Abstract
An F6:8 recombinant inbred line (RIL) population derived from the cross between WAOAT2132 (Dw6) and Caracas along with the two parents were used to evaluate the genetic effects of Dw6 dwarfing gene on plant height and other agronomic traits in oat (Avena sativa L.) across three environments, and develop closely linked markers for marker-assisted selection (MAS) for Dw6. The two parents differed in all investigated agronomic traits except for the number of whorls. The RIL lines showed a bimodal distribution for plant height in all three tested environments, supporting the height of this population was controlled by a single gene. Dw6 significantly reduced plant height (37.66∼44.29%) and panicle length (13.99∼22.10%) but without compromising the coleoptile length which was often positively associated with the reduced stature caused by dwarfing genes. Dw6 has also strong negative effects on hundred kernel weight (14.00∼29.55%), and kernel length (4.21∼9.47%), whereas the effects of Dw6 on the kernel width were not uniform across three environments. By contrast, lines with Dw6 produced more productive tillers (10.11∼10.53%) than lines without Dw6. All these together suggested the potential yield penalty associated with Dw6 might be partially due to the decrease of kernel weight which is attributed largely to the reduction of kernel length. Eighty-one simple sequence repeat (SSR) primer pairs from chromosome 6D were tested, five of them were polymorphic in two parents and in two contrasting bulks, confirming the 6D location of Dw6. By using the five polymorphic markers, Dw6 was mapped to an interval of 1.0 cM flanked by markers SSR83 and SSR120. Caution should be applied in using this information since maker order conflicts were observed. The close linkages of these two markers to Dw6 were further validated in a range of oat lines. The newly developed markers will provide a solid basis for future efforts both in the identification of Dw6 in oat germplasm and in the determination of the nature of the gene through positional cloning.
Highlights
The cultivated oat (Avena sativa L.) is the sixth important cereal crop that is widely used as both animal feed and human food
The results indicated that all investigated traits except number of whorls are significantly different between two parents in all tested environments
The tall parent Caracas displayed significantly higher values in plant height, panicle length, spikelet number per panicle, hundred kernel weight, kernel width, kernel length, kernel perimeter as well as coleoptile length than the dwarf line WAOAT2132, and it showed more whorls per panicle compared to the latter (Table 1)
Summary
The cultivated oat (Avena sativa L.) is the sixth important cereal crop that is widely used as both animal feed and human food. Its cropped area has rapidly declined during the past decades (FAOSTATS, 2019), even the demand in oat for human consumption has increased in recent years due to its documented health benefits. This is partly attributed to the lower yield of oat compared with that of the other cereal crops (FAOSTATS, 2019; Yan et al, 2020). Dw6 is the most extensively used gene that has been introduced into commercial oat varieties (Milach and Federizzi, 2001)
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