in [[magnesium]]. Over a hundred species in the family accumulate [[heavy metals]], particularly [[zinc]] and [[nickel]], which is a record percentage.<ref name=MOBOT>{{cite web|website= MOBOT|title= Brassicales|url= http://www.mobot.org/MOBOT/research/APweb/orders/brassicalesweb.htm#Brassicaceae|access-date= 2017-07-18}}</ref> Several ''Alyssum'' species can accumulate nickel up to 0.3% of their dry weight, and may be useful in [[soil remediation]] or even [[bio-mining]].<ref>{{cite journal|first1= Catherine L.|last1= Broadhurst|first2= Rufus L.|last2= Chaney|year= 2016|title= Growth and Metal Accumulation of an Alyssum murale Nickel Hyperaccumulator Ecotype Co-cropped with Alyssum montanum and Perennial Ryegrass in Serpentine Soil|journal= [[Frontiers in Plant Science]]|volume= 7|issue= 451|pages= 451|doi=10.3389/fpls.2016.00451|pmc=4824781|pmid=27092164|doi-access= free}}</ref>

Brassicaceae contain [[glucosinolate]]s as well as [[myrosinase]]s inside their cells. When the cell is damaged, the myrosinases [[Hydrolysis|hydrolise]] the glucosinolates, leading to the synthesis of [[isothiocyanate]]s, which are [[Plant defense against herbivory|compounds toxic to most animals]], fungi and bacteria. Some insect herbivores have developed counter adaptations such as rapid absorption of the glucosinates, quick alternative breakdown into non-toxic compounds and avoiding cell damage. In the whites family (Pieridae), one counter mechanism involves glucosinolate sulphatase, which changes the glucosinolate, so that it cannot be converted to isothiocyanate. A second is that the glucosinates are quickly broken down, forming nitriles.<ref name=HAW>{{cite book|first= Harry Arthur|last= Woods|title= Ecological and Environmental Physiology of Insects|volume= 3|series= Ecological and Environmental Physiology Series|publisher= Oxford biological}}</ref> Differences between the mixtures of glucosinolates between species and even within species is large, and individual plants may produce in excess of fifty individual substances. The energy penalty for synthesising all these glucosinolates may be as high as 15% of the total needed to produce a leaf. ''[[Barbarea vulgaris]]'' (bittercress) also produces [[triterpenoid saponin]]s. These adaptations and counter adaptations probably have led to extensive diversification in both the Brassicaceae and one of its major pests, the butterfly family [[Pieridae]]. A particular cocktail of volatile glucosinates triggers egg-laying in many species. Thus a particular crop can sometimes be protected by planting bittercress as a deadly bait, for the saponins kill the caterpillars, but the butterfly is still lured by the bittercress to lay its egg on the leaves.<ref>{{cite journal|last1= Winde|first1= I|last2= Wittstock|first2= U.|title= Insect herbivore counteradaptations to the plant glucosinolate-myrosinase system|year= 2011|journal= Phytochemistry|volume= 72|issue= 13|pages= 1566–75|doi=10.1016/j.phytochem.2011.01.016|pmid=21316065|bibcode= 2011PChem..72.1566W}}</ref>
A moth that feeds on a range of Brassicaceae is the [[diamondback moth]] (''Plutella xylostella''). Like the Pieridae, it is capable of converting isothiocyanates into less problematic [[nitrile]]s. Managing this pest in crops became more complicated after resistance developed against a toxin produced by ''[[Bacillus thuringiensis]]'', which is used as a wide spectrum biological [[plant protection]] against caterpillars. [[Parasitoid]] wasps that feed on such insect herbivores are attracted to the chemical compounds released by the plants, and thus are able to locate their prey. The [[cabbage aphid]] (''Brevicoryne brassicae'') stores glucosinolates and synthesises its own myrosinases, which may deter its potential predators.<ref name=MOBOT />

Since its introduction in the 19th century, ''Alliaria petiolata'' has been shown to be extremely successful as an [[invasive species]] in temperate North America due, in part, to its secretion of allelopathic chemicals. These inhibit the [[germination]] of most competing plants and kill beneficial soil [[fungi]] needed by many plants, such as many tree species, to successfully see their seedlings grow to maturity. The [[monoculture]] formation of an herb layer carpet by this plant has been shown to dramatically alter forests, making them wetter, having fewer and fewer trees, and having more vines such as poison ivy (''[[Toxicodendron radicans]]''). The overall herb layer [[biodiversity]] is also drastically reduced, particularly in terms of [[sedge]]s and [[forb]]s. Research has found that removing 80% of the garlic mustard [[infestation]] plants did not lead to a particularly significant recovery of that [[Biodiversity|diversity]]. Instead, it required around 100% removal. Given that not one of an estimated 76 [[species]] that [[prey]] on the plant has been approved for [[biological control]] in [[North America]] and the variety of mechanisms the plant has to ensure its dominance without them (e.g. high seed production, self-fertility, [[allelopathy]], spring growth that occurs before nearly all native plants, roots that break easily when pulling attempts are made, a complete lack of palatability for herbivores at all life stages, etc.) it is unlikely that such a high level of control can be established and maintained on the whole.<ref>{{cite report |first1=Roger |last1=Becker |first2=Esther |last2=Gerber |first3=Hariet L. |last3=Hinz |first4=Elizabeth |last4=Katovich |first5=Brendon |last5=Panke |first6=Richard |last6=Reardon |first7=Mark |last7=Renz |first8=Laura |last8=Van Riper |date=November 2013 |title=Biology and Biological Control of Garlic Mustard |url=https://www.lccmr.mn.gov/projects/2010/finals/2010_06a_rpt_biology-garlic-mustard.pdf }}</ref><ref>{{Cite web |last= |first= |title=Biological Control - Plant Management in Florida Waters - An Integrated Approach - University of Florida, Institute of Food and Agricultural Sciences - UF/IFAS |url=https://plants.ifas.ufl.edu/control-methods/biological-control/ |access-date=2024-10-17 |website=plants.ifas.ufl.edu |language=en}}</ref><ref name="wiki.bugwood.org">{{Cite web |title=BCIPEUS - Bugwoodwiki |url=https://wiki.bugwood.org/Archive:BCIPEUS |access-date=2024-10-17 |website=wiki.bugwood.org}}</ref><ref>{{Cite web |title=USDA ARS Online Magazine Vol. 57, No. 6 |url=https://agresearchmag.ars.usda.gov/2009/jul/weevil/ |access-date=2024-10-17 |website=agresearchmag.ars.usda.gov}}</ref><ref>Blossy, B., Ode, P., Pell, J.K., 1999. Development of Biological Control for Garlic Mustard. Cornell University. https://www.dnr.illinois.gov/grants/documents/wpfgrantreports/1998l06w.pdf</ref> It is estimated that adequate control can be achieved with the introduction of two European [[weevil]]s, including one that is [[monophagous]].<ref name=Landis>{{cite web |url=http://www.ipm.msu.edu/invasive_species/garlic_mustard/management_options |title=Management Options |last=Landis |first=Doug |website=Integrated Pest Management |publisher=Michigan State University |access-date=10 September 2017}}</ref><ref name="Reardon 2017">{{cite web |url=https://www.fs.fed.us/foresthealth/technology/pdfs/bc_prog_update_10_16.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.fs.fed.us/foresthealth/technology/pdfs/bc_prog_update_10_16.pdf |archive-date=2022-10-09 |url-status=live |title=FHTET Biological Control Program—Sponsored Projects |last=Reardon |first=Richard |website=FHTET Biological Control Program |publisher=USDA Forest Service |access-date=10 September 2017}}</ref> The [[USDA]]'s TAG group has blocked these introductions since 2004.<ref name="Becker 2017">{{cite web |last=Becker |first=R. |date=2017 |title=Implementing Biological Control of Garlic Mustard—Environment and Natural Resources Trust Fund 2017 RFP |url=http://www.lccmr.leg.mn/proposals/2017/original/107-d.pdf |archive-url=https://web.archive.org/web/20170904154820/http://www.lccmr.leg.mn/proposals/2017/original/107-d.pdf |archive-date=2017-09-04 |url-status=live}}</ref> In addition to being invasive, garlic mustard also is a threat to native North American ''[[Pieris (butterfly)|Pieris]]'' butterflies<ref name="wiki.bugwood.org" /><ref>{{cite thesis |last1=Davis |first1=Samantha |title=Evaluating Threats to the Rare Butterfly, ''Pieris virginiensis'' |date=2015 |url=https://corescholar.libraries.wright.edu/etd_all/1433/ }}</ref> such as ''[[Pieris oleracea|P.&nbsp;oleracea]]'', as they preferentially [[oviposit]] on it, although it is toxic to their [[larva]]e.

Invasive aggressive mustard species are known for being self-fertile, seeding very heavily with small seeds that have a lengthy lifespan coupled with a very high rate of viability and germination, and for being completely unpalatable to both herbivores and insects in areas to which they are not native. Garlic mustard is toxic to several rarer North American ''Pieris'' species.