玉米果穗顶部籽秕粒瘪或未结籽粒，称之为秃顶，又叫\"秃尖”，是玉米生产中常见的现象，一般会导致玉米减产5%～10%，严重的甚至在30%以上。造成玉米秃尖有品种的遗传因素，但也受到种植密度和干旱胁迫等环境条件的影响。近日，为了解析玉米秃尖的分子生理机制，阿根廷布宜诺斯艾利斯大学的科研人员系统研究了杂交品种、播种密度和灌溉条件对玉米秃尖的影响。进一步地，研究人员在同步人工授粉后的2-6天内，收集果穗籽粒样本研究其基因表达模式并分析籽粒的糖份含量。研究发现具有高败育风险的籽粒中葡萄糖和果糖含量增加，而FASCICLIN-LIKE阿拉伯半乳聚糖蛋白基因(FLA)的表达与籽粒败育呈负相关，且ZmFLA7基因的表达只在果穗的顶部响应干旱胁迫。在干旱胁迫和β-Glucosyl Yariv的药剂处理条件下，籽粒中的阿拉伯半乳聚糖蛋白(AGP)含量降低，进而加剧了籽粒的败育。类似地，干旱胁迫也减少了拟南芥角果中AtFLA9基因的表达。拟南芥FLA9基因缺失突变体的功能分析表明，AtFLA9基因表达调控也与籽粒败育呈负相关。基于基因表达模式，药理学和遗传学证据，该研究结果表明环境胁迫诱导FLA基因的下调表达是玉米和拟南芥籽粒败育的主要原因。

Plant, Cell& Environment , 5 January 2018

Reduced expression of selectedFASCICLIN-LIKE ARABINOGALACTAN PROTEINgenes associates with the abortion of kernels in field crops ofZea mays(maize) and of Arabidopsis seeds

Authors

Juan Ignacio Cagnola,Gonzalo Javier Dumont de Chassart,Silvia Elizabeth Ibarra,...María Elena Otegui,José Manuel Estevez,Jorge José Casal

Universidad de Buenos Aires, Argentina

Abstract

Abortion of fertilised ovaries at the tip of the ear can generate significant yield losses in maize crops. To investigate the mechanisms involved in this process, two maize hybrids were grown in field crops at two sowing densities and under three irrigation regimes (well watered control, drought before pollination and drought during pollination), in all possible combinations. Samples of ear tips were taken 2-6 days after synchronous hand pollination and used for the analysis of gene expression and sugars. Glucose and fructose levels increased in kernels with high abortion risk. SeveralFASCICLIN-LIKE ARABINOGALACTAN PROTEIN(FLA) genes, showed negative correlation with abortion. The expression ofZmFLA7responded to drought only at the tip of the ear.The abundance of arabinogalactan protein (AGP) glycan epitopes decreased with drought and pharmacological treatments that reduce AGP activity enhanced the abortion of fertilised ovaries. Drought also reduced the expression ofAthFLA9in the siliques of Arabidopsis thaliana. Gain- and loss-of-function mutants of Arabidopsis showed a negative correlation betweenAthFLA9and seed abortion. Based on gene expression patterns, pharmacological and genetic evidence, we propose that stress-induced reductions in the expression of selectedFLAgenes enhance abortion of fertilised ovaries in maize and Arabidopsis.