Tie-dyed1 Regulates carbohydrate accumulation in maize leaves.

David M Braun,Michael G Muszynski,Yi Ma,Noriko Inada,R Frank Baker

doi:10.1104/pp.106.090381

David M Braun, Michael G Muszynski + Show 3 more

Open Access

https://doi.org/10.1104/pp.106.090381

Copy DOI

Abstract

Acquisition of cell identity requires communication among neighboring cells. To dissect the genetic pathways regulating cell signaling in later leaf development, a screen was performed to identify mutants with chloroplast pigmentation sectors that violate cell lineage boundaries in maize (Zea mays) leaves. We have characterized a recessive mutant, tie-dyed1 (tdy1), which develops stable, nonclonal variegated yellow and green leaf sectors. Sector formation requires high light, occurs during a limited developmental time, and is restricted to leaf blade tissue. Yellow tdy1 sectors accumulate excessive soluble sugars and starch, whereas green sectors appear unaffected. Significantly, starch accumulation precedes chlorosis in cells that will become a yellow sector. Retention of carbohydrates in tdy1 leaves is associated with a delay in reproductive maturity, decreased stature, and reduced yield. To explain the tdy1 sectoring pattern, we propose a threshold model that incorporates the light requirement and the hyperaccumulation of photoassimilates. A possible function consistent with this model is that TDY1 acts as a sugar sensor to regulate an inducible sugar export pathway as leaves develop under high light conditions.

Highlights

The maize (Zea mays) leaf has long been an attractive model system to study genes controlling leaf development and cell fate acquisition
While mutational analysis and the cloning and characterization of the respective genes have elucidated many of the early leaf patterning genes, much remains to be understood about the role cell-cell signaling plays in later leaf development
We describe the isolation and characterization of tie-dyed1, the first of a large group of mutants referred to as nonclonal sectoring mutants. tdy1 was isolated from an ethyl methanesulfonate (EMS) mutagenized population, and is inherited as a stable, nuclear recessive mutation that conditions variegated yellow and green leaf sectors. tdy1 sectoring is restricted to a limited time in leaf development and is uniform throughout a sector implicating cell signaling in sector formation

Summary

Introduction

The maize (Zea mays) leaf has long been an attractive model system to study genes controlling leaf development and cell fate acquisition. The mesophyll cells in green tdy sectors display intense membrane staining equivalent to wild type and bundle sheath cells show the same dark precipitate (Fig. 4B). Tdy yellow sectors accumulate excess carbohydrates prior to chlorosis To test whether all photosynthetic cells in a yellow sector were accumulating high levels of starch, we qualitatively examined wild type and tdy sectored leaves by iodine staining (Fig. 6). Yellow tdy leaf sectors displayed approximately 3% of the stomatal conductance compared to wild type leaves, whereas green sectors were not significantly different than wild type Together these results may suggest that the tdy yellow sectors are not actively synthesizing the large amounts of carbohydrates present in these tissues. These data suggest that the retention of carbohydrates in tdy leaves leads to the retardation of growth and yield of mutant plants

Discussion

Materials and Methods

Findings

Literature Cited