2017 ASHS Annual Conference
Using a Maize Cytokinin Mutant to Study Organ Formation
Using a Maize Cytokinin Mutant to Study Organ Formation
Wednesday, September 20, 2017
Kona Ballroom (Hilton Waikoloa Village)
Spatially organized patterns of cells and tissues are the driving force behind organ
formation or organogenesis. Understanding the signals that regulate this spatial
organization is important to gain new and deeper insights into the complex networks
guiding organ formation that impact plant development. We use the maize leaf, as a
model to understand the molecular signals underlying organ formation. The maize leaf,
like all grass leaves, is composed of four segments organized in a specific proximaldistal
(P-D) pattern. The sheath is proximal, the blade is distal and auricle and ligule
separate the two. We are studying a semi-dominant maize mutant named Hairy Sheath
Frayed1 (Hsf1) that alters this P-D leaf pattern. Leaves from Hsf1 mutant plants have
outgrowths, called “prongs”, consisting of proximal sheath, auricle and ligule tissue
growing in the distal blade. Our analysis found this altered P-D leaf pattern was caused
by too much signaling of the plant hormone cytokinin (CK) during early leaf
development. Since CK is an important plant hormone, many of its functions are well
understood. However, a role in leaf patterning had not been described and so studying
the Hsf1 mutant opens new opportunities to reveal novel CK functions. Using lasercapture
microdissection (LCM) coupled with whole transcriptome sequencing, we found
about 800 differentially expressed (DE) genes in the initiating prong. Enriched among
these DE genes are numerous transcription factors and hormone pathway genes. This
set of genes resembles the expression module known to control organ formation in
monocots and eudicots. I will present results from our analysis of the function of some
of these DE genes in prong formation and other aspects of development.
formation or organogenesis. Understanding the signals that regulate this spatial
organization is important to gain new and deeper insights into the complex networks
guiding organ formation that impact plant development. We use the maize leaf, as a
model to understand the molecular signals underlying organ formation. The maize leaf,
like all grass leaves, is composed of four segments organized in a specific proximaldistal
(P-D) pattern. The sheath is proximal, the blade is distal and auricle and ligule
separate the two. We are studying a semi-dominant maize mutant named Hairy Sheath
Frayed1 (Hsf1) that alters this P-D leaf pattern. Leaves from Hsf1 mutant plants have
outgrowths, called “prongs”, consisting of proximal sheath, auricle and ligule tissue
growing in the distal blade. Our analysis found this altered P-D leaf pattern was caused
by too much signaling of the plant hormone cytokinin (CK) during early leaf
development. Since CK is an important plant hormone, many of its functions are well
understood. However, a role in leaf patterning had not been described and so studying
the Hsf1 mutant opens new opportunities to reveal novel CK functions. Using lasercapture
microdissection (LCM) coupled with whole transcriptome sequencing, we found
about 800 differentially expressed (DE) genes in the initiating prong. Enriched among
these DE genes are numerous transcription factors and hormone pathway genes. This
set of genes resembles the expression module known to control organ formation in
monocots and eudicots. I will present results from our analysis of the function of some
of these DE genes in prong formation and other aspects of development.