Integrated Genome-Scale Analysis Identifies Novel Genes and Networks Underlying Senescence in Maize

First author: Rajandeep S Sekhon; Affiliations: Clemson University (克莱姆森大学): South Carolina, USA

Corresponding author: Rajandeep S Sekhon

Premature senescence in annual crops reduces yield while delayed senescence, termed stay-green, imposes positive and negative impacts on yield and nutrition quality. Despite its importance, scant information is available on the genetic architecture of senescence in maize (Zea mays L.) and other cereals. We combined a systematic characterization of natural diversity for senescence in maize and co-expression networks derived from transcriptome analysis of normally senescing and stay-green lines. Sixty-four candidate genes were identified by genome-wide association study (GWAS), and fourteen of these are supported by additional evidence for involvement in senescence-related processes including proteolysis, sugar transport and signaling, and sink activity. Eight of the GWAS candidates, independently supported by a co-expression network underlying stay-green, include a trehalose-6-phosphate synthase, a NAC transcription factor, and two xylan biosynthetic enzymes. Source-sink communication and the activity of cell walls as a secondary sink emerge as key determinants of stay-green. Mutant analysis supports the role of a candidate encoding cysteine protease in stay-green in Arabidopsis (Arabidopsis thaliana), and analysis of natural alleles suggest a similar role in maize. This study provides a foundation for enhanced understanding and manipulation of senescence for increasing carbon yield, nutritional quality, and stress tolerance of maize and other cereals.

一年生作物早衰会降低产量，而延缓衰老，即保持绿色，会对产量和营养质量分别产生有利和不利的影响。尽管衰老很重要，但有关玉米和其它谷物中衰老的遗传机构还很少。本文中，作者对玉米中衰老的自然多样性进行了系统鉴定，并对正常衰老和绿色保持系的玉米转录组构建了共表达网络。作者通过全基因关联研究坚定了64个候选基因，其中14个候选基因已知参与蛋白质水解、糖转运和信号转导以及“库”活性等衰老相关的生物学进程。八个由GWAS鉴定的候选基因有绿色保持系共表达网络证据的支持，包括一个海藻糖-6-磷酸合酶、一个NAC转录因子以及两个木聚糖生物合成酶。源-库之间的信号交流以及作为次级库的细胞壁活性是绿色保持系的关键因素。突变体分析显示拟南芥中一个编码半胱氨酸蛋白酶的候选基因作用于绿色保持系，并且对于该基因在玉米中的自然等位基因变异分析显示其可能在玉米中也具有类似的功能。本文的研究为玉米及其它谷物有关调控衰老以增加碳产能、营养品质以及胁迫抗性等提供了理论基础。

通讯：Rajandeep S Sekhon (https://www.clemson.edu/science/departments/genetics-biochemistry/people/profiles/sekhon)

个人简介：1986年，旁遮普农业大学，学士；1994年，旁遮普农业大学，硕士；2007年，宾夕法尼亚州立大学，博士。

研究方向：利用高分辨率基因型数据、组织特异性转录组以及统计基因组学方法来鉴定数量性状的遗传成分。

doi: https://doi.org/10.1105/tpc.18.00930

Journal: Plant Cell

First Published: June 25, 2019