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Carbon
partitioning in Lotus japonicus
We
have used our TILLING
platform to isolate mutants of carbon partitioning in Lotus
japonicus, especially those related to nodule carbon supply.
To date these included the enzymes: plastidial phosphoglucomutase;
phosphoglucoisomerase; ADPG pyrophosphorylase; sucrose synthase (susy; 4 isoforms); nodule-enhanced
malate dehydrogenase (MDH) and nodule alkaline invertase (AI).
We are currently evaluating the mutant phenotypes to determine
the pathway of carbon to the bacteroid and the growing nodule.
We
have determined that at least two susy isoforms are
active in the nodule and have been examining whether mutants of
them have the same impact on nodule metabolism as those at the
rug4
locus in pea. We have discovered that, unlike pea where one isoform
dominates, both isoforms make a significant contribution to N
assimilation in L japonicus (Horst et al, 2007). Click
here for a short pdf show. In contrast, nodule-enhanced AI does not affect N assimilation, but does have a dramatic effect on plant development (Welham et al, 2009). Click here for a short pdf show.
Horst
I, Welham T, Kelly S, Kaneko T, Sato S, Tabata S, Parniske M,
Wang TL. TILLING mutants of Lotus japonicus reveal that
nitrogen assimilation and fixation can occur in the absence of
nodule-enhanced sucrose synthase. Plant Physiology 144: 806-820,2007.
Welham T., Pike P., Horst I., Flemetakis E., Katinakis P., Kaneko T., Sato, S. Tabata S., Perry J., Parniske P., Wang TL. A cytosolic invertase is required for normal growth and cell development in the model legume, Lotus japonicus. Journal of Experimental Botany 60, 3353-3365, 2009. |
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