Effects of plant height on type I and type II resistance to fusarium head blight in wheat

Abstract

By carefully separating type I and type II resistances, the possible effects of plant height on fusarium head blight (FHB) resistance in wheat were assessed using near-isogenic lines (NILs) for several different reduced-height (Rht) genes. Tall isolines all gave better type I resistance than their respective dwarf counterparts when assessed at their natural heights. These differences largely disappeared when the dwarf isolines were physically raised so that their spikes were positioned at the same height as those of their respective tall counterparts. The effects of plant height on type II resistance was less clear. For those NIL pairs which showed significant differences, it was the dwarf isolines which gave better resistance. As the Rht genes involved in these NILs locate at different genomic regions, the differences in FHB between the dwarf and tall isolines are unlikely to be the result of linkages between each of the different Rht loci with a beneficial or a deleterious gene affecting type I or type II resistance. Rather, the different FHB resistances are probably caused by direct or indirect effects of height difference per se, and microclimate may have contributed to the better type I resistance of the tall plants. Thus, caution should be exercised when attempting to exploit any of the FHB resistant loci co-located with Rht genes.

GWAS for Fusarium Head Blight Related Traits in Winter Wheat (Triticum Aestivum L.) in an Artificially Warmed Treatment

“…Short plants have higher disease levels due to the microclimate around the spike where high moisture and humidity and close proximity to the inoculum are favorable for increased disease [50]. Yan et al [51] demonstrated this result by studying near-isogenic lines for Rht genes. His group observed that tall plants were more resistant to infection (type I) than the semi-dwarf phenotypes, however when both phenotypes were at the same height that difference disappeared [51].…”

“…Yan et al [51] demonstrated this result by studying near-isogenic lines for Rht genes. His group observed that tall plants were more resistant to infection (type I) than the semi-dwarf phenotypes, however when both phenotypes were at the same height that difference disappeared [51].…”

QTL mapping of Fusarium head blight resistance in three related durum wheat populations

“…DELLA proteins have been shown to be associated with abiotic and biotic stress tolerance (Achard and Genschik 2009) and, in the case of FHB, a DELLA protein mutation may have physiological effects linked to changes in cell death response (Saville et al 2012). Alternatively to these genetic effects, differences in microclimatic conditions around the heads of tall and dwarf genotypes have been considered to play a significant role particularly under field conditions, with short plants being exposed to higher infection pressure than tall plants (Yan et al 2011). The Rht - B1b allele is also known to have pleiotropic effects on different morphological and structural traits including reduced peduncle length and increased cell density, which may also affect response to FHB.…”

“…Plant height is one of the foremost morphological traits affecting FHB response and the widely deployed Norin 10 semi-dwarfing Rht alleles, namely Rht - B1b and Rht - D1b , have been found associated with increased FHB severity under field conditions in common wheat (Hilton et al 1999; Miedaner and Voss 2008; Voss et al 2008) and in durum wheat (Buerstmayr et al 2012). Their effect on FHB development may be imputed to plant height per se and differences in canopy structure (Yan et al 2011) as well as to pleiotropic physiological effects of the Rht genes and/or the presence of tightly linked genes (Srinivasachary et al 2009; Saville et al 2012). …”

Effects of Drought-Stress on Fusarium Crown Rot Development in Barley

“…Clearly, crown and spikes have different structures and they are also exposed to different microenvironments (temperature and humidity) due to their different distances from the soil surface. Previous studies showed that these factors affect the development of both FHB [25] and FCR [26]. …”