Abstract
Maize (Zea mays) leaves develop basipetally (tip to base); the upper blade emerges from the shoot apical meristem (SAM) before the expansion of the lower sheath. Founder cells, leaf initials located in the periphery of the SAM, are distinguished from the SAM proper by the differential accumulation of KNOX proteins. KNOX proteins accumulate in the SAM, but are excluded from maize leaf primordia and leaf founder cells. As in Arabidopsis and tomato (Lycopersicon esculentum), maize shoots failed to initiate new leaves when cultured in the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). We demonstrate that NPA-induced arrest of leaf initiation in maize is correlated with the failure to down-regulate KNOX accumulation in the SAM. In addition, NPA-cultured shoots formed abnormal tubular leaf bases in which the margins failed to separate in the lower leaf zone. The tubular leaf bases always formed in the fourth leaf from the arrested meristem. Moreover, the unseparated margin domains of these tubular leaf bases accumulated ectopic KNOX protein(s). Transfer of NPA-cultured apices to NPA-free media resulted in the resumption of leaf initiation from the SAM and the restoration of normal patterns of KNOX down-regulation, accordingly. These data suggest that the lower sheath margins emerge from the leaf base late in maize leaf development and that the separation of these leaf margin domains is correlated with auxin transport and down-regulation of KNOX proteins. In addition, these results suggest that the down-regulation of KNOX accumulation in maize apices is not upstream of polar auxin transport, although a more complicated feedback network may exist. A model for L1-derived margin development in maize leaves is presented.
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Claims 5
Claim · model-written summary
NPA-cultured maize shoots failed to initiate new leaves.
- Treatment
- polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA)e1
- Outcome
- initiate new leavese1
Zea maysNot reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“maize shoots failed to initiate new leaves when cultured in the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA)”
Claim · model-written summary
NPA-induced arrest of maize leaf initiation is correlated with failure to down-regulate KNOX accumulation in the shoot apical meristem.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“We demonstrate that NPA-induced arrest of leaf initiation in maize is correlated with the failure to down-regulate KNOX accumulation in the SAM”
Claim · model-written summary
NPA-cultured maize shoots formed abnormal tubular leaf bases, always in the fourth leaf from the arrested meristem, with margins that failed to separate.
- Organ / stage
- fourth leaf from the arrested meristeme4
- Treatment
- NPAe3
- Outcome
- abnormal tubular leaf basese3
- Qualifier
- the margins failed to separate in the lower leaf zonee3
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leaf Margins in Maize”
e3“NPA-cultured shoots formed abnormal tubular leaf bases in which the margins failed to separate in the lower leaf zone”
e4“The tubular leaf bases always formed in the fourth leaf from the arrested meristem”
Claim · model-written summary
Unseparated margin domains of the tubular leaf bases in maize accumulated ectopic KNOX protein(s).
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leaf Margins in Maize”
e5“the unseparated margin domains of these tubular leaf bases accumulated ectopic KNOX protein(s)”
Claim · model-written summary
Transferring NPA-cultured maize apices to NPA-free media resumed leaf initiation from the shoot apical meristem and restored normal KNOX down-regulation.
- Treatment
- NPA-free mediae6
- Outcome
- resumption of leaf initiation from the SAM and the restoration of normal patterns of KNOX down-regulatione6
- Comparator
- NPA-cultured apicese6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Leaf Margins in Maize”
e6“Transfer of NPA-cultured apices to NPA-free media resulted in the resumption of leaf initiation from the SAM and the restoration of normal patterns of KNOX down-regulation”
The same questions in other papers
in vitro · molecular: expression · Zea mays (maize)Positive and negative results
4 papers in the same direction as this paper · 3 in the opposite direction
- negative
- no effect
- no effect
4 papers more in this group
See all 8 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.