Abstract Detail

Applications of CRISPR technology across the plant tree of life

ODIPIO, JOHN [1], Titus, Alicai [1], Dmitri A, Nusinow [2], Rebecca, Bart [3], Nigel J, Taylor [3].

Suppression of endogenous anti-flowering TFL1-like gene triggers early, reproducible and fertile flowering in cassava.

Lack of synchronised flowering hinders conventional breeding of cassava, a major tropical staple crop. The molecular basis of this phenomenon in cassava remains unclear. To address this challenge, we tested the efficacy of CRISPR/Cas9-mediated genome editing and a Virus Induced Gene Silencing (VIGS) approaches to trigger early flowering by downregulating floral repressor gene TERMINAL FLOWER 1(TFL1). To demonstrate that CRISPR/Cas9 can precisely and efficiently modify endogenous genes in cassava, we successfully edited Phytoene desaturase with an average efficiency of 95% in two cultivars, 60444 and TME 204. We then generated CRISPR/Cas9-induced mutations in multiple TFL1 genes in two cultivars (60444 and TME 204). The edited plants flowered in-vitro, and sustained early and multiple flowering cycles when grown in a greenhouse. In addition, VIGS-mediated downregulation of two independent TFL1-like genes also produced early flowering in two cassava cultivars TME 204s and TME 7s, thus confirming that TFL1 is a floral repressor. Vegetative propagation of both edited and VIGS infected plants yielded re-growths that retained repetitive flowering traits, unlike control plants. RT-qPCR analysis revealed simultaneous suppression of at least two TFL1-like genes, upregulation of more than two inducer-like FT/MFT, and at least three floral meristem identity genes in the apical shoot of test plants compared to controls. Controlled pollination of mature flowers derived from silver thiosulphate treatment of edited and VIGS infected plants produced mature fruits and seeds in the greenhouse, confirming fertility of the generated flowers. The data proves that CRISPR/Cas9 is a valuable tool for creating novel allelic variants, attaining functional discovery, and demonstrating that TFL1 is a floral repressor in cassava. The knowledge generated can efficiently be used for functional discovery and trait development in cassava and other species.

Related Links:
Accelerating flowering in cassava by manipulation of endogenous flowering locus T-like genes

1 - National Agricultural Crops Resources Research Institute-Namulonge, Root Crops, P.O Box 7084, Kampal, 256, Uganda
2 - Donald Danforth Plant Science Center, IICI, 975 , North Warson Road, St. Louis, MO, 63132, USA
3 - Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO, 63132, USA

Keywords:
CRISPR
Flowering
Cassava.

Presentation Type: Symposium Presentation
Session: SY6, Applications of CRISPR technology across the plant tree of life
Location: /
Date: Friday, July 23rd, 2021
Time: 10:15 AM(EDT)
Number: SY6002
Abstract ID:170
Candidate for Awards:Edgar T. Wherry award,Economic Botany Section best student paper,Physiological Section Best Paper Presentation