<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Cotton is widely grown in the southern US and <italic>Meloidogyne incognita</italic> is its most significant pathogen. The germplasm line M-120 RNR is highly resistant to <italic>M. incognita</italic> due to two resistance QTLs (quantitative trait loci), <italic>qMi-C11</italic> and <italic>qMi-C14</italic>. Both QTLs reduce total egg production, but the QTLs affect <italic>M. incognita</italic> development at different life stages. The QTLs do not appear to affect initial penetration of <italic>M. incognita</italic> but genotypes containing <italic>qMi-C11</italic> had fewer nematodes in the roots 8 days after inoculation than near isolines without <italic>qMi-C11</italic>, which may indicate <italic>M. incognita</italic> egression from roots. Three greenhouse trials were conducted using cotton isolines to determine whether <italic>qMi-C11</italic> and <italic>qMi-C14</italic> affect egression of <italic>M. incognita</italic> juveniles from roots. On each of the five sampling dates (4, 6, 8, 10, and 12 DAI), nematodes that egressed from roots were counted and roots were stained to count nematodes that remained in the roots. The effect of resistance QTLs on <italic>M. incognita</italic> egression from the roots differed among the trials. Nematode egression was consistently numerically greater, but inconsistently statistically different, from plants with both QTLs than from plants with neither QTL. Plants with only one QTL generally did not differ from plants with both QTLs, and the effects of <italic>qMi-C11</italic> and <italic>qMi-C14</italic> did not differ in any consistent way. In a separate experiment, plants with neither QTL had more eggs per egg mass than did plants with both QTLs, whereas plants with only one QTL had an intermediate number. Root gall size was measured in two trials and no consistent differences in gall size were observed. We conclude that (1) <italic>qMi-C11</italic> and <italic>qMi-C14</italic> do not stimulate nematode egression from cotton roots, (2) both <italic>qMi-C11</italic> and <italic>qMi-C14</italic> reduce <italic>M. incognita</italic> eggs/egg mass, and (3) neither <italic>qMi-C11</italic> nor <italic>qMi-C14</italic> affect gall size.</p>
</abstract>

Cotton is widely grown in the southern US and Meloidogyne incognita is its most significant pathogen. The germplasm line M-120 RNR is highly resistant to M. incognita due to two resistance QTLs (quantitative trait loci), qMi-C11 and qMi-C14. Both QTLs reduce total egg production, but the QTLs affect M. incognita development at different life stages. The QTLs do not appear to affect initial penetration of M. incognita but genotypes containing qMi-C11 had fewer nematodes in the roots 8 days after inoculation than near isolines without qMi-C11, which may indicate M. incognita egression from roots. Three greenhouse trials were conducted using cotton isolines to determine whether qMi-C11 and qMi-C14 affect egression of M. incognita juveniles from roots. On each of the five sampling dates (4, 6, 8, 10, and 12 DAI), nematodes that egressed from roots were counted and roots were stained to count nematodes that remained in the roots. The effect of resistance QTLs on M. incognita egression from the roots differed among the trials. Nematode egression was consistently numerically greater, but inconsistently statistically different, from plants with both QTLs than from plants with neither QTL. Plants with only one QTL generally did not differ from plants with both QTLs, and the effects of qMi-C11 and qMi-C14 did not differ in any consistent way. In a separate experiment, plants with neither QTL had more eggs per egg mass than did plants with both QTLs, whereas plants with only one QTL had an intermediate number. Root gall size was measured in two trials and no consistent differences in gall size were observed. We conclude that (1) qMi-C11 and qMi-C14 do not stimulate nematode egression from cotton roots, (2) both qMi-C11 and qMi-C14 reduce M. incognita eggs/egg mass, and (3) neither qMi-C11 nor qMi-C14 affect gall size.

The effect of two QTLs for resistance to <italic>Meloidogyne incognita</italic> in cotton on nematode egression from roots

Journal of Nematology

This work is licensed under the Creative Commons Attribution 4.0 International License.

The effect of two QTLs for resistance to  in cotton on nematode egression from roots

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Cotton is widely grown in the southern US and Meloidogyne incognita is its most significant pathogen. The germplasm line M-120 RNR is highly resistant to M....

	Gall size (cm²) ¹			Hatch (%)	Eggs/egg mass
Genotype	0 days	7 days	14 days	40 DAI²	30 DAI	40 DAI
Coker	0.0085 A a	0.0091 A a	0.0081 A a	17.20 A	182 A	495 A
CH14	0.0080 A a	0.0090 A a	0.0080 A a	14.96 A	123 AB	325 BC
CH11	0.0091 A ab	0.0100 A a	0.0068 A b	19.24 A	146 B	386 B
M-120	0.0056 B b	0.0074 A a	0.0075 A a	18.60 A	135 AB	300 C

The effect of two QTLs for resistance to Meloidogyne incognita in cotton on nematode egression from roots

Publié en ligne: 13 janv. 2021

Pages: 1 - 8

DOI: https://doi.org/10.21307/jofnem-2020-122

Mots clés
Cotton, Nematode resistance, Resistance expression

© 2021 Mychele B. da Silva et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1:

Figure 2:

Gall size, percentage egg hatch, and eggs/egg mass for cotton isolines that differ in M. incognita-resistance genes at 0, 7, and 14 days.

The effect of two QTLs for resistance to Meloidogyne incognita in cotton on nematode egression from roots

Publié en ligne: 13 janv. 2021

Pages: 1 - 8

DOI: https://doi.org/10.21307/jofnem-2020-122

Mots clésCotton, Nematode resistance, Resistance expression

© 2021 Mychele B. da Silva et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1:

Figure 2:

Gall size, percentage egg hatch, and eggs/egg mass for cotton isolines that differ in M. incognita-resistance genes at 0, 7, and 14 days.

Mots clés
Cotton, Nematode resistance, Resistance expression