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Characterization of a allelic mutant of the rice NAL1 gene reveals its role in regulating cell division.

Jiang D, Fang J, Lou L, Zhao J, Yuan S, Yin L, Sun W, Peng L, Guo B, Li X - PLoS ONE (2015)

Bottom Line: In addition to defects in cell proliferation, the mutants showed abnormal midrib in leaves.Map-based cloning revealed that nal1-2 is a allelic mutant of NAL1 since both the whole promoter and a 404-bp fragment in the first exon of NAL1 were deleted, and that a 6-bp fragment was deleted in the mutant nal1-3.The altered transcript level of G1- and S-phase-specific genes suggested that NAL1 affects cell cycle regulation.

View Article: PubMed Central - PubMed

Affiliation: College of Life Sciences, Qingdao Agricultural University, Qingdao, China; National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.

ABSTRACT
Leaf morphology is closely associated with cell division. In rice, mutations in Narrow leaf 1 (NAL1) show narrow leaf phenotypes. Previous studies have shown that NAL1 plays a role in regulating vein patterning and increasing grain yield in indica cultivars, but its role in leaf growth and development remains unknown. In this report, we characterized two allelic mutants of NARROW LEAF1 (NAL1), nal1-2 and nal1-3, both of which showed a 50% reduction in leaf width and length, as well as a dwarf culm. Longitudinal and transverse histological analyses of leaves and internodes revealed that cell division was suppressed in the anticlinal orientation but enhanced in the periclinal orientation in the mutants, while cell size remained unaltered. In addition to defects in cell proliferation, the mutants showed abnormal midrib in leaves. Map-based cloning revealed that nal1-2 is a allelic mutant of NAL1 since both the whole promoter and a 404-bp fragment in the first exon of NAL1 were deleted, and that a 6-bp fragment was deleted in the mutant nal1-3. We demonstrated that NAL1 functions in the regulation of cell division as early as during leaf primordia initiation. The altered transcript level of G1- and S-phase-specific genes suggested that NAL1 affects cell cycle regulation. Heterogeneous expression of NAL1 in fission yeast (Schizosaccharomyces pombe) further supported that NAL1 affects cell division. These results suggest that NAL1 controls leaf width and plant height through its effects on cell division.

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Phenotypes of nal1-2.(A) Morphology of wild-type (WT; Nipponbare, left) and nal1-2 (right) plants at the heading stage (bar = 5 cm). (B) Comparison of leaf width between the WT (left) and nal1-2 (right) (bar = 5 mm). (C) Comparison of leaf length between the WT (left) and nal1-2 (right) (bar = 5 cm). (D) Comparison of seed phenotype between the WT (left) and nal1-2 (right) (bar = 0.5 mm). (E, F) Transverse sections through the middle part of the mature upper second leaves of WT (E) and nal1-2 plants (F) (bars = 1 mm). Asterisk and circle in E and F indicate large vein and small vein, respectively.
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pone.0118169.g001: Phenotypes of nal1-2.(A) Morphology of wild-type (WT; Nipponbare, left) and nal1-2 (right) plants at the heading stage (bar = 5 cm). (B) Comparison of leaf width between the WT (left) and nal1-2 (right) (bar = 5 mm). (C) Comparison of leaf length between the WT (left) and nal1-2 (right) (bar = 5 cm). (D) Comparison of seed phenotype between the WT (left) and nal1-2 (right) (bar = 0.5 mm). (E, F) Transverse sections through the middle part of the mature upper second leaves of WT (E) and nal1-2 plants (F) (bars = 1 mm). Asterisk and circle in E and F indicate large vein and small vein, respectively.

Mentions: The phenotypes of nal1-2 mainly showed reduced leaf width and length by more than 50% compared with the WT (Fig. 1A, B, C; Table 1). The leaf index (the ratio of the leaf length to width) of flag leaves in nal1-2 was normal, which suggested that the shape of leaves in nal1-2 was not affected, similar to seed shape and size (Fig. 1C, D; Table 1). The amount of large and small veins within the upper second leaf in nal1-2 reached only 68% and 32% of their WT counterparts, respectively (Fig. 1E, F; Table 1). Tiller number in nal1-2 approached approximately 240% compared to the WT at the filling stage (Table 1). The decrease in plant height in nal1-2 was evident. As shown in Fig. 1A and Table 1, the height of nal1-2 was reduced by approximately 50% compared to the WT. These results indicated that the mutant nal1-2 possesses severe phenotypes.


Characterization of a allelic mutant of the rice NAL1 gene reveals its role in regulating cell division.

Jiang D, Fang J, Lou L, Zhao J, Yuan S, Yin L, Sun W, Peng L, Guo B, Li X - PLoS ONE (2015)

Phenotypes of nal1-2.(A) Morphology of wild-type (WT; Nipponbare, left) and nal1-2 (right) plants at the heading stage (bar = 5 cm). (B) Comparison of leaf width between the WT (left) and nal1-2 (right) (bar = 5 mm). (C) Comparison of leaf length between the WT (left) and nal1-2 (right) (bar = 5 cm). (D) Comparison of seed phenotype between the WT (left) and nal1-2 (right) (bar = 0.5 mm). (E, F) Transverse sections through the middle part of the mature upper second leaves of WT (E) and nal1-2 plants (F) (bars = 1 mm). Asterisk and circle in E and F indicate large vein and small vein, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4320051&req=5

pone.0118169.g001: Phenotypes of nal1-2.(A) Morphology of wild-type (WT; Nipponbare, left) and nal1-2 (right) plants at the heading stage (bar = 5 cm). (B) Comparison of leaf width between the WT (left) and nal1-2 (right) (bar = 5 mm). (C) Comparison of leaf length between the WT (left) and nal1-2 (right) (bar = 5 cm). (D) Comparison of seed phenotype between the WT (left) and nal1-2 (right) (bar = 0.5 mm). (E, F) Transverse sections through the middle part of the mature upper second leaves of WT (E) and nal1-2 plants (F) (bars = 1 mm). Asterisk and circle in E and F indicate large vein and small vein, respectively.
Mentions: The phenotypes of nal1-2 mainly showed reduced leaf width and length by more than 50% compared with the WT (Fig. 1A, B, C; Table 1). The leaf index (the ratio of the leaf length to width) of flag leaves in nal1-2 was normal, which suggested that the shape of leaves in nal1-2 was not affected, similar to seed shape and size (Fig. 1C, D; Table 1). The amount of large and small veins within the upper second leaf in nal1-2 reached only 68% and 32% of their WT counterparts, respectively (Fig. 1E, F; Table 1). Tiller number in nal1-2 approached approximately 240% compared to the WT at the filling stage (Table 1). The decrease in plant height in nal1-2 was evident. As shown in Fig. 1A and Table 1, the height of nal1-2 was reduced by approximately 50% compared to the WT. These results indicated that the mutant nal1-2 possesses severe phenotypes.

Bottom Line: In addition to defects in cell proliferation, the mutants showed abnormal midrib in leaves.Map-based cloning revealed that nal1-2 is a allelic mutant of NAL1 since both the whole promoter and a 404-bp fragment in the first exon of NAL1 were deleted, and that a 6-bp fragment was deleted in the mutant nal1-3.The altered transcript level of G1- and S-phase-specific genes suggested that NAL1 affects cell cycle regulation.

View Article: PubMed Central - PubMed

Affiliation: College of Life Sciences, Qingdao Agricultural University, Qingdao, China; National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.

ABSTRACT
Leaf morphology is closely associated with cell division. In rice, mutations in Narrow leaf 1 (NAL1) show narrow leaf phenotypes. Previous studies have shown that NAL1 plays a role in regulating vein patterning and increasing grain yield in indica cultivars, but its role in leaf growth and development remains unknown. In this report, we characterized two allelic mutants of NARROW LEAF1 (NAL1), nal1-2 and nal1-3, both of which showed a 50% reduction in leaf width and length, as well as a dwarf culm. Longitudinal and transverse histological analyses of leaves and internodes revealed that cell division was suppressed in the anticlinal orientation but enhanced in the periclinal orientation in the mutants, while cell size remained unaltered. In addition to defects in cell proliferation, the mutants showed abnormal midrib in leaves. Map-based cloning revealed that nal1-2 is a allelic mutant of NAL1 since both the whole promoter and a 404-bp fragment in the first exon of NAL1 were deleted, and that a 6-bp fragment was deleted in the mutant nal1-3. We demonstrated that NAL1 functions in the regulation of cell division as early as during leaf primordia initiation. The altered transcript level of G1- and S-phase-specific genes suggested that NAL1 affects cell cycle regulation. Heterogeneous expression of NAL1 in fission yeast (Schizosaccharomyces pombe) further supported that NAL1 affects cell division. These results suggest that NAL1 controls leaf width and plant height through its effects on cell division.

Show MeSH
Related in: MedlinePlus