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Microtubule Orientation in the Brassinosteroid Mutants lk, lka and lkb of Pea


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Knowles, CL and Koutoulis, A and Reid, JB (2004) Microtubule Orientation in the Brassinosteroid Mutants lk, lka and lkb of Pea. Journal of Plant Growth Regulation, 23. pp. 146-155. ISSN 0721-7595

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Short brassinosteroid (BR) mutants lk, lka and lkb of pea (Pisum sativum L.) were investigated by immunofluorescence microscopy to elucidate the role of brassinosteroids in cell elongation via an effect on the microtubules (MTs). This study adds to our knowledge the fact that brassinolide (BL) can cause MT realignment in azuki bean and rescue the MT organization of BR mutants in Arabidopsis. It provides novel information on both cortical and epidermal cells and presents detailed information about the ratios of all MT orientations present, ranging from transverse (perpendicular to the elongating axis) to longitudinal (parallel to the elongating axis). Experiments were conducted in vivo using intact plants with direct application of a small amount of brassinolide (BL) to the internode. Employing a BR-receptor mutant, lka, and the BRsynthesis mutants, lk and lkb, allowed the identification and isolation of any BR-induced responses in the MT cytoskeleton following BL application. Increases in growth rate were noted in all pea lines including WT following BL application. These increases were strong in the BR-synthesis mutants, but weak in the BR-receptor mutant. Immunofluorescence revealed significant differences in the average MT orientation of cortical cells of mutants versus WTs. Importantly, these mutants possessed abundant MTs, unlike the BR-deficient bul1-1 mutant in Arabidopsis. Following BL application, the epidermal and cortical cells of lk and lkb plants showed a large and significant shift in MT orientation towards more transverse, whereas lka plants showed a small and nonsignificant response in these cells. These results suggest that the BR response pathwa

Item Type: Article
Journal or Publication Title: Journal of Plant Growth Regulation
Page Range: pp. 146-155
ISSN: 0721-7595
Identification Number - DOI: 10.1007/s00344-004-0010-x
Additional Information: The final publication is available at
Date Deposited: 06 Feb 2012 02:32
Last Modified: 18 Nov 2014 04:27
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