G. N. Collins (J. Agric. Res. 1:293-302) reported on root characteristics of Hopi maize which make it more adapted for suboptimal conditions. Our source was Navajo, received from the Germplasm Resources Laboratory, Beltsville, Maryland, USA. The marker was the same described in the preceding work.
Whole ears of segregating F2 selfed and siblings of the cross on different opportunities were planted 15-20 cm deep in a sand pool dug within a greenhouse floor. A few seedlings that emerged proved on digging to be "scapes" having not dropped to the desired depth. After a few unsuccessful attempts we put F2 families to germinate in paper dolls in a standard germinator at about 250 C. After six days the seedlings were classified in two classes: absence of seminal roots (Asr), and presence of seminal roots (asr). The first is characteristic of Navajo, the second of common maize including the marker. The results of three families segregating su are presented in Tables 1 and 2. They must be somewhat disturbed by bad adaptation of material. For the first two families there is a little deficiency in Asr for fitting a 3:1 segregation, 304 observed versus 322.5 expected, which is detected for the total, not for each family individually, although the deviation is consistent. For the third family there isn't significant deviation from a 9:7 ratio of Asr:asr. The results suggest that depending on environmental conditions or genetic background the absence of seminal roots segregates as a single dominant, or as a pair of complementary dominants. One of these genes has a linkage with Su. We propose for it the symbol Asr1 (absence of seminal roots 1).
Table 1. F2 phenotypes observed derived from the cross of adapted Mangelsdorf
Tester (asr) x Navajo (Asr). Asr stands for Navajo type of root with absence
of seminal roots, and asr for presence.
|Families||Su Asr||Su asr||su Asr||su asr||Segregation Asr:asr||p*|
|I||114||39||26||21||3:1||38.0 ± 3.1|
|II||129||50||35||16||3:1||47.5 ± 3.2|
|I + II||243||89||61||37||3:1||43.0 ± 2.2|
|III||70||9||61||21||9:7||30.0 ± 4.3|
*p calculated by the product method for the segregations indicated.
Table 2. Chi-square analysis of data in Table 1.
|Families||Su su||Asr asr||Exact interaction|
|I + II||1.119||4.245*||4.378*|
By the product method with the first two families, which gave a 3:1 ratio of Asr:asr, the value calculated was p = 43.0 ± 2.2. For the family that gave a 9:7 ratio the value was p = 30.0 ± 4.3.
Luiz Torres de Miranda
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