INVESTIGATING RHT GA3-SENSITIVE GENES TO IMPROVE WHEAT DROUGHT TOLERANCE THROUGH QTL-SEQ APPROACH
Author(s)
Date Issued
2024
Type
conferenceObject
Abstract
The discovery of gibberellic acid (GA3)-insensitive dwarfing genes (e.g.
Rht-B1b and Rht-D1b) during the wheat Green Revolution and their
introduction in breeding programs has revolutionized the wheat ideotype.
The reduction in plant height and the pleiotropic effect produced by the
Rht genes on spike fertility significantly increased the grain yield.
Despite their enormous benefits, GA3-insensitive genes negatively impact
coleoptile length and early seedling vigor, which are favorable traits for
improving grain yield in water-limited environments. By contrast, GA3
sensitive dwarfing genes (e.g., Rht14, Rht16, Rht18, Rht24, Rht25), are
particularly intriguing since they reduce the plant height without
compromising the coleoptile length, allowing deeper sowing and promoting
excellent crop establishment, especially in arid and semi-arid conditions.
In the present study, a F2 population of durum wheat (Triticum durum
Desf.), obtained by crossing Castelporziano (Rht14) and Atoudur (Rht1), was
grown under controlled conditions to map QTL and identified candidate genes
for coleoptile and shoot length. Based on phenotypic distributions, two
contrasting bulks (CS:short and CL:long) were built and deeply sequenced
along parental lines through an exome capture platform. Using the QTL-seq
approach, seven regions on chromosomes 1B, 3A, 3B, 4B, 6A, 6B, and 7B were
identified as putatively associated with the coleoptile and shoot length.
Since, previous studies mapped GA3-sensitive genes to chromosome 6A (e.g.,
Rht14, Rht16, Rht18, Rht24, and Rht25), an in-depth characterization of
candidate genes was performed in the chromosomal region identified by QTL
6A. Out of 220 candidate genes identified on chromosome 6A, twenty-six
showed deleterious variations (high impact), including stop gained,
frameshift, and splice region variants. Among them, transcription factors
belonging to the MYB family, pathogenesis-related proteins (PR), cysteine
proteases (CysProt), and a protein phosphatase 2C (PP2C) showed a different
expression between the two parental varieties, suggesting their putative
role in regulating the GA pathway. Molecular validation analyses of
candidate genes through Real-Time PCR and the study of EMS mutants are
ongoing to confirm the above results.
Conference(s)
LXVII SIGA Annual Congress