A role for TRIANGULAR HULL1 in fine-tuning spikelet morphogenesis in rice

Area of Science:

• Plant biology
• Genetics
• Developmental biology

Background:

• The lemma and palea are key structures in rice spikelets, enclosing reproductive parts.
• Understanding genes controlling their development is vital for rice breeding and morphology studies.

Purpose of the Study:

• To investigate the function of the TRIANGULAR HULL1 (TH1) gene in rice spikelet development.
• To characterize the morphological changes associated with a defect in TH1.

Main Methods:

• Isolation and analysis of a rice mutant line (ng6569) with altered lemma and palea.
• Detailed morphological analysis of spikelet structures.
• In situ hybridization to examine TH1 gene expression patterns.
• Analysis of epistasis with other developmental mutants (g1, eg1).

Main Results:

• A mutant defective in TH1 exhibited narrower lemmas and paleas with reduced tubercle size, particularly at the apex, creating a beak-like appearance.
• TH1 expression is high in lemma and palea primordia, but low in sterile lemma and rudimentary glume primordia.
• The th1 mutation significantly impacted the extra lemma in eg1 mutants but not the transformed lemma in g1 mutants.

Conclusions:

• The TH1 gene plays a significant role in regulating the fine-tuning of lemma and palea morphogenesis in rice.
• TH1's function appears specific to certain developmental pathways, as evidenced by differential effects in g1 and eg1 mutants.