Two QTL for kernel number per spike identified from durum wheat

Figures & data

Figure 1. Phenotypic distribution of kernel number per spike (KNPS) in four environments. Different environments (E1–E4): 2017-18 (E1) and 2018-19 (E2), 2019-20 (E3), 2020-21 (E4).

Table 1. Phenotypic value of kernel number per spike (KNPS) in the DW population at different environments.

Environment	Parents		Population
	DU	WE	Range	Mean	STD	H²
E1	84.6**	38.2	21.3-86.4	44.0	9.88
E2	81.2**	34.2	18.8-87.5	45.6	12.66
E3	89.4**	39.4	20.8-94.9	46.6	10.88
E4	65.2**	32.6	14.1-65.2	34.6	9.58
BLUP	84.6**	38.2	21.3-86.4	44.0	9.88	0.80

Environments, aka. four consecutive years, 2017–18 (E1) and 2018–19 (E2), 2019–20 (E3), 2020–21 (E4); STD: standard deviation; H²: broad-sense heritability; BLUP: phenotype values based on the best linear unbiased prediction. ^* Significance level at p < 0.05; ^** Significance level at p < 0.01.

Table 2. Correlation coefficients of KNPS in different environments.

Environment	E1	E2	E3	E4
E1	1
E2	0.55**	1
E3	0.98**	0.52**	1
E4	0.60**	0.45**	0.46**	1

Environments, aka. four consecutive years, 2017–18 (E1) and 2018–19 (E2), 2019–20 (E3), 2020–21 (E4); ^* Significance level at p < 0.05; ^** Significance level at p < 0.01.

Table 3. Quantiative trait loci (QTL) for KNPS detected at four environments in the DW population.

QTL	Environment/BLUP	Chromosome	Interval (cM)	Left marker	Right marker	LOD	PVE(%)	Add
Qknps-DW-1A	E1	1A	100.78-101.23	AX-108857471	AX-110594754	2.94	6.06	2.36
Qknps-DW-3A.1	E1	3A	92.05-96.39	AX-110932569	AX-110919471	4.45	10.05	3.03
	E2	3A	92.05-96.39	AX-110932569	AX-110919471	4.81	10.39	4.23
	BLUP	3A	92.05-96.39	AX-110932569	AX-110919471	6.76	12.52	2.75
Qknps-DW-3A.2	E1	3A	151.86-152.31	AX-109399066	AX-111043802	6.63	17.29	3.98
	E3	3A	150.46-151.39	AX-108755294	AX-108764773	39.83	29.52	15.83
	E4	3A	149.54-150.46	AX-109397884	AX-108755294	3.64	13.73	3.56
	BLUP	3A	151.86-152.31	AX-109399066	AX-111043802	7.48	13.54	2.87
Qknps-DW-6A.1	E1	6A	84.77-85.22	AX-109304510	AX-111047262	4.31	9.16	2.9
	E3	6A	85.67-86.13	AX-109926578	AX-108803666	4.5	1.51	3.59
Qknps-DW-6A.2	E2	6A	43.38-70.39	AX-89321181	AX-108839851	5.03	14.99	5.08
Qknps-DW-6A.3	E2	6A	110.70-112.06	AX-109040041	AX-111680204	3.03	5.93	3.22
Qknps-DW-6A.4	BLUP	6A	101.90-105.24	AX-110018729	AX-108770250	6.87	12.09	2.71
Qknps-DW-7A	E2	7A	80.49-86.64	AX-108740541	AX-110090057	4.78	10.46	4.27
Qknps-DW-1B	BLUP	1B	78.60-80.45	AX-110915806	AX-110067443	5.26	9.21	2.41
Qknps-DW-5B.1	E1	5B	43.70-44.16	AX-111181463	AX-108838982	5.38	12.19	3.33
	E3	5B	41.37-43.24	AX-110957611	AX-109897538	5.3	1.82	3.92
Qknps-DW-5B.2	BLUP	5B	30.30-31.23	AX-111024537	AX-108839293	5.36	9.2	2.36
Qknps-DW-5B.3	E2	5B	69.87-72.25	AX-110492762	AX-110927083	5.99	12.44	4.64
Qknps-DW-7B	BLUP	7B	154.69-157.12	AX-109955661	AX-108945293	3.18	5.27	1.79

Environment, aka. four consecutive years, 2017–18 (E1) and 2018–19 (E2), 2019–20 (E3), 2020–21 (E4); BLUP best linear unbiased prediction; LOD logarithm of odds; PVE phenotype variance explained; Add additive effect, positive values: alleles from DU09123, negative values: alleles from WE34021.

Figure 2. Genetic maps of the two major QTL and their effects. *Significance level at p < 0.05, **Significance level at p < 0.01.

Figure 3. Effects of the two major QTL, Qknps-DW-3A.1 and Qknps-DW-3A.2, on increasing KNPS in the mapping population. ‘+’ and ‘–’ represent lines carrying the positive allele of the corresponding QTL or not, respectively. ** Significance at the 0.01 probability level, * significance at the 0.05 probability level.

Table 4. Correlation coefficients between KNPS and other agronomic traits.

Trait	PH	FD	ET	SL	SNS	KL	KW	TKW	KWP
KNPS	−0.016	0.189*	−0.162	0.149	0.321**	−0.189*	0.123	0.024	0.396**

PH, plant height; SNS, spikelet number per spike; SL, spike length; ET, effective tiller; FD, flowering date; KNPS, kernel number per spike; KWS, kernel weight per spike; KL, kernel length; KW, kernel width; TKW, thousand kernel weight; ^* Significance level at p < 0.05; ^** Significance level at p < 0.01.

Data availability statement

All data generated or analysed during this study are included in this article and its supplementary information files; further inquiries can be directed to the corresponding author.