Palm Biology

Cover for Palm Biology Issue of Annals of BotanyA Special issue from December 2011 ded­ic­ated to research in Palm (Arecaceae) Biology.

The con­tin­ued import­ance of the Arecaceae to man­kind is in no doubt; neither is the fas­cin­a­tion that palms hold to research­ers, due in no small part to the dis­tinct and often strik­ing forms seen in the fam­ily. This issue provides a snap­shot of recent and ongo­ing research dir­ec­tions and rein­forces the con­vic­tion within the world­wide com­munity that new gen­er­a­tions of sci­ent­ists will con­tinue to be drawn to the chal­lenge of palm bio­logy in the years to come.


A fam­ily por­trait: unrav­el­ling the com­plex­it­ies of palms by James W. Tregear, Alain Rival, and Jean-Christophe Pintaud.


Geographical ecology of the palms (Review)

Geographical eco­logy of the palms (Review)

Geographical eco­logy of the palms (Arecaceae): determ­in­ants of diversity and dis­tri­bu­tions across spa­tial scales by Wolf L. Eiserhardt, Jens-Christian Svenning, W. Daniel Kissling, and Henrik Balslev.

Palms (Arecaceae) are an import­ant ele­ment of trop­ical veget­a­tion across the world and serve as a model sys­tem in geo­graph­ical eco­logy.Eiserhardt et al. review how the abi­otic envir­on­ment, biotic inter­ac­tions and dis­persal influ­ence palm dis­tri­bu­tion and diversity pat­terns across spa­tial scales, and dis­cuss con­tem­por­ary vs. his­tor­ical impacts of these factors and the scale at which they func­tion. A key find­ing is that determ­in­ants of palm dis­tri­bu­tions, com­pos­i­tion and rich­ness vary with spa­tial scale.

Phylogeny of arecoid palms

Phylogeny of arec­oid palms

Phylogenetic rela­tion­ships among arec­oid palms (Arecaceae: Arecoideae) by William J. Baker, Maria V. Norup, James J. Clarkson, Thomas L. P. Couvreur, John L. Dowe, Carl E. Lewis, Jean-Christophe Pintaud, Vincent Savolainen, Tomas Wilmot, and Mark W. Chase.

The Arecoideae is the largest, most diverse and most eco­nom­ic­ally import­ant palm sub­fam­ily and yet rela­tion­ships within the group are poorly under­stood. Baker et al. col­lect nuc­lear DNA sequence data for the low-copy nuc­lear genes PRK and RPB2 from 190 palm spe­cies, cov­er­ing 103 gen­era of Arecoideae, and gen­er­ate the most extens­ive arec­oid phylo­geny pub­lished to date. Their find­ings strongly sup­port the cur­rent clas­si­fic­a­tion of palms, resolve sev­eral well-supported ‘deep’ rela­tion­ships and identify pri­or­it­ies for future research.

Single-copy nuclear genes for palm phylogenetics

Single-copy nuc­lear genes for palm phylogenetics

Phylogenetic util­ity of the nuc­lear genes AGAMOUS 1 and PHYTOCHROME B in palms (Arecaceae): an example within Bactridinae by Bertha Ludeña, Nathalie Chabrillange, Frédérique Aberlenc-Bertossi, Hélène Adam, James W. Tregear, and Jean-Christophe Pintaud.

Molecular phylo­gen­etic stud­ies of palms (Arecaceae) have not yet provided a fully resolved phylo­geny of the fam­ily. Ludeña et al. test the value of AGAMOUS 1 and PHYTOCHROME B genes as new nuc­lear mark­ers to improve phylo­gen­etic res­ol­u­tion in the fam­ily, using the sub­tribe Bactridinae as a case study. The res­ults provide new insights into the intergen­eric rela­tion­ships within Bactridinae and the intra­gen­eric struc­ture of Astrocaryum, and the exist­ence of a mono­phyletic group sis­ter to Astrocayum, cor­res­pond­ing to the debated genus Hexopetion, is sup­por­ted. The new mark­ers thus provide addi­tional phylo­gen­etic inform­a­tion within the palm fam­ily, and should prove use­ful in com­bin­a­tion with other genes to improve the res­ol­u­tion of palm phylogenies.

DNA barcoding: a new tool for palm taxonomists?

DNA bar­cod­ing: a new tool for palm taxonomists?

DNA bar­cod­ing: a new tool for palm tax­onom­ists? by Marc L. Jeanson, Jean-Noël Labat, and Damon P. Little.

Although tax­onomy of palms (Arecaceae) is fairly well known, many prob­lems remain and this is, in part, due to the dif­fi­cultly of rep­res­ent­ing palm diversity with herb­ar­ium spe­ci­mens. For the first time in Arecaceae, Jeanson et al. test the ultil­ity of DNA bar­cod­ing, examin­ing 40 out of the 48 spe­cies of the south-east Asian tribe Caryoteae (sub­fam­ily Coryphoideae). The res­ults show 92 % spe­cies’ dis­crim­in­a­tion, which is a high rate for a bar­cod­ing exper­i­ment. They find that the two recom­men­ded ‘core’ mark­ers, rbcL and matK, have a low dis­crim­in­a­tion rate and need to be sup­ple­men­ted by another marker, with nrITS2 being the pre­ferred choice for Caryoteae.

Epigenetic floral variant of clonal oil palm (Review)

Epigenetic floral vari­ant of clonal oil palm (Review)

Epigenetic imbal­ance and the floral devel­op­mental abnor­mal­ity of the in vitro-regenerated oil palm Elaeis guin­een­sis by Estelle Jaligot, Sophie Adler, Émilie Debladis, Thierry Beulé, Frédérique Richaud, Pascal Ilbert, E. Jean Finnegan, and Alain Rival.

The mantled somaclonal vari­ation of oil palm (Elaeis guin­een­sis) hampers oil pro­duc­tion as the super­nu­mer­ary female organs are either sterile or pro­duce fruits with poor oil yields. Jaligot et al. provide an over­view of research focus­ing on this intriguing floral phen­o­type, which also provides a unique oppor­tun­ity to invest­ig­ate epi­gen­etic reg­u­la­tion of repro­duct­ive devel­op­ment in palms. They pro­pose that future efforts should con­cen­trate on epi­gen­etic reg­u­la­tion tar­get­ing MADS-box genes and trans­pos­able ele­ments, since both types of sequences are most likely to be involved in this vari­ant phenotype.

In vitro regenration of peach palm

In vitro regen­ra­tion of peach palm

A tem­por­ary immer­sion sys­tem improves in vitro regen­er­a­tion of peach palm through sec­ond­ary somatic embryo­gen­esis by D. A. Steinmacher, M. P. Guerra, K. Saare-Surminski, and R. Lieberei.

Secondary somatic embryo­gen­esis has been pos­tu­lated to occur dur­ing induc­tion of peach palm (Bactris gas­ipaes) somatic embryo­gen­esis. Steinmacher et al. study this morpho­gen­etic path­way and use zygotic embryos as explants to develop a tech­nique for the estab­lish­ment of cyc­ling cul­tures using a tem­por­ary immer­sion sys­tem (TIS). They con­firm the occur­rence of sec­ond­ary somatic embryos in peach palm and describe a feas­ible pro­tocol for regen­er­a­tion in vitro. Plantlets are obtained and after 3 months in cul­ture their growth is sig­ni­fic­antly bet­ter in TIS than on solid cul­ture medium.

Shoot apical meristem structure in oil palm

Shoot apical mer­istem struc­ture in oil palm

The shoot apical mer­istem of oil palm (Elaeis guin­een­sis; Arecaceae): devel­op­mental pro­gres­sion and dynam­ics by Stefan Jouannic, Marc Lartaud, Jonathan Hervé, Myriam Collin, Yves Orieux, Jean-Luc Verdeil, and James W. Tregear.

Oil palm (Elaeis guin­een­sis) is an unbranched palm, pos­sess­ing a single shoot apical mer­istem (SAM) that may remain act­ive for more than 100 years. Through his­to­lo­gical ana­lysis and 3-D recon­struc­tions, Jouannic et al. detail the SAM struc­tural vari­ations that occur dur­ing the oil palm life cycle, and find that devel­op­ment of the SAM is char­ac­ter­ized by a juvenile-to-mature phase trans­ition accom­pan­ied by estab­lish­ment of a zonal pat­tern and mod­i­fied shape. SAM zon­a­tion is dynamic dur­ing the plasto­chron period and dis­plays dis­tinct fea­tures com­pared with other monocots.

Pericarp development and fruit structure in Borasseae

Pericarp devel­op­ment and fruit struc­ture in Borasseae

Pericarp devel­op­ment and fruit struc­ture in bor­ass­oid palms (Arecaceae–Coryphoideae–Borasseae) by Mikhail S. Romanov, Alexey V. F. Ch. Bobrov, D. Siril A. Wijesundara, and Ekaterina S. Romanova.

The Borasseae form a highly sup­por­ted mono­phyletic clade in the Arecaceae–Coryphoideae, and the large fruits of bor­ass­oid palms con­tain massive pyrenes, which develop from the middle zone of the meso­carp. Romanov et al. study peri­carp ana­tomy dur­ing devel­op­ment in all eight Borasseae gen­era and find that the mul­tilayered pyrene devel­ops in the middle zone of the meso­carp, and that the grow­ing seed dra­mat­ic­ally com­presses the inner par­en­chymat­ous zone of the meso­carp. The peri­carp ana­tom­ical struc­ture and mode of its devel­op­ment dif­fer sig­ni­fic­antly from fruits of other Coryphoideae.

Pollination mechanisms in palms (Review)

Pollination mech­an­isms in palms (Review)

Twenty-five years of pro­gress in under­stand­ing pol­lin­a­tion mech­an­isms in palms (Arecaceae) by Anders S. Barfod, Melanie Hagen, and Finn Borchsenius.

Understanding of palm–pollinator inter­ac­tions has implic­a­tions for trop­ical sil­vi­cul­ture, as well as for our know­ledge of the evol­u­tion and diver­si­fic­a­tion of Arecaceae. Barfod et al. review 25 years of pro­gress in palm pol­lin­a­tion eco­logy and note that more than 60 stud­ies have been pub­lished in this period that provide new insights on aute­co­lo­gical, com­par­at­ive and syn­eco­lo­gical aspects of palm pol­lin­a­tion. However, with detailed stud­ies of only 3 % of all palm spe­cies and a strong geo­graph­ical bias towards the South American region and a taxo­nomic bias towards the tribe Cocoseae, cau­tion should be exer­cised when mak­ing gen­er­al­iz­a­tions across the family.

Acervulate partial inflorescence in Chamaedoreeae

Acervulate par­tial inflor­es­cence in Chamaedoreeae

Ontogeny and struc­ture of the acer­vu­late par­tial inflor­es­cence in Hyophorbe lagen­i­caulis (Arecaceae; Arecoideae) by N. Ortega-Chávez and F. W. Stauffer.

The palm tribe Chamaedoreeae dis­plays flowers arranged in a com­plex par­tial inflor­es­cence called an acer­vu­lus. Ortega-Chávez and Stauffer exam­ine onto­geny in Hyophorbe lagen­i­caulis and show that the acer­vu­lus and the inflor­es­cence rachilla form a con­densed and cymose branch­ing sys­tem resem­bling a coen­o­some. Syndesmy res­ults from a com­bined pro­cess of rapid devel­op­ment and adna­tion, without or with reduced axis elong­a­tion. A study of the ten taxa of the Chamaedoreeae show that a more gen­eral defin­i­tion of the type of par­tial inflor­es­cence observed within the large sub­fam­ily Arecoideae would cor­res­pond to a cyme rather than to a floral triad.

Environmental regulation of sex determination in oil palm (Review)

Environmental reg­u­la­tion of sex determ­in­a­tion in oil palm (Review)

Environmental reg­u­la­tion of sex determ­in­a­tion in oil palm: cur­rent know­ledge and insights from other spe­cies by Hélène Adam, Myriam Collin, Frédérique Richaud, Thierry Beulé, David Cros, Alphonse Omoré, Leifi Nodichao, Bruno Nouy, and James W. Tregear.

In the African oil palm, Elaeis guin­een­sis, male and female inflor­es­cences are pro­duced sep­ar­ately in an altern­at­ing cycle that is influ­enced by the envir­on­ment: stress con­di­tions pro­mote male flower­ing, but the under­ly­ing mech­an­isms of this pro­cess are unknown. Adam et al. review cur­rent know­ledge of sex dif­fer­en­ti­ation in oil palm together with per­spect­ives gained from other spe­cies, and sug­gest that at least four dif­fer­ent types of factor can be iden­ti­fied that might par­ti­cip­ate in sex determ­in­a­tion and dif­fer­en­ti­ation: abi­otic factors (e.g. water stress), meta­bolic factors (e.g. car­bon reserves), hor­mone status and genetic factors. They present a basic frame­work as a step towards under­stand­ing the inter­ac­tions between the vari­ous para­met­ers of import­ance in oil palm sex determination.

Book reviews

The ana­tomy of palms (Arecaceae–Palmae) review by James Tregear.

The book of palms review by James Tregear.

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