Effect of different carbohydrates in the corn anther culture medium
--Beaumont, VH; Miao, SH; Widholm, JM
Higher yield was reported when sucrose was replaced with maltose for barley, rye and wheat anther culture. The purpose of our study was to compare different sugars in corn anther culture. HF1, a diplohaploid obtained through anther culture of the cross H99 x FR16, was chosen for this experiment because of its high ability to produce embryos in anther culture (around 50 embryos/100 anthers). Plants were grown in the field (Champaign, Illinois) during the summer of 1993, or in our growth chamber (16 hours of light: intensity 700 mEm-2s-1 one meter above the floor, 29 C, 60% RH; 8 hours of darkness, 19 C, 80% RH; fertilization every three days). The anther culture protocol has been described elsewhere (Beaumont et al., MNL66: 114-115, 1992). Each tassel was plated both in 10 ml of the control medium and 10 ml of one of the modified media (30 anthers/Petri dish). Because of this design, no bias existed from the plant to plant variations usually observed in corn tissue culture. About 17 tassels were plated for each treatment. The number of responding plants (%RESP.P:) and the number of embryos produced from 100 anthers plated (E/100A) was recorded.
Table 1. Composition of the different media tested.
|Control||YP medium + 60 g/l sucrose (0.18 M)|
|TRE||YP medium + 66g/l trehalose (0.18 M)|
|TOL||YP medium + 32 g/l mannitol (0.18 M)|
|TRI||YP medium + 88 g/l maltotriose (0.18 M)|
|MAL||YP medium + 63 g/l maltose (0.18 M)|
|ST||YP medium + 30 g/l soluble starch + 32 g/l mannitol (0.18 M)|
|TOL15||As TOL but 10 ml of control medium was added after 15 days|
The results obtained with the different carbohydrates are presented in Figure 1. No plant responded to produce embryos in the medium containing mannitol, even when complemented with sucrose after two weeks. Since mannitol cannot be metabolised by the cells, the result shows that a source of carbohydrate is needed for the pollen grain to induce division and that the anther tissue cannot supply this carbohydrate.
Figure 1. Effect of different carbohydrates on the yield in anther culture. The results are expressed in percentage of the control and are the average of 12 (MAL) to 25 (ST) replications. See Table 1 for the different treatments
Starch (supplemented with 55 g/l mannitol to maintain 0.18 M osmotic pressure in the medium), trehalose and maltotriose when used as unique sources of carbon in the medium, failed to induce the production of embryos from pollen grains. The yield obtained with maltose was close but did not reach that observed with sucrose (control). The results found here suggest that the corn microspore does not react in the same way as microspores of other cereal crops.
The excellent technical assistance of James Hageman, Veronique Villalba;
and Xiuping Sun is greatly acknowledged. This note is dedicated to the
memory of S.H. Miao, a pioneer in corn anther culture.
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