MSD1 regulates pedicellate spikelet fertility in sorghum through the jasmonic acid pathway

Yinping Jiao,Ratan Chopra,Doreen Ware,Gloria Burow,Chad Hayes,John Burke,Young Koung Lee,Michael Regulski,Nicholas Gladman,Shawn A Christensen,Zhanguo Xin

doi:10.1038/s41467-018-03238-4

Abstract

Grain number per panicle (GNP) is a major determinant of grain yield in cereals. However, the mechanisms that regulate GNP remain unclear. To address this issue, we isolate a series of sorghum [Sorghum bicolor (L.) Moench] multiseeded (msd) mutants that can double GNP by increasing panicle size and altering floral development so that all spikelets are fertile and set grain. Through bulk segregant analysis by next-generation sequencing, we identify MSD1 as a TCP (Teosinte branched/Cycloidea/PCF) transcription factor. Whole-genome expression profiling reveals that jasmonic acid (JA) biosynthetic enzymes are transiently activated in pedicellate spikelets. Young msd1 panicles have 50% less JA than wild-type (WT) panicles, and application of exogenous JA can rescue the msd1 phenotype. Our results reveal a new mechanism for increasing GNP, with the potential to boost grain yield, and provide insight into the regulation of plant inflorescence architecture and development.

Highlights

Grain number per panicle (GNP) is a major determinant of grain yield in cereals
Using bulked segregant analysis of nextgeneration sequencing data from pooled msd[1] mutants selected from a F2 population, we identify the MSD1 gene, which encodes a plant-specific transcription factor with a TCP domain
Spikelets are classified into two types based on their mode of attachment to the inflorescence branch: sessile spikelet (SS) are directly attached, while pedicellate spikelets (PSs) are attached through a short petiole called the pedicel

Summary

Introduction

The mechanisms that regulate GNP remain unclear To address this issue, we isolate a series of sorghum [Sorghum bicolor (L.) Moench] multiseeded (msd) mutants that can double GNP by increasing panicle size and altering floral development so that all spikelets are fertile and set grain. Our results reveal a new mechanism for increasing GNP, with the potential to boost grain yield, and provide insight into the regulation of plant inflorescence architecture and development. Using bulked segregant analysis of nextgeneration sequencing data from pooled msd[1] mutants selected from a F2 population, we identify the MSD1 gene, which encodes a plant-specific transcription factor with a TCP domain. The TCP designation is coined based on the names of three founding genes: Teosinte branched 1 (Tb1) in maize, Cycloidea (Cyc) in snapdragon, and Proliferating Cell nuclear antigen binding Factor a b d

Methods

Findings

Conclusion