Q: What do plant fertilization, diurnal rhythms and hybrid vigour all have in common?

A: They are all con­nec­ted by Epigenetics.

Jeff Chen

Dr. Z. Jeff Chen inspects a cot­ton plant. Photo © Marsha Miller.

Presenting the first Annals of Botany Special Seminar* at the Plant Sciences Department at Oxford University on March 31st, Professor Jeff Chen (University of Texas) explained how his interest in poly­ploidy (the pos­ses­sion of more than the usual dip­loid sets of chro­mo­somes) had led him to an under­stand­ing of hybrid vigour – where crosses between dif­fer­ent plant lines can pro­duce plants with yields greater than either par­ent and per­haps the most import­ant chal­lenge of mod­ern plant breeding.

Some time ago Jeff real­ized that the dif­fer­ent chro­mo­some sets of poly­ploids some­how com­mu­nic­ated with each other, and by enter­ing the new and com­plex world of epi­gen­et­ics – where modi­fic­a­tion of chro­matin pro­teins and non-sequence-changing chem­ical alter­a­tions to the DNA can res­ult in her­it­able traits – he was able to show that this was car­ried out via pop­u­la­tions of small, non-coding RNA molecules. He showed the audi­ence how, through a series of exper­i­ments using Arabidopsis poly­ploids and hybrids, his group had dis­covered that epi­gen­etic sys­tems reg­u­late the level and rhythm of the expres­sion of genes involved in pho­to­syn­thesis and starch metabolism.

In these high-performing poly­ploids and hybrids, these genes were expressed at high levels dur­ing the day with several-fold increases over their par­ents. When, and pre­cisely how, these expres­sion pat­terns are set up will clearly require more research, but quot­ing unpub­lished work from his labor­at­ory Jeff indic­ated that ‘rela­tion­ships’ estab­lished between gen­omes dur­ing fer­til­isa­tion by small RNA pop­u­la­tions were import­ant in determ­in­ing which genes in which gen­omes were expressed in early development.

Jeff Chen is the D.J. Sibly Centenniel Professor in Plant Molecular Genetics in Texas, and cur­rently holds a Fulbright Visiting Fellowship in Professor Sir David Baulcombe’s group at the Department of Plant Sciences, Cambridge University.

* Annals of Botany Special Seminars — a series of sem­inars run by Annals of Botany Editors that fund emin­ent research­ers in plant sci­ences to give talks at their uni­ver­sit­ies and Institutes. []

Lab webpage: http://​poly​ploidy​.biosci​.utexas​.edu/

Key paper: Ni, Z., Kim, E., Ha, M., Lackey, E., Liu, J., Zhang, Y., Sun, Q., and Chen, Z. J. (2009) Altered cir­ca­dian rhythms reg­u­late growth vigour in hybrids and allo­poly­ploids. Nature 457: 327–331 doi:10.1038/nature07523 (Mendeley)

Review: Chen, Z. J. (2010) Molecular mech­an­isms of poly­ploidy and hybrid vigor. Trends in Plant Science 15: 57–71. doi:10.1016/j.tplants.2009.12.003 (Mendeley)

Relevant AoB Reviews on epigenetics

(i) Grant-Downton, R. and Dickinson, H.G. (2005) Epigenetics and its implic­a­tions in plant bio­logy. 1. The epi­gen­etic net­work in plants. Annals of Botany 96: 1143–1164. doi:10.1093/aob/mci273 (Mendeley)

(ii) Grant-Downton, R. and Dickinson, H.G. (2006) Epigenetics and its implic­a­tions in plant bio­logy; The ‘epi­gen­etic epi­phany’. 2. epi­gen­et­ics, evol­u­tion and bey­ond. Annals of Botany 97: 11–27. doi:10.1093/aob/mcj001 (Mendeley)

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