Biological Basis Study for Grain Shattering in Proso Millet and Identification of Genes Regulating Grain Shattering

doi:10.13560/j.cnki.biotech.bull.1985.2025-0150

Abstract

Abstract:

Objective Proso millet (Panicum miliaceum L.) plays an important role in dryland agriculture, saline alkali land development and utilization, and disaster relief and replanting in China. Grain shattering is a crucial factor affecting yield of proso millet. Investigating the mechanism of grain shattering in proso millet is very important for breeding new varieties with low grain shattering and improving crop production. Method Having the proso millet gerplasm 'Yemizi' with strong grain shattering and 'Hongnianmi' with low grain shattering by paraffin sections, we studied the structural differences of abscission layer cells among millet varieties with different grain shattering characteristics. In addition, we identified proso millet grain shattering genes using reverse genetics strategies. Result Our results showed that 'Yemizi' had a distinct abscission layer, while no complete abscission layer was observed in 'Hongnianmi'. In addition, the homologous genes of rice (Oryza sativa) grain shattering genes were identified in proso millet and their expression in 'Yemeizi' at 1, 20, and 35 d after flowering was analyzed. The results showed that most genes had the highest gene expression at 1 d after flowering. Finally, PmSh1-1, was further analyzed, and the results showed that the expression of the PmSh1-1 in 'Yemizi' and 'Hongnianmi' was not significantly different, but the cDNA sequence of the PmSh1-1 in 'Hongnianmi' was shorter compared with it in 'Yemizi'. Conclusion We found that incomplete abscission layer may lead to a reduction of grain shattering and PmSh1-1, and a homologous gene of rice OsSh1 could be a potential grain shattering gene in proso millet.

Key words: proso millet, grain shattering, abscission zone, paraffin sectioning, transcriptome sequencing, parallel domestication, Sh1, homologous genes

WANG Yue-chen, HAN Xin-qi, WEI Wen-min, CUI Zhao-lan, LUO Yang-mei, CHEN Peng-ru, WANG Hai-gang, LIU long-long, ZHANG Li, WANG Lun. Biological Basis Study for Grain Shattering in Proso Millet and Identification of Genes Regulating Grain Shattering[J]. Biotechnology Bulletin, 2025, 41(7): 164-171.

Figures/Tables 8

Table 1 Grain shattering genes in rice (Oryza sativa) and proso millet (Panicum miliaceum)

基因名称 Gene name	基因编号 Gene ID	编码蛋白 Protein name	黍稷同源基因1 Homologous gene 1	黍稷同源基因2 Homologous gene 2
qSH1	Os01g0848400	BEL1型同源异型蛋白	PM13G13360	PM07G28580
OsSh1	Os03g0650000	YABBY转录因子	PM01G33800	PM02G06310
sh4/SHA1	Os04g0670900	MYB转录因子	PM16G23590	PM15G25020
SHAT1	Os04g0649100	AP2转录因子	PM16G22000	PM15G23430
SH5	Os05g0455200	BELI型同源异型蛋白	PM05G36060	PM06G19790
OsCPL1	Os07g0207700	CTD磷酸化酶	PM15G01070	PM16G00940

Fig. 1 Histological observation of the abscission zone of 'Yemizi' and 'Hongnianmi'A: Mature spikelet of 'Yemizi'. B: Paraffin section of 'Yemizi' spikelet. C: Mature spikelet of 'Hongnianmi'. D: Paraffin section of 'Hongnianmi' spikelet

Table 2 Chromosome location of homologous grain shattering genes in proso millet

基因名称 Gene name	基因编号 Gene ID	‘0390’染色体位置 Chromosome location in ‘0390’	‘晋黍7号’染色体位置 Chromosome location in ‘Jinsu7’	‘隆糜4号’染色体位置 Chromosome location in ‘Longmei4’
PmSH5-1	PM05G36060	05G	3B	Chr03
PmSH5-2	PM06G19790	06G	3A	Chr10
PmqSH1-1	PM07G28580	07G	5B	Chr05
PmqSH1-2	PM13G13360	13G	5A	Chr08
PmSh1-1	PM01G33800	01G	9B	Chr01
PmSh1-2	PM02G06310	02G	9A	Chr04
PmCPL1-1	PM15G01070	15G	7B	Chr14
PmCPL1-2	PM16G00940	16G	7A	Chr15
PmSHAT1-1	PM15G23430	15G	7B	Chr14
PmSHAT1-2	PM16G22000	16G	7A	Chr15
Pmsh4/SHA1-1	PM15G25020	15G	7B	Chr14
Pmsh4/SHA1-2	PM16G23590	16G	7A	Chr15

Fig. 2 Chromosome distribution of grain shattering genes in proso milletA: 0390; B: Longmi 4; C: Jinsu 7

Fig. 3 Phylogenetic relationships of homologous shattering proteins of grain shattering

Fig. 4 Heat-map showing the tissue-specific expressions of homologous grain shattering genes in proso milletOrange-red indicates up-regulated expression, blue indicates down-regulated, and expression difference greater than 2 times is considered significant. GFS1 refers to 1 d after flowering, GFS20 refers to 20 d after flowering, GFS35 refers to 35 d after flowering

Fig. 5 Detection of PmSh1-1 cDNA by agarose gel electrophoresisM: Marker; 1 and 3: Yemizi; 2 and 4: Hongnianmi

Fig. 6 cDNA sequence alignment of PmSh1-1 in 'Yemizi' and 'Hongnianmi'The indel sequence and SNPs are marked with red squares

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