根系深度是作物根繫結構的重要組成性狀，在作物生長發育、產量決定和非生物脅迫耐性等方面發揮著重要作用，但影響該性狀的遺傳機制尚不清楚。最近，中國農科院景蕊蓮和毛新國團隊鑑定到一個影響小麥根系深度的基因，該基因啟動子區的轉座子插入降低了小麥根系深度。
研究人員利用小麥660K SNP基因組晶片對323份小麥種質進行了基因分型，並調查了這些材料的根深數據。通過GWAS分析，研究者在孕穗期檢測到TaVSR1-B基因啟動子中125 bp的MITE轉座元件（miniature inverted‐repeat transposable element）與根深性狀存在顯著的相關性。研究者進一步發現，這個MITE元件會通過DNA甲基化和H3K27三甲基化抑制TaVSR1-B基因的表達。轉基因小麥、水稻和tavsr1 TILLING突變體的表型鑑定揭示了TaVSR1-B對根系生長的作用。綜合來看，TaVSR1-B表達增加，根伸長區變短，分生區變長，根深增加。
因此，該研究為揭示小麥根系深度性狀的遺傳調控機制，為小麥根繫結構遺傳改良提供了新的目標。
Plant Biotechnology Journal, 08 February 2021
A transposon in the vacuolar sorting receptor gene TaVSR1-B promoter region is associated with wheat root depth at booting stage
Author
Jingyi Wang, Long Li, Chaonan Li, Xi Yang, Yinghong Xue, Zhi Zhu, Xinguo Mao, Ruilian Jing
National Key Facility for Crop Gene Resources and Genetic Improvement/Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, China
Abstract
Root depth, as an important component of root architecture, plays a significant role in growth, grain yield determination and abiotic stress tolerance in crop plants, but its genetic basis remains poorly elucidated. In this study, a panel composed of 323 wheat (Triticum aestivum L.) accessions was assessed for variation in root depth and genotyped with the Wheat 660K SNP Array. GWAS (genome‐wide association study) detected significant association between a 125 bp miniature inverted‐repeat transposable element (MITE) in the promoter of the TaVSR1‐B gene with root depth at the booting stage. We showed that the MITE repressed TaVSR1‐B expression by DNA methylation and H3K27 tri‐methylation. The roles of TaVSR1‐B in root growth were verified by altered expression of the gene in transgenic wheat, rice and a tavsr1 TILLING mutant. Increased TaVSR1‐B expression made the root elongation zone shorter and the differentiation zone longer, leading to deeper root. This work provides novel insight into the genetic basis of variation in root depth and a promising target for genetic improvement of root architecture in wheat.
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