Funds flood into plant water use research

Image: Wikimedia Commons.

Image: Wikimedia Commons.

For too long, CAM [crassu­lacean acid meta­bol­ism, in which CO2 is fixed into an organic acid at night when sto­mata are open(!) in such plants and re-fixed via the Calvin–Benson–Bassham et al. Cycle – C3 pho­to­syn­thesis dur­ing day­light, when sto­mata are shut(!!)…] has been on the plant physiolo­gical side­lines as a quirky bit of bio­chem­istry at one end of the spec­trum of pho­to­syn­thetic variations-on-a-theme. But now it is poised to take centre stage as more water-efficient solu­tions for plant bio­logy are sought as we enter a water-frugal age.

Famously, the water-use effi­ciency (WUE), which describes ‘a plant’s pho­to­syn­thetic pro­duc­tion rate rel­at­ive to the rate at which it tran­spires water to the atmo­sphere’ (e.g. Lucas Cernusak et al.) of CAM plants is rather low, which is good. However, they do also tend to grow rather slowly – albeit in hot­ter climes than tem­per­ate ones – which is not so good if you are inter­ested in high-yielding crops to feed a grow­ing world pop­u­la­tion or gen­er­ate lots of bio­mass in a hurry. But if you are con­cerned about the abil­ity of today’s plants to cope with drier, warmer cli­mates in future, CAM might have a lot to offer.

If a new transat­lantic alli­ance has its way, CAM is set to invade the world of the C3 pho­to­syn­thes­isers with US$14.3 mil­lion of fund­ing from the USA’s Department of Energy. The dosh will be dished out amongst the Universities of Nevada and Tennessee (in the USA), Liverpool and Newcastle (in the UK), and the USA’s Oak Ridge National Laboratory.

Although crops may bene­fit from this research in the longer term, a more imme­di­ate shorter-term goal is to engin­eer CAM into the fast-growing bio­mass energy tree pop­lar so it can cope bet­ter with anti­cip­ated future grow­ing con­di­tions. CAM, coupled with a genet­ic­ally engin­eered semi-dwarf stature in pop­lar (Ani Elias et al.), may be a ‘neg­at­ive double-whammy’ that can deliver tree phen­o­types that are not only more water-use-efficient, but advant­age­ous for short-rotation forestry and bio­mass energy purposes.

So no longer will CAM be the exclus­ive pre­serve of such exot­ics as pine­apples, epi­phytic orch­ids and Crassula spe­cies, and the notion of pop­lar as a ‘fac­ultat­ive CAM plant’ – a sort of Mesembryanthemum crys­tallinum of the tem­per­ate forest – might just be sci­ence fic­tion turned into sci­ence fact. However, if Ming Yuan et al.’s work on Camellia – ‘tree-like shrubs’ – is widely applic­able, then CAM can be induced in C3 spe­cies (such as, say – and chosen entirely at ran­dom you under­stand – pop­lar) by the much cheaper option of fungus infec­tion. Hmmm, who’ll be the first to tell the UK–USA team/DoE that..?


Nigel Chaffey. ORCID 0000-0002-4231-9082

Nigel is a botanist and full-time academic at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany he contributes the monthly Plant Cuttings column to that august international botanical organ. His main goal is to inform (hopefully, in an educational, and entertaining way...) about plants and plant-people interactions.

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