Due to its quantitative nature and environmental sensitivity, inflorescence PTD constitutes a complex mechanism affecting final grain number. This mechanism appears to be predictable and heritable, consistent with a developmental program.
Photosynthesis, immature spike greening, and energy metabolism appear to be significant contributors to proper spikelet growth and differentiation, and were restricted to basal and central spike parts. The researchers discovered, however, that the degenerating apical spike region undergoes sugar and amino acid depletion along with enhanced abscisic acid biosynthesis and signaling.
"Moreover, we functionally validated one of the apically expressed transcription factor genes, barley GRASSY TILLERS1 (HvGT1), an ortholog of maize GT1, as a growth repressor of apical spikelet development," emphasizes Nandhakumar Shanmugaraj, first author of the study.
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